JSONObject和JSONArray解析和構造json字串，jsonobjectjson

JSONObject和JSONArray解析和構造json字串，jsonobjectjson

JSON-lib包（最關鍵的兩個類分別是JSONObject和JSONArray）完成對json的構造和一些基本方法的使用。

二者區別：

        ①JSONObject構造的字串是索引值對形式（key:value），多個索引值對間以英文逗號串連；

        ②JSONArray構造的字串是數組形式（[array1,array2,...]）。

需要使用的包下載連結：http://pan.baidu.com/s/1o7MZ8X8 

一、JSONObject的使用。

（1）JSON字串的兩種構造方法：

①使用Java對象；②使用Map集合。

步驟一：首先建立Java工程，匯入依賴包；

步驟二：建立兩個測試類別：

Teacher.java

package com.snnu.json;import java.util.List;public class Teacher {    private String name;    private String sex;    private int age;    private List<Transport> myTool;            public Teacher(){            }        public Teacher(String name,String sex,int age,List<Transport> myTool){        this.name = name;        this.sex = sex;        this.age = age;        this.myTool = myTool;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    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;    }    public List<Transport> getMyTool() {        return myTool;    }    public void setMyTool(List<Transport> myTool) {        this.myTool = myTool;    }}

Transport.java

package com.snnu.json;public class Transport {        private String name;    private float price;        public Transport(){            }        public Transport(String name,float price){        this.name = name;        this.price = price;    }            public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public float getPrice() {        return price;    }    public void setPrice(float price) {        this.price = price;    }                }

步驟三：寫main方法

       方式一：

package com.snnu.json;import java.util.ArrayList;import java.util.List;import net.sf.json.JSONObject;public class Demo_creajsonFromObject {    // 利用java對象產生json字串    public JSONObject createJsonFromObject(Object object) {        return JSONObject.fromObject(object);    }    public static void main(String[] args) {        // TODO Auto-generated method stub        Demo_creajsonFromObject demo = new Demo_creajsonFromObject();        Teacher t = new Teacher();        t.setName("張三");        t.setSex("男");        t.setAge(21);        Transport bike = new Transport("單車", 267);        Transport motorcycle = new Transport(">機車", 3267);        Transport car = new Transport("小汽車", 100000);        List<Transport> tools = new ArrayList<Transport>();        tools.add(bike);        tools.add(motorcycle);        tools.add(car);        t.setMyTool(tools);        JSONObject ob = demo.createJsonFromObject(t);        System.out.println(ob);    }}

       產生的json字串為：

{    "age": 21,    "myTool": [        {            "name": "單車",            "price": 267        },        {            "name": ">機車",            "price": 3267        },        {            "name": "小汽車",            "price": 100000        }    ],    "name": "張三",    "sex": "男"}

   

 

 方式二：

package com.snnu.json;import java.util.HashMap;import java.util.Map;import net.sf.json.JSONObject;public class Demo_creajsonFromMap {    //使用map集合產生json字串    public JSONObject createJsonFromMap(Map<String,String> map){        JSONObject jsob=new JSONObject();        jsob.putAll(map);        return jsob;    }            public static void main(String[] args) {        // TODO Auto-generated method stub        Demo_creajsonFromMap demo=new Demo_creajsonFromMap();                Map<String,String> mmap=new HashMap<String,String>();        mmap.put("name", "張三");        mmap.put("sex", "男");        mmap.put("age", "21");                JSONObject ob=demo.createJsonFromMap(mmap);        System.out.println(ob);            }}

