Build a Restful Service

最近项目中遇到的REST的问题很多，很多情况下受weblogic以及Jdeveloper版本的影响，无法直接从Jdeveloper中生成一个RESTful Service出来，所以基于流行的Spring框架测试了一下，记录下来以后遇到的时候参考。

1.安装eclipse(过程略)

2.安装和配置Spring 4插件，参考

http://jingyan.baidu.com/article/1612d5005fd087e20f1eee10.html

3.安装和配置maven,参考

https://yq.aliyun.com/articles/28591

4.新建一个maven project项目，选择maven-archetype-webapp,如图

输入groupid和artifact id,然后finish

5.修改pom.xml文件，加入如下依赖包

<properties>
        <spring.version>4.0..RELEASE</spring.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.</version>
        </dependency>
        <!-- web项目编译时需要，部署到tomcat中就不需要了 -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
            <scope>provided</scope>
        </dependency>
        <!-- web项目编译时需要，部署到tomcat中就不需要了 -->

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.3.</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.8.</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.4.</version>
        </dependency>

    </dependencies>

    <repositories>
        <repository>
            <id>spring-releases</id>
            <url>https://repo.spring.io/libs-release</url>
        </repository>
    </repositories>

  <build>
    <finalName>test1</finalName>
     <sourceDirectory>${basedir}/src</sourceDirectory>
               <outputDirectory>${basedir}/webapp/WEB-INF/classes
               </outputDirectory>  

    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.7</source>
                <target>1.7</target>
            </configuration>
        </plugin>
    </plugins>
<resources>
    <resource>
        <directory>src</directory>
        <includes>
            <include>**/**</include>
        </includes>
    </resource>
</resources>
  </build>
</project>

6.修改web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <display-name>simpletest</display-name>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value></param-value>
    </context-param>

    <filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <servlet>
        <servlet-name>springMVC</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>WEB-INF/applicationcontext.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springMVC</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

在 WEB-INFO目录下创建spring bean configuration文件，内容如下

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">      

  <context:component-scan base-package="hello" />

    <bean    class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/>
    <bean    class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <property name="messageConverters">
            <list>
                <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" />
            </list>
        </property>
    </bean>

</beans>

7.建立具体的类，Greeting.java和GreetingContoller.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;
    }
}

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;
    }
}

8.Run as -> maven install,问题来了，发现项目怎么也不把java代码编译.查阅无数帖子，发现首先需要配置maven的jdk,于是在maven安装路径的config下，修改settings.xml

加入（这里有个问题，maven如何知道jdk的路径?)，当然之后需要更新pom.xml文件。

<profile>
    <id>jdk17</id>
    <activation>
        <activeByDefault>true</activeByDefault>
        <jdk>1.7</jdk>
    </activation>
    <properties>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
        <maven.compiler.compilerVersion>1.7</maven.compiler.compilerVersion>
    </properties>
</profile>  

在eclipse中配置1.7的jdk

然后选中项目，maven->update project.(这个很关键)

最后在项目的properties中选择project facets,把java缺省的1.5修改成1.7

再进行maven-install,就可以编译了。

9.将war包放到tomcat的webapp下访问，遇到一个错误，信息是:

通配符的匹配很全面, 但无法找到元素 'context:component-scan'

主要原因是applicationContext.xml中schema的引入问题，将相应的包引入，重新发布，就可以看到结果。