【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); 

} 

}