将JSON字符串转为list

引入hutool依赖

使用到该依赖的HTTP请求方法

<dependency>
  <groupId>cn.hutool</groupId>
  <artifactId>hutool-all</artifactId>
  <version>5.5.9</version>
</dependency>

HTTP请求的地址为：http://www.zoutl.cn/getFruitListJson ，返回的结果如下图（下面四种方法只能处理中括号[]以及其中的内容，所以要对HTTP请求返回的结果进行截取处理）

Fruit实体类

/**
 * @author LeDao
 * @company
 * @create 2021-07-17 22:27
 */
public class Fruit {

    private Integer id;

    private String name;

    private Integer num;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getNum() {
        return num;
    }

    public void setNum(Integer num) {
        this.num = num;
    }
}

使用GSON

引入依赖

<dependency>
  <groupId>com.google.code.gson</groupId>
  <artifactId>gson</artifactId>
  <version>2.8.5</version>
</dependency>

Java代码

import cn.hutool.http.HttpUtil;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

import java.util.List;

/**
 * @author LeDao
 * @company
 * @create 2021-06-21 12:38
 */
public class Test {

    public static void main(String[] args) {
        //http请求获取json字符串
        String str = HttpUtil.get("https://www.zoutl.cn/getFruitListJson");
        int start = str.indexOf("[");
        int end = str.indexOf("]") + 1;
        //截取字符串
        str = str.substring(start, end);
        System.out.println(str);
        //转为list
        Gson gson = new Gson();
        List<Fruit> fruitList = gson.fromJson(str, new TypeToken<List<Fruit>>(){}.getType());
        for (Fruit fruit : fruitList) {
            System.out.println(fruit.getId() + "," + fruit.getName() + "," + fruit.getNum());
        }
    }
}

使用FastJSON

引入依赖

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>fastjson</artifactId>
  <version>1.2.75</version>
</dependency>

Java代码

import cn.hutool.http.HttpUtil;
import com.alibaba.fastjson.JSON;

import java.util.List;

/**
 * @author LeDao
 * @company
 * @create 2021-06-21 12:38
 */
public class Test {

    public static void main(String[] args) {
        //http请求获取json字符串
        String str = HttpUtil.get("https://www.zoutl.cn/getFruitListJson");
        int start = str.indexOf("[");
        int end = str.indexOf("]") + 1;
        //截取字符串
        str = str.substring(start, end);
        System.out.println(str);
        //转为list
        List<Fruit> fruitList = JSON.parseArray(str, Fruit.class);
        for (Fruit fruit : fruitList) {
            System.out.println(fruit.getId() + "," + fruit.getName() + "," + fruit.getNum());
        }
    }
}

使用JackJSON

引入依赖

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.9.1</version>
</dependency>

Java代码

import cn.hutool.http.HttpUtil;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.util.List;

/**
 * @author LeDao
 * @company
 * @create 2021-06-21 12:38
 */
public class Test {

    public static void main(String[] args) throws IOException {
        //http请求获取json字符串
        String str = HttpUtil.get("https://www.zoutl.cn/getFruitListJson");
        int start = str.indexOf("[");
        int end = str.indexOf("]") + 1;
        //截取字符串
        str = str.substring(start, end);
        System.out.println(str);
        //转为list
        ObjectMapper objectMapper = new ObjectMapper();
        List<Fruit> fruitList = objectMapper.readValue(str, new TypeReference<List<Fruit>>(){});
        for (Fruit fruit : fruitList) {
            System.out.println(fruit.getId() + "," + fruit.getName() + "," + fruit.getNum());
        }
    }
}

传统方式org.json

引入依赖

<dependency>
  <groupId>org.json</groupId>
  <artifactId>json</artifactId>
  <version>20210307</version>
</dependency>

Java代码

import cn.hutool.http.HttpUtil;
import org.json.JSONArray;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

/**
 * @author LeDao
 * @company
 * @create 2021-06-21 12:38
 */
public class Test {

    public static void main(String[] args) {
        //http请求获取json字符串
        String str = HttpUtil.get("https://www.zoutl.cn/getFruitListJson");
        int start = str.indexOf("[");
        int end = str.indexOf("]") + 1;
        //截取字符串
        str = str.substring(start, end);
        System.out.println(str);
        //先转为jsonArray
        JSONArray jsonArray = new JSONArray(str);
        //转为list
        List<Fruit> fruitList = new ArrayList<>();
        for (Object o : jsonArray) {
            //将数组的每个元素转为jsonObject
            JSONObject jsonObject = new JSONObject(o.toString());
            Fruit fruit = new Fruit();
            fruit.setId((Integer) jsonObject.get("id"));
            fruit.setName((String) jsonObject.get("name"));
            fruit.setNum((Integer) jsonObject.get("num"));
            fruitList.add(fruit);
        }
        for (Fruit fruit : fruitList) {
            System.out.println(fruit.getId() + "," + fruit.getName() + "," + fruit.getNum());
        }
    }
}

结果