Spring REST

前面介绍过Spring的MVC结合不同的view显示不同的数据，如：结合json的 view显示json、结合xml的view显示xml文档。那么这些数据除了在WebBrowser中用JavaScript来调用以外，还可以用远程 服务器的Java程序、C#程序来调用。也就是说现在的程序不仅在BS中能调用，在CS中同样也能调用，不过你需要借助RestTemplate这个类来 完成。RestTemplate有点类似于一个WebService客户端请求的模版，可以调用http请求的WebService，并将结果转换成相应 的对象类型。至少你可以这样理解！

 

上一次博文介绍SpringMVC结合不同的View，显示不同的数据。http://www.cnblogs.com/hoojo/archive/2011/04/29/2032571.html

 

Email：[e-mail]

Blog：http://blog.csdn.net/IBM_hoojo

http://hoojo.cnblogs.com/

 

一、准备工作

1、 下载jar包

spring各版本jar下载地址：http://ebr.springsource.com/repository/app/library/detail?name=org.springframework.spring

相关的依赖包也可以在这里找到：http://ebr.springsource.com/repository/app/library

 

2、 需要jar包如下

 

3、 当前工程的web.xml配置

<?
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">

    <!-- 配置Spring核心控制器 -->

    <
servlet
>

        <
servlet-name
>
dispatcher</
servlet-name
>

        <
servlet-class
>
org.springframework.web.servlet.DispatcherServlet</
servlet-class
>

        <
init-param
>

            <
param-name
>
contextConfigLocation</
param-name
>

            <
param-value
>
/WEB-INF/dispatcher.xml</
param-value
>

        </
init-param
>

        <
load-on-startup
>
1</
load-on-startup
>

    </
servlet
>

    <
servlet-mapping
>

        <
servlet-name
>
dispatcher</
servlet-name
>

        <
url-pattern
>
*.do</
url-pattern
>

    </
servlet-mapping
>

    <
welcome-file-list
>

      <
welcome-file
>
index.jsp</
welcome-file
>

    </
welcome-file-list
>

</
web-app
>

4、 WEB-INF中的dispatcher.xml配置

<?
xml
 version
="1.0"
 encoding
="UTF-8"
?>

<
beans
 xmlns
="http://www.springframework.org/schema/beans"

    xmlns:mvc
="http://www.springframework.org/schema/mvc"

    xmlns:context
="http://www.springframework.org/schema/context"

    xmlns:util
="http://www.springframework.org/schema/util"

    xmlns:xsi
="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation
="http://www.springframework.org/schema/beans 

    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

    http://www.springframework.org/schema/mvc

    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd

    http://www.springframework.org/schema/context 

    http://www.springframework.org/schema/context/spring-context-3.0.xsd

    http://www.springframework.org/schema/util

    http://www.springframework.org/schema/util/spring-util-3.0.xsd">

    <
context:component-scan
 base-package
="com.hoo.*"
>

        <!-- 忽略这个类 -->

        <
context:exclude-filter
 type
="assignable"
 expression
="com.hoo.client.RESTClient"
/>

    </
context:component-scan
>

    <!-- annotation的方法映射适配器 -->

    <
bean
 id
="handlerAdapter"
 class
="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"
/>

    <!-- xml视图，XStreamMarshaller，可以转换任何形式的java对象 -->

    <
bean
 name
="xStreamMarshallingView"
 class
="org.springframework.web.servlet.view.xml.MarshallingView"
>

        <
property
 name
="marshaller"
>

            <
bean
 class
="org.springframework.oxm.xstream.XStreamMarshaller"
>
  

                <!--  为了初始化XStreamMarshaller，这个类会把我们接口中得到结果以XML文档形式展现出来 -->

                <
property
 name
="autodetectAnnotations"
 value
="true"
/>
  

            </
bean
>
  

        </
property
>

    </
bean
>

    <!-- 视图解析器，根据视图的名称new ModelAndView(name)，在配置文件查找对应的bean配置 -->

    <
bean
 class
="org.springframework.web.servlet.view.BeanNameViewResolver"
>

        <
property
 name
="order"
 value
="3"
/>

    </
bean
>

    <!--  annotation默认的方法映射适配器 -->

    <
bean
 id
="handlerMapping"
 class
="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"
>

