浅谈JSONObject的使用

简介

在程序开发过程中,在参数传递,函数返回值等方面,越来越多的使用JSON。JSON(JavaScript Object Notation)是一种轻量级的数据交换格式,同时也易于机器解析和生成、易于理解、阅读和撰写,而且Json采用完全独立于语言的文本格式,这使得Json成为理想的数据交换语言。 

JSON建构于两种结构:


“名称/值”对的集合(A Collection of name/value pairs),在不同的语言中,它被理解为对象(Object), 记录(record), 结构(struct), 字典(dictionary), 有趣列表(keyed list), 哈希表(hash table)或者关联数组(associative array)。


JSONObject依赖:


最后一行需要保留,有两个jdk版本的实现: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




jar包下载:https://pan.baidu.com/s/1iZiXw55TPwIxYFQQCaR9Gw


JSONObject

创建JSONObject,添加属性


//创建JSONObject

JSONObject 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("sex", "男");

json.put("age", 18);

System.out.println(json);

根据key返回输出


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

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);

把JSONArray添加到JSONObject中


/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);

全部代码:


import net.sf.json.JSONArray;

import net.sf.json.JSONObject;

 

public class Json {

public static void main(String[] args) {

//创建JSONObject

JSONObject 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("sex", "男");

json.put("age", 18);

System.out.println(json);

//根据key返回

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

//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:




JSONArray

创建JSONArray,添加属性值


//创建JSONArray

JSONArray 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.

全部代码:


import net.sf.json.JSONArray;

import net.sf.json.JSONObject;

 

public class Json {

public static void main(String[] args) {

//创建JSONArray

JSONArray 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与json字符串互转

student类:


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

}

@Override

public String toString() {

return "Student [username=" + username + ", password=" + password + "]";

}

}

定义对象,JavaBean对象转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字符串转为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());

全部代码:


import net.sf.json.JSONObject;

 

public class Json {

public static void main(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:




List与json字符串互转

先定义list集合,list转json字符串


//定义list集合

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list


//json字符串转list

List 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);

全部代码


import java.util.ArrayList;

import java.util.List;

 

import net.sf.json.JSONArray;

import net.sf.json.JSONObject;

 

public class Json {

public static void main(String[] args) {

//定义list集合

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list

List 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




Map与json字符串互转

定义map集合,Map转json字符串


//定义map集合

Map map = new HashMap();

map.put("1", new Student("张三", "123"));

map.put("2", new Student("李四", "456"));

//Map转json字符串

JSONObject jsonMap = JSONObject.fromObject(map);

System.out.println(jsonMap);

定义字符串map集合,map集合字符串转为map


//定义字符串map集合

String jsondata = "{\"1\":{\"password\":\"123\",\"username\":\"张三\"},\"2\":{\"password\":\"456\",\"username\":\"李四\"}}";

//map集合字符串转为map

Map map2 = (Map)JSONObject.fromObject(jsondata);

Set set = map2.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(map2.get(key));

//转为对象

Student stu = (Student)JSONObject.toBean(jsonObject, Student.class);

System.out.println(key+"   "+stu);

}

全部代码


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 main(String[] args) {

//定义map集合

Map map = new HashMap();

map.put("1", new Student("张三", "123"));

map.put("2", new Student("李四", "456"));

//Map转json字符串

JSONObject jsonMap = JSONObject.fromObject(map);

System.out.println(jsonMap);

//定义字符串map集合

String jsondata = "{\"1\":{\"password\":\"123\",\"username\":\"张三\"},\"2\":{\"password\":\"456\",\"username\":\"李四\"}}";

//map集合字符串转为map

Map map2 = (Map)JSONObject.fromObject(jsondata);

Set set = map2.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(map2.get(key));

//转为对象

Student stu = (Student)JSONObject.toBean(jsonObject, Student.class);

System.out.println(key+"   "+stu);

}

}

}

运行结果




JSONArray与List互转

定义list集合,List转型JSONArray


//定义list集合

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

list.add(new Student("张三", "123"));

list.add(new Student("李四", "456"));

//List转型JSONArray

JSONArray jsonArray = JSONArray.fromObject(list);

System.out.println(jsonArray.toString());

JSONArray转型List,JSONArray是用的上面的那个jsonArray变量


//JSONArray转型List

List<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);

}

全部代码

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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 main(String[] args) {

//定义list集合

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

list.add(new Student("张三", "123"));

list.add(new Student("李四", "456"));

//List转型JSONArray

JSONArray jsonArray = JSONArray.fromObject(list);

System.out.println(jsonArray.toString());

//JSONArray转型List

List<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




JSONArray与数组互转

定义数组,数组转JSONArray


//定义数组

boolean[] boolArray = {true, false, true};

//java数组转JSONArray

JSONArray jsonArray = JSONArray.fromObject(boolArray);

System.out.println(jsonArray.toString());

JSONArray转java数组


//JSONArray转java数组

Object obj[] = jsonArray.toArray();

for(Object o : obj) {

System.out.print(o+"\t");

}

全部代码


import net.sf.json.JSONArray;

 

public class Json {

public static void main(String[] args) {

//定义数组

boolean[] boolArray = {true, false, true};

//java数组转JSONArray

JSONArray 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");

}

}

}



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