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
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
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
List
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
map1.put("id", "17051801");
map1.put("name", "lucy");
Map
map2.put("id", "17051802");
map2.put("name", "peter");
List
list.add(map1);
list.add(map2);
Map
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
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
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
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.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
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
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
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 \n" + 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\n username=" + username
+ "\t 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 \n" + 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 \n" + 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 \n" + xml);
}
public static void xmlToJSON(){
System.out.println("xml字符串转json字符串");
String xml = "
JSON json=XMLSerializer.read(xml);
System.out.println("xml--->json \n"+json.toString());
}
public static void main(String args[]) {
javaToJSON();
jsonToJAVA();
jsonToXML();
javaBeanToJSON();
javaBeanToXML();
xmlToJSON();
}
}
转自：https://blog.csdn.net/zhengTornado/article/details/102832587