fastjson

官网地址
https://github.com/alibaba/fastjson/wiki/Quick-Start-CN

1. 什么是fastjson?

fastjson是阿里巴巴的开源JSON解析库，它可以解析JSON格式的字符串，支持将Java Bean序列化为JSON字符串，也可以从JSON字符串反序列化到JavaBean。

fastjson的API十分简洁。

json 基本值类型 true ,false, number,string, object,array, null

String text = JSON.toJSONString(obj); //序列化
VO vo = JSON.parseObject("{...}", VO.class); //反序列化

import com.alibaba.fastjson.JSON;

  Model model = new Model();
        model.id = 1001;
        model.name = "gaotie";

        Model model2 = new Model();
        model2.id = 1002;
        model2.name = "gaotie2";

        Vector<Model> modelVec=new Vector<>();
        modelVec.add(model);
        modelVec.add(model2);

        ModelBig modelBig=new ModelBig();
        modelBig.id= 2001;
        modelBig.name="bigname1";
        modelBig.modelVec=modelVec;


        // class 转 string 
        String jsonString1 = JSON.toJSONString(modelBig);
        System.out.println(" Java对象 转换为 string ,打印String对象 为：  " + jsonString1);
       //Java对象 转换为 string ,打印String对象 为：  {"id":2001,"modelVec":[{"id":1001,"name":"gaotie"},{"id":1002,"name":"gaotie2"}],"name":"bigname1"}

com.alibaba.fastjson.JSONObject jsonObject2 = (com.alibaba.fastjson.JSONObject) com.alibaba.fastjson.JSONObject.toJSON(modelBig);
        System.out.println("Java对象转化为  object对象  强转为 JSONObject ，打印JSONObject  为：   \n" + jsonObject2);//
        //Java对象转化为  object对象  强转为 JSONObject ，打印JSONObject  为：   
       //{"id":2001,"name":"bigname1","modelVec":[{"id":1001,"name":"gaotie"},{"id":1002,"name":"gaotie2"}]}

//  Demo
//  parse Tree

import com.alibaba.fastjson.*;

JSONObject jsonObj = JSON.parseObject(jsonStr);

//  parse POJO

import com.alibaba.fastjson.JSON;

Model model = JSON.parseObject(jsonStr, Model.class);

//  parse POJO Generic

import com.alibaba.fastjson.JSON;

Type type = new TypeReference<List<Model>>() {}.getType(); 
List<Model> list = JSON.parseObject(jsonStr, type);

//  convert POJO to json string

import com.alibaba.fastjson.JSON;

Model model = ...; 
String jsonStr = JSON.toJSONString(model);

//  convert POJO to json bytes

import com.alibaba.fastjson.JSON;

Model model = ...; 
byte[] jsonBytes = JSON.toJSONBytes(model);

//  write POJO as json string to OutputStream

import com.alibaba.fastjson.JSON;

Model model = ...; 
OutputStream os;
JSON.writeJSONString(os, model);

//  write POJO as json string to Writer

import com.alibaba.fastjson.JSON;

Model model = ...; 
Writer writer = ...;
JSON.writeJSONString(writer, model);

 

3.2 Java类库

Fastjson
Jackson
Gson
Xstream