protobuf---三种序列化方式比较

前言

学习protobuf需要先知道为什么会有它的存在。前后端之间的协议传输从而产生了流量，在当下力图节省流量成为了趋势。如何使得协议体减小便成为了研发过程中应该去考虑的一个问题。想到以前学习时常说的一句话就是"万物皆对象"，在协议这里也可以得到验证。协议的封装其实可以看做是一个对象，前端负责将传递的消息封装在对象中，后端接收后再按照对象的格式去解析。那么，这种“封装为对象并再解析为消息的过程”就被成为序列化与反序列化。
在之前java学习过程中学习过几种序列化方式，比如说：ObjectOutputStream的常规序列化、jackson的ObjectMapper序列化、以及今天要讲解的protobuf序列化方式。在这么多的序列化方式中选择一种合适的方式就成为了研究的目标。下面我们一起探究下如何进行选择。

测试环境

1. 测试三种序列化方式的代码将会构造在maven工程下
2. 工程如下：
   
3. Student.java

   package com.howie;
   
   import java.io.Serializable;
   
   public class Student implements Serializable {
   
       private String username;
       private String password;
       private String email;
       private int age;
       private long timespane;
       private double dValue;
   
       public String getUsername() {
           return username;
       }
   
       public void setUsername(String username) {
           this.username = username;
       }
   
       public String getPassword() {
           return password;
       }
   
       public void setPassword(String password) {
           this.password = password;
       }
   
       public String getEmail() {
           return email;
       }
   
       public void setEmail(String email) {
           this.email = email;
       }
   
       public int getAge() {
           return age;
       }
   
       public void setAge(int age) {
           this.age = age;
       }
   
       public long getTimespane() {
           return timespane;
       }
   
       public void setTimespane(long timespane) {
           this.timespane = timespane;
       }
   
       public double getdValue() {
           return dValue;
       }
   
       public void setdValue(double dValue) {
           this.dValue = dValue;
       }
   }
   
   

常规序列化

1. 创建TestOfNomral.java，工程如下：
   
2. TestOfNomral.java

   package com.howie;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.io.ObjectOutputStream;
   import java.util.Arrays;
   
   public class TestOfNomral {
   
       public static void normalSerialize(Student student) {
           ByteArrayOutputStream baos = new ByteArrayOutputStream();
           ObjectOutputStream oos = null;
           try {
               oos = new ObjectOutputStream(baos);
               oos.writeObject(student);
               oos.flush();
               byte[] bytes = baos.toByteArray();
               System.out.println("字节数组:" + Arrays.toString(bytes));
               System.out.println("字节数组长度:" + bytes.length);
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   
       public static void main(String[] args) {
           // 创建student对象并赋值
           Student student = new Student();
   
           student.setUsername("admin");
           student.setPassword("123456");
           student.setEmail("987654321@163.com");
           student.setAge(Integer.MAX_VALUE);
           student.setdValue(Double.MAX_VALUE);
           student.setTimespane(System.currentTimeMillis());
   
           normalSerialize(student);
       }
   }
   
   

3. 执行结果：

   字节数组:[-84, -19, 0, 5, 115, 114, 0, 17, 99, 111, 109, 46, 104, 111, 119, 105, 101, 46, 83, 116, 117, 100, 101, 110, 116, -105, -32, -118, 3, 35, 32, -70, 68, 2, 0, 6, 73, 0, 3, 97, 103, 101, 68, 0, 6, 100, 86, 97, 108, 117, 101, 74, 0, 9, 116, 105, 109, 101, 115, 112, 97, 110, 101, 76, 0, 5, 101, 109, 97, 105, 108, 116, 0, 18, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 83, 116, 114, 105, 110, 103, 59, 76, 0, 8, 112, 97, 115, 115, 119, 111, 114, 100, 113, 0, 126, 0, 1, 76, 0, 8, 117, 115, 101, 114, 110, 97, 109, 101, 113, 0, 126, 0, 1, 120, 112, 127, -1, -1, -1, 127, -17, -1, -1, -1, -1, -1, -1, 0, 0, 1, 120, -122, -117, -59, -35, 116, 0, 17, 57, 56, 55, 54, 53, 52, 51, 50, 49, 64, 49, 54, 51, 46, 99, 111, 109, 116, 0, 6, 49, 50, 51, 52, 53, 54, 116, 0, 5, 97, 100, 109, 105, 110]
   字节数组长度:183
   
   

ObjectMapper序列化

1. pom.xml中加入jackson依赖

   <?xml version="1.0" encoding="UTF-8"?>
   <project xmlns="http://maven.apache.org/POM/4.0.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
       <modelVersion>4.0.0</modelVersion>
   
       <groupId>com.howie</groupId>
       <artifactId>protocol_test</artifactId>
       <version>1.0</version>
   
       <properties>
           <maven.compiler.source>8</maven.compiler.source>
           <maven.compiler.target>8</maven.compiler.target>
       </properties>
   
