Jackson框架提供的JsonGenerator ObjectMapper以及JSONObject 、JSONArray学习

1、jackson 框架：这个框架提供了JsonGenerator ，ObjectMapper两个类通过这两个类提供的方法可以将java 对象转化为json 对象，json 数组格式，也可以将json对象、数组格式转化为java对象。

2、json-lib框架也可以进行json格式和java 对象之间的相互转化，json-lib提供的类主要有：JSONObject ,JSONArray....

3、展现使用两种框架进行相互转化：

一、json-lib:

package com.inspur.json;

import java.util.ArrayList;

import java.util.List;

import net.sf.json.JSONArray;

import net.sf.json.JSONObject;

public class JSONTest {

public static void main(String[] args) {

User u = new User();

u.setName("name1");

u.setAge(1);

u.setPhone("123");

User u2 = new User();

u2.setName("name2");

u2.setAge(2);

u2.setPhone("321");

List list = new ArrayList();

list.add(u);

list.add(u2);

// 创建JSONObject 对象

JSONObject jobg = new JSONObject();

// 创建JSONObject 对象

JSONArray arr = new JSONArray();

// 将对象转化为json对象的格式

JSONObject str = jobg.fromObject(u);

// 将list集合转化为json数组的格式

JSONArray str1 = arr.fromObject(list);

System.out.print(str);

System.out.print("\n");

System.out.print(str1);

}

}

/* 运行结果 */

{"age":1,"name":"name1","phone":"123"}

[{"age":1,"name":"name1","phone":"123"},{"age":2,"name":"name2","phone":"321"}]

二、jackson框架提供的两个类 JsonGenerator ObjectMapper

package com.jackson.test;

import java.util.ArrayList;

import java.util.List;

import org.codehaus.jackson.JsonEncoding;

import org.codehaus.jackson.JsonGenerator;

import org.codehaus.jackson.map.ObjectMapper;

public class Test {

public static void main(String[] args) {

User u = new User();

u.setName("name1");

u.setAge(1);

u.setSex("man");

User u2 = new User();

u2.setName("name2");

u2.setAge(2);

u2.setSex("man");

List list = new ArrayList();

list.add(u);

list.add(u2);

ObjectMapper obj = new ObjectMapper();

JsonGenerator jg = null;

try {

jg = obj.getJsonFactory().createJsonGenerator(System.out,

JsonEncoding.UTF8);

System.out.println("jsonGenerator");

// writeObject可以转换java对象，eg:JavaBean/Map/List/Array等

jg.writeObject(u);

System.out.println();

jg.writeObject(list);

System.out.println();

System.out.println("ObjectMapper");

// writeValue具有和writeObject相同的功能

obj.writeValue(System.out, list);

} catch (Exception e) {

e.printStackTrace();

}

}

}

/ * 运行结果 */

jsonGenerator

{"name":"name1","age":1,"sex":"man"}

[{"name":"name1","age":1,"sex":"man"},{"name":"name2","age":2,"sex":"man"}]

ObjectMapper

[{"name":"name1","age":1,"sex":"man"},{"name":"name2","age":2,"sex":"man"}]

jackson框架jar包下载：http://download.csdn.net/detail/qh_java/7767473

json 框架jar包下载：http://download.csdn.net/detail/qh_java/7767511