使用json-lib进行Java和JSON之间的转换

1. json-lib是一个java类库，提供将Java对象，包括beans, maps, collections, java arrays and XML等转换成JSON，或者反向转换的功能。

2. json-lib 主页 ： http://json-lib.sourceforge.net/ 

3.执行环境

     需要以下类库支持

• jakarta commons-lang 2.5
• jakarta commons-beanutils 1.8.0
• jakarta commons-collections 3.2.1
• jakarta commons-logging 1.1.1
• ezmorph 1.0.6

4.功能示例

   这里通过JUnit-Case例子给出代码示例

package com.mai.json;

import static org.junit.Assert.assertEquals;

import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import net.sf.ezmorph.Morpher;
import net.sf.ezmorph.MorpherRegistry;
import net.sf.ezmorph.bean.BeanMorpher;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.util.JSONUtils;

import org.apache.commons.beanutils.PropertyUtils;
import org.junit.Test;

public class JsonLibTest {

    /*
     *  普通类型、List、Collection等都是用JSONArray解析
     *  
     *  Map、自定义类型是用JSONObject解析
     *  可以将Map理解成一个对象，里面的key/value对可以理解成对象的属性/属性值
     *  即{key1:value1,key2,value2......}
     * 
     * 1.JSONObject是一个name:values集合，通过它的get(key)方法取得的是key后对应的value部分(字符串)
     *         通过它的getJSONObject(key)可以取到一个JSONObject，--> 转换成map,
     *         通过它的getJSONArray(key) 可以取到一个JSONArray ，
     * 
     * 
     */
    
    //一般数组转换成JSON
    @Test
    public void testArrayToJSON(){
        boolean[] boolArray = new boolean[]{true,false,true};  
        JSONArray jsonArray = JSONArray.fromObject( boolArray );  
        System.out.println( jsonArray );  
        // prints [true,false,true]  
    }
    
    
    //Collection对象转换成JSON
    @Test
    public void testListToJSON(){
        List list = new ArrayList();  
        list.add( "first" );  
        list.add( "second" );  
        JSONArray jsonArray = JSONArray.fromObject( list );  
        System.out.println( jsonArray );  
        // prints ["first","second"]  
    }
    
    
    //字符串json转换成json， 根据情况是用JSONArray或JSONObject
    @Test
    public void testJsonStrToJSON(){
        JSONArray jsonArray = JSONArray.fromObject( "['json','is','easy']" );  
        System.out.println( jsonArray );  
        // prints ["json","is","easy"]  
    }
    
    
    //Map转换成json， 是用jsonObject
    @Test
    public void testMapToJSON(){
        Map map = new HashMap();  
        map.put( "name", "json" );  
        map.put( "bool", Boolean.TRUE );  
        map.put( "int", new Integer(1) );  
        map.put( "arr", new String[]{"a","b"} );  
        map.put( "func", "function(i){ return this.arr[i]; }" );  
          
        JSONObject jsonObject = JSONObject.fromObject( map );  
        System.out.println( jsonObject );  
    }
    
    //复合类型bean转成成json
    @Test
    public void testBeadToJSON(){
        MyBean bean = new MyBean();
        bean.setId("001");
        bean.setName("银行卡");
        bean.setDate(new Date());
        
        List cardNum = new ArrayList();
        cardNum.add("农行");
        cardNum.add("工行");
        cardNum.add("建行");
        cardNum.add(new Person("test"));
        
        bean.setCardNum(cardNum);
        
        JSONObject jsonObject = JSONObject.fromObject(bean);
        System.out.println(jsonObject);
        
