【Apache CXF】CXF对JAX-RS的支持

用CXF构建RESTful services有两种方式:
?CXF对JAX-RS的实现。
?使用JAX-WS Provider/Dispatch API。
官网上还有Http Bindings方式，他需要做一些繁琐的工作去创建资源再映射到服务上，这种方式从2.6时已经被移除了。
刚好我这里有几个工程都是用第一种方式实现的，在这里便主要记录一下spring+CXF构建RESTful service。

首先列举一下JAX-RS的一些常用注解。
?@Path:指定资源的URI。
?@Produces/@Consumes:指定请求/响应的媒体类型。当类和方法同时被标注时，方法标注会覆盖类标注。
?@GET,@POST,0);">@PUT,0);">@DELETE,0);">@HEAD,0);">@OPTIONS:指定请求的Http method。
?@QueryParam,0);">@PathParam,0);">@HeaderParam,0);">@FormParam,0);">@CookieParam:指定参数值的来源，可标注于类、方法、属性。
符合以下规则的参数值可以被接收：
?原始类型
?拥有一个String参数的constructor
?有valueOf或者fromString静态method
另外部分来源也支持SortedSet<T>、List<T>和Set<T>，T需要满足上面的规则。

相关dependency:

<dependency>
????<groupId>org.apache.cxf</groupId>
????<artifactId>cxf-bundle-jaxrs</artifactId>
????<version>${cxf.version}</version>
</dependency>

现在我打算定义一个服务用来返回一组用户信息。

当以get method访问users资源时将以XML表述:

package?pac.king.webservice;
import?javax.ws.rs.GET;
import?javax.ws.rs.Path;
import?javax.ws.rs.Produces;
import?javax.ws.rs.core.MediaType;
import?pac.king.pojo.User;
@Path("/")
public?interface?MyRestService?{
???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????@GET
????@Path("users")
????@Produces({?MediaType.APPLICATION_XML?})
????public?User[]?userInfos();
}

接口实现我就简单写一下:

public?class?MyRestServiceImpl?implements?MyRestService{
????@WebMethod
????public?User[]?userInfos()?{
????????User[]?myInfos?=?new?User[4];
????????myInfos[0]?=?new?User("0001","Kim","t;stmdtkg");
????????myInfos[1]?=?new?User("0002","King.","t;stmdtkg");
????????myInfos[2]?=?new?User("0003","sweet_dreams","t;stmdtkg");
????????myInfos[3]?=?new?User("0004","show_time","t;stmdtkg");
????????return?myInfos;
????}
}

定义User时需要注意加上无参的constructor和@XmlRootElement

package?pac.king.pojo;
import?javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
public?class?User?{
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????private?String?id;
????private?String?name;
????private?String?password;
????public?String?getPassword()?{
????????return?password;
????}
????public?void?setPassword(String?password)?{
????????this.password?=?password;
????}
????public?String?getId()?{
????????return?id;
????}
????public?void?setId(String?id)?{
????????this.id?=?id;
????}
????public?String?getName()?{
????????return?name;
????}
????public?void?setName(String?name)?{
????????this.name?=?name;
????}
????public?User()?{}
????public?User(String?id,?String?name,?String?password)?{
????????super();
????????this.id?=?id;
????????this.name?=?name;
????????this.password?=?password;
????}
}

使用org.apache.cxf.jaxrs.JAXRSServerFactoryBean启动服务:

JAXRSServerFactoryBean?rsFactory?=?new?JAXRSServerFactoryBean();
rsFactory.setAddress("http://localhost:8888/myRest");
rsFactory.setResourceClasses(MyRestServiceImpl.class);
rsFactory.create();

访问http://localhost:8888/myRest/users，输出：

用CXF+Spring方式构建RESTful service也非常方便，虽然也会带来一些问题。
服务就继续用上面定义的MyRestService，但是Service的部分属性将定义在XML configration中，并将service放到容器里。
(其实也可以non-Spring配置到容器里，很难想象为什么要用这种方式，但似乎可以明白点点什么。)
spring配置，引入了一些不必要的namespace，但也没什么大问题:

<?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"
????xmlns:util="http://www.springframework.org/schema/util"
????xmlns:p="http://www.springframework.org/schema/p"
????xmlns:jaxws="http://cxf.apache.org/jaxws"
????xmlns:jaxrs="http://cxf.apache.org/jaxrs"
????xmlns:cxf="http://cxf.apache.org/core"
?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????xsi:schemaLocation="
????????http://www.springframework.org/schema/beans?http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
????????http://www.springframework.org/schema/context?http://www.springframework.org/schema/context/spring-context-4.0.xsd
????????http://www.springframework.org/schema/util?http://www.springframework.org/schema/util/spring-util-4.0.xsd
????????http://cxf.apache.org/jaxws?http://cxf.apache.org/schemas/jaxws.xsd
????????http://cxf.apache.org/core?http://cxf.apache.org/schemas/core.xsd
????????http://cxf.apache.org/jaxrs?http://cxf.apache.org/schemas/jaxrs.xsd
????????"
????????default-autowire="byName">
<import?resource="classpath:META-INF/cxf/cxf.xml"/>
????<import?resource="classpath:META-INF/cxf/cxf-servlet.xml"/>
????<import?resource="classpath:META-INF/cxf/osgi/cxf-extension-osgi.xml"?/>
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????<jaxrs:server?id="customerService"?address="/rest"?>
????????<jaxrs:serviceBeans>
????????????<ref??bean="myRestService"/>
????????</jaxrs:serviceBeans>
????</jaxrs:server>
????<bean?id="myRestService"?class="pac.king.webservice.impl.MyRestServiceImpl"/>
??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
</beans>

