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:

  1. asm-3.1.jar
  2. jersey-client-1.17.1.jar
  3. jersey-core-1.17.1.jar
  4. jersey-server-1.17.1.jar
  5. jersey-servlet-1.17.1.jar
  6. jsr311-api-1.1.1.jar

jersey

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>

RESTful的java客户端调用案例源码

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