Java后台框架篇--Spring之WebService入门

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。

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;@RestControllerpublic 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;@SpringBootApplicationpublic 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@ResponseBodypublic @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

如果您觉得这篇文章对您有帮助，欢迎点击右下角【推荐】支持一下我，谢谢！

这篇文章为原创文章，转载请注明出处！

作者 TZYY / 原文链接 http://www.cnblogs.com/tzyy/p/4837701.html