- com.alibaba.fastjson.JSONObject
- net.sf.json.JSONObject
- org.json.JSONObject
java对象和json数据之间的转换方式一般有两种，一种是引用第三方的jar包，如Gson（谷歌）、Fastjson（阿里）、Jackson等，这种方式优点是语法精练，可以实现一句话转化，但缺点是会引入庞大的第三方库。
第二种是直接使用Java自带的org.json解析，但这个库功能比较基础，解析会写很多重复的代码。
一 、com.alibaba.fastjson.JSONObject的使用
1 POM.xml
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.51</version>
</dependency>
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
}
private static void json2JsonObject() {
String s = "{"name":"peter"}";
JSONObject object = JSON.parseObject(s);
System.out.println(object.get("name"));
}
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());
}
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"));
}
}
private static void json2JavaBeanList() {
String s = "[{"id":"17051801","name":"lucy"},{"id":"17051802","name":"peter"}]";
List<User> list = JSON.parseArray(s, User.class);
for (User user : list) {
System.out.println(user.getName());
}
}
private static void javaBean2Json() {
User user = new User("17051801", "lucy");
String string = JSON.toJSONString(user);
System.out.println(string);
}
private static void javaBean2JsonObject() {
User user = new User("17051801", "lucy");
JSONObject json = (JSONObject) JSON.toJSON(user);
System.out.println(json.get("id"));
}
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<JavaBean>形式
List<User> list = JSON.parseArray(str, User.class);
for (User user : list) {
System.out.println(user.getName());
}
}
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<String, Object> map1 = new HashMap<String,Object>();
map1.put("id", "17051801");
map1.put("name", "lucy");
Map<String, Object> map2 = new HashMap<String,Object>();
map2.put("id", "17051802");
map2.put("name", "peter");
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
list.add(map1);
list.add(map2);
Map<String, Object> map = new HashMap<String,Object>();
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);
}
private static void stringToMap(){
String str = "{"age":"24","name":"cool_summer_moon"}";
JSONObject jsonObject = JSONObject.parseObject(str);
//json对象转Map
Map<String,Object> map = (Map<String,Object>)jsonObject;
System.out.println("map对象是：" + map);
Object object = map.get("age");
System.out.println("age的值是"+object);
}
private static void mapToString(){
Map<String,Object> 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);
}
private static void mapToJsonObject(){
Map<String,Object> 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<Long> longs = new ArrayList<Long>();
longs.add(1L);
longs.add(2L);
longs.add(3L);
String actual = JSON.toJSONString(longs);
Assert.assertEquals("[1,2,3]", actual);
}
}
二 、org.json.JSONObject的使用
1.引入org.json依赖
<dependency> <groupId>org.json</groupId> <artifactId>json</artifactId> <version>20160810</version> </dependency>
3.JSONObject转javaBean
public static void main(String[] args) {
String str="{"student":[{"name":"leilei","age":23},{"name":"leilei02","age":23}]}";
Student stu = null;
List<Student> list = null;
try {
ObjectMapper objectMapper=new ObjectMapper();
StudentList studentList=objectMapper.readValue(str, StudentList.class);
list=studentList.getStudent();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
for(Student s:list){
System.out.println(s.getName());
}
}
ObjectMapper objectMapper=new ObjectMapper(); out = objectMapper.readValue(org.json.JSONObject.valueToString(arg0), OutputObject.class);
三 net.sf.json.JSONObject的使用
1 引入maven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>
使用范例
package json;
import net.sf.json.JSON;
import net.sf.json.JSONObject;
import net.sf.json.xml.XMLSerializer;
public class JSONObject_1_3 {
public static void javaToJSON() {
System.out.println("java代码封装为json字符串");
JSONObject jsonObj = new JSONObject();
jsonObj.put("username", "张三");
jsonObj.put("password", "123456");
System.out.println("java--->json
" + jsonObj.toString());
}
public static void jsonToJAVA() {
System.out.println("json字符串转java代码");
String jsonStr = "{"password":"123456","username":"张三"}";
JSONObject jsonObj = JSONObject.fromString(jsonStr);
String username = jsonObj.getString("username");
String password = jsonObj.optString("password");
System.out.println("json--->java
username=" + username
+ " password=" + password);
}
public static void jsonToXML() {
System.out.println("json字符串转xml字符串");
String jsonStr = "{"password":"123456","username":"张三"}";
JSONObject json = JSONObject.fromString(jsonStr);
XMLSerializer xmlSerializer = new XMLSerializer();
xmlSerializer.setRootName("user_info");
xmlSerializer.setTypeHintsEnabled(false);
String xml = xmlSerializer.write(json);
System.out.println("json--->xml
" + xml);
}
public static void javaBeanToJSON() {
System.out.println("javabean转json字符串");
UserInfo userInfo = new UserInfo();
userInfo.setUsername("张三");
userInfo.setPassword("123456");
JSONObject json = JSONObject.fromBean(userInfo);
System.out.println("javabean--->json
" + json.toString());
}
public static void javaBeanToXML() {
System.out.println("javabean转xml字符串");
UserInfo userInfo = new UserInfo();
userInfo.setUsername("张三");
userInfo.setPassword("123456");
JSONObject json = JSONObject.fromBean(userInfo);
XMLSerializer xmlSerializer = new XMLSerializer();
String xml = xmlSerializer.write(json, "UTF-8");
System.out.println("javabean--->xml
" + xml);
}
public static void xmlToJSON(){
System.out.println("xml字符串转json字符串");
String xml = "<?xml version="1.0" encoding="UTF-8"?><user_info><password>123456</password><username>张三</username></user_info>";
JSON json=XMLSerializer.read(xml);
System.out.println("xml--->json
"+json.toString());
}
public static void main(String args[]) {
javaToJSON();
jsonToJAVA();
jsonToXML();
javaBeanToJSON();
javaBeanToXML();
xmlToJSON();
}
}
转自：https://blog.csdn.net/zhengTornado/article/details/102832587