在web.xml中加入CXFServlet，注意我写的url pattern是/services/*:

<servlet>
????<servlet-name>CXFServlet</servlet-name>
????<servlet-class>org.apache.cxf.transport.servlet.CXFServlet</servlet-class>
????<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
????<servlet-name>CXFServlet</servlet-name>
????<url-pattern>/services/*</url-pattern>
</servlet-mapping>
<servlet>

访问http://localhost:8080/runtrain/services，效果如下(还有一个是上一篇的JAX-WS服务):

访问http://localhost:8080/runtrain/services/rest/users，效果如下：

最后说一下lifecycle的问题。
像这个例子中用bean标签定义一个服务，此时给他加上scope标签不会有任何效果。
他始终是默认的――singleton。

jaxrs:server下还有一个子标签叫jaxrs:serviceFactories,里面可以存放org.apache.cxf.jaxrs.spring.SpringResourceFactory类型的Bean,SpringResourceFactory将会把服务的声明周期委派给ApplicationContext来管理。
我可以做如下配置:

<bean?id="myRestService"?class="pac.king.webservice.impl.MyRestServiceImpl"?scope="prototype"/>
<jaxrs:server?id="customerService"?address="/rest"?>
????<jaxrs:serviceFactories>
????????<ref?bean="resourceFactory"?/>
????</jaxrs:serviceFactories>
</jaxrs:server>
<bean?id="resourceFactory"?class="org.apache.cxf.jaxrs.spring.SpringResourceFactory">
????<property?name="beanId"?value="myRestService"?/>
</bean>

但这种方式有些麻烦，难道我就为了让scope生效定义bean又定义SpringResourceFactory又设置serviceFactoris?
可以更简便地配置，如下:

<beans>
????<jaxrs:server?id="customerService"?address="/rest"
????????beanNames="myRestService"?/>
????<bean?id="myRestService"?class="pac.king.webservice.impl.MyRestServiceImpl"?scope="prototype"/>
</beans>

需要注意的是beanNames属性中写多个值时以space分隔。

别人辛苦构建了RESTful Service，总不能只用浏览器调用。
继续说说Client端的API。

继续使用上面的例子，这次加个参数，如下:

package?pac.king.webservice;
import?javax.ws.rs.GET;
import?javax.ws.rs.Path;
import?javax.ws.rs.PathParam;
import?javax.ws.rs.Produces;
import?javax.ws.rs.core.MediaType;
import?pac.king.pojo.User;
@Path("/")
public?interface?MyRestService?{
???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????@GET
????@Path("limitUsers/{count}")
????@Produces({?MediaType.APPLICATION_XML?})
????public?User[]?userInfos(@PathParam("count")int?cnt);
}

实现:

public?User[]?userInfos(int?count)?{
????System.out.println("count="+count);
?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????User[]?myInfos?=?new?User[count];
????for?(int?i?=?0;?i?<?count;?i++)?{
????????myInfos[i]?=?new?User(i+1+"","King."+UUID.randomUUID(),"t;stmdtkg");
????}
????return?myInfos;
}

User类:

package?pac.king.pojo;
import?javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
public?class?User?{
?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????private?String?id;
????private?String?name;
????private?String?password;
????public?String?getPassword()?{
????????return?password;
????}
????public?void?setPassword(String?password)?{
????????this.password?=?password;
????}
????public?String?getId()?{
????????return?id;
????}
????public?void?setId(String?id)?{
????????this.id?=?id;
????}
????public?String?getName()?{
????????return?name;
????}
????public?void?setName(String?name)?{
????????this.name?=?name;
????}
????public?User()?{}
????public?User(String?id,?String?password)?{
????????super();
????????this.id?=?id;
????????this.name?=?name;
????????this.password?=?password;
????}
}

当然，某种程度上org.apache.commons.httpclient.HttpClient也可以调用。
但稍有复杂的情况就无法胜任。
基于代理的API主要是(和spring里的那几个ProxyFactoryBean不同，名字里不带Proxy)
?org.apache.cxf.jaxrs.client.JAXRSClientFactoryBean

比如我可以这样使用:

JAXRSClientFactoryBean?bean?=?new?JAXRSClientFactoryBean();
bean.setAddress("http://localhost:8080/runtrain/services/rest");
bean.setResourceClass(MyRestServiceImpl.class);
????????MyRestServiceImpl?proxy?=?(MyRestServiceImpl)bean.create();

另外，JAXRSClientFactoryBean有一个工厂类:
?org.apache.cxf.jaxrs.client.JAXRSClientFactory

比如可以这样使用:

MyRestServiceImpl?client?=?JAXRSClientFactory.create("http://localhost:8080/runtrain/services/rest",?MyRestServiceImpl.class);
User[]?users?=?client.userInfos(10);

让人感觉很奇怪，提供了一个工厂类却可以直接使用Bean，官网上没找到答案，我也不纠结了吧。

上面代码中使用的MyRestServiceImpl和Server端可以是没有任何关系的，让远程调用变得透明也正是proxy的意义。
值得注意的是，有一个threadSafe属性，同一个代理是否允许被多线程访问取决于此。

除了JAXRSClientFactoryBean，还有Http-centric web client:
?org.apache.cxf.jaxrs.client.WebClient

举个例子:

WebClient?webClient?=?WebClient.create("http://localhost:8080/runtrain/services/rest");
????????webClient?.path("limitUsers").path(new?Integer(10));
????????webClient?.type(MediaType.APPLICATION_XML).accept(MediaType.APPLICATION_XML);
????????User[]?res?=?webClient.get(User[].class);
????????System.out.println(res.length);