       <dependencies>
           <dependency>
               <groupId>com.fasterxml.jackson.core</groupId>
               <artifactId>jackson-core</artifactId>
               <version>2.9.6</version>
           </dependency>
           <dependency>
               <groupId>com.fasterxml.jackson.core</groupId>
               <artifactId>jackson-annotations</artifactId>
               <version>2.9.6</version>
           </dependency>
           <dependency>
               <groupId>com.fasterxml.jackson.core</groupId>
               <artifactId>jackson-databind</artifactId>
               <version>2.9.6</version>
           </dependency>
       </dependencies>
   </project>
   

2. 创建TestOfOM.java，工程如下：
   
3. TestOfOM.java

   package com.howie;
   
   import com.fasterxml.jackson.databind.ObjectMapper;
   import java.util.Arrays;
   
   public class TestOfOM {
   
       public static void jacksonSerialize(Student student) {
           try {
               ObjectMapper mapper = new ObjectMapper();
               String stuStr = mapper.writeValueAsString(student);
               byte[] bytes = stuStr.getBytes("UTF-8");
               System.out.println("字节数组:" + Arrays.toString(bytes));
               System.out.println("字节数组长度:" + bytes.length);
           } catch (Exception e) {
               e.printStackTrace();
           }
       }
   
       public static void main(String[] args) {
           // 创建student对象并赋值
           Student student = new Student();
   
           student.setUsername("admin");
           student.setPassword("123456");
           student.setEmail("987654321@163.com");
           student.setAge(Integer.MAX_VALUE);
           student.setdValue(Double.MAX_VALUE);
           student.setTimespane(System.currentTimeMillis());
   
           jacksonSerialize(student);
       }
   }
   
   

4. 执行结果：

   字节数组:[123, 34, 117, 115, 101, 114, 110, 97, 109, 101, 34, 58, 34, 97, 100, 109, 105, 110, 34, 44, 34, 112, 97, 115, 115, 119, 111, 114, 100, 34, 58, 34, 49, 50, 51, 52, 53, 54, 34, 44, 34, 101, 109, 97, 105, 108, 34, 58, 34, 57, 56, 55, 54, 53, 52, 51, 50, 49, 64, 49, 54, 51, 46, 99, 111, 109, 34, 44, 34, 97, 103, 101, 34, 58, 50, 49, 52, 55, 52, 56, 51, 54, 52, 55, 44, 34, 116, 105, 109, 101, 115, 112, 97, 110, 101, 34, 58, 49, 54, 49, 55, 49, 54, 53, 54, 54, 53, 53, 48, 52, 44, 34, 100, 86, 97, 108, 117, 101, 34, 58, 49, 46, 55, 57, 55, 54, 57, 51, 49, 51, 52, 56, 54, 50, 51, 49, 53, 55, 69, 51, 48, 56, 125]
   字节数组长度:143
   

ProtocolBuffer序列化

1. pom.xml中加入protobuf依赖

      <dependency>
           <groupId>com.google.protobuf</groupId>
           <artifactId>protobuf-java</artifactId>
           <version>3.9.0</version>
      </dependency>
   

2. protobuf的编译器的环境搭建
   ①下载protobuf的编译器(这里以MacOS为例)
   下载地址
   ②Mac上配置protoc的环境变量：
   
   ③protobuf各语言中的数据类型
   详情见地址
   ④protobuf在java中的案例
   详情见地址
   ⑤协议编译的命令伪代码

   protoc --proto_path=src --java_out=build/gen src/foo.proto
   

3. 编译器目录结构
   

4. 协议编译.sh脚本内容：

   #!/bin/bash
   
   proto_path=/Users/weihuanwen/software/JetBrains/protobuf/protoc-3.15.6-osx-x86_64/protomsg
   java_out=$proto_path/javaout
   src=$proto_path/Student.proto3
   
   protoc --proto_path=$proto_path --java_out=$java_out $src
   

5. 执行脚本后生成java的协议类
   

6. 将StudentProto3.java拷贝至Idea工程下：
   

7. StudentProto3.java文件内容：

   // Generated by the protocol buffer compiler.  DO NOT EDIT!
   // source: Student.proto3
   
   package com.howie;
   
   public final class StudentProto3 {
     private StudentProto3() {}
     public static void registerAllExtensions(
         com.google.protobuf.ExtensionRegistryLite registry) {
     }
   
     public static void registerAllExtensions(
         com.google.protobuf.ExtensionRegistry registry) {
       registerAllExtensions(
           (com.google.protobuf.ExtensionRegistryLite) registry);
     }
     public interface StudentOrBuilder extends
         // @@protoc_insertion_point(interface_extends:Student)
         com.google.protobuf.MessageOrBuilder {
   
       /**
        * <code>string username = 1;</code>
        * @return The username.
        */
       String getUsername();
       /**
        * <code>string username = 1;</code>
        * @return The bytes for username.
        */
       com.google.protobuf.ByteString
           getUsernameBytes();
   
       /**
        * <code>string password = 2;</code>
        * @return The password.
        */
       String getPassword();
       /**
        * <code>string password = 2;</code>
        * @return The bytes for password.
        */
       com.google.protobuf.ByteString
           getPasswordBytes();
   
       /**
        * <code>string email = 3;</code>
        * @return The email.
        */
       String getEmail();
       /**
        * <code>string email = 3;</code>
        * @return The bytes for email.
        */
       com.google.protobuf.ByteString
           getEmailBytes();
   
