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:hoojo_@126.com
Blog:http://blog.csdn.net/IBM_hoojo
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 hoojo_@126.com * @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 hoojo_@126.com * @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 hoojo_@126.com * @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;
