JSONArray和JSONObject的简单使用
一、为什么要使用JSONArray和JSONObject
1、后台 --》前台 可以把java对象和集合转化成json字符串格式，这样在前台的ajax方法中可以直接转化成json对象使用 ，从后台向前台传值
2、前台 --》使用JSON.stringify(mdses)方法把js对象，数组，转化成json字符串 ，后台使用JSONArray或JSONObject 转化成 java对象或集合
有助于前端参数传递到后端，和后端取值y
3、json现在以成为大多数据传输的载体
二、后台解析前台ajax提交数据,使用较少一般都把list 或map转化为json形式的字符串传值到前台的ajax中：
//根据接收的json字符串来解析字符串中所包含的数据和数据对象
@Test
public void parsJsonFromFront(){
//接收到的json
String result = "[{\"username\": \"your name\", \"user_json\": {\"username\": \"your name\", \"nickname\": \"your nickname\"}}]";
//根据字符串陈
//根据字符串生成JSON对象
//如果是数组的形式 就使用 JSONArray.fromObject(result) 转化为JSONArray 对象
//如果是json对象 就是使用JSONObject.fromObject(result) 转化为JSONObject 对象
JSONArray resultArray = JSONArray.fromObject(result);
JSONObject jsonObject = resultArray.getJSONObject(0);
JSONObject user_json = jsonObject.getJSONObject("user_json");
//根据key值取值
String username = user_json.getString("username");
String nickname = user_json.getString("nickname");
System.out.println("username =" + username + ":" + "nickname = " + nickname);
//console ： username =your name:nickname = your nickname
}三 、后台转化list 或map转化为json形式的字符串传值到前台的ajax中
user bean
public class User {
private String name;
private Adress adress;
private List students;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Adress getAdress() {
return adress;
}
public void setAdress(Adress adress) {
this.adress = adress;
}
public List getStudents() {
return students;
}
public void setStudents(List students) {
this.students = students;
}
public User(String name, Adress adress, List students) {
super();
this.name = name;
this.adress = adress;
this.students = students;
}
public User() {
super();
}
} public class Adress {
private String streetName;
private String district;
public String getStreetName() {
return streetName;
}
public void setStreetName(String streetName) {
this.streetName = streetName;
}
public String getDistrict() {
return district;
}
public void setDistrict(String district) {
this.district = district;
}
public Adress(String streetName, String district) {
super();
this.streetName = streetName;
this.district = district;
}
public Adress() {
super();
// TODO Auto-generated constructor stub
}
}1）bean to json
@Test
public void beanToJson(){
List list = new ArrayList();
list.add( "xiaowang" );
list.add( "xiaohua" );
Adress adress = new Adress("streetName", "district");
JSONObject jsonObject = JSONObject.fromObject(new User("name", adress, list));
System.out.println(jsonObject.toString());
//console ：{"adress":{"district":"district","streetName":"streetName"},"name":"name","students":["xiaowang","xiaohua"]}
}2）
@Test
public void list2Json(){
List list = new ArrayList();
list.add( "first" );
list.add( "second" );
JSONArray jsonArray = JSONArray.fromObject(list);
System.out.println(jsonArray.toString());
}
public Map getMap(){
//声明一个Hash对象并添加数据
Map params = new HashMap();
params.put("username", "username");
params.put("user_json", "user");
return params;
}
@Test
public void map2Json(){
Map map = getMap();
Map map1 = getMap();
List list = new ArrayList();
list.add(map);
list.add(map1);
JSONArray jsonArray = JSONArray.fromObject(list);
System.out.println("jsonArray--->" + jsonArray.toString());
JSONArray jsonArray1 = JSONArray.fromObject(map);
System.out.println("jsonArray1--->" + jsonArray1.toString());
}完整：
public class SimpleExample {
@Test
public void list2Json(){
List list = new ArrayList();
list.add( "first" );
list.add( "second" );
JSONArray jsonArray = JSONArray.fromObject(list);
System.out.println(jsonArray.toString());
}
public Map getMap(){
//声明一个Hash对象并添加数据
Map params = new HashMap();
params.put("username", "username");
params.put("user_json", "user");
return params;
}
@Test
public void map2Json(){
Map map = getMap();
Map map1 = getMap();
List list = new ArrayList();
list.add(map);
list.add(map1);
JSONArray jsonArray = JSONArray.fromObject(list);
System.out.println("jsonArray--->" + jsonArray.toString());
JSONArray jsonArray1 = JSONArray.fromObject(map);
System.out.println("jsonArray1--->" + jsonArray1.toString());
}
//根据接收的json字符串来解析字符串中所包含的数据和数据对象
@Test
public void parsJsonFromFront(){
//接收到的json
String result = "[{\"username\": \"your name\", \"user_json\": {\"username\": \"your name\", \"nickname\": \"your nickname\"}}]";
//根据字符串陈
//根据字符串生成JSON对象
//如果是数组的形式 就使用 JSONArray.fromObject(result) 转化为JSONArray 对象
//如果是json对象 就是使用JSONObject.fromObject(result) 转化为JSONObject 对象
JSONArray resultArray = JSONArray.fromObject(result);
JSONObject jsonObject = resultArray.getJSONObject(0);
JSONObject user_json = jsonObject.getJSONObject("user_json");
//根据key值取值
String username = user_json.getString("username");
String nickname = user_json.getString("nickname");
System.out.println("username =" + username + ":" + "nickname = " + nickname);
//console ： username =your name:nickname = your nickname
}
@Test
public void beanToJson(){
List list = new ArrayList();
list.add( "xiaowang" );
list.add( "xiaohua" );
Adress adress = new Adress("streetName", "district");
JSONObject jsonObject = JSONObject.fromObject(new User("name", adress, list));
System.out.println(jsonObject.toString());
//console ：{"adress":{"district":"district","streetName":"streetName"},"name":"name","students":["xiaowang","xiaohua"]}
}
}相关依赖jar下载：http://download.csdn.net/detail/hao007cn/8995465