       /**
        * <code>int32 age = 4;</code>
        * @return The age.
        */
       int getAge();
   
       /**
        * <code>int64 timespane = 5;</code>
        * @return The timespane.
        */
       long getTimespane();
   
       /**
        * <code>double dValue = 6;</code>
        * @return The dValue.
        */
       double getDValue();
     }
     /**
      * Protobuf type {@code Student}
      */
     public static final class Student extends
         com.google.protobuf.GeneratedMessageV3 implements
         // @@protoc_insertion_point(message_implements:Student)
         StudentOrBuilder {
     private static final long serialVersionUID = 0L;
       // Use Student.newBuilder() to construct.
       private Student(com.google.protobuf.GeneratedMessageV3.Builder<?> builder) {
         super(builder);
       }
       private Student() {
         username_ = "";
         password_ = "";
         email_ = "";
       }
   
       @Override
       @SuppressWarnings({"unused"})
       protected Object newInstance(
           UnusedPrivateParameter unused) {
         return new Student();
       }
   
       @Override
       public final com.google.protobuf.UnknownFieldSet
       getUnknownFields() {
         return this.unknownFields;
       }
       private Student(
           com.google.protobuf.CodedInputStream input,
           com.google.protobuf.ExtensionRegistryLite extensionRegistry)
           throws com.google.protobuf.InvalidProtocolBufferException {
         this();
         if (extensionRegistry == null) {
           throw new NullPointerException();
         }
         com.google.protobuf.UnknownFieldSet.Builder unknownFields =
             com.google.protobuf.UnknownFieldSet.newBuilder();
         try {
           boolean done = false;
           while (!done) {
             int tag = input.readTag();
             switch (tag) {
               case 0:
                 done = true;
                 break;
               case 10: {
                 String s = input.readStringRequireUtf8();
   
                 username_ = s;
                 break;
               }
               case 18: {
                 String s = input.readStringRequireUtf8();
   
                 password_ = s;
                 break;
               }
               case 26: {
                 String s = input.readStringRequireUtf8();
   
                 email_ = s;
                 break;
               }
               case 32: {
   
                 age_ = input.readInt32();
                 break;
               }
               case 40: {
   
                 timespane_ = input.readInt64();
                 break;
               }
               case 49: {
   
                 dValue_ = input.readDouble();
                 break;
               }
               default: {
                 if (!parseUnknownField(
                     input, unknownFields, extensionRegistry, tag)) {
                   done = true;
                 }
                 break;
               }
             }
           }
         } catch (com.google.protobuf.InvalidProtocolBufferException e) {
           throw e.setUnfinishedMessage(this);
         } catch (java.io.IOException e) {
           throw new com.google.protobuf.InvalidProtocolBufferException(
               e).setUnfinishedMessage(this);
         } finally {
           this.unknownFields = unknownFields.build();
           makeExtensionsImmutable();
         }
       }
       public static final com.google.protobuf.Descriptors.Descriptor
           getDescriptor() {
         return StudentProto3.internal_static_Student_descriptor;
       }
   
       @Override
       protected FieldAccessorTable
           internalGetFieldAccessorTable() {
         return StudentProto3.internal_static_Student_fieldAccessorTable
             .ensureFieldAccessorsInitialized(
                 Student.class, Builder.class);
       }
   
       public static final int USERNAME_FIELD_NUMBER = 1;
       private volatile Object username_;
       /**
        * <code>string username = 1;</code>
        * @return The username.
        */
       @Override
       public String getUsername() {
         Object ref = username_;
         if (ref instanceof String) {
           return (String) ref;
         } else {
           com.google.protobuf.ByteString bs = 
               (com.google.protobuf.ByteString) ref;
           String s = bs.toStringUtf8();
           username_ = s;
           return s;
         }
       }
       /**
        * <code>string username = 1;</code>
        * @return The bytes for username.
        */
       @Override
       public com.google.protobuf.ByteString
           getUsernameBytes() {
         Object ref = username_;
         if (ref instanceof String) {
           com.google.protobuf.ByteString b = 
               com.google.protobuf.ByteString.copyFromUtf8(
                   (String) ref);
           username_ = b;
           return b;
         } else {
           return (com.google.protobuf.ByteString) ref;
         }
       }
   
       public static final int PASSWORD_FIELD_NUMBER = 2;
       private volatile Object password_;
       /**
        * <code>string password = 2;</code>
        * @return The password.
        */
       @Override
       public String getPassword() {
         Object ref = password_;
         if (ref instanceof String) {
           return (String) ref;
         } else {
           com.google.protobuf.ByteString bs = 
               (com.google.protobuf.ByteString) ref;
           String s = bs.toStringUtf8();
           password_ = s;
           return s;
         }
       }
       /**
        * <code>string password = 2;</code>
        * @return The bytes for password.
        */
       @Override
       public com.google.protobuf.ByteString
           getPasswordBytes() {
         Object ref = password_;
         if (ref instanceof String) {
           com.google.protobuf.ByteString b = 
               com.google.protobuf.ByteString.copyFromUtf8(
                   (String) ref);
           password_ = b;
           return b;
         } else {
           return (com.google.protobuf.ByteString) ref;
         }
       }
   
