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());

        }

        

    }

    

    

    

}