【Java】java获取json中某个字段

import com.alibaba.fastjson.JSONObject;
public class JsonTest {
    public static void main(String[] args) {
        // json串(以自己的为准)
        String str = "{"id":"75","shoppingCartItemList":[{"id":"407","num":"10"}]}";
        JSONObject jsonObject = JSONObject.parseObject(str);
        // 获取到key为shoppingCartItemList的值
        String r = jsonObject.getString("shoppingCartItemList");
        System.out.println(r);
    }
}
package com.cmbc.cms.action.addrebatchno; 
 
import java.util.List; 
 
import com.alibaba.fastjson.JSONObject; 
 
public class Test { 
 
public int getId() { 
return id; 
} 
 
public void setId(int id) { 
this.id = id; 
} 
 
public int getNum() { 
return num; 
} 
 
public void setNum(int num) { 
this.num = num; 
} 
 
private int id; 
private int num; 
 
public static void main(String[] args) { 
// TODO Auto-generated method stub 
String str = "{\"id\":\"75\",\"shoppingCartItemList\":[{\"id\":\"407\",\"num\":\"10\"}]}"; 
JSONObject jsonObject = JSONObject.parseObject(str); 
// 获取到key为shoppingCartItemList的值 
String r = jsonObject.getString("shoppingCartItemList"); 
System.out.println(r); 
 
//取外面的id 
String id = jsonObject.getString("id"); 
System.out.println(id); 
 
//取里面的id 
List<Test> list = JSONObject.parseArray(r,Test.class); 
int id2 = list.get(0).getId(); 
System.out.println(id2); 
 
} 
 
}