產生的json字串為：

{    "sex": "男",    "name": "張三",    "age": "21"}

（2）JSONObject的三個常用方法舉例。

package com.snnu.json;import java.util.ArrayList;import java.util.List;import net.sf.json.JSONObject;public class MethodTest {    //put方法：在一個json中插入一個節點，若該節點已存在，則該節點的值將會被替換    public JSONObject testPut(){        JSONObject jo1=new JSONObject();                jo1.put("a", "1");        jo1.put("b", "2");        jo1.put("c", "3");                Transport bike=new Transport("bike",200);        jo1.put("d", bike);                List<String> list=new ArrayList<String>();        list.add("one");        list.add("two");        list.add("three");        jo1.put("e", list);                jo1.put("a", "100");                return jo1;    }            //accumulate方法:可以在同一個key下累積值，若key對應的value有值，則以數組形式累積；否則相當於put方法    public JSONObject testAccumulate(){        JSONObject jo2=new JSONObject();                jo2.put("a", "1");        jo2.put("b", "2");        jo2.put("c", "3");        jo2.accumulate("c", "300");                Transport bike=new Transport("bike",200);        jo2.accumulate("c", bike);                List<String> list=new ArrayList<String>();        list.add("one");        list.add("two");        list.add("three");        jo2.accumulate("c", list);                jo2.put("d", "4");                return jo2;    }            //與put方法基本一致    public JSONObject testElement(){        JSONObject jo3=new JSONObject();                jo3.put("a", "1");        jo3.put("b", "2");        jo3.put("c", "3");        jo3.element("c", "300");                        return jo3;    }                public static void main(String[] args) {        // TODO Auto-generated method stub        MethodTest test=new MethodTest();        System.out.println("JSONObject的put方法使用"+test.testPut());        System.out.println("JSONObject的accumulate方法使用"+test.testAccumulate());        System.out.println("JSONObject的element方法使用"+test.testElement());            }}

 

    ①put方法輸出json字串格式化結果為：

{    "a": "100",    "b": "2",    "c": "3",    "d": {        "name": "bike",        "price": 200    },    "e": [        "one",        "two",        "three"    ]}

    ②accumulate方法輸出json字串格式化結果為：

{    "a": "1",    "b": "2",    "c": [        "3",        "300",        {            "name": "bike",            "price": 200        },        [            "one",            "two",            "three"        ]    ],    "d": "4"}

    ③element方法輸出json字串格式化結果為：

{    "a": "1",    "b": "2",    "c": "300"}

 二、JSONArray的使用

（1）基本使用：

package com.snnu.json;import net.sf.json.JSONArray;import net.sf.json.JSONObject;public class demo_JsonArray {            public JSONObject testJsonArray(){        JSONObject ob=new JSONObject();                JSONArray ja=new JSONArray();        ja.add("1");        ja.add("2");        ja.add("3");        ja.add("4");        ja.add("5");                ob.put("array", ja);                return ob;    }            public static void main(String[] args) {        // TODO Auto-generated method stub        demo_JsonArray djs=new demo_JsonArray();        System.out.println("JSONArray的使用："+djs.testJsonArray());            }}

對輸出後的字串進行格式化：

{    "array": [        "1",        "2",        "3",        "4",        "5"    ]}

三、綜合執行個體

package com.snnu.json;import net.sf.json.JSONArray;import net.sf.json.JSONObject;public class demo_testJson {                public JSONObject test(){                JSONObject jo=new JSONObject();        jo.put("name", "張三");        jo.put("sex","f");        jo.put("age",21);                Transport bike=new Transport("bike",250);        jo.put("extra", bike);        Transport car=new Transport("car",10000);        jo.accumulate("extra", car);        Transport motor=new Transport("motor",3000);        jo.accumulate("extra", motor);                System.out.println(jo);                //根據key值（為extra）取對應的value        String value=jo.getString("extra");        System.out.println(value);                //將字串轉化為JSONArray        JSONArray jsar=JSONArray.fromObject(value);        String str_2=String.valueOf(jsar.get(1));        System.out.println(str_2);                //將字串轉化為JSONObject        JSONObject jsob=JSONObject.fromObject(str_2);        System.out.println("名稱："+jsob.getString("name"));        System.out.println("價錢："+jsob.getString("price"));                System.out.println("-------------------------------分界線-------------------------------------------");                return jo;            }    public static void main(String[] args) {        // TODO Auto-generated method stub        demo_testJson dtj=new demo_testJson();        System.out.println("綜合測試："+dtj.test());    }}

輸出結果為：

{"name":"張三","sex":"f","age":21,"extra":[{"name":"bike","price":250},{"name":"car","price":10000},{"name":"motor","price":3000}]}[{"name":"bike","price":250},{"name":"car","price":10000},{"name":"motor","price":3000}]{"name":"car","price":10000}名稱：car價錢：10000-------------------------------分界線-------------------------------------------綜合測試：{"name":"張三","sex":"f","age":21,"extra":[{"name":"bike","price":250},{"name":"car","price":10000},{"name":"motor","price":3000}]}