retrofit 介绍 使用

一.原理:
· 大概原理
通过java接口以及注解来描述网络请求，并用动态代理的方式，在调用接口方法前后（before／after）注入自己的方法，before通过接口方法和注解生成网络请求的request，after通过client调用相应的网络框架（默认okhttp）去发起网络请求，并将返回的response通过converterFactorty转换成相应的数据model，最后通过calladapter转换成其他数据方式（如rxjava Observable）

· 动态代理
代理对象拦截真实对象的方法调用，在真实对象调用前／后实现自己的逻辑调用
见Retrofit.create()方法

· 重点类
1.Retrofit类 创建接口api的动态代理对象（create()返回api service动态代理对象，调用代理对象上的方法时，会触发代理对象上的invoke方法，这里面会封装好OKHttpCall对象，OKHttpCall的数据返回根据calladapter转换为Observable）
2.ServiceMethod 核心处理类，解析方法和注解，生成HttpRequest（toRequest方法；创建responseConverter（将response流转换为String或者实体类）； 创建callAdapter（转换为rxjava observable）
3.OKHttpCall 封装okhttp3的调用

4.Rxjava2CallAdapter 转换成Observable （BodyObservable会对http code做检查，如果错误直接走onError流程）
原理链接：https://blog.youkuaiyun.com/ActiveLi/article/details/80610031

案例
1.导入依赖

//RxJava依赖
    implementation 'io.reactivex.rxjava2:rxjava:2.2.6'
    implementation 'io.reactivex.rxjava2:rxandroid:2.1.0'

    //Retrofit依赖
    implementation 'com.squareup.retrofit2:retrofit:2.4.0'
    //Gson converter gson解析
    implementation 'com.squareup.retrofit2:converter-gson:2.4.0'

    //RxJava2 Adapter
    implementation "com.squareup.retrofit2:adapter-rxjava2:2.3.0"
    //okhttp
    implementation 'com.squareup.okhttp3:okhttp:3.4.1'
    implementation 'com.squareup.okhttp3:logging-interceptor:3.9.1'

2.添加网络权限

<uses-permission android:name="android.permission.INTERNET" />

3.API接口

public interface API {

    @FormUrlEncoded
    @POST("register")
    Observable<UserEntity> getResisterData2(@FieldMap HashMap<String,String> hashMap);

    @FormUrlEncoded
    @POST("login")
    Observable<UserEntity> getLoginData2(@FieldMap HashMap<String,String> hashMap);

}

封装RetrofitManager

package com.example.a12_11lx_retrofit;

import java.io.IOException;
import java.util.concurrent.TimeUnit;

import okhttp3.Interceptor;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.logging.HttpLoggingInterceptor;
import retrofit2.Retrofit;
import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory;
import retrofit2.converter.gson.GsonConverterFactory;

public class RetrofitManager2 {

    private RetrofitManager2(){

    }
    private static RetrofitManager2 retrofitManager2 =new RetrofitManager2();

    public static RetrofitManager2 getInstance(){
            return retrofitManager2;
    }
    Retrofit retrofit;
    public void create(){
         retrofit =new Retrofit.Builder()
                .baseUrl("https://www.wanandroid.com/user/")
                .client(new OkHttpClient.Builder()
                        .writeTimeout(1, TimeUnit.MINUTES)
                        .readTimeout(1, TimeUnit.MINUTES)
                        .connectTimeout(1,TimeUnit.MINUTES)
                        .addInterceptor(new Interceptor() {
                            @Override
                            public Response intercept(Chain chain) throws IOException {
                                Request request = chain.request().newBuilder().addHeader("appversion", "1.0").build();
                                return chain.proceed(request);
                            }
                        })
                        .addInterceptor(new HttpLoggingInterceptor().setLevel(HttpLoggingInterceptor.Level.BODY))
                        .build())
                        .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .build();
    }

    public Retrofit getRetrofit(){
        if (retrofit ==null){
            create();
        }
        return retrofit;
    }

}

实体类UserEntity

package com.example.a12_11lx_retrofit;

import java.util.List;

public class UserEntity {
    @Override
    public String toString() {
        return "UserEntity{" +
                "data=" + data +
                ", errorCode=" + errorCode +
                ", errorMsg='" + errorMsg + '\'' +
                '}';
    }

    /**
     * admin : false
     * chapterTops : []
     * coinCount : 0
     * collectIds : []
     * email :
     * icon :
     * id : 116924
     * nickname : zang11111
     * password :
     * publicName : zang11111
     * token :
     * type : 0
     * username : zang11111
     */

    private DataBean data;
    /**
     * data : {"admin":false,"chapterTops":[],"coinCount":0,"collectIds":[],"email":"","icon":"","id":116924,"nickname":"zang11111","password":"","publicName":"zang11111","token":"","type":0,"username":"zang11111"}
     * errorCode : 0
     * errorMsg :
     */

    private int errorCode;
    private String errorMsg;

    public DataBean getData() {
        return data;
    }

    public void setData(DataBean data) {
        this.data = data;
    }

    public int getErrorCode() {
        return errorCode;
    }

    public void setErrorCode(int errorCode) {
        this.errorCode = errorCode;
    }

    public String getErrorMsg() {
        return errorMsg;
    }

    public void setErrorMsg(String errorMsg) {
        this.errorMsg = errorMsg;
    }

    public static class DataBean {
        private boolean admin;
        private int coinCount;
        private String email;
        private String icon;
        private int id;
        private String nickname;
        private String password;
        private String publicName;
        private String token;
        private int type;
        private String username;
        private List<?> chapterTops;
        private List<?> collectIds;

