JSONObject JSONArray

一、JAR包简介

要使程序可以运行必须引入json-lib包，json-lib包同时依赖于以下的jar包(当时环境下所配备的jar版本)：

1.commons-lang-2.4.jar (注:不是lang3版本的jar包，若是引入commons-lang3-3.1.jar，会发生 java.lang.NoClassDefFoundError:org/apache/commons/lang/exception/NestableRuntimeException)

2.commons-beanutils-1.8.3.jar

3.commons-collections-3.2.1.jar

4.commons-logging-1.1.jar

5.ezmorph-1.0.6.jar

6.json-lib-2.4-jdk15.jar

************import net.sf.json.JSONObject; 而不是org.json.simple.JSONObject ************

二、例子(新建Book对象包含属性name和price)

1、从Object到String：先用Object对象构造一个JSONObject对象或是JSONArray对象，再调用toString()方法

示例一：object——>String

package renren.action;

import java.util.ArrayList;

import java.util.List;

import net.sf.json.JSONArray;

import net.sf.json.JSONObject;

public class Json {

public static void main(String[] args) {

Book book=new Book();

book.setName("Java");

book.setPrice(52.3f);

JSONObject obj = JSONObject.fromObject(book);

System.out.println(book.toString()); //
renren.action.Book@10f6d3

System.out.println(obj.toString()); // {"name":"Java","price":52.3}

}

}

示例二：List<Object>——>String

public class Json {

public static void main(String[] args) {

Book book=new Book();

book.setName("Java");

book.setPrice(52.3f);

Book book2 = new Book();

book2.setName("C++");

book2.setPrice(42.3f);

List list = new ArrayList();

list.add(book);

list.add(book2);

JSONArray array = JSONArray.fromObject(list);

System.out.println(list.toString()); // [renren.action.Book@17ee8b8,
renren.action.Book@e0b6f5]

System.out.println(array.toString()); // [{"name":"Java","price":52.3},{"name":"C++","price":42.3}]

}

}

示例三：Object对象数组——>String

Book[] book=new Book[2]; //对象数组申明

for(int i=0; i<book.length; i++) {

book[i] = new Book(); //对象数组初始化

}

book[0].setName("Java");

book[0].setPrice(52.3f);

book[1].setName("C++");

book[1].setPrice(42.3f);

JSONArray arr = JSONArray.fromObject(book);

System.out.println(arr.toString()); // [{"name":"Java","price":52.3},{"name":"C++","price":42.3}]

2、从String到Object：先用String对象构造JSONObject对象或是JSONArray对象

示例一：

String str = "{name:'Java',Price:52.3}";

JSONObject obj = JSONObject.fromObject(str);

System.out.println(obj.get("name") + " " + obj.get("Price")); //Java 52.3

System.out.println(obj.toString()); //{"name":"Java","Price":52.3}

示例二：

String str = "[{name:'Java',price:52.3},{name:'C++',price:42.3}]";

JSONArray arr = JSONArray.fromObject(str);

for(int i=0; i<arr.size(); i++) {

Map o = (Map)arr.get(i);

System.out.println(o.get("name") + " " + o.get("price"));

}

//Java 52.3

//C++ 42.3

3、从String到Bean

示例一：单个Bean对象

String str = "{name:'Java',price:52.3}";

JSONObject obj = JSONObject.fromObject(str);

Book book = (Book)JSONObject.toBean(obj, Book.class);

System.out.println(book.getName() + " " + book.getPrice());

示例二：Bean数组

String str = "[{name:'Java',price:52.3},{name:'C++',price:42.3}]";

JSONArray arr = JSONArray.fromObject(str);

Book[] books = (Book[])JSONArray.toArray(arr, Book.class);

for(Book b:books) {

System.out.println(b.getName() + " " + b.getPrice());

}

三、自定义封装JSON操作的类

package com.util;

import java.util.List;

import java.util.Map;

import net.sf.json.JSONArray;

import net.sf.json.JSONObject;

public class JsonHelper {

//从普通的Bean转换为字符串

public static String getJson(Object o){

JSONObject jo=JSONObject.fromObject(o);

return jo.toString();

}

//从Java的列表转换为字符串

public static String getJson(List list){

JSONArray ja=JSONArray.fromObject(list);

return ja.toString();

}

//从Java对象数组转换为字符串

public static String getJson(Object[] arry){

JSONArray ja=JSONArray.fromObject(arry);

return ja.toString();

}

//从json格式的字符串转换为Map对象

public static Map getObject(String s){

return JSONObject.fromObject(s);

}

//从json格式的字符串转换为List数组

public static List getArray(String s){

return JSONArray.fromObject(s);

}

//从json格式的字符串转换为某个Bean

public static Object getObject(String s,Class cls){

JSONObject jo=JSONObject.fromObject(s);

return JSONObject.toBean(jo, cls);

}

//从json格式的字符串转换为某类对象的数组

public static Object getArray(String s,Class cls){

JSONArray ja=JSONArray.fromObject(s);

return JSONArray.toArray(ja, cls);

}

}