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,@PUT,@DELETE,@HEAD,@OPTIONS:指定请求的Http method。
·@QueryParam,@PathParam,@HeaderParam,@FormParam,@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:
wKiom1NwZpzzcbZHAAEFqQscg-c810.jpg



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):

wKiom1NwquOC0yScAAGaZKy6WCs022.jpg



访问http://localhost:8080/runtrain/services/rest/users,效果如下:
wKioL1Nwqv-RkOOFAAEIWlo3j3I022.jpg



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 name, 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);