前置技能
这个技能必须点一级，以便快速配置项目。
本文实际上是我学习Spring的过程中搬的官网上的demo，使用maven配置项目。
② jdk 1.8+ 该服务demo需要在jdk1.8+的环境下运行
新建项目，配置依赖文件
① 安装好eclipse的maven插件后，使用file——new——other——maven——maven project 新建一个空的maven项目。
② 访问Spring官网demo http://spring.io/guides/gs/rest-service/
将Build With Maven 模块中提供的pom内容复制到我们自己的pom文件中，注意将项目坐标替换成上图中的配置。
最终得到pom文件：
<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>
<groupId>com.sogou.testspring</groupId>
<artifactId>testspring-demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.2.5.RELEASE</version>
</parent> <dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
</dependencies> <properties>
<java.version>1.8</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestone</id>
<url>https://repo.spring.io/libs-release</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestone</id>
<url>https://repo.spring.io/libs-release</url>
</pluginRepository>
</pluginRepositories>
</project>
编写Model和Controller
在source目录 src/main/java下新建hello包，在hello包下新建
① 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;
}
}
② GreetingController.java
package hello; import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicLong;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController; @RestController
public class GreetingController { private static final String template = "Hello, %s!";
private final AtomicLong counter = new AtomicLong(); @RequestMapping("/greeting")
public Greeting greeting(@RequestParam(value="name", defaultValue="World") String name) {
return new Greeting(counter.incrementAndGet(),
String.format(template, name));
}
@RequestMapping(value="/greeting2")
public String Greeting2(@RequestParam(value="name",defaultValue="meiyou") String name){
return name;
}
@RequestMapping("/greeting3")
public List<Greeting> greeting3(@RequestParam(value="name", defaultValue="World") String name) {
List<Greeting> list=new ArrayList<Greeting>();
list.add(new Greeting(counter.incrementAndGet(),
String.format(template, name)));
list.add(new Greeting(counter.incrementAndGet(),
String.format(template, name)));
return list;
}
}
③ 启动服务 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);
} }
官网的demo至此为止，可以发现这个demo并不需要配置web.xml或者spring dispatherServlet的xml文件，也需要依赖web容器就可以运行。 看起来这更像是一个普通的Java应用程序。
启动服务&访问
① 因为在pom中配置了插件
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
所以我们可以直接 runAs——maven build，target输入 spring-boot:run 来启动服务
② 通过maven package打包项目，生成jar包，然后在target目录下 java -jar jar包名称，即可启动项目
但是
原搬原官网的demo，启动的时候会报错，顺着报错信息找下去，发现
spring-boot-autoconfigure-1.2.5.RELEASE.jar包下
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafProperties 类中
有这么一段代码
public static final String DEFAULT_PREFIX = "classpath:/templates/"; public static final String DEFAULT_SUFFIX = ".html";
看样子需要一个templates的目录，于是在resources目录下新建一个templates目录，再次启动成功。
在浏览器中访问：
http://localhost:8080/greeting
{"id":2,"content":"Hello, World!"}
http://localhost:8080/greeting2
meiyou
http://localhost:8080/greeting3
[{"id":3,"content":"Hello, World!"},{"id":4,"content":"Hello, World!"}]
其他
注意到demo的控制器中使用了一个注解 @RestController ，这个在spring3.x里边是没有的。
/*
* Copyright 2002-2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/ package org.springframework.web.bind.annotation; import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target; import org.springframework.stereotype.Controller; /**
* A convenience annotation that is itself annotated with {@link Controller @Controller}
* and {@link ResponseBody @ResponseBody}.
* <p>
* Types that carry this annotation are treated as controllers where
* {@link RequestMapping @RequestMapping} methods assume
* {@link ResponseBody @ResponseBody} semantics by default.
*
* @author Rossen Stoyanchev
* @author Sam Brannen
* @since 4.0
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Controller
@ResponseBody
public @interface RestController { /**
* The value may indicate a suggestion for a logical component name,
* to be turned into a Spring bean in case of an autodetected component.
* @return the suggested component name, if any
* @since 4.0.1
*/
String value() default ""; }
可以看到该注解是一个类注解，其功能相当于同时应用了 @Controller 和 @ResponseBody