Jason 和 Java 对象转化示例

1.工程

2.代码：

JsonUtil.java

package com.my.json;



import java.util.ArrayList;

import java.util.List;



import net.sf.json.JSONArray;

import net.sf.json.JSONObject;



public class JsonUtil {



    /**

     * 从一个JSON 对象字符格式中得到一个java对象

     * 

     * @param jsonString

     *            json字符串

     * 

     * @param pojoCalss

     *            java对象的class

     * 

     * @return

     */



    public static Object jsonString2Object(String jsonString, Class pojoCalss) {



        Object pojo;



        JSONObject jsonObject = JSONObject.fromObject(jsonString);



        pojo = JSONObject.toBean(jsonObject, pojoCalss);



        return pojo;



    }



    /**

     * 

     * 将java对象转换成json字符串<br>

     * 支持复杂类型：Java bean 中既有属性又有list

     * 

     * @param javaObj

     * 

     * @return

     */



    public static String object2JsonString(Object javaObj) {



        JSONObject json;



        json = JSONObject.fromObject(javaObj);



        return json.toString();



    }







    /**

     * 

     * 从json对象集合表达式中得到一个java对象列表

     * 

     * @param jsonString

     * 

     * @param pojoClass

     * 

     * @return

     */



    public static List jsonList2JavaList(String jsonString, Class pojoClass) {



        JSONArray jsonArray = JSONArray.fromObject(jsonString);



        JSONObject jsonObject;



        Object pojoValue;



        List list = new ArrayList();



        for (int i = 0; i < jsonArray.size(); i++) {



            jsonObject = jsonArray.getJSONObject(i);



            pojoValue = JSONObject.toBean(jsonObject, pojoClass);



            list.add(pojoValue);



        }



        return list;



    }



    /**

     * 

     * 从json对象集合表达式中得到一个java对象列表

     * 

     * @param jsonString

     * 

     * @param pojoClass

     * 

     * @return

     */



    public static String javaList2JsonList(List list) {



        JSONArray jsonArray = JSONArray.fromObject(list);

        return jsonArray.toString();

    }

/**
* Json转化为map
*/
public static Map<String, Object> parseJSON2Map(String jsonStr){  

        Map<String, Object> map = new HashMap<String, Object>();  

        //最外层解析  

        JSONObject json = JSONObject.fromObject(jsonStr);  

        for(Object k : json.keySet()){  

            Object v = json.get(k);   

            //如果内层还是数组的话，继续解析  

            if(v instanceof JSONArray){  

                List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();  

                Iterator<JSONObject> it = ((JSONArray)v).iterator();  

                while(it.hasNext()){  

                    JSONObject json2 = it.next();  

                    list.add(parseJSON2Map(json2.toString()));  

                }  

                map.put(k.toString(), list);  

            } else {  

                map.put(k.toString(), v);  

            }  

        }  

        return map;  

    } 

　　

}

Person.java

package com.my.json;



import java.util.ArrayList;

import java.util.List;



public class Person {



    private String name;



    private List<Person> list = new ArrayList<Person>();



    public List<Person> getList() {

        return list;

    }



    public void setList(List<Person> list) {

        this.list = list;

    }



    @Override

    public String toString() {

        return "Person [name=" + name + ", num=" + num + ", sex=" + sex

                + ", age=" + age + "]";

    }



    private int num;

    private String sex;

    private int age;



    public Person() {

        // TODO Auto-generated constructor stub

    }



    public Person(String name, int num, String sex, int age) {

        super();

        this.name = name;

        this.num = num;

        this.sex = sex;

        this.age = age;

    }



    public String getName() {

        return name;

    }



    public void setName(String name) {

        this.name = name;

    }



    public int getNum() {

        return num;

    }



    public void setNum(int num) {

        this.num = num;

    }



    public String getSex() {

        return sex;

    }



    public void setSex(String sex) {

        this.sex = sex;

    }



    public int getAge() {

        return age;

    }



    public void setAge(int age) {

        this.age = age;