       public static final int EMAIL_FIELD_NUMBER = 3;
       private volatile Object email_;
       /**
        * <code>string email = 3;</code>
        * @return The email.
        */
       @Override
       public String getEmail() {
         Object ref = email_;
         if (ref instanceof String) {
           return (String) ref;
         } else {
           com.google.protobuf.ByteString bs = 
               (com.google.protobuf.ByteString) ref;
           String s = bs.toStringUtf8();
           email_ = s;
           return s;
         }
       }
       /**
        * <code>string email = 3;</code>
        * @return The bytes for email.
        */
       @Override
       public com.google.protobuf.ByteString
           getEmailBytes() {
         Object ref = email_;
         if (ref instanceof String) {
           com.google.protobuf.ByteString b = 
               com.google.protobuf.ByteString.copyFromUtf8(
                   (String) ref);
           email_ = b;
           return b;
         } else {
           return (com.google.protobuf.ByteString) ref;
         }
       }
   
       public static final int AGE_FIELD_NUMBER = 4;
       private int age_;
       /**
        * <code>int32 age = 4;</code>
        * @return The age.
        */
       @Override
       public int getAge() {
         return age_;
       }
   
       public static final int TIMESPANE_FIELD_NUMBER = 5;
       private long timespane_;
       /**
        * <code>int64 timespane = 5;</code>
        * @return The timespane.
        */
       @Override
       public long getTimespane() {
         return timespane_;
       }
   
       public static final int DVALUE_FIELD_NUMBER = 6;
       private double dValue_;
       /**
        * <code>double dValue = 6;</code>
        * @return The dValue.
        */
       @Override
       public double getDValue() {
         return dValue_;
       }
   
       private byte memoizedIsInitialized = -1;
       @Override
       public final boolean isInitialized() {
         byte isInitialized = memoizedIsInitialized;
         if (isInitialized == 1) return true;
         if (isInitialized == 0) return false;
   
         memoizedIsInitialized = 1;
         return true;
       }
   
       @Override
       public void writeTo(com.google.protobuf.CodedOutputStream output)
                           throws java.io.IOException {
         if (!getUsernameBytes().isEmpty()) {
           com.google.protobuf.GeneratedMessageV3.writeString(output, 1, username_);
         }
         if (!getPasswordBytes().isEmpty()) {
           com.google.protobuf.GeneratedMessageV3.writeString(output, 2, password_);
         }
         if (!getEmailBytes().isEmpty()) {
           com.google.protobuf.GeneratedMessageV3.writeString(output, 3, email_);
         }
         if (age_ != 0) {
           output.writeInt32(4, age_);
         }
         if (timespane_ != 0L) {
           output.writeInt64(5, timespane_);
         }
         if (dValue_ != 0D) {
           output.writeDouble(6, dValue_);
         }
         unknownFields.writeTo(output);
       }
   
       @Override
       public int getSerializedSize() {
         int size = memoizedSize;
         if (size != -1) return size;
   
         size = 0;
         if (!getUsernameBytes().isEmpty()) {
           size += com.google.protobuf.GeneratedMessageV3.computeStringSize(1, username_);
         }
         if (!getPasswordBytes().isEmpty()) {
           size += com.google.protobuf.GeneratedMessageV3.computeStringSize(2, password_);
         }
         if (!getEmailBytes().isEmpty()) {
           size += com.google.protobuf.GeneratedMessageV3.computeStringSize(3, email_);
         }
         if (age_ != 0) {
           size += com.google.protobuf.CodedOutputStream
             .computeInt32Size(4, age_);
         }
         if (timespane_ != 0L) {
           size += com.google.protobuf.CodedOutputStream
             .computeInt64Size(5, timespane_);
         }
         if (dValue_ != 0D) {
           size += com.google.protobuf.CodedOutputStream
             .computeDoubleSize(6, dValue_);
         }
         size += unknownFields.getSerializedSize();
         memoizedSize = size;
         return size;
       }
   
       @Override
       public boolean equals(final Object obj) {
         if (obj == this) {
          return true;
         }
         if (!(obj instanceof Student)) {
           return super.equals(obj);
         }
         Student other = (Student) obj;
   
         if (!getUsername()
             .equals(other.getUsername())) return false;
         if (!getPassword()
             .equals(other.getPassword())) return false;
         if (!getEmail()
             .equals(other.getEmail())) return false;
         if (getAge()
             != other.getAge()) return false;
         if (getTimespane()
             != other.getTimespane()) return false;
         if (Double.doubleToLongBits(getDValue())
             != Double.doubleToLongBits(
                 other.getDValue())) return false;
         if (!unknownFields.equals(other.unknownFields)) return false;
         return true;
       }
   
