三种json类库举例
三种类库为：json-lib；Gson；Jackson
用法源码见附件。
1：json-lib
中心jar：json-lib-2.4.jar
支持jar：
commons-beanutils-1.9.2.jar
commons-collections-3.2.1.jar
commons-lang-2.6.jar
commons-logging-1.1.3.jar
ezmorph-1.0.6.jar
用法举例：
// 创建JSONObject对象
private static JSONObject createJSONObject() {
JSONObject jsonObject = new JSONObject();
jsonObject.put("name", "kevin");
jsonObject.put("age", 20);
jsonObject.put("sex", "男");
return jsonObject;
}
public static void main(String[] args) {
JSONObject jsonObject = createJSONObject();
// 添加属性
jsonObject.element("job", "程序员");
// 获取属性值
System.out.println(jsonObject.get("job"));
// jsonObject转String
String jsonString = jsonObject.toString();
System.out.println(jsonString);
//String转jsonObject
JSONObject jsonObject2 = jsonObject.fromObject(jsonString);
System.out.println(jsonObject2.get("name"));
}
2：Gson
需要的jar:gson-2.2.4.jar
public static User createUser(){
User u = new User();
u.setAge(20);
u.setJob("程序员");
u.setName("lyl");
u.setSex("男");
return u;
}
public static void main(String[] args) {
User u = createUser();
Gson gson = new Gson();
//对象转json串
String gsonString = gson.toJson(u);
System.out.println(gsonString);
//json串转对象
User u2 = gson.fromJson(gsonString, User.class);
System.out.println(u2.getName());
}
3：jackson
中心jar：jackson-core-2.3.2.jar
其他支持jar
jackson-annotations-2.3.2.jar
jackson-databind-2.3.2.jar
public static User createUser(){
User u = new User();
u.setAge(20);
u.setJob("程序员");
u.setName("lyl");
u.setSex("男");
return u;
}
public static void main(String[] args) throws JsonParseException, JsonMappingException, IOException {
ObjectMapper mapper = new ObjectMapper();
User u = createUser();
//json对象转json串
Writer strWriter = new StringWriter();
mapper.writeValue(strWriter, u);
String userDataJSON = strWriter.toString();
System.out.println(userDataJSON);
//json串转json对象
User userFromJSON = mapper.readValue(userDataJSON, User.class);
System.out.println(userFromJSON);
}