        <
property
 name
="order"
 value
="1"
 />

    </
bean
>

</
beans
>

5、 启动后，可以看到index.jsp 没有出现异常或错误。那么当前SpringMVC的配置就成功了。

 

二、REST控制器实现

REST控制器主要完成CRUD操作，也就是对于http中的post、get、put、delete。

还有其他的操作，如head、options、trace。

具体代码：

package
 com.hoo.controller;

import
 org.springframework.stereotype.Controller;

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.servlet.ModelAndView;

/**

 * <b>function:</b>SpringMVC REST示例

 * @author hoojo

 * @createDate 2011-6-9 上午11:34:08

 * @file RESTController.java

 * @package com.hoo.controller

 * @project SpringRestWS

 * @blog http://blog.csdn.net/IBM_hoojo

 * @email [e-mail]

 * @version 1.0

 */

@RequestMapping("/restful"
)

@Controller

public
 class
 RESTController {

    @RequestMapping(value = "/show"
, method = RequestMethod.GET)

    public
 ModelAndView show() {

        System.out.println("show"
);

        ModelAndView model = new
 ModelAndView("xStreamMarshallingView"
);

        model.addObject("show method"
);

        return
 model; 

    }

    @RequestMapping(value = "/get/{id}"
, method = RequestMethod.GET)

    public
 ModelAndView getUserById(@PathVariable String id) {

        System.out.println("getUserById-"
 + id);

        ModelAndView model = new
 ModelAndView("xStreamMarshallingView"
);

        model.addObject("getUserById method -"
 + id);

        return
 model; 

    }

    @RequestMapping(value = "/add"
, method = RequestMethod.POST)

    public
 ModelAndView addUser(String user) {

        System.out.println("addUser-"
 + user);

        ModelAndView model = new
 ModelAndView("xStreamMarshallingView"
);

        model.addObject("addUser method -"
 + user);

        return
 model; 

    }

    @RequestMapping(value = "/edit"
, method = RequestMethod.PUT)

    public
 ModelAndView editUser(String user) {

        System.out.println("editUser-"
 + user);

        ModelAndView model = new
 ModelAndView("xStreamMarshallingView"
);

        model.addObject("editUser method -"
 + user);

        return
 model;

    }

    @RequestMapping(value = "/remove/{id}"
, method = RequestMethod.DELETE)

    public
 ModelAndView removeUser(@PathVariable String id) {

        System.out.println("removeUser-"
 + id);

        ModelAndView model = new
 ModelAndView("xStreamMarshallingView"
);

        model.addObject("removeUser method -"
 + id);

        return
 model;

    }

}

上面的方法对应的http操作：

/show -> get 查询

/get/id -> get 查询

/add -> post 添加

/edit -> put 修改

/remove/id -> delete 删除

在这个方法中，就可以看到RESTful风格的url资源标识

@RequestMapping(value = "/get/{id}"
, method = RequestMethod.GET)

public
 ModelAndView getUserById(@PathVariable String id) {

    System.out.println("getUserById-"
 + id);

    ModelAndView model = new
 ModelAndView("xStreamMarshallingView"
);

    model.addObject("getUserById method -"
 + id);

    return
 model; 

}

value=”/get/{id}”就是url中包含get，并且带有id参数的get请求，就会执行这个方法。这个url在请求的时候，会通过 Annotation的@PathVariable来将url中的id值设置到getUserById的参数中去。 ModelAndView返回的视图是xStreamMarshallingView是一个xml视图，执行当前请求后，会显示一篇xml文档。文档的内 容是添加到model中的值。

 

三、利用RestTemplate调用REST资源

代码如下：

package
 com.hoo.client;

import
 org.springframework.beans.factory.annotation.Autowired;

import
 org.springframework.stereotype.Component;

import
 org.springframework.web.client.RestTemplate;

/**

 * <b>function:</b>RestTemplate调用REST资源

 * @author hoojo

 * @createDate 2011-6-9 上午11:56:16

 * @file RESTClient.java

 * @package com.hoo.client

 * @project SpringRestWS

 * @blog http://blog.csdn.net/IBM_hoojo

 * @email [e-mail]

 * @version 1.0

 */

@Component

public
 class
 RESTClient {

    @Autowired

    private
 RestTemplate template;

    private
 final
 static
 String url = "http://localhost:8080/SpringRestWS/restful/"
;

    public
 String show() {

        return
 template.getForObject(url + "show.do"
, String.class
, new
 String[]{});