       @Override
       public int hashCode() {
         if (memoizedHashCode != 0) {
           return memoizedHashCode;
         }
         int hash = 41;
         hash = (19 * hash) + getDescriptor().hashCode();
         hash = (37 * hash) + USERNAME_FIELD_NUMBER;
         hash = (53 * hash) + getUsername().hashCode();
         hash = (37 * hash) + PASSWORD_FIELD_NUMBER;
         hash = (53 * hash) + getPassword().hashCode();
         hash = (37 * hash) + EMAIL_FIELD_NUMBER;
         hash = (53 * hash) + getEmail().hashCode();
         hash = (37 * hash) + AGE_FIELD_NUMBER;
         hash = (53 * hash) + getAge();
         hash = (37 * hash) + TIMESPANE_FIELD_NUMBER;
         hash = (53 * hash) + com.google.protobuf.Internal.hashLong(
             getTimespane());
         hash = (37 * hash) + DVALUE_FIELD_NUMBER;
         hash = (53 * hash) + com.google.protobuf.Internal.hashLong(
             Double.doubleToLongBits(getDValue()));
         hash = (29 * hash) + unknownFields.hashCode();
         memoizedHashCode = hash;
         return hash;
       }
   
       public static Student parseFrom(
           java.nio.ByteBuffer data)
           throws com.google.protobuf.InvalidProtocolBufferException {
         return PARSER.parseFrom(data);
       }
       public static Student parseFrom(
           java.nio.ByteBuffer data,
           com.google.protobuf.ExtensionRegistryLite extensionRegistry)
           throws com.google.protobuf.InvalidProtocolBufferException {
         return PARSER.parseFrom(data, extensionRegistry);
       }
       public static Student parseFrom(
           com.google.protobuf.ByteString data)
           throws com.google.protobuf.InvalidProtocolBufferException {
         return PARSER.parseFrom(data);
       }
       public static Student parseFrom(
           com.google.protobuf.ByteString data,
           com.google.protobuf.ExtensionRegistryLite extensionRegistry)
           throws com.google.protobuf.InvalidProtocolBufferException {
         return PARSER.parseFrom(data, extensionRegistry);
       }
       public static Student parseFrom(byte[] data)
           throws com.google.protobuf.InvalidProtocolBufferException {
         return PARSER.parseFrom(data);
       }
       public static Student parseFrom(
           byte[] data,
           com.google.protobuf.ExtensionRegistryLite extensionRegistry)
           throws com.google.protobuf.InvalidProtocolBufferException {
         return PARSER.parseFrom(data, extensionRegistry);
       }
       public static Student parseFrom(java.io.InputStream input)
           throws java.io.IOException {
         return com.google.protobuf.GeneratedMessageV3
             .parseWithIOException(PARSER, input);
       }
       public static Student parseFrom(
           java.io.InputStream input,
           com.google.protobuf.ExtensionRegistryLite extensionRegistry)
           throws java.io.IOException {
         return com.google.protobuf.GeneratedMessageV3
             .parseWithIOException(PARSER, input, extensionRegistry);
       }
       public static Student parseDelimitedFrom(java.io.InputStream input)
           throws java.io.IOException {
         return com.google.protobuf.GeneratedMessageV3
             .parseDelimitedWithIOException(PARSER, input);
       }
       public static Student parseDelimitedFrom(
           java.io.InputStream input,
           com.google.protobuf.ExtensionRegistryLite extensionRegistry)
           throws java.io.IOException {
         return com.google.protobuf.GeneratedMessageV3
             .parseDelimitedWithIOException(PARSER, input, extensionRegistry);
       }
       public static Student parseFrom(
           com.google.protobuf.CodedInputStream input)
           throws java.io.IOException {
         return com.google.protobuf.GeneratedMessageV3
             .parseWithIOException(PARSER, input);
       }
       public static Student parseFrom(
           com.google.protobuf.CodedInputStream input,
           com.google.protobuf.ExtensionRegistryLite extensionRegistry)
           throws java.io.IOException {
         return com.google.protobuf.GeneratedMessageV3
             .parseWithIOException(PARSER, input, extensionRegistry);
       }
   
       @Override
       public Builder newBuilderForType() { return newBuilder(); }
       public static Builder newBuilder() {
         return DEFAULT_INSTANCE.toBuilder();
       }
       public static Builder newBuilder(Student prototype) {
         return DEFAULT_INSTANCE.toBuilder().mergeFrom(prototype);
       }
       @Override
       public Builder toBuilder() {
         return this == DEFAULT_INSTANCE
             ? new Builder() : new Builder().mergeFrom(this);
       }
   
       @Override
       protected Builder newBuilderForType(
           BuilderParent parent) {
         Builder builder = new Builder(parent);
         return builder;
       }
       /**
        * Protobuf type {@code Student}
        */
       public static final class Builder extends
           com.google.protobuf.GeneratedMessageV3.Builder<Builder> implements
           // @@protoc_insertion_point(builder_implements:Student)
           StudentOrBuilder {
         public static final com.google.protobuf.Descriptors.Descriptor
             getDescriptor() {
           return StudentProto3.internal_static_Student_descriptor;
         }
   
         @Override
         protected FieldAccessorTable
             internalGetFieldAccessorTable() {
           return StudentProto3.internal_static_Student_fieldAccessorTable
               .ensureFieldAccessorsInitialized(
                   Student.class, Builder.class);
         }
   
