在程序开发过程中，JSON越来越多的应用在参数传递和函数返回值上。Json(JavaScript Object Notation)是一种轻量级的数据交换格式，也便于机器分析和生成，易于理解和读写。而且，JSON采用了完全独立于语言的文本格式，这使得Json成为一种理想的数据交换语言。

JSON有两种结构:

名称/值对的***被理解为不同语言中的对象、记录、结构、字典、键列表、哈希表或关联数组。

JSON依赖性:

最后一行需要保留。jdk有两个版本:json-lib-2.1-jdk13.jar和JSON-LIB-2.1-JDK15.jar。

<dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.4</version> <classifier>jdk15</classifier></dependency>

使用net.sf.json需要导入的Jar包

包下载:
https://pan.baidu.com/s/1izixw55tpwwixyfqqcar9gw

对象

创建JSONObject并添加属性

//创建JSONObjectJSONObject json = new JSONObject();//添加属性json.put("username", "张三");json.put("password", "123");//打印System.out.println(json); //增加属性json.element("***", "男");json.put("age", 18);System.out.println(json);

根据键返回输出。

System.out.println(json.get("***"));

确定输出对象的类型。

boolean isArray = json.isArray();boolean isEmpty = json.isEmpty();boolean isNullObject = json.isNullObject();System.out.println("是否数组："+isArray+", 是否空："+isEmpty+", 是否空为空对象："+isNullObject);

将JSONArray添加到JSONObject

/把JSONArray添加到JSONObject中JSONArray jsonArray = new JSONArray();jsonArray.add(0, "张三");jsonArray.add(1, "123");//开始添加json.element("student", jsonArray);System.out.println(json);

所有代码:

import net.sf.json.JSONArray;import net.sf.json.JSONObject; public class Json {public static void ***in(String[] args) {//创建JSONObjectJSONObject json = new JSONObject();//添加属性json.put("username", "张三");json.put("password", "123");//打印System.out.println(json);//增加属性json.element("***", "男");json.put("age", 18);System.out.println(json);//根据key返回System.out.println(json.get("***"));//判断输出对象的类型boolean isArray = json.isArray();boolean isEmpty = json.isEmpty();boolean isNullObject = json.isNullObject();System.out.println("是否数组："+isArray+", 是否空："+isEmpty+", 是否空为空对象："+isNullObject);System.out.println("=====");//把JSONArray添加到JSONObject中JSONArray jsonArray = new JSONArray();jsonArray.add(0, "张三");jsonArray.add(1, "123");//开始添加json.element("student", jsonArray);System.out.println(json);}}

运行结果:

对象

创建JSONArray并添加属性值

//创建JSONArrayJSONArray jsonArray = new JSONArray();//添加jsonArray.add(0, "张三");jsonArray.add(1, "123");jsonArray.element("男");System.

根据下标返回输出。

System.out.println(jsonArray.get(0));

根据下标设置新值，修改

jsonArray.set(0, "李四");System.out.println(jsonArray);把JSONObject放入到JSONArray中//把JSONObject放入到JSONArray中JSONObject jsonObject = new JSONObject();jsonObject.put("username", "张三");jsonObject.put("password", "123");jsonArray.add(jsonObject);System.

所有代码:

import net.sf.json.JSONArray;import net.sf.json.JSONObject; public class Json {public static void ***in(String[] args) {//创建JSONArrayJSONArray jsonArray = new JSONArray();//添加jsonArray.add(0, "张三");jsonArray.add(1, "123");jsonArray.element("男");System.out.println(jsonArray);//根据下标返回输出System.out.println(jsonArray.get(0));//根据下标设置新值，修改jsonArray.set(0, "李四");System.out.println(jsonArray);//把JSONObject放入到JSONArray中JSONObject jsonObject = new JSONObject();jsonObject.put("username", "张三");jsonObject.put("password", "123");jsonArray.add(jsonObject);System.out.println(jsonArray);//循环输出for(int i = 0; i < jsonArray.size(); i++) {System.out.println(jsonArray.get(i));}}}

运行结果

JavaBean和json字符串交换。

学生班级:

public class Student {private String username;private String password;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public Student(String username, String password) {super();this.username = username;this.password = password;}public Student() {super();// TODO Auto-generated constructor stub}@Overridepublic String toString() {return "Student [username=" + username + ", password=" + password + "]";}}

对象，JavaBean对象到json字符串

//定义对象Student stu = new Student("张三", "123456");//JavaBean对象转json字符串JSONObject jsonObject = JSONObject.fromObject(stu);System.out.println(jsonObject);

Json字符串到javaBean

//json字符串转为javaBean//定义json字符串String jsondata = "{"username":"李四", "password":"123"}";//转为json对象JSONObject json = JSONObject.fromObject(jsondata);//转为JavaBean对象Student stu2 = (Student)JSONObject.toBean(json, Student.class);System.out.println(stu2.toString());

所有代码:

import net.sf.json.JSONObject; public class Json {public static void ***in(String[] args) {//定义对象Student stu = new Student("张三", "123456");//JavaBean对象转json字符串JSONObject jsonObject = JSONObject.fromObject(stu);System.out.println(jsonObject);//json字符串转为javaBean//定义json字符串String jsondata = "{"username":"李四", "password":"123"}";//转为json对象JSONObject json = JSONObject.fromObject(jsondata);//转为JavaBean对象Student stu2 = (Student)JSONObject.toBean(json, Student.class);System.out.println(stu2.toString());}}

输出结果:

与List json字符串交换

首先定义列表集，并将列表转换成json字符串

//定义list***List list = new ArrayList();list.add(new Student("张三", "123"));list.add(new Student("李四", "456"));//list转json字符串JSONArray jsonArray = JSONArray.fromObject(list);System.out.println(jsonArray);

