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；
