REST WebService

REST WebService

前置技能

① 使用maven来管理java项目

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。

REST WebService

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:

REST WebService
<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>
REST WebService

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

REST WebService
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;
}
}
REST WebService

② GreetingController.java

REST WebService
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;
}
}
REST WebService

③ 启动服务  Application.java

REST WebService
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);
} }
REST WebService

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。

REST WebService
/*
* 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 ""; }
REST WebService

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

 
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