要列出的Json字符串

//json字符串转listList list2 = new ArrayList();String jsondata = "[{"password":"123","username":"张三"},{"password":"456","username":"李四"}]";JSONArray jsonArray1 = JSONArray.fromObject(jsondata);for(int i = 0; i < jsonArray1.size(); i++) {JSONObject jsonObject2 = jsonArray1.getJSONObject(i);Student stu2 = (Student)JSONObject.toBean(jsonObject2, Student.class);list2.add(stu2);}System.out.println(list2);

所有代码

import java.util.ArrayList;import java.util.List; import net.sf.json.JSONArray;import net.sf.json.JSONObject; public class Json {public static void ***in(String[] args) {//定义list***List list = new ArrayList();list.add(new Student("张三", "123"));list.add(new Student("李四", "456"));//list转json字符串JSONArray jsonArray = JSONArray.fromObject(list);System.out.println(jsonArray);//json字符串转listList list2 = new ArrayList();String jsondata = "[{"password":"123","username":"张三"},{"password":"456","username":"李四"}]";JSONArray jsonArray1 = JSONArray.fromObject(jsondata);for(int i = 0; i < jsonArray1.size(); i++) {JSONObject jsonObject2 = jsonArray1.getJSONObject(i);Student stu2 = (Student)JSONObject.toBean(jsonObject2, Student.class);list2.add(stu2);}System.out.println(list2);}}

运行结果

在***pjson字符串之间来回转换

定义映射***，并映射到json字符串

//定义***p***Map ***p = new HashMap();***p.put("1", new Student("张三", "123"));***p.put("2", new Student("李四", "456"));//Map转json字符串JSONObject jsonMap = JSONObject.fromObject(***p);System.out.println(jsonMap);

定义字符串映射集，映射集的字符串就变成了***p。

//定义字符串***p***String jsondata = "{"1":{"password":"123","username":"张三"},"2":{"password":"456","username":"李四"}}";//***p***字符串转为***pMap ***p2 = (Map)JSONObject.fromObject(jsondata);Set set = ***p2.keySet();//定义迭代器，迭代输出Iterator ite = set.iterator();while(ite.hasNext()) {//取出一个字符串对象String key = (String)ite.next();//转为json格式JSONObject jsonObject = JSONObject.fromObject(***p2.get(key));//转为对象Student stu = (Student)JSONObject.toBean(jsonObject, Student.class);System.out.println(key+" "+stu);}

所有代码

import java.util.HashMap;import java.util.Iterator;import java.util.Map;import java.util.Set; import net.sf.json.JSONObject; public class Json {public static void ***in(String[] args) {//定义***p***Map ***p = new HashMap();***p.put("1", new Student("张三", "123"));***p.put("2", new Student("李四", "456"));//Map转json字符串JSONObject jsonMap = JSONObject.fromObject(***p);System.out.println(jsonMap);//定义字符串***p***String jsondata = "{"1":{"password":"123","username":"张三"},"2":{"password":"456","username":"李四"}}";//***p***字符串转为***pMap ***p2 = (Map)JSONObject.fromObject(jsondata);Set set = ***p2.keySet();//定义迭代器，迭代输出Iterator ite = set.iterator();while(ite.hasNext()) {//取出一个字符串对象String key = (String)ite.next();//转为json格式JSONObject jsonObject = JSONObject.fromObject(***p2.get(key));//转为对象Student stu = (Student)JSONObject.toBean(jsonObject, Student.class);System.out.println(key+" "+stu);}}}

运行结果:

SONArray和List相互转换

定义列表集，并将列表转换成JSONArray

//定义list***List<Student> list = new ArrayList<Student>();list.add(new Student("张三", "123"));list.add(new Student("李四", "456"));//List转型JSONArrayJSONArray jsonArray = JSONArray.fromObject(list);System.out.println(jsonArray.toString());

JSON转换列表，JSONArray就是上面的JSONArray变量。

//JSONArray转型ListList<Student> list2 = JSONArray.toList(jsonArray, new Student(), new JsonConfig());Iterator<Student> ite = list2.iterator();while(ite.hasNext()) {Student stu = ite.next();System.out.println(stu);}

所有代码

import java.util.ArrayList;import java.util.Iterator;import java.util.List; import net.sf.json.JSONArray;import net.sf.json.JsonConfig; public class Json {public static void ***in(String[] args) {//定义list***List<Student> list = new ArrayList<Student>();list.add(new Student("张三", "123"));list.add(new Student("李四", "456"));//List转型JSONArrayJSONArray jsonArray = JSONArray.fromObject(list);System.out.println(jsonArray.toString());//JSONArray转型ListList<Student> list2 = JSONArray.toList(jsonArray, new Student(), new JsonConfig());Iterator<Student> ite = list2.iterator();while(ite.hasNext()) {Student stu = ite.next();System.out.println(stu);}}}

运行结果

JSON和array相互转换

定义数组，并将数组转换为JSONArray

//定义数组boolean[] boolArray = {true, false, true};//java数组转JSONArrayJSONArray jsonArray = JSONArray.fromObject(boolArray);System.out.println(jsonArray.toString());

JSONArray到java数组

//JSONArray转java数组Object obj[] = jsonArray.toArray();for(Object o : obj) {System.out.print(o+"t");}

所有代码

import net.sf.json.JSONArray; public class Json {public static void ***in(String[] args) {//定义数组boolean[] boolArray = {true, false, true};//java数组转JSONArrayJSONArray jsonArray = JSONArray.fromObject(boolArray);System.out.println(jsonArray.toString());//JSONArray转java数组Object obj[] = jsonArray.toArray();for(Object o : obj) {System.out.print(o+"t");}}}