使用Jquery，Jackson JSON，JAX-RS，Apache Wink，Spring实现REST应用开发

简介
REST 是英文 Representational State Transfer 的缩写，有中文翻译为“具象状态传输”。相较于基于 SOAP 和 WSDL 的 Web 服务，REST 模式提供了更为简洁的实现方案。目前，越来越多的 Web 服务开始采用 REST 风格设计和实现。

REST中的一个重要概念是资源的存在性，每个资源都一个全局引用标识符，即URI。特别是数据和函数都被认为是可通过URI识别和访问的资源。为了操纵这些资源，网络组件，客户端和服务器通过一个标准的接口通信，如HTTP和一个组固定的动词 — GET，PUT，POST和DELETE — 交换这些资源。

JAX-RS为在Java中构建RESTful Web服务提供了标准化API，API提供了一组注解，以及相关的类和接口。对POJO应用注解允许你暴露Web资源，这个方法使得在Java中创建RESTful Web服务变得简单。

Apache Wink是一个简单而强大的RESTful Web服务创建框架。它由一个服务器端模块和一个客户端模块组成。Apache Wink的服务器端模块是JAX-RS1.0规范的一个完全实现。除了对基本协议的实现外，Apache Wink服务器端模块还提供了一系列便于开发RESTful Web服务的新特性。Apache Wink客户端模块提供了调用RESTful Web服务的相关功能，该模块基于JDK HttpURLConnection实现。

简单的说：REST是一种Web Service的设计模式，本文提到的实现方式，是从浏览器客户端借用jQuery发送Ajax请求到server端的Apache Wink提供的JAX-RS服务 (每个Resource是由spring负责实例化的) 从而实现WebService。


好了，废话不多说了，现在贴出具体的代码样例。

开发环境：
JDK1.5以上
Jquery1.4以上
jackson-all-1.6.2.jar
jsr311-api.jar
wink-server-1.1.2-incubating.jar
Spring2.0以上


JaxRSResource.java
--该接口没有任何方法，只是为了让spring过滤所有实现该接口的Resource

package com.cuishen.jaxrs.demo;

public interface JaxRSResource {

}

WinkApplication.java
--继承自javax.ws.rs.core.Application，并重写getSingletons()，在该方法中调用spring的getBean()接口，并过滤出所有实现了JaxRSResource接口的bean，然后返回给Application

package com.cuishen.jaxrs.demo;

import java.util.HashSet;
import java.util.Set;

import javax.ws.rs.core.Application;

import com.cuishen.jaxrs.demo.factory.MyBeanFactory;;

public class WinkApplication extends Application {

	public WinkApplication() { }

	@Override
	public Set<Object> getSingletons() {
		String beans[] = MyBeanFactory.getBeanNamesForType(JaxRSResource.class);
		Set<Object> result = new HashSet<Object>();
		if (beans != null) {
			for (int i = 0; i < beans.length; i++) {
				String beanName = beans[i];
				result.add(MyBeanFactory.getBean(beanName));
			}
		}
		return result;
	}
}

DemoResource.java
--具体的Resource实现，实现JaxRSResource接口，也是spring托管的一个bean

package com.cuishen.jaxrs.demo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.ws.rs.*;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.codehaus.jackson.map.ObjectMapper;

import com.cuishen.jaxrs.demo.bean.TestBean;

@Path("/accountDemo")
public class DemoResource implements JaxRSResource {
	private static final Log log = LogFactory.getLog(DemoResource.class);

	@POST
	@Path("/transactions/{id}")
	@Produces("application/json")
	public Map<String, String> getTransactions(@PathParam("id") String id) throws Exception {
		log.error("============================= successful getTransactions =================");
		Map<String, String> map = new HashMap<String, String>();
		map.put("id", id);
		return map;
	}

	@POST
	@Path("/transactions/")
	@Consumes("application/json")
	@Produces("application/json")
	public String getTransactions(HashMap<String, String> params) throws Exception {
		log.error("============================= successful getTransactions 2 =================");
		List<TestBean> list = new ArrayList<TestBean>();
		TestBean bean = new TestBean();
		String id = (String) params.get("id");
		bean.setId(id);
		bean.setName("xiao ming");
		list.add(bean);
		bean = new TestBean();
		bean.setId("222");
		bean.setName("xiao zhang");
		list.add(bean);
		ObjectMapper objectMapper = new ObjectMapper();
		String listJson = objectMapper.writeValueAsString(list);
		return listJson;
	}

	@POST
	@Path("/demoData")
	@Consumes("application/x-www-form-urlencoded")
	@Produces("application/json")
	public String getDemoData(@FormParam("id") String id, @FormParam("name") String name) throws Exception {
		log.error("============================= successful getDemoData =================");
		List<TestBean> list = new ArrayList<TestBean>();
		TestBean bean = new TestBean();
		bean.setId(id);
		bean.setName(name);
		list.add(bean);
		bean = new TestBean();
		bean.setId("222");
		bean.setName("xiao zhang");
		list.add(bean);
		ObjectMapper objectMapper = new ObjectMapper();
		String listJson = objectMapper.writeValueAsString(list);
		return listJson;
	}
	@POST
	@Path("/demoData")
	@Consumes("application/json")
	@Produces("application/json")
	public String getDemoData(HashMap<String, String> params) throws Exception {
		log.error("============================= successful getDemoData 2 =================");
		List<TestBean> list = new ArrayList<TestBean>();
		TestBean bean = new TestBean();
		String id = (String) params.get("id");
		bean.setId(id);
		String name = (String) params.get("name");
		bean.setName(name);
		String birthday = (String) params.get("birthday");
		bean.setBirthday(birthday);
		list.add(bean);
		bean = new TestBean();
		bean.setId("222");
		bean.setName("xiao zhang");
		list.add(bean);
		ObjectMapper objectMapper = new ObjectMapper();
		String listJson = objectMapper.writeValueAsString(list);
		return listJson;		
	}
}