    }
    
    //普通类型的json转换成对象
    @Test
    public void testJSONToObject() throws Exception{
        String json = "{name="json",bool:true,int:1,double:2.2,func:function(a){ return a; },array:[1,2]}";  
        JSONObject jsonObject = JSONObject.fromObject( json ); 
        System.out.println(jsonObject);
        Object bean = JSONObject.toBean( jsonObject ); 
        assertEquals( jsonObject.get( "name" ), PropertyUtils.getProperty( bean, "name" ) );  
        assertEquals( jsonObject.get( "bool" ), PropertyUtils.getProperty( bean, "bool" ) );  
        assertEquals( jsonObject.get( "int" ), PropertyUtils.getProperty( bean, "int" ) );  
        assertEquals( jsonObject.get( "double" ), PropertyUtils.getProperty( bean, "double" ) );  
        assertEquals( jsonObject.get( "func" ), PropertyUtils.getProperty( bean, "func" ) );  
        System.out.println(PropertyUtils.getProperty(bean, "name"));
        System.out.println(PropertyUtils.getProperty(bean, "bool"));
        System.out.println(PropertyUtils.getProperty(bean, "int"));
        System.out.println(PropertyUtils.getProperty(bean, "double"));
        System.out.println(PropertyUtils.getProperty(bean, "func"));
        System.out.println(PropertyUtils.getProperty(bean, "array"));
        
        List arrayList = (List)JSONArray.toCollection(jsonObject.getJSONArray("array"));
        for(Object object : arrayList){
            System.out.println(object);
        }
        
    }
    
    
    //将json解析成复合类型对象, 包含List
    @Test
    public void testJSONToBeanHavaList(){
        String json = "{list:[{name:'test1'},{name:'test2'}],map:[{test1:{name:'test1'}},{test2:{name:'test2'}}]}";
//        String json = "{list:[{name:'test1'},{name:'test2'}]}";
        Map classMap = new HashMap();
        classMap.put("list", Person.class);
        MyBeanWithPerson diyBean = (MyBeanWithPerson)JSONObject.toBean(JSONObject.fromObject(json),MyBeanWithPerson.class , classMap);
        System.out.println(diyBean);
        
        List list = diyBean.getList();
        for(Object o : list){
            if(o instanceof Person){
                Person p = (Person)o;
                System.out.println(p.getName());
            }
        }
    }
    
    
    //将json解析成复合类型对象, 包含Map
    @Test
    public void testJSONToBeanHavaMap(){
        //把Map看成一个对象
        String json = "{list:[{name:'test1'},{name:'test2'}],map:{test1:{name:'test1'},test2:{name:'test2'}}}";
        Map classMap = new HashMap();
        classMap.put("list", Person.class);
        classMap.put("map", Map.class);
        //使用暗示，直接将json解析为指定自定义对象，其中List完全解析,Map没有完全解析
        MyBeanWithPerson diyBean = (MyBeanWithPerson)JSONObject.toBean(JSONObject.fromObject(json),MyBeanWithPerson.class , classMap);
        System.out.println(diyBean);
        
        System.out.println("do the list release");
        List<Person> list = diyBean.getList();
        for(Person o : list){
            Person p = (Person)o;
            System.out.println(p.getName());
        }
        
        System.out.println("do the map release");
        
        //先往注册器中注册变换器，需要用到ezmorph包中的类
        MorpherRegistry morpherRegistry = JSONUtils.getMorpherRegistry();
        Morpher dynaMorpher = new BeanMorpher( Person.class,  morpherRegistry);  
        morpherRegistry.registerMorpher( dynaMorpher );  
        
        
        Map map = diyBean.getMap();
        /*这里的map没进行类型暗示，故按默认的，里面存的为net.sf.ezmorph.bean.MorphDynaBean类型的对象*/
        System.out.println(map);
        List<Person> output = new ArrayList();  
        for( Iterator i = map.values().iterator(); i.hasNext(); ){  
            //使用注册器对指定DynaBean进行对象变换
           output.add( (Person)morpherRegistry.morph( Person.class, i.next() ) );  
        }  
        
        for(Person p : output){
            System.out.println(p.getName());
        }
        
    }
    
    
    
}