简单纪要：Json转化的三种方式

1. Gson

1.1 添加pom依赖

<dependency>
   <groupId>com.google.code.gson</groupId>
   <artifactId>gson</artifactId>
   <version>2.2.4</version>
</dependency>

1.2 转化方法

① 对象转 Json

Gson gson = new Gson();
String json = gson.toJson(Object object);

② Json转对象

gson.fromJson(String json, Class<T> classOfT) 

③ 集合转Json

Gson gson = new Gson();
String json = gson.toJson(Object object);

④ Json转集合

TypeToken<T> typeOfT = new TypeToken<T>(){};
T fromJson = (T)gson.fromJson(json, typeOfT.getType());

2. Json-lib

2.1 添加pom依赖

<dependency>
    <groupId>net.sf.json-lib</groupId>
    <artifactId>json-lib</artifactId>
    <version>2.4</version>
    <classifier>jdk15</classifier>
</dependency>

2.2 转化方法

① 对象转 Json

　JSONObject fromObject = JSONObject.fromObject(Object object);

String string = fromObject.toString();

② Json转对象

　JSONObject fromObject2 = JSONObject.fromObject(string);

Object bean =JSONObject.toBean(JSONObject jsonObject, Class beanClass);

③ 集合转Json

　JSONArray fromObject = JSONArray.fromObject(Object object);

String string = fromObject.toString();

④ Json转集合

　JSONArray fromObject2 = JSONArray.fromObject(string);

　Collection collection = JSONArray.toCollection(JSONArray jsonArray, Class objectClass);

3. Fastjson

2.1 添加pom依赖

<dependency>

　　<groupId>com.alibaba</groupId>

　　<artifactId>fastjson</artifactId>

　　<version>1.2.31</version>

</dependency>

2.2 转化方法

① 对象转 Json

　JSON.toJSONString(Object object);

② Json转对象

　JSON.parseObject(String text,Class<T> Class);

③ 集合转Json

　JSON.toJSONString(Object object);

④ Json转集合

　JSON.parseArray(String text,Class<T> Class);