    }



}

Test.java

package com.my.json;



import java.util.ArrayList;

import java.util.List;

import java.util.Map;



import net.sf.json.JSONObject;



public class Test {

    public static void main(String[] args) {



        // 将一个java对象转换为Json字符串

        Person p = new Person("gu1", 123, "male", 23);

        String str = JsonUtil.object2JsonString(p);

        System.out.println(str);



        // 将一个JSON字符串转化为Java对象

        String s = "{\"age\":23,\"name\":\"gu1\",\"num\":123,\"sex\":\"male\"}";

        Person p2 = (Person) JsonUtil.jsonString2Object(s, Person.class);

        System.out.println(p2);



        // 将一个对象列表转化为JSON列表

        List<Person> list = new ArrayList<Person>();

        for (int i = 0; i < 5; i++) {

            Person persion = new Person("zhang" + i, 1 + i, "man" + i, 1 + i);

            list.add(persion);

        }

        String jsonList = JsonUtil.javaList2JsonList(list);

        System.out.println(jsonList);



        // 将一个JSON列表转化为Java列表

        String jst = "[{\"age\":1,\"list\":[],\"name\":\"zhang0\",\"num\":1,\"sex\":\"man0\"},{\"age\":2,\"list\":[],\"name\":\"zhang1\",\"num\":2,\"sex\":\"man1\"},{\"age\":3,\"list\":[],\"name\":\"zhang2\",\"num\":3,\"sex\":\"man2\"},{\"age\":4,\"list\":[],\"name\":\"zhang3\",\"num\":4,\"sex\":\"man3\"},{\"age\":5,\"list\":[],\"name\":\"zhang4\",\"num\":5,\"sex\":\"man4\"}]";

        List<Person> l = (List<Person>) JsonUtil.jsonList2JavaList(jst,

                Person.class);

        System.out.println(l.size());



        // 复杂类型转JSON：Java bean 中既有属性又有list（项目中经常见到）

        List<Person> list2 = new ArrayList<Person>();

        for (int i = 0; i < 10; i++) {

            Person persion = new Person("zhang" + i, 1 + i, "man" + i, 1 + i);

            list2.add(persion);

        }

        Person me = new Person("zhang", 1, "man", 1);

        me.setList(list2);



        String str2 = JsonUtil.object2JsonString(me);

        System.out.println(str2);



        // 复杂类型转Java：JSON 中既有属性又有list（项目中经常见到）

        String ss = "{\"age\":1,\"list\":[{\"age\":1,\"list\":[],\"name\":\"zhang0\",\"num\":1,\"sex\":\"man0\"},{\"age\":2,\"list\":[],\"name\":\"zhang1\",\"num\":2,\"sex\":\"man1\"},{\"age\":3,\"list\":[],\"name\":\"zhang2\",\"num\":3,\"sex\":\"man2\"},{\"age\":4,\"list\":[],\"name\":\"zhang3\",\"num\":4,\"sex\":\"man3\"},{\"age\":5,\"list\":[],\"name\":\"zhang4\",\"num\":5,\"sex\":\"man4\"},{\"age\":6,\"list\":[],\"name\":\"zhang5\",\"num\":6,\"sex\":\"man5\"},{\"age\":7,\"list\":[],\"name\":\"zhang6\",\"num\":7,\"sex\":\"man6\"},{\"age\":8,\"list\":[],\"name\":\"zhang7\",\"num\":8,\"sex\":\"man7\"},{\"age\":9,\"list\":[],\"name\":\"zhang8\",\"num\":9,\"sex\":\"man8\"},{\"age\":10,\"list\":[],\"name\":\"zhang9\",\"num\":10,\"sex\":\"man9\"}],\"name\":\"zhang\",\"num\":1,\"sex\":\"man\"}";

        Map map = (Map)JSONObject.fromObject(ss); 

        

        System.out.println("------------------------------");

        System.out.println(map);

        String name = (String)map.get("name");

        int num = (Integer)map.get("num");

        String sex = (String)map.get("sex");

        int age = (Integer)map.get("age");

        System.out.println("name="+name);

        System.out.println("num="+"num");

