您必须掌握的Java基础：JSON解析工具-json-lib

一、简介 

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

二、准备 

在使用json-lib之前，我们应该到官方网址下载如下包： 

• 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 

并将这些jar包引入到Eclipse项目当中，即可调用。 

三、讲解 

在进行下面的代码演示之前，我们先将几个基本的类介绍一下： 

MyBean类： 

public class MyBean { 
    private String id = null; 
    private String name = null; 
? ? private Date date = null; 
? ? private List cardNum = null; 
    private String[] cardType = {"身份证", "银行卡" , "公车卡"}; 
 
? ? public String getId() { 
        return id; 
    } 
? ? public void setId(String id) { 
        this.id = id; 
    } 
    public String getName() { 
        return name; 
    } 
? ? public void setName(String name) { 
        this.name = name; 
    } 
? ? public Date getDate() { 
        return date; 
    } 
? ? public void setDate(Date date) { 
        this.date = date; 
    } 
? ? public List getCardNum() { 
? ? ? ? return cardNum; 
    } 
? ? public void setCardNum(List cardNum) { 
? ? ? ? this.cardNum = cardNum; 
    } 
? ? public String[] getCardType() { 
? ? ? ? return cardType; 
    } 
? ? public void setCardType(String[] cardType) { 
         this.cardType = cardType; 
    } 
} 

Person类： 

public class Person { 
    private String name = null; 
    public Person(){ 
    } 
    public Person(String name){ 
        this.name = name; 
    } 
? ? public String getName() { 
        return name; 
    } 
? ? public void setName(String name) { 
        this.name = name; 
    } 
} 
 
MyBeanWithPerson类： 
public class MyBeanWithPerson { 
    private List<Person> list = null; 
? ? private Map<String,Person> map = null; 
? ? public List getList() { 
        return list; 
    } 
? ? public void setList(List list) { 
        this.list = list; 
    } 
? ? public Map getMap() { 
        return map; 
    } 
? ? public void setMap(Map map) { 
        this.map = map; 
    } 
} 

1.将json字符串转换成JSON，根据情况用JSONArray或JSONObject 

public static void testJsonStrToJSON() { 
    JSONArray jsonArray = JSONArray.fromObject("[\"json\",\"is\",\"easy\"]"); 
? ? System.out.println(jsonArray); 
} 

2.将Java Bean转换成JSON对象 

public static 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); 
} 

3.将一般的数组转换成JSON 

public static void testArrayToJSON() { 
    boolean[] boolArray = new boolean[] { true, false, true }; 
    JSONArray jsonArray = JSONArray.fromObject(boolArray); 
    System.out.println(jsonArray); 
} 

4.将Collection对象转换成JSON 

public static void testListToJSON() { 
    List list = new ArrayList(); 
    list.add("first"); 
    list.add("second"); 
? ? JSONArray jsonArray = JSONArray.fromObject(list); 
? ? System.out.println(jsonArray); 
}  

5.将Map转换成JSON 

public static 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); 
} 

6.将普通类型的JSON字符串转换成JSON 

public static void testJSONToObject() throws Exception { 
    // 将JSon字符串转换成JsonObject对象 
    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); 
 
     // 将JsonObject对象转换成JavaBean对象 
    Object bean = JSONObject.toBean(jsonObject); 
? ? 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); 
    } 
}  

7.将复合类型的JSON字符串转换成复合对象，包含List 

public static void testJSONToBeanHavaList() { 
    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()); 
        } 
    } 
} 

8.将复合类型的JSON字符串转换成复合对象，包含Map 

public static 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()); 
    } 
}