构建一个RESTful API以及单元测试

一、关键步骤

首先，说明一下常用注解的用法：

• @Controller：修饰class，用来创建处理http请求的对象
• @RestController：Spring4之后加入的注解，原来在@Controller中返回json需要@ResponseBody来配合，如果直接用@RestController替代@Controller就不需要再配置@ResponseBody，默认返回json格式
• @RequestMapping：配置url映射

本文我们使用Spring MVC来实现一组对User对象操作的RESTful API，配合注释详细说明在 Spring MVC中如何映射HTTP请求、如何传参、如何编写单元测试

RESTful API具体设计如下：

pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <groupId>com.wells.demo</groupId>
        <artifactId>spring-boot</artifactId>
        <version>1.0.0.1</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>chapter2-1</artifactId>
    <packaging>jar</packaging>
    <name>chapter2-1</name>
    <description>Demo project for Chapter2-1</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

User实体类定义：

package com.wells.demo.chapter21.entity;


import lombok.Data;

/**
 * Created by Wells on 2019年01月12日
 */

@Data
public class User {
    private Long id;

    private String name;

    private Integer age;
}

UserController实现：

package com.wells.demo.chapter21.controller;

import com.wells.demo.chapter21.entity.User;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by Wells on 2019年01月12日
 */

@RestController
@RequestMapping("users")
public class UserController {
    static Map<Long, User> userMap = new HashMap<>();

    @PostMapping("/")
    public String addUser(@ModelAttribute User user){
        userMap.put(user.getId(), user);
        return "success";
    }

    @GetMapping(value = "/{id}")
    public User getUserById(@PathVariable Long id){
        return userMap.get(id);
    }

    @GetMapping("/")
    public List<User> findUserList(){
        List<User> userList = new ArrayList<>();
        for(Map.Entry<Long, User> entry : userMap.entrySet()){
            userList.add(entry.getValue());
        }
        return userList;
    }

    @PutMapping(value = "/{id}")
    public String uptUser(@PathVariable Long id, @ModelAttribute User user){
        User oldUser = userMap.get(id);
        oldUser.setName(user.getName());
        oldUser.setAge(user.getAge());
        userMap.put(id, oldUser);
        return "success";
    }

    @DeleteMapping(value = "/{id}")
    public String delUserById(@PathVariable Long id){
        userMap.remove(id);
        return "success";
    }
}

测试类：

package com.wells.demo.chapter21;

import com.wells.demo.chapter21.controller.UserController;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.RequestBuilder;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;

import static org.hamcrest.Matchers.equalTo;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;

@RunWith(SpringRunner.class)
@SpringBootTest
public class Chapter21ApplicationTests {
    private MockMvc mvc;

    @Before
    public void setup() throws Exception {
        mvc = MockMvcBuilders.standaloneSetup(new UserController()).build();
    }

    @Test
    public void testAddUser() throws Exception{
        // 测试UserController
        RequestBuilder request = null;
        String result = "";

        // 1.post：新增一个user
        request = post("/users/")
                .param("id", "1")
                .param("name", "wells")
                .param("age", "18");
        mvc.perform(request)
                .andExpect(content().string(equalTo("success")));

        // 2.get：根据id查询用户
        request = get("/users/1");
        result = mvc.perform(request)
                .andReturn().getResponse().getContentAsString();
        System.out.println(result);

        // 3.put：修改用户名
        request = put("/users/1")
                .param("age", "20");
        mvc.perform(request)
                .andExpect(content().string(equalTo("success")));

        // 4.get：查询用户列表
        request = get("/users/");
        result = mvc.perform(request)
                .andReturn().getResponse().getContentAsString();
        System.out.println(result);

        // 5.del: 删除用户
        request = delete("/users/1");
        mvc.perform(request)
                .andExpect(content().string(equalTo("success")));

        // 6.get：查询用户列表
        request = get("/users/");
        result = mvc.perform(request)
                .andReturn().getResponse().getContentAsString();
        System.out.println(result);
    }
}

至此，我们通过引入web模块（没有做其他的任何配置），就可以轻松利用Spring MVC的功能，以非常简洁的代码完成了对User对象的RESTful API的创建以及单元测试的编写。

二、代码示例

完整示例：SpringBoot Restful

三、其他说明

RESTful API设计指南：http://www.ruanyifeng.com/blog/2014/05/restful_api.html
MockMVC使用指南：https://blog.csdn.net/Adam_allen/article/details/79919921