        System.out.println("sex="+"sex");

        System.out.println("age="+"age");

        System.out.println("list="+map.get("list"));

        //获取list字符串，再转化为Java 对象,其实是再次构建成Java bean

        String listStr = map.get("list").toString();//一定要用toString，不能强转

        List<Person> ll = JsonUtil.jsonList2JavaList(listStr, Person.class);

        //构建新的bean：不知是否有其他方案,根据需要是否构建

        Person pp = new Person(name,num,sex,age);

        pp.setList(ll);

        //输出bean

        for (Person ps : pp.getList())

        {

            System.out.println(ps.getName());

        }

            

    }

}

输出：

{"age":23,"list":[],"name":"gu1","num":123,"sex":"male"}
Person [name=gu1, num=123, sex=male, age=23]
[{"age":1,"list":[],"name":"zhang0","num":1,"sex":"man0"},{"age":2,"list":[],"name":"zhang1","num":2,"sex":"man1"},{"age":3,"list":[],"name":"zhang2","num":3,"sex":"man2"},{"age":4,"list":[],"name":"zhang3","num":4,"sex":"man3"},{"age":5,"list":[],"name":"zhang4","num":5,"sex":"man4"}]
5
{"age":1,"list":[{"age":1,"list":[],"name":"zhang0","num":1,"sex":"man0"},{"age":2,"list":[],"name":"zhang1","num":2,"sex":"man1"},{"age":3,"list":[],"name":"zhang2","num":3,"sex":"man2"},{"age":4,"list":[],"name":"zhang3","num":4,"sex":"man3"},{"age":5,"list":[],"name":"zhang4","num":5,"sex":"man4"},{"age":6,"list":[],"name":"zhang5","num":6,"sex":"man5"},{"age":7,"list":[],"name":"zhang6","num":7,"sex":"man6"},{"age":8,"list":[],"name":"zhang7","num":8,"sex":"man7"},{"age":9,"list":[],"name":"zhang8","num":9,"sex":"man8"},{"age":10,"list":[],"name":"zhang9","num":10,"sex":"man9"}],"name":"zhang","num":1,"sex":"man"}
------------------------------
{"age":1,"list":[{"age":1,"list":[],"name":"zhang0","num":1,"sex":"man0"},{"age":2,"list":[],"name":"zhang1","num":2,"sex":"man1"},{"age":3,"list":[],"name":"zhang2","num":3,"sex":"man2"},{"age":4,"list":[],"name":"zhang3","num":4,"sex":"man3"},{"age":5,"list":[],"name":"zhang4","num":5,"sex":"man4"},{"age":6,"list":[],"name":"zhang5","num":6,"sex":"man5"},{"age":7,"list":[],"name":"zhang6","num":7,"sex":"man6"},{"age":8,"list":[],"name":"zhang7","num":8,"sex":"man7"},{"age":9,"list":[],"name":"zhang8","num":9,"sex":"man8"},{"age":10,"list":[],"name":"zhang9","num":10,"sex":"man9"}],"name":"zhang","num":1,"sex":"man"}
name=zhang
num=num
sex=sex
age=age
list=[{"age":1,"list":[],"name":"zhang0","num":1,"sex":"man0"},{"age":2,"list":[],"name":"zhang1","num":2,"sex":"man1"},{"age":3,"list":[],"name":"zhang2","num":3,"sex":"man2"},{"age":4,"list":[],"name":"zhang3","num":4,"sex":"man3"},{"age":5,"list":[],"name":"zhang4","num":5,"sex":"man4"},{"age":6,"list":[],"name":"zhang5","num":6,"sex":"man5"},{"age":7,"list":[],"name":"zhang6","num":7,"sex":"man6"},{"age":8,"list":[],"name":"zhang7","num":8,"sex":"man7"},{"age":9,"list":[],"name":"zhang8","num":9,"sex":"man8"},{"age":10,"list":[],"name":"zhang9","num":10,"sex":"man9"}]
zhang0
zhang1
zhang2
zhang3
zhang4
zhang5
zhang6
zhang7
zhang8
zhang9