Spring Boot 构建 RESTful 网络服务

2019-04-20 本文已影响6人又语

本文介绍 Spring Boot 2 开发构建 RESTful 网络服务（API）的方法。

开发环境

Oracle JDK 1.8.0_201
Apache Maven 3.6.0
IntelliJ IDEA (Version 2018.3.3)

基础示例

创建 Spring Boot 工程，参考：IntelliJ IDEA 创建 Spring Boot 工程。
生成的 pom 文件如下，注意需要添加 spring-boot-starter-web 依赖。

<?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">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath/>
    </parent>
    <groupId>tutorial.spring.boot</groupId>
    <artifactId>spring-boot-rest</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-rest</name>
    <description>Spring Boot RESTful</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>

创建实体类（领域模型）。

package tutorial.spring.boot.rest.domain;

public class User {

    private long id;

    private String name;

    public User(long id, String name) {
        this.id = id;
        this.name = name;
    }

    public long getId() {
        return id;
    }

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

编写对应增、删、改、查操作的 RESTful API。

package tutorial.spring.boot.rest.controller;

import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.*;
import tutorial.spring.boot.rest.domain.User;

import javax.annotation.PostConstruct;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicLong;

@RestController
@RequestMapping("/users")
public class UserController {

    private final AtomicLong idCounter = new AtomicLong();

    private Map<Long, User> users;

    /**
     * 初始化用户信息
     */
    @PostConstruct
    public void init() {
        users = new HashMap<>(16);
        long id = idCounter.incrementAndGet();
        users.put(id, new User(id, "User1"));
        id = idCounter.incrementAndGet();
        users.put(id, new User(id, "User2"));
        id = idCounter.incrementAndGet();
        users.put(id, new User(id, "User3"));
    }

    /**
     * 处理 [/users/{id}] GET 请求，根据用户 ID 获取用户信息
     */
    @GetMapping("/{id}")
    public User get(@PathVariable Long id) {
        return users.get(id);
    }

    /**
     * 处理 [/users/] GET 请求，获取全部用户信息
     */
    @GetMapping("/")
    public List<User> list() {
        return new ArrayList<>(users.values());
    }

    /**
     * 处理 [/users/] POST 请求，添加新用户
     */
    @PostMapping("/")
    public String add(String name) {
        if (!StringUtils.hasText(name)) {
            return "Failed: invalid user name!";
        }
        long id = idCounter.incrementAndGet();
        users.put(id, new User(id, name.trim()));
        return "Success: add user.";
    }

    /**
     * 处理 [/users/{id}] PUT 请求，更新用户信息
     */
    @PutMapping("/{id}")
    public String update(@PathVariable Long id, String name) {
        User user = users.get(id);
        if (user == null) {
            return "Failed: user id is not existed!";
        }
        user.setName(name);
        return "Success: update user " + user;
    }

    /**
     * 处理 [/users/{id}] DELETE 请求，根据用户 ID 删除用户
     */
    @DeleteMapping("/{id}")
    public String delete(@PathVariable Long id) {
        User user = users.remove(id);
        if (user == null) {
            return "Failed: user id is not existed!";
        }
        return "Success: remove user " + user;
    }
}