你必须掌握的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;
ﾠ ﾠ private Date date = null;
ﾠ ﾠ private List cardNum = null;
    private String[] cardType = {"身份证", "银行卡" , "公车卡"}; 

ﾠ ﾠ public String getId() {
        return id;
    }
ﾠ ﾠ public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
ﾠ ﾠ public void setName(String name) {
        this.name = name;
    }
ﾠ ﾠ public Date getDate() {
        return date;
    }
ﾠ ﾠ public void setDate(Date date) {
        this.date = date;
    }
ﾠ ﾠ public List getCardNum() {
ﾠ ﾠ ﾠ ﾠ return cardNum;
    }
ﾠ ﾠ public void setCardNum(List cardNum) {
ﾠ ﾠ ﾠ ﾠ this.cardNum = cardNum;
    }
ﾠ ﾠ public String[] getCardType() {
ﾠ ﾠ ﾠ ﾠ return cardType;
    }
ﾠ ﾠ 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;
    }
ﾠ ﾠ public String getName() {
        return name;
    }
ﾠ ﾠ public void setName(String name) {
        this.name = name;
    }
} 

MyBeanWithPerson类：
public class MyBeanWithPerson {
    private List<Person> list = null;
ﾠ ﾠ private Map<String,Person> map = null;
ﾠ ﾠ public List getList() {
        return list;
    }
ﾠ ﾠ public void setList(List list) {
        this.list = list;
    }
ﾠ ﾠ public Map getMap() {
        return map;
    }
ﾠ ﾠ 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\"]");
ﾠ ﾠ 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()); 

ﾠ ﾠ List cardNum = new ArrayList();
    cardNum.add("农行");
    cardNum.add("工行");
    cardNum.add("建行");
    cardNum.add(new Person("test")); 

ﾠ ﾠ bean.setCardNum(cardNum); 

ﾠ ﾠ JSONObject jsonObject = JSONObject.fromObject(bean);
ﾠ ﾠ 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");
ﾠ ﾠ JSONArray jsonArray = JSONArray.fromObject(list);
ﾠ ﾠ 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]; }"); 

ﾠ ﾠ JSONObject jsonObject = JSONObject.fromObject(map);
ﾠ ﾠ 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);
ﾠ ﾠ System.out.println(PropertyUtils.getProperty(bean, "name"));
ﾠ ﾠ System.out.println(PropertyUtils.getProperty(bean, "bool"));
ﾠ ﾠ System.out.println(PropertyUtils.getProperty(bean, "int"));
    System.out.println(PropertyUtils.getProperty(bean, "double"));
ﾠ ﾠ System.out.println(PropertyUtils.getProperty(bean, "func"));
ﾠ ﾠ System.out.println(PropertyUtils.getProperty(bean, "array"));
ﾠ ﾠ List arrayList = (List) JSONArray.toCollection(jsonObject.getJSONArray("array"));
ﾠ ﾠ 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);
ﾠ ﾠ MyBeanWithPerson diyBean = (MyBeanWithPerson) JSONObject.toBean(
ﾠ ﾠ JSONObject.fromObject(json), MyBeanWithPerson.class, classMap);
ﾠ ﾠ System.out.println(diyBean); 

ﾠ ﾠ List list = diyBean.getList();
    for (Object o : list) {
        if (o instanceof Person) {
            Person p = (Person) o;
ﾠ ﾠ ﾠ ﾠ ﾠ ﾠ 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);
ﾠ ﾠ System.out.println(diyBean); 

ﾠ ﾠ System.out.println("do the list release");
    List<Person> list = diyBean.getList();
    for (Person o : list) {
        Person p = (Person) o;
ﾠ ﾠ ﾠ ﾠ System.out.println(p.getName());
    } 

ﾠ ﾠ 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();
ﾠ ﾠ Morpher dynaMorpher = new BeanMorpher(Person.class, morpherRegistry);
    morpherRegistry.registerMorpher(dynaMorpher); 

ﾠ ﾠ 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
ﾠ ﾠ System.out.println(map);
ﾠ ﾠ ﾠList<Person> output = new ArrayList();
ﾠ ﾠ 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) {
ﾠ ﾠ ﾠ ﾠ System.out.println(p.getName());
    }
}