SOA专题
用Jersey开发RESTful服务
REST基础概念：
- 在REST中的一切都被认为是一种资源。
- 每个资源由URI标识。
- 使用统一的接口。处理资源使用POST，GET，PUT，DELETE操作类似创建，读取，更新和删除（CRUD）操作。
- 无状态。每个请求是一个独立的请求。从客户端到服务器的每个请求都必须包含所有必要的信息，以便于理解。
- 通信都是通过展现。例如XML，JSON
RESTful Web服务由于其简单替代了基于SOAP的Web服务，并大型服务提供商所接受。这篇文章使用Jersey框架延伸JAX-RS API将展示如何创建一个REST风格的Web服务和客户端。
在Eclipse中，创建一个新的动态Web项目名为"RESTfulWS"：
下载Jersey zip bundle 这里 here. 需要包：
- asm-3.1.jar
- jersey-client-1.17.1.jar
- jersey-core-1.17.1.jar
- jersey-server-1.17.1.jar
- jersey-servlet-1.17.1.jar
- jsr311-api-1.1.1.jar
加入项目：
创建Web服务类：
package com.eviac.blog.restws;
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;
/**
*
* @author pavithra
*
*/
// @Path here defines class level path. Identifies the URI path that
// a resource class will serve requests for.
@Path("UserInfoService")
public class UserInfo {
// @GET here defines, this method will method will process HTTP GET
// requests.
@GET
// @Path here defines method level path. Identifies the URI path that a
// resource class method will serve requests for.
@Path("/name/{i}")
// @Produces here defines the media type(s) that the methods
// of a resource class can produce.
@Produces(MediaType.TEXT_XML)
// @PathParam injects the value of URI parameter that defined in @Path
// expression, into the method.
public String userName(@PathParam("i") String i) {
String name = i;
return "<User>" + "<Name>" + name + "</Name>" + "</User>";
}
@GET
@Path("/age/{j}")
@Produces(MediaType.TEXT_XML)
public String userAge(@PathParam("j") int j) {
int age = j;
return "<User>" + "<Age>" + age + "</Age>" + "</User>";
}
}
配置web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>RESTfulWS</display-name>
<servlet>
<servlet-name>Jersey REST Service</servlet-name>
<servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>com.sun.jersey.config.property.packages</param-name>
<param-value>com.eviac.blog.restws</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Jersey REST Service</servlet-name>
<url-pattern>/rest/*</url-pattern>
</servlet-mapping>
</web-app>
点按这个项目 run as ->run on server.
浏览器浏览：http://localhost:8080/RESTfulWS/rest/UserInfoService/name/Pavithra
URL说明：
创建一个调用客户端：
package com.eviac.blog.restclient;
import javax.ws.rs.core.MediaType;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
/**
*
* @author pavithra
*
*/
public class UserInfoClient {
public static final String BASE_URI = "http://localhost:8080/RESTfulWS";
public static final String PATH_NAME = "/UserInfoService/name/";
public static final String PATH_AGE = "/UserInfoService/age/";
public static void main(String[] args) {
String name = "Pavithra";
int age = 25;
ClientConfig config = new DefaultClientConfig();
Client client = Client.create(config);
WebResource resource = client.resource(BASE_URI);
WebResource nameResource = resource.path("rest").path(PATH_NAME + name);
System.out.println("Client Response \n"
+ getClientResponse(nameResource));
System.out.println("Response \n" + getResponse(nameResource) + "\n\n");
WebResource ageResource = resource.path("rest").path(PATH_AGE + age);
System.out.println("Client Response \n"
+ getClientResponse(ageResource));
System.out.println("Response \n" + getResponse(ageResource));
}
/**
* Returns client response.
* e.g :
* GET http://localhost:8080/RESTfulWS/rest/UserInfoService/name/Pavithra
* returned a response status of 200 OK
*
* @param service
* @return
*/
private static String getClientResponse(WebResource resource) {
return resource.accept(MediaType.TEXT_XML).get(ClientResponse.class)
.toString();
}
/**
* Returns the response as XML
* e.g : <User><Name>Pavithra</Name></User>
*
* @param service
* @return
*/
private static String getResponse(WebResource resource) {
return resource.accept(MediaType.TEXT_XML).get(String.class);
}
}
运行这个客户端代码，得到结果：
Client Response
GET http://localhost:8080/RESTfulWS/rest/UserInfoService/name/Pavithra returned a response status of 200 OK
Response
<User><Name>Pavithra</Name></User>
Client Response
GET http://localhost:8080/RESTfulWS/rest/UserInfoService/age/25 returned a response status of 200 OK
Response
<User><Age>25</Age></User>