Web编程学习四: 使用Jersey来创建RESTful WebService

浏览数：25 / 时间：2015年06月09日

RESTful Web Service是轻量级的service，可以通过HTTP的方式来实现对后台数据库的CRUD，

在Web开发和移动开发时使用的比较广泛，非常方便。

在Java世界里， JAX-RS规范定义了对RESTful Web Service的实现。

Oracle的Jersey框架则是对JAX-RS的一个实现。

下面我们学习如何使用Jersey来创建RESTful WebService。

我的开发环境：

Eclipse Juno, Java 1.6, Tomcat 7.0, Jersey 1.18

1. 创建第一个RESTful web service

1.1创建一个叫jersey1的Dynamic Web Project.

1.2在WEB-INF/lib文件夹中导入jersey的包。

1.3创建web.xml，定义Jersey的使用。

<?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>sample</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>sample</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>

1.4创建Java class

package sample;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

//Sets the path to base URL + /hello
@Path("/hello")
public class Hello {

	// This method is called if TEXT_PLAIN is request
	@GET
	@Produces(MediaType.TEXT_PLAIN)
	public String sayPlainTextHello() {
		return "Hello Jersey";
	}

	// This method is called if XML is request
	@GET
	@Produces(MediaType.TEXT_XML)
	public String sayXMLHello() {
		return "<?xml version=\"1.0\"?>" + "<hello> Hello Jersey" + "</hello>";
	}

	// This method is called if HTML is request
	@GET
	@Produces(MediaType.TEXT_HTML)
	public String sayHtmlHello() {
		return "<html> " + "<title>" + "Hello Jersey" + "</title>"
				+ "<body><h1>" + "Hello Jersey" + "</body></h1>" + "</html> ";
	}

}

1.5.创建测试应用

package sample;

import java.net.URI;

import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.UriBuilder;

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;

public class Test {
	public static void main(String[] args) {
		ClientConfig config = new DefaultClientConfig();
		Client client = Client.create(config);
		WebResource service = client.resource(getBaseURI());
		// Fluent interfaces
		System.out.println(service.path("rest").path("hello")
				.accept(MediaType.TEXT_PLAIN).get(ClientResponse.class)
				.toString());
		// Get plain text
		System.out.println(service.path("rest").path("hello")
				.accept(MediaType.TEXT_PLAIN).get(String.class));
		// Get XML
		System.out.println(service.path("rest").path("hello")
				.accept(MediaType.TEXT_XML).get(String.class));
		// The HTML
		System.out.println(service.path("rest").path("hello")
				.accept(MediaType.TEXT_HTML).get(String.class));

	}

	private static URI getBaseURI() {
		return UriBuilder.fromUri(
				"http://localhost:8080/jersey1").build();
	}

}

1.6. 部署项目到tomcat后，运行Test程序：

2.然后来结合JAXB来创建RESTful web service.

JAX-RS可以直接通过JAXB来创建XML和JSON的输出。

JAXB是Java对xml的实现。

2.1 创建叫jersey2的Dynamic Web Project，导入jersey库。

2.2 创建一个对象，这里注意下，加上@XmlRootElement就可以了。

package sample;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement

public class Todo {
	private String summary;
	private String description;

	public String getSummary() {
		return summary;
	}

	public void setSummary(String summary) {
		this.summary = summary;
	}

	public String getDescription() {
		return description;
	}

	public void setDescription(String description) {
		this.description = description;
	}

}

2.3 创建一个class来调用jersey

package sample;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;


@Path("/todo")
public class TodoResource {
	// This method is called if XMLis request
	@GET
	@Produces({ MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON })
	public Todo getXML() {
		Todo todo = new Todo();
		todo.setSummary("This is my first todo");
		todo.setDescription("This is my first todo");
		return todo;
	}

	// This can be used to test the integration with the browser
	@GET
	@Produces({ MediaType.TEXT_XML })
	public Todo getHTML() {
		Todo todo = new Todo();
		todo.setSummary("This is my first todo");
		todo.setDescription("This is my first todo");
		return todo;
	}

}

2.4 web.xml文件

<?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>sample</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>sample</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>

2.5 部署项目，然后通过浏览器来测试

输入url： http://localhost:8080/jersey2/rest/todo

可以看到RESTful web service的输出：