         // Construct using com.howie.StudentProto3.Student.newBuilder()
         private Builder() {
           maybeForceBuilderInitialization();
         }
   
         private Builder(
             BuilderParent parent) {
           super(parent);
           maybeForceBuilderInitialization();
         }
         private void maybeForceBuilderInitialization() {
           if (com.google.protobuf.GeneratedMessageV3
                   .alwaysUseFieldBuilders) {
           }
         }
         @Override
         public Builder clear() {
           super.clear();
           username_ = "";
   
           password_ = "";
   
           email_ = "";
   
           age_ = 0;
   
           timespane_ = 0L;
   
           dValue_ = 0D;
   
           return this;
         }
   
         @Override
         public com.google.protobuf.Descriptors.Descriptor
             getDescriptorForType() {
           return StudentProto3.internal_static_Student_descriptor;
         }
   
         @Override
         public Student getDefaultInstanceForType() {
           return Student.getDefaultInstance();
         }
   
         @Override
         public Student build() {
           Student result = buildPartial();
           if (!result.isInitialized()) {
             throw newUninitializedMessageException(result);
           }
           return result;
         }
   
         @Override
         public Student buildPartial() {
           Student result = new Student(this);
           result.username_ = username_;
           result.password_ = password_;
           result.email_ = email_;
           result.age_ = age_;
           result.timespane_ = timespane_;
           result.dValue_ = dValue_;
           onBuilt();
           return result;
         }
   
         @Override
         public Builder clone() {
           return super.clone();
         }
         @Override
         public Builder setField(
             com.google.protobuf.Descriptors.FieldDescriptor field,
             Object value) {
           return super.setField(field, value);
         }
         @Override
         public Builder clearField(
             com.google.protobuf.Descriptors.FieldDescriptor field) {
           return super.clearField(field);
         }
         @Override
         public Builder clearOneof(
             com.google.protobuf.Descriptors.OneofDescriptor oneof) {
           return super.clearOneof(oneof);
         }
         @Override
         public Builder setRepeatedField(
             com.google.protobuf.Descriptors.FieldDescriptor field,
             int index, Object value) {
           return super.setRepeatedField(field, index, value);
         }
         @Override
         public Builder addRepeatedField(
             com.google.protobuf.Descriptors.FieldDescriptor field,
             Object value) {
           return super.addRepeatedField(field, value);
         }
         @Override
         public Builder mergeFrom(com.google.protobuf.Message other) {
           if (other instanceof Student) {
             return mergeFrom((Student)other);
           } else {
             super.mergeFrom(other);
             return this;
           }
         }
   
         public Builder mergeFrom(Student other) {
           if (other == Student.getDefaultInstance()) return this;
           if (!other.getUsername().isEmpty()) {
             username_ = other.username_;
             onChanged();
           }
           if (!other.getPassword().isEmpty()) {
             password_ = other.password_;
             onChanged();
           }
           if (!other.getEmail().isEmpty()) {
             email_ = other.email_;
             onChanged();
           }
           if (other.getAge() != 0) {
             setAge(other.getAge());
           }
           if (other.getTimespane() != 0L) {
             setTimespane(other.getTimespane());
           }
           if (other.getDValue() != 0D) {
             setDValue(other.getDValue());
           }
           this.mergeUnknownFields(other.unknownFields);
           onChanged();
           return this;
         }
   
         @Override
         public final boolean isInitialized() {
           return true;
         }
   
         @Override
         public Builder mergeFrom(
             com.google.protobuf.CodedInputStream input,
             com.google.protobuf.ExtensionRegistryLite extensionRegistry)
             throws java.io.IOException {
           Student parsedMessage = null;
           try {
             parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);
           } catch (com.google.protobuf.InvalidProtocolBufferException e) {
             parsedMessage = (Student) e.getUnfinishedMessage();
             throw e.unwrapIOException();
           } finally {
             if (parsedMessage != null) {
               mergeFrom(parsedMessage);
             }
           }
           return this;
         }
   
         private Object username_ = "";
         /**
          * <code>string username = 1;</code>
          * @return The username.
          */
         public String getUsername() {
           Object ref = username_;
           if (!(ref instanceof String)) {
             com.google.protobuf.ByteString bs =
                 (com.google.protobuf.ByteString) ref;
             String s = bs.toStringUtf8();
             username_ = s;
             return s;
           } else {
             return (String) ref;
           }
         }
         /**
          * <code>string username = 1;</code>
          * @return The bytes for username.
          */
         public com.google.protobuf.ByteString
             getUsernameBytes() {
           Object ref = username_;
           if (ref instanceof String) {
             com.google.protobuf.ByteString b = 
                 com.google.protobuf.ByteString.copyFromUtf8(
                     (String) ref);
             username_ = b;
             return b;
           } else {
             return (com.google.protobuf.ByteString) ref;
           }
         }
         /**
          * <code>string username = 1;</code>
          * @param value The username to set.
          * @return This builder for chaining.
          */
         public Builder setUsername(
             String value) {
           if (value == null) {
       throw new NullPointerException();
     }
     
           username_ = value;
           onChanged();
           return this;
         }
         /**
          * <code>string username = 1;</code>
          * @return This builder for chaining.
          */
         public Builder clearUsername() {
           
           username_ = getDefaultInstance().getUsername();
           onChanged();
           return this;
         }
         /**
          * <code>string username = 1;</code>
          * @param value The bytes for username to set.
          * @return This builder for chaining.
          */
         public Builder setUsernameBytes(
             com.google.protobuf.ByteString value) {
           if (value == null) {
       throw new NullPointerException();
     }
     checkByteStringIsUtf8(value);
           