        @Override
        public String toString() {
            return "DataBean{" +
                    "admin=" + admin +
                    ", coinCount=" + coinCount +
                    ", email='" + email + '\'' +
                    ", icon='" + icon + '\'' +
                    ", id=" + id +
                    ", nickname='" + nickname + '\'' +
                    ", password='" + password + '\'' +
                    ", publicName='" + publicName + '\'' +
                    ", token='" + token + '\'' +
                    ", type=" + type +
                    ", username='" + username + '\'' +
                    ", chapterTops=" + chapterTops +
                    ", collectIds=" + collectIds +
                    '}';
        }

        public boolean isAdmin() {
            return admin;
        }

        public void setAdmin(boolean admin) {
            this.admin = admin;
        }

        public int getCoinCount() {
            return coinCount;
        }

        public void setCoinCount(int coinCount) {
            this.coinCount = coinCount;
        }

        public String getEmail() {
            return email;
        }

        public void setEmail(String email) {
            this.email = email;
        }

        public String getIcon() {
            return icon;
        }

        public void setIcon(String icon) {
            this.icon = icon;
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getNickname() {
            return nickname;
        }

        public void setNickname(String nickname) {
            this.nickname = nickname;
        }

        public String getPassword() {
            return password;
        }

        public void setPassword(String password) {
            this.password = password;
        }

        public String getPublicName() {
            return publicName;
        }

        public void setPublicName(String publicName) {
            this.publicName = publicName;
        }

        public String getToken() {
            return token;
        }

        public void setToken(String token) {
            this.token = token;
        }

        public int getType() {
            return type;
        }

        public void setType(int type) {
            this.type = type;
        }

        public String getUsername() {
            return username;
        }

        public void setUsername(String username) {
            this.username = username;
        }

        public List<?> getChapterTops() {
            return chapterTops;
        }

        public void setChapterTops(List<?> chapterTops) {
            this.chapterTops = chapterTops;
        }

        public List<?> getCollectIds() {
            return collectIds;
        }

        public void setCollectIds(List<?> collectIds) {
            this.collectIds = collectIds;
        }
    }
}

布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:hint="账号"
        android:id="@+id/ed_username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></EditText>

    <EditText
        android:inputType="textPassword"
        android:hint="密码"
        android:id="@+id/ed_password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></EditText>

    <EditText
        android:inputType="textPassword"
        android:hint="再次输入密码"
        android:id="@+id/ed_repassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></EditText>

    <Button
        android:id="@+id/login"
        android:text="登录"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"></Button>

</LinearLayout>

MainActivity

package com.example.a12_11lx_retrofit;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import java.util.HashMap;

import io.reactivex.Observer;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.Disposable;
import io.reactivex.schedulers.Schedulers;
import retrofit2.Retrofit;

public class MainActivity extends AppCompatActivity {

    private EditText edUsername;
    private EditText edPassword;
    private Button login;
    private EditText edRepassword;
    String username;
    String password;
    String repassword;
    HashMap<String, String> hashMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
          username = edUsername.getText().toString();
         password = edPassword.getText().toString();
        repassword = edRepassword.getText().toString();

        hashMap = new HashMap<>();
        hashMap.put("username", "jialichao12");
        hashMap.put("password", "jialichao12");
        hashMap.put("repassword","jialichao12");

        //注册
       login.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {



               RetrofitManager2.getInstance().getRetrofit().create(API.class)
                       .getResisterData2(hashMap)
                       .subscribeOn(Schedulers.io())
                       .observeOn(AndroidSchedulers.mainThread())
                       .subscribe(new Observer<UserEntity>() {
                           @Override
                           public void onSubscribe(Disposable d) {

                           }

                           @Override
                           public void onNext(UserEntity userEntity) {
                               System.out.println("========"+userEntity);
                               int errorCode = userEntity.getErrorCode();
                               if (errorCode==0){
                                   Toast.makeText(MainActivity.this,"注册成功",Toast.LENGTH_SHORT).show();
                                   startActivity(new Intent(MainActivity.this,LoginActivity.class));
                               }else {
                                   Toast.makeText(MainActivity.this,userEntity.getErrorMsg(),Toast.LENGTH_SHORT).show();
                               }
                           }

                           @Override
                           public void onError(Throwable e) {

                           }

                           @Override
                           public void onComplete() {

                           }
                       });
           }
       });

    }

    private void initView() {
        edUsername = (EditText) findViewById(R.id.ed_username);
        edPassword = (EditText) findViewById(R.id.ed_password);
        login = (Button) findViewById(R.id.login);
        edRepassword = (EditText) findViewById(R.id.ed_repassword);
    }
}