json串与对象之间转换的几种实现方式-优快云博客

本文介绍了四种常用的JSON处理工具：gson、fastjson、jackson和json-lib，并提供了它们将Java对象转换为JSON字符串及反向转换的示例代码。

这里使用了gson,fastjson,jackson,json等工具实现了json串与对象之间的相互转换。

主要实现了bean到json串,json串到bean,json串到List的转换。

公共Bean:User.java


package com.json.bean;

/**
 * 
 * @author yangjianzhou
 *
 * Jan 24, 2015 4:32:26 PM
 * 
 * TODO
 */
public class User {

private String name ; 

	private int age ;

	private String address ;

	public User(String name , int age , String address){
		this.name = name ;
		this.address = address ;
		this.age = age ;
	}

	public User(){
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

}

GsonUtils.java代码如下：


package com.json.utils;

import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;
import com.json.bean.User;

/**
 * 
 * @author yangjianzhou
 *
 * Jan 24, 2015 3:39:49 PM
 * 
 * Gson的应用
 * 对象与json之间的转换
 */
public class GsonUtils {

	/**
	 * 将对象转换为json字符串
	 * @param obj
	 * @return
	 */
	public static String toJson(Object obj) {
		Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
		return gson.toJson(obj);
	}

	/**
	 * 将json字符串转换为对象
	 * @param jsonString
	 * @param type
	 * @return
	 */
	public static <T> T jsonToObject(String jsonString , TypeToken<T> type) {
		Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
		return gson.fromJson(jsonString, type.getType());
	}

	/**
	 * 将json字符串转换为对象
	 * @param jsonString
	 * @param clazz
	 * @return
	 */
	public static <T> T jsonToObject(String jsonString , Class<T> clazz) {
		Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
		return gson.fromJson(jsonString, clazz);
	}

	public static void main(String[] args) {
		User user = new User("zhangsan",21,"shanghai");
		String jsonStr = toJson(user);
		System.out.println("jsonStr : " +jsonStr);
		user = null ;
		user = jsonToObject(jsonStr,User.class);
        user = null ;
        user = jsonToObject(jsonStr, new TypeToken<User>(){});

		List<User> userList = new ArrayList<User>();
		userList.add(new User("zhangsan",21,"shanghai"));
		userList.add(new User("lisi",22,"shanghai"));
		String jsonListStr = toJson(userList);
		userList = null ;
		userList = jsonToObject(jsonListStr , new TypeToken<List<User>>(){});

	}
}

运行结果如下：


jsonStr : {"name":"zhangsan","age":21,"address":"shanghai"}
jsonListStr : [{"name":"zhangsan","age":21,"address":"shanghai"},{"name":"lisi","age":22,"address":"shanghai"}]

FastjsonUtils.java代码如下：


package com.json.utils;

import java.util.ArrayList;
import java.util.List;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.json.bean.User;

/**
 * 
 * @author yangjianzhou
 *
 *         Jan 24, 2015 3:34:34 PM
 * 
 *         fastjson的应用
 *         对象与json之间的转换
 */
public class FastjsonUtils {

	/**
	 * 将对象转换为json
	 * @param obj
	 * @return
	 */
	public static String toJson(Object obj) {
		return JSON.toJSONStringWithDateFormat(obj, "yyyy-MM-dd HH:mm:ss", SerializerFeature.WriteNullNumberAsZero);
	}

	/**
	 * 将json字符串转换为对象
	 * @param jsonString
	 * @param clazz
	 * @return
	 */
	public static <T> T jsonToObject(String jsonString, Class<T> clazz) {
		return JSON.parseObject(jsonString, clazz);
	}

	/**
	 * 将字符串转换为List
	 * @param jsonString
	 * @param clazz
	 * @return
	 */
	public static <T> List<T> jsonToList(String jsonString, Class<T> clazz) {
		return JSON.parseArray(jsonString, clazz);
	}

	public static void main(String[] args) {
		User user = new User("zhangsan",21,"shanghai");
		String jsonStr = toJson(user);
		System.out.println("jsonStr : " +jsonStr);
		user = null ; 
		user = jsonToObject(jsonStr, User.class);
		List<User> userList = new ArrayList<User>();
		userList.add(new User("zhangsan",21,"shanghai"));
		userList.add(new User("zhangsan",21,"shanghai"));
		String jsonListStr = toJson(userList);
		System.out.println("jsonListStr : " +jsonListStr);
		userList = null ;
		userList = jsonToList(jsonListStr,User.class);
	}
}