           username_ = value;
           onChanged();
           return this;
         }
   
         private Object password_ = "";
         /**
          * <code>string password = 2;</code>
          * @return The password.
          */
         public String getPassword() {
           Object ref = password_;
           if (!(ref instanceof String)) {
             com.google.protobuf.ByteString bs =
                 (com.google.protobuf.ByteString) ref;
             String s = bs.toStringUtf8();
             password_ = s;
             return s;
           } else {
             return (String) ref;
           }
         }
         /**
          * <code>string password = 2;</code>
          * @return The bytes for password.
          */
         public com.google.protobuf.ByteString
             getPasswordBytes() {
           Object ref = password_;
           if (ref instanceof String) {
             com.google.protobuf.ByteString b = 
                 com.google.protobuf.ByteString.copyFromUtf8(
                     (String) ref);
             password_ = b;
             return b;
           } else {
             return (com.google.protobuf.ByteString) ref;
           }
         }
         /**
          * <code>string password = 2;</code>
          * @param value The password to set.
          * @return This builder for chaining.
          */
         public Builder setPassword(
             String value) {
           if (value == null) {
       throw new NullPointerException();
     }
     
           password_ = value;
           onChanged();
           return this;
         }
         /**
          * <code>string password = 2;</code>
          * @return This builder for chaining.
          */
         public Builder clearPassword() {
           
           password_ = getDefaultInstance().getPassword();
           onChanged();
           return this;
         }
         /**
          * <code>string password = 2;</code>
          * @param value The bytes for password to set.
          * @return This builder for chaining.
          */
         public Builder setPasswordBytes(
             com.google.protobuf.ByteString value) {
           if (value == null) {
       throw new NullPointerException();
     }
     checkByteStringIsUtf8(value);
           
           password_ = value;
           onChanged();
           return this;
         }
   
         private Object email_ = "";
         /**
          * <code>string email = 3;</code>
          * @return The email.
          */
         public String getEmail() {
           Object ref = email_;
           if (!(ref instanceof String)) {
             com.google.protobuf.ByteString bs =
                 (com.google.protobuf.ByteString) ref;
             String s = bs.toStringUtf8();
             email_ = s;
             return s;
           } else {
             return (String) ref;
           }
         }
         /**
          * <code>string email = 3;</code>
          * @return The bytes for email.
          */
         public com.google.protobuf.ByteString
             getEmailBytes() {
           Object ref = email_;
           if (ref instanceof String) {
             com.google.protobuf.ByteString b = 
                 com.google.protobuf.ByteString.copyFromUtf8(
                     (String) ref);
             email_ = b;
             return b;
           } else {
             return (com.google.protobuf.ByteString) ref;
           }
         }
         /**
          * <code>string email = 3;</code>
          * @param value The email to set.
          * @return This builder for chaining.
          */
         public Builder setEmail(
             String value) {
           if (value == null) {
       throw new NullPointerException();
     }
     
           email_ = value;
           onChanged();
           return this;
         }
         /**
          * <code>string email = 3;</code>
          * @return This builder for chaining.
          */
         public Builder clearEmail() {
           
           email_ = getDefaultInstance().getEmail();
           onChanged();
           return this;
         }
         /**
          * <code>string email = 3;</code>
          * @param value The bytes for email to set.
          * @return This builder for chaining.
          */
         public Builder setEmailBytes(
             com.google.protobuf.ByteString value) {
           if (value == null) {
       throw new NullPointerException();
     }
     checkByteStringIsUtf8(value);
           
           email_ = value;
           onChanged();
           return this;
         }
   
         private int age_ ;
         /**
          * <code>int32 age = 4;</code>
          * @return The age.
          */
         @Override
         public int getAge() {
           return age_;
         }
         /**
          * <code>int32 age = 4;</code>
          * @param value The age to set.
          * @return This builder for chaining.
          */
         public Builder setAge(int value) {
           
           age_ = value;
           onChanged();
           return this;
         }
         /**
          * <code>int32 age = 4;</code>
          * @return This builder for chaining.
          */
         public Builder clearAge() {
           
           age_ = 0;
           onChanged();
           return this;
         }
   
         private long timespane_ ;
         /**
          * <code>int64 timespane = 5;</code>
          * @return The timespane.
          */
         @Override
         public long getTimespane() {
           return timespane_;
         }
         /**
          * <code>int64 timespane = 5;</code>
          * @param value The timespane to set.
          * @return This builder for chaining.
          */
         public Builder setTimespane(long value) {
           
           timespane_ = value;
           onChanged();
           return this;
         }
         /**
          * <code>int64 timespane = 5;</code>
          * @return This builder for chaining.
          */
         public Builder clearTimespane() {
           
           timespane_ = 0L;
           onChanged();
           return this;
         }
   
         private double dValue_ ;
         /**
          * <code>double dValue = 6;</code>
          * @return The dValue.
          */
         @Override
         public double getDValue() {
           return dValue_;
         }
         /**
          * <code>double dValue = 6;</code>
          * @param value The dValue to set.
          * @return This builder for chaining.
          */
         public Builder setDValue(double value) {
           
           dValue_ = value;
           onChanged();
           return this;
         }
         /**
          * <code>double dValue = 6;</code>
          * @return This builder for chaining.
          */
         public Builder clearDValue() {
           
           dValue_ = 0D;
           onChanged();
           return this;
         }
         @Override
         public final Builder setUnknownFields(
             final com.google.protobuf.UnknownFieldSet unknownFields) {
           return super.setUnknownFields(unknownFields);
         }
   
