SpringBoot: Eclipse中开发Restful Web App

0. 系统版本

• 操作系统：window10
• spring boot ：2.1.4 release
• eclipse Version : 2019-03 (4.11.0)

1. 在eclipse里安装Spring tools

点击Help-Eclipse Marketplace
在Popular里找到Spring tools 4 - Spring boot，安装

2. 新建Springboot项目

点击New-other，选择Springboot - spring starter project创建
输入项目名字信息，组件选择Web

3. 修改POM.xml

• 首先需要继承母POM: spring-boot-starter-parent
• 选用依赖：
  1. spring-boot-starter-web（新建项目时选了web就会自动加上，自己手动加也一样）
  2. spring-boot-starter-test (测试用）
  3. json-path (JSON解析）
• 构建组件：spring-boot-maven-plugin (打包用)

<?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 /> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.hiramchen</groupId>
	<artifactId>SpringBoot-rest-service</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>SpringBoot-rest-service</name>
	<description>SpringBoot-rest-service</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>
		<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>

4. 新增模型类Greeting.java

在src/main/java下随便建个package，创建文件Greeting.java，这是MVC中的M

package com.hiramchen.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 this.id;
	}
	public String getContent() {
		return this.content;
	}
}

5. 新增控制类GreetingController.java

在src/main/java下随便建个package，创建文件GreetingController.java，这是MVC中的C

package com.hiramchen.hello;

import java.util.concurrent.atomic.AtomicLong;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api/greeting")
public class GreetingController {
	private static final String template = "Hello, %s!";
	private final AtomicLong counter =new AtomicLong();
	@RequestMapping(value="/{name}",method=RequestMethod.GET)
	public Greeting greeting(@PathVariable String name) {
		return new Greeting(counter.incrementAndGet(),String.format(template, name));
	}
}

6. 运行

在application类右键，点击run as -> Spring boot app 运行，成功后可以进入http://localhost:8080查看，若成功应该弹出一个Error Page，因为没有配置首页，这是正常的。

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.

Tue Apr 23 16:30:54 CST 2019
There was an unexpected error (type=Not Found, status=404).
No message available

进入http://localhost:8080/api/greeting/yourname
可以返回一个JSON对象，说明路由配置成功！

{"id":1,"content":"Hello, yourname!"}

7. 问题

Q：多次run as会出现8080端口被占用的问题
A：
查看端口情况

netstat -ano

根据上面的PID查找占用端口的进程

tasklist |findstr "9808"

杀死进程

taskkill /f /t /im javaw.exe

永久解决方案：加入spring-boot-devtools依赖，每次run as会帮你restart，不用重新创建，而且更新文件时会实时刷新，很方便。

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<optional>true</optional>
		</dependency>