运行结果如下：


jsonStr : {"address":"shanghai","age":21,"name":"zhangsan"}
jsonListStr : [{"address":"shanghai","age":21,"name":"zhangsan"},{"address":"shanghai","age":21,"name":"zhangsan"}]

JacksonUtils.java代码如下：


package com.json.utils;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider;
import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.Impl;
import com.fasterxml.jackson.databind.ser.std.NullSerializer;

import com.json.bean.User;
/**
 * 
 * @author yangjianzhou
 *
 *         Jan 24, 2015 3:51:54 PM
 * 
 *         TODO
 */
public class JacksonUtils {

	static ObjectMapper objectMapper;

	static {
		DefaultSerializerProvider sp = new Impl();
		sp.setNullValueSerializer(NullSerializer.instance);
		objectMapper = new ObjectMapper(null, sp, null);
		objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
	}

	public static String toJson(Object object) throws Exception {
		return objectMapper.writeValueAsString(object);
	}

	@SuppressWarnings("unchecked")
	public static <T> T jsonToObject(String jsonString, TypeReference<T> tr) throws IOException {
		return (T) objectMapper.readValue(jsonString, tr);
	}

	public static void main(String[] args) throws Exception{
		User user = new User("zhangsan",21,"shanghai");
		String jsonStr = toJson(user);
		System.out.println("jsonStr : " +jsonStr);
		user = null ;
		user = jsonToObject(jsonStr,new TypeReference<User>() {
		});
        user = null ;

		List<User> userList = new ArrayList<User>();
		userList.add(new User("zhangsan",21,"shanghai"));
		userList.add(new User("lisi",22,"shanghai"));
		String jsonListStr = toJson(userList);
		userList = null ;
		userList = jsonToObject(jsonListStr , new TypeReference<List<User>>(){});
	}
}

运行结果如下：


jsonStr : {"name":"zhangsan","age":21,"address":"shanghai"}
jsonListStr : [{"name":"zhangsan","age":21,"address":"shanghai"},{"name":"lisi","age":22,"address":"shanghai"}]

JsonlibUtils.java代码如下：


package com.json.utils;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

import com.json.bean.User;

/**
 * 
 * @author yangjianzhou
 *
 * Jan 24, 2015 4:03:03 PM
 * 
 * JSONObject与对象之间的转换
 */
public class JsonlibUtils {

	/**
	 * 转换为json字符串
	 * @param obj
	 * @return
	 */
	public static <T> String toJson(Object obj , Class<T> clazz) {
		if(clazz.isAssignableFrom(List.class)){
			return JSONArray.fromObject(obj).toString();
		}
		return JSONObject.fromObject(obj).toString();
	}

	/**
	 * jsonString转换为对象
	 * @param jsonString
	 * @param clazz
	 * @return
	 */
	@SuppressWarnings("unchecked")
	public static <T> T jsonToObject(String jsonString, Class<T> clazz) {
		JSONObject jsonObject = JSONObject.fromObject(jsonString);
		return (T)JSONObject.toBean(jsonObject, clazz);
	}

	/**
	 * jsonString转换为List
	 * @param jsonString
	 * @param clazz
	 * @return
	 */
	@SuppressWarnings({ "unchecked", "rawtypes" })
	public static <T>  List<T> jsonToList(String jsonString , Class<T> clazz) {
		Collection<T> collection = JSONArray.toCollection(JSONArray.fromObject(jsonString), clazz);
		return new ArrayList(collection);
	}

	public static void main(String[] args) {
		User user = new User("zhangsan",21,"shanghai");
		String jsonStr = toJson(user , User.class);
		System.out.println("jsonStr : " +jsonStr);
		user = null ;
		user = jsonToObject(jsonStr,User.class);

		List<User> userList = new ArrayList<User>();
		userList.add(new User("zhangsan",21,"shanghai"));
		userList.add(new User("lisi",22,"shanghai"));
		String jsonListStr = toJson(userList,List.class);
		System.out.println("jsonListStr : " +jsonListStr);
		userList = null ;
		userList = jsonToList(jsonListStr , User.class);
	}
}

运行结果如下：


jsonStr : {"address":"shanghai","name":"zhangsan","age":21}
jsonListStr : [{"address":"shanghai","name":"zhangsan","age":21},{"address":"shanghai","name":"lisi","age":22}]