         @Override
         public final Builder mergeUnknownFields(
             final com.google.protobuf.UnknownFieldSet unknownFields) {
           return super.mergeUnknownFields(unknownFields);
         }
   
   
         // @@protoc_insertion_point(builder_scope:Student)
       }
   
       // @@protoc_insertion_point(class_scope:Student)
       private static final Student DEFAULT_INSTANCE;
       static {
         DEFAULT_INSTANCE = new Student();
       }
   
       public static Student getDefaultInstance() {
         return DEFAULT_INSTANCE;
       }
   
       private static final com.google.protobuf.Parser<Student>
           PARSER = new com.google.protobuf.AbstractParser<Student>() {
         @Override
         public Student parsePartialFrom(
             com.google.protobuf.CodedInputStream input,
             com.google.protobuf.ExtensionRegistryLite extensionRegistry)
             throws com.google.protobuf.InvalidProtocolBufferException {
           return new Student(input, extensionRegistry);
         }
       };
   
       public static com.google.protobuf.Parser<Student> parser() {
         return PARSER;
       }
   
       @Override
       public com.google.protobuf.Parser<Student> getParserForType() {
         return PARSER;
       }
   
       @Override
       public Student getDefaultInstanceForType() {
         return DEFAULT_INSTANCE;
       }
   
     }
   
     private static final com.google.protobuf.Descriptors.Descriptor
       internal_static_Student_descriptor;
     private static final 
       com.google.protobuf.GeneratedMessageV3.FieldAccessorTable
         internal_static_Student_fieldAccessorTable;
   
     public static com.google.protobuf.Descriptors.FileDescriptor
         getDescriptor() {
       return descriptor;
     }
     private static  com.google.protobuf.Descriptors.FileDescriptor
         descriptor;
     static {
       String[] descriptorData = {
         "\n\016Student.proto3\"l\n\007Student\022\020\n\010username\030" +
         "\001 \001(\t\022\020\n\010password\030\002 \001(\t\022\r\n\005email\030\003 \001(\t\022\013" +
         "\n\003age\030\004 \001(\005\022\021\n\ttimespane\030\005 \001(\003\022\016\n\006dValue" +
         "\030\006 \001(\001B\013\n\tcom.howieb\006proto3"
       };
       descriptor = com.google.protobuf.Descriptors.FileDescriptor
         .internalBuildGeneratedFileFrom(descriptorData,
           new com.google.protobuf.Descriptors.FileDescriptor[] {
           });
       internal_static_Student_descriptor =
         getDescriptor().getMessageTypes().get(0);
       internal_static_Student_fieldAccessorTable = new
         com.google.protobuf.GeneratedMessageV3.FieldAccessorTable(
           internal_static_Student_descriptor,
           new String[] { "Username", "Password", "Email", "Age", "Timespane", "DValue", });
     }
   
     // @@protoc_insertion_point(outer_class_scope)
   }
   
   

8. 创建TestOfPB.java，工程如下：
   

9. TestOfPB.java：

   package com.howie;
   
   import java.util.Arrays;
   
   import static com.howie.TestOfOM.jacksonSerialize;
   
   public class TestOfPB {
   
       public static void protoSerialize(Student student){
           StudentProto3.Student stu = StudentProto3.Student.newBuilder()
                   .setUsername(student.getUsername())
                   .setPassword(student.getPassword())
                   .setEmail(student.getEmail())
                   .setAge(student.getAge())
                   .setDValue(student.getdValue())
                   .setTimespane(student.getTimespane())
                   .build();
           byte[] bytes = stu.toByteArray();
           System.out.println("字节数组:" + Arrays.toString(bytes));
           System.out.println("字节数组长度:" + bytes.length);
       }
   
       public static void main(String[] args) {
           // 创建student对象并赋值
           Student student = new Student();
   
           student.setUsername("admin");
           student.setPassword("123456");
           student.setEmail("987654321@163.com");
           student.setAge(Integer.MAX_VALUE);
           student.setdValue(Double.MAX_VALUE);
           student.setTimespane(System.currentTimeMillis());
   
           protoSerialize(student);
       }
   }
   
   

10. 执行结果：

    字节数组:[10, 5, 97, 100, 109, 105, 110, 18, 6, 49, 50, 51, 52, 53, 54, 26, 17, 57, 56, 55, 54, 53, 52, 51, 50, 49, 64, 49, 54, 51, 46, 99, 111, 109, 32, -1, -1, -1, -1, 7, 40, -125, -117, -125, -74, -120, 47, 49, -1, -1, -1, -1, -1, -1, -17, 127]
    字节数组长度:56
    

总结

几种序列化方式比较起来，protobuf协议传输协议所占流量少

附录

参考视频