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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":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: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);
}
} （编辑：李大同）
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