com.alibaba.fastjson.JSONObject;的使用
原文链接： https://blog.csdn.net/mameng1988/article/details/83722257
1 POM.xml
com.alibaba
fastjson
1.2.51
2 附上代码例子
2.1 创建2个实体类，供后面例子使用
public class School {
private String id;
private String name;
List students = new ArrayList();
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List getStudents() {
return students;
}
public void setStudents(List students) {
this.students = students;
}
}
public class User {
private String id;
private String name;
public User(){
}
public User(String id, String name){
this.id = id;
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
2.2 Json字符串与Map、List、object之间的相互转换
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
public class TestFastJson {
public static void main(String[] args){
json2JsonObject();//将Json字符串转换为JSONObject对象
json2JavaBean();//将Json字符串转换为JavaBean对象
json2JsonArray();//将Json字符串转换为JSONArray对象
json2JavaBeanList();//将Json字符串转换为JavaBean的集合
javaBean2Json();//将JavaBean转换为Json格式的数据
javaBean2JsonObject();//将JavaBean转换为JSONObject对象
json2ListInMap();//从Json字符串的Map中获取List对象
list2JsonInMap();//将含list的Map对象转换为Json字符串
stringToMap();//json字符串转map
mapToString();//map转json字符串
mapToJsonObject();//map转json对象
testList2String()；//list转json字符串
}
//将Json字符串转换为JSONObject对象
private static void json2JsonObject() {
String s = "{\"name\":\"peter\"}";
JSONObject object = JSON.parseObject(s);
System.out.println(object.get("name"));
}
//将Json字符串转换为JSONObject对象
private static void json2JavaBean() {
String s = "{\"id\":\"17051801\",\"name\":\"lucy\"}";
User user = JSON.parseObject(s, User.class);
System.out.println(user.getId());
System.out.println(user.getName());
}
//将Json字符串转换为JSONArray对象
private static void json2JsonArray() {
String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
JSONArray array = JSON.parseArray(s);
for (int i = 0; i < array.size(); i++) {
//JSONArray中的数据转换为String类型需要在外边加"";不然会报出类型强转异常！
String str = array.get(i)+"";
JSONObject object = JSON.parseObject(str);
System.out.println(object.get("name"));
}
}
//将Json字符串转换为JavaBean的集合
private static void json2JavaBeanList() {
String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
List list = JSON.parseArray(s, User.class);
for (User user : list) {
System.out.println(user.getName());
}
}
//将JavaBean转换为Json格式的数据
private static void javaBean2Json() {
User user = new User("17051801", "lucy");
String string = JSON.toJSONString(user);
System.out.println(string);
}
//将JavaBean转换为JSONObject对象
private static void javaBean2JsonObject() {
User user = new User("17051801", "lucy");
JSONObject json = (JSONObject) JSON.toJSON(user);
System.out.println(json.get("id"));
}
//从Json字符串的Map中获取List对象
private static void json2ListInMap() {
String s = "{json:[{id:\"17051801\",\"name\":\"lucy\"},{id:\"17051802\",\"name\":\"peter\"},"
+ "{id:\"17051803\",\"name\":\"tom\"},{id:\"17051804\",\"name\":\"lily\"}]}";
//将Json字符串转换为JSONObject对象,并取出list对象的值
JSONObject object = JSON.parseObject(s);
Object objArray = object.get("json");
String str = objArray+"";
//方式1:转换成JSONArray对象形式
JSONArray array = JSON.parseArray(str);
for (int i = 0; i < array.size(); i++) {
JSONObject obj = JSON.parseObject(array.get(i)+"");
System.out.println(obj.get("name"));
}
//方式2:转换成List形式
List list = JSON.parseArray(str, User.class);
for (User user : list) {
System.out.println(user.getName());
}
}
//将含list的Map对象转换为Json字符串
private static void list2JsonInMap() {
//方式1:构建一个带有list的JavaBean对象
School school = new School();
school.setId("1");
school.setName("schoolA");
User user1 = new User();
user1.setId("17051801");
user1.setName("lucy");
User user2 = new User();
user2.setId("17051802");
user2.setName("peter");
school.getStudents().add(user1);
school.getStudents().add(user2);
//将JavaBean对象转换成Json字符串
String string1 = JSON.toJSONString(school);
System.out.println(string1);
//方式2:构建一个带有list的Map对象
Map map1 = new HashMap();
map1.put("id", "17051801");
map1.put("name", "lucy");
Map map2 = new HashMap();
map2.put("id", "17051802");
map2.put("name", "peter");
List> list = new ArrayList>();
list.add(map1);
list.add(map2);
Map map = new HashMap();
map.put("id", "1");
map.put("name", "schoolA");
map.put("students", list);
//将map对象转换成Json字符串
String string2 = JSON.toJSONString(map);
System.out.println(string2);
}
//json字符串转map
private static void stringToMap(){
String str = "{\"age\":\"24\",\"name\":\"cool_summer_moon\"}";
JSONObject jsonObject = JSONObject.parseObject(str);
//json对象转Map
Map map = (Map)jsonObject;
System.out.println("map对象是：" + map);
Object object = map.get("age");
System.out.println("age的值是"+object);
}
//map转json字符串
private static void mapToString(){
Map map = new HashMap<>();
map.put("age", 24);
map.put("name", "cool_summer_moon");
String jsonString = JSON.toJSONString(map);
System.out.println("json字符串是："+jsonString);
}
//map转json对象
private static void mapToJsonObject(){
Map map = new HashMap<>();
map.put("age", 24);
map.put("name", "cool_summer_moon");
JSONObject json = new JSONObject(map);
System.out.println("Json对象是：" + json);
}
/**
* 测试包装类型的List转换为json字符串
*/
public static void testList2String() {
List longs = new ArrayList();
longs.add(1L);
longs.add(2L);
longs.add(3L);
String actual = JSON.toJSONString(longs);
Assert.assertEquals("[1,2,3]", actual);
}
}
3 参考
https://blog.csdn.net/flysun3344/article/details/54707965
https://blog.csdn.net/jeffleo/article/details/73612224
https://blog.csdn.net/m0_37846887/article/details/80724630
使用fastjson时，对象转json遇到的首字母大小写问题