    }

    public
 String getUserById(String id) {

        return
 template.getForObject(url + "get/{id}.do"
, String.class
, id); 

    }

    public
 String addUser(String user) {

        return
 template.postForObject(url + "add.do?user={user}"
, null, String.class
, user);

    }

    public
 String editUser(String user) {

        template.put(url + "edit.do?user={user}"
, null, user);

        return
 user;

    }

    public
 String removeUser(String id) {

        template.delete(url + "/remove/{id}.do"
, id);

        return
 id;

    }

}

RestTemplate的getForObject完成get请求、postForObject完成post请求、put对应的完成put请求、 delete完成delete请求；还有execute可以执行任何请求的方法，需要你设置RequestMethod来指定当前请求类型。

RestTemplate.getForObject(String url, Class<String> responseType, String... urlVariables)

参数url是http请求的地址，参数Class是请求响应返回后的数据的类型，最后一个参数是请求中需要设置的参数。

template.getForObject(url + "get/{id}.do", String.class, id);

如上面的参数是{id}，返回的是一个string类型，设置的参数是id。最后执行该方法会返回一个String类型的结果。

 

下面建立一个测试类，完成对RESTClient的测试。代码如下：

package
 com.hoo.client;

import
 org.springframework.beans.factory.annotation.Autowired;

import
 org.springframework.test.context.ContextConfiguration;

import
 org.springframework.test.context.junit38.AbstractJUnit38SpringContextTests;

/**

 * <b>function:</b>RESTClient TEST

 * @author hoojo

 * @createDate 2011-6-9 下午03:50:21

 * @file RESTClientTest.java

 * @package com.hoo.client

 * @project SpringRestWS

 * @blog http://blog.csdn.net/IBM_hoojo

 * @email [e-mail]

 * @version 1.0

 */

@ContextConfiguration("classpath:applicationContext-*.xml"
)

public
 class
 RESTClientTest extends
 AbstractJUnit38SpringContextTests {

    @Autowired

    private
 RESTClient client;

    public
 void
 testShow() {

        System.out.println(client.show());

    }

    public
 void
 testGetUserById() {

        System.out.println(client.getUserById("abc"
));

    }

    public
 void
 testAddUser() {

        System.out.println(client.addUser("jack"
));

    }

    public
 void
 testEditUser() {

        System.out.println(client.editUser("tom"
));

    }

    public
 void
 testRemoveUser() {

        System.out.println(client.removeUser("aabb"
));

    }

}

我们需要在src目录下添加applicationContext-beans.xml完成对restTemplate的配置。restTemplate需要配置MessageConvert将返回的xml文档进行转换，解析成JavaObject。

<?
xml
 version
="1.0"
 encoding
="UTF-8"
?>

<
beans
 xmlns
="http://www.springframework.org/schema/beans"

    xmlns:context
="http://www.springframework.org/schema/context"

    xmlns:xsi
="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation
="http://www.springframework.org/schema/beans 

    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

    http://www.springframework.org/schema/context

    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <
context:component-scan
 base-package
="com.hoo.*"
/>

    <
bean
 id
="restTemplate"
 class
="org.springframework.web.client.RestTemplate"
>

        <
property
 name
="messageConverters"
>

            <
list
>

                <
bean
 class
="org.springframework.http.converter.xml.MarshallingHttpMessageConverter"
>

                    <
property
 name
="marshaller"
 ref
="xStreamMarshaller"
/>

                    <
property
 name
="unmarshaller"
 ref
="xStreamMarshaller"
/>

                </
bean
>

            </
list
>

        </
property
>

    </
bean
>

    <
bean
 id
="xStreamMarshaller"
 class
="org.springframework.oxm.xstream.XStreamMarshaller"
>

        <
property
 name
="annotatedClasses"
>

            <
array
>
                

            </
array
>

        </
property
>

    </
bean
>

</
beans
>

上面配置了xStreamMarshaller是和RESTController中的ModelAndView的view对应的。因为那边是用 xStreamMarshaller进行编组的，所以RestTemplate这边也需要用它来解组。RestTemplate还指出其他的 MarshallingHttpMessageConverter；