Spring Boot：Hello World

源码结构

.
├── src
│   ├── main
│   │   └── java
│   │       └── hello
│   │           ├── Application.java
│   │           ├── Greeting.java
│   │           └── GreetingController.java
│   └── test
│       └── java
│           └── hello
│               └── GreetingControllerTests.java
└── pom.xml

以上即为全部内容，包含了单元测试。除了pom.xml外，没有其它任何配置文件。

单元测试：mvn clean test

打（可执行）包：mvn clean package

启动：mvn spring-boot:run 或 java -jar target/gs-rest-service-1.0.jar

访问：http://localhost:8080/greeting 或 http://localhost:8080/greeting?name=Lewis

源码

定义项目及其依赖

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.lewis.guide</groupId>
    <artifactId>gs-rest-service</artifactId>
    <version>1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <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>
        <dependency>
            <groupId>com.jayway.jsonpath</groupId>
            <artifactId>json-path</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

项目基于 Spring Boot

src/main/java/hello/Application.java

package hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

定义一个简单对象

src/main/java/hello/Greeting.java

package hello;

public class Greeting {

    private final long id;
    private final String content;

    public Greeting(long id, String content) {
        this.id = id;
        this.content = content;
    }

    public long getId() {
        return id;
    }

    public String getContent() {
        return content;
    }

}

最后完成一个 GET 请求

src/main/java/hello/GreetingController.java

package hello;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.atomic.AtomicLong;

@RestController
public class GreetingController {

    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @GetMapping("/greeting")
    public Greeting greeting(@RequestParam(name = "name", defaultValue = "World") String name) {
        return new Greeting(counter.incrementAndGet(), String.format(template, name));
    }

}

单元测试

src/test/java/hello/GreetingControllerTests.java

package hello;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureMockMvc
public class GreetingControllerTests {

    @Autowired
    private MockMvc mockMvc;

    @Test
    public void noParamGreetingShouldReturnDefaultMessage() throws Exception {
        this.mockMvc.perform(get("/greeting"))
                .andDo(print()).andExpect(status().isOk())
                .andExpect(jsonPath("$.content").value("Hello, World!"));
    }

    @Test
    public void paramGreetingShouldReturnTailoredMessage() throws Exception {
        this.mockMvc.perform(get("/greeting").param("name", "Spring Community"))
                .andDo(print()).andExpect(status().isOk())
                .andExpect(jsonPath("$.content").value("Hello, Spring Community!"));
    }

}