TestBean.java
--Json序列化时要用到

package com.cuishen.jaxrs.demo.bean;

import java.io.Serializable;

//import org.codehaus.jackson.annotate.JsonProperty;

public class TestBean implements Serializable {
	private static final long serialVersionUID = -8079868256837582676L;
	//@JsonProperty("id")
	private String id;
	//@JsonProperty("name")
	private String name;
	
	private String birthday;

	public String getBirthday() {
		return birthday;
	}

	public void setBirthday(String birthday) {
		this.birthday = birthday;
	}

	//@JsonProperty("id")
	public String getId() {
		return id;
	}

	//@JsonProperty("id")
	public void setId(String id) {
		this.id = id;
	}

	//@JsonProperty("name")
	public String getName() {
		return name;
	}

	//@JsonProperty("name")
	public void setName(String name) {
		this.name = name;
	}
	/**
	@Override
	public String toString() {
		return "TestBean{" + "id='" + id + '\'' + ",name='" + name + '\''  + '}';
	}*/
}

MyBeanFactory.java
--这个大家都懂的，具体的实现自己看着办吧

package com.cuishen.jaxrs.demo.factory;

public class MyBeanFactory {
	public static String[] getBeanNamesForType(Class clazz) {
		// do something to get bean names for bean type from spring IOC container
		return null;
	}
	public static Object getBean(String beanName) {
		// do something to get bean by beanName from spring IOC container
		return null;
	}
}

spring-application-context-jaxrs-demo.xml
--这个怎么用大家也都懂的。

<?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:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">

	<bean name="jaxrs.demo.accountDemo" class="com.cuishen.jaxrs.demo.DemoResource">
	</bean>

</beans>

web.xml
--这个也不用说了吧

<servlet>
	<servlet-name>jaxrs</servlet-name>
	<servlet-class>org.apache.wink.server.internal.servlet.RestServlet
	</servlet-class>
	<init-param>
		<param-name>javax.ws.rs.Application</param-name>
		<param-value>com.cuishen.jaxrs.demo.WinkApplication</param-value>
	</init-param>
	<load-on-startup>10</load-on-startup>
</servlet>
<servlet-mapping>
	<servlet-name>jaxrs</servlet-name>
	<url-pattern>/REST/*</url-pattern>
</servlet-mapping>

index.jsp

<form id="formDemo" name="formDemo" action="/DomainID/REST/accountDemo/demoData" method=post>
	<input type="text" value="333333" id="id" name="id">
	<input type="text" value="ZhangSan" id="name" name="name">
	<input type="text" value="1981" id="birthday" name="birthday">
</form>
<script type="text/javascript">
function form2Json() {
	var formObj = $("#formDemo");
	var JsonObj = "'{";
	var a = formObj.serializeArray();
	var index = 0;
	$.each(a, function() {
		index++;
		JsonObj += "\"" + this.name + "\":\"" + this.value + "\"";
		if(a.length != 1 && a.length != index) {
			JsonObj += ",";
		}
	});
	JsonObj += "}'";
	return eval(JsonObj);
}

function doit() {
// sample one
jQuery.ajax({url:'/DomainID/REST/accountDemo/transactions/111111',
        type:'POST',
        dataType:'json',
        success:function(data, status, xhr) {
           // here you can do whatever is necessary with the data.
           alert("sample one");
           alert(data.id);
        },
        error:function(xhr,error,exception) {
           // handle the error.
           alert(exception.toString());
        }
});
// sample two
$.ajax({url:'/DomainID/REST/accountDemo/transactions',     
        data:'{"id":222222}',
        type:'POST',
        dataType:'json',
        contentType:'application/json',
        success:function(data, status, xhr) {
           // here you can do whatever is necessary with the data.
           alert("sample two");
           alert(data[0].id);
           alert(data[0].name);
        },
        error:function(xhr,error,exception) {
           // handle the error.
           alert(exception.toString());
        }
});
// sample three
$.ajax({url:$("#formDemo").attr('action'),
			type:'POST',
			data:$("#formDemo").serialize(),
			dataType:'json',
			contentType:'application/x-www-form-urlencoded',
			success:function(data, status, xhr) {
			// here you can do whatever is necessary with the data.
				alert("sample three");
				alert(data[0].id);
				alert(data[0].name);
			},
			Error:function(xhr,error,exception) {
			// handle the error.
				alert(exception.toString());
			}
});
// sample four
$.ajax({url:$("#formDemo").attr('action'),
			type:'POST',
			data:form2Json(),
			dataType:'json',
			contentType:'application/json',
			success:function(data, status, xhr) {
			// here you can do whatever is necessary with the data.
				alert("sample four");
				alert(data[0].id);
				alert(data[0].name);
				alert(data[0].birthday);
			},
			Error:function(xhr,error,exception) {
			// handle the error.
				alert(exception.toString());
			}
});
}
</SCRIPT>
<input type="button" value="click me" onclick="doit()">

ok！代码演示完了，有几个注意点：
1. 如果遇到404 Not Found的错，肯定是Ajax请求找不到URL或者说那个resource里面的方法。
2. 不仅方法名，参数要匹配，而且参数类型也要匹配。
3. resource里面，@Consumes("application/json")表示请求的数据类型是json，@Produces("application/json")表示返回的数据类型是json
4. js里面，contentType:'application/json'表示发出的请求要以json为数据格式，dataType:'json'表示接收的数据类型为json
5. POST和GET都可以，但是js和resource两边要一致。