场景

若依前后端分离版手把手教你本地搭建环境并运行项目：

https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/108465662

在上面搭建SpringBoot项目的基础上，并且在项目中引入fastjson、hutool等所需依赖后。

Jayway JsonPath：

https://github.com/json-path/JsonPath

A Java DSL for reading JSON documents

需要对接第三方接口，接口返回的json数据需要解析获取数据。

可以通过配置每个返回字段的对应json数据的表达式，使其在代码中根据配置的表达式动态获取。

注：

博客：
https://blog.csdn.net/badao_liumang_qizhi

实现

1、添加项目依赖

        <dependency>
            <groupId>com.jayway.jsonpath</groupId>
            <artifactId>json-path</artifactId>
            <version>2.8.0</version>
        </dependency>

2、JsonPath表达式引用JSON结构的方式与XPath表达式与XML文档结合使用的方式相同。

采用接口模拟工具模拟官方提供的示例json数据

{
    "store": {
        "book": [
            {
                "category": "reference",
                "author": "Nigel Rees",
                "title": "Sayings of the Century",
                "price": 8.95
            },
            {
                "category": "fiction",
                "author": "Evelyn Waugh",
                "title": "Sword of Honour",
                "price": 12.99
            },
            {
                "category": "fiction",
                "author": "Herman Melville",
                "title": "Moby Dick",
                "isbn": "0-553-21311-3",
                "price": 8.99
            },
            {
                "category": "fiction",
                "author": "J. R. R. Tolkien",
                "title": "The Lord of the Rings",
                "isbn": "0-395-19395-8",
                "price": 22.99
            }
        ],
        "bicycle": {
            "color": "red",
            "price": 19.95
        }
    },
    "expensive": 10
}

3、快速开始

解析上面json数据中所有book节点的author字段信息

List<String> authors = JsonPath.read(body, "$.store.book[*].author");

获取第一本书的title字段

String title = JsonPath.read(body, "$['store']['book'][0]['title']");

也可以这样写

String title2 = JsonPath.read(body, "$.store.book[0].title");

获取所有book的数量

Integer number = JsonPath.read(body, "$..book.length()");

获取所有价格大于10的book

List<Map<String, Object>> expensiveBooks= JsonPath.read(body, "$.store.book[?(@.price > 10)]");

4、Json Path的语法较多，各种符号、函数、过滤等可参考官方文档。

下面记录一个读取json数据中指定结构的list数据。

首先需要读取所有book的数量，然后遍历循环，再通过配置的json数据的映射关系

获取配置的映射关系的表达式，进而解析获取对应字段的数据。

            int dataSize = JsonPath.read(body, "$..book.length()");
            JSONObject mapping = JSON.parseObject("{\"title\":\"$.store.book[%d].title\",\"author\":\"$.store.book[%d].author\"}");
            for (int i = 0; i < dataSize; i++) {
                String titleName = mapping.containsKey("title") ? JsonPath.read(body, String.format(mapping.getString("title"), i)).toString() : null;
                System.out.println(titleName);
                String author = mapping.containsKey("author") ? JsonPath.read(body, String.format(mapping.getString("author"), i)).toString() : null;
                System.out.println(author);
            }

其中JSON.parseObject是引用的fastjson。

单元测试结果

5、完整单元测试示例代码

import cn.hutool.http.HttpRequest;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.jayway.jsonpath.JsonPath;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.List;
import java.util.Map;

@RunWith(SpringRunner.class)
@SpringBootTest(classes = RuoYiApplication.class,webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class JsonPathTest {

    @Test
    public void getData() {
        String body = "";
        try {
            //模拟获取接口数据
            body = HttpRequest
                    .get("http://127.0.0.1:4523/m1/2858210-0-default/testJsonPath")
                    .timeout(20000)
                    .execute()
                    .body();
            //获取book的所有auther
            List<String> authors = JsonPath.read(body, "$.store.book[*].author");
            System.out.println(authors);
            //第一本book的title
            String title = JsonPath.read(body, "$['store']['book'][0]['title']");
            String title2 = JsonPath.read(body, "$.store.book[0].title");
            System.out.println(title);
            System.out.println(title2);
            //所有book 的数量
            Integer number = JsonPath.read(body, "$..book.length()");
            System.out.println(number);
            //获取所有价格大于10的book
            List<Map<String, Object>> expensiveBooks= JsonPath.read(body, "$.store.book[?(@.price > 10)]");
            System.out.println(expensiveBooks);

            //根据配置的json数据的映射关系，获取指定表达式下的数据
            int dataSize = JsonPath.read(body, "$..book.length()");
            JSONObject mapping = JSON.parseObject("{\"title\":\"$.store.book[%d].title\",\"author\":\"$.store.book[%d].author\"}");
            for (int i = 0; i < dataSize; i++) {
                String titleName = mapping.containsKey("title") ? JsonPath.read(body, String.format(mapping.getString("title"), i)).toString() : null;
                System.out.println(titleName);
                String author = mapping.containsKey("author") ? JsonPath.read(body, String.format(mapping.getString("author"), i)).toString() : null;
                System.out.println(author);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}