利用jaxb将XML转化为POJO

  在Java client中对restful webservice发送http post请求，将得到的请求转化为java pojo。
  restful ws返回信息格式为

 <RequestPhysicalInventoryPollingMessage> 
 <interval>int</interval> 
 <from>String</from> 
 <to>String</to> 
 <pollingurl> 
   String
 </pollingurl> 
 </RequestPhysicalInventoryPollingMessage> 
 

  那么为了将这个xml转化为POJO，需要先创建这个POJO类：

package com.client.jaxb;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "RequestPhysicalInventoryPollingMessage")
public class RequestPhysicalInventoryPollingMessage {
	String interval;
	String from;
	String to;
	String pollingurl;

	public RequestPhysicalInventoryPollingMessage() {
		interval = "c";
		from = "a";
		to = "b";
	}

	public String getInterval() {
		return interval;
	}

	public void setInterval(String interval) {
		this.interval = interval;
	}

	public String getFrom() {
		return from;
	}

	public void setFrom(String from) {
		this.from = from;
	}

	public String getTo() {
		return to;
	}

	public void setTo(String to) {
		this.to = to;

	}

	public String getPollingurl() {
		return pollingurl;
	}

	public void setPollingurl(String pollingurl) {
		this.pollingurl = pollingurl;
	}

}

只需要在定义类的前面注明@XmlRootElement(name = "RequestPhysicalInventoryPollingMessage")
如果在每个属性前面加@XmlAttribute，则会报错。

package com.client.jaxb;

import java.io.ByteArrayInputStream;
import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.FileRequestEntity;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.RequestEntity;

import com.client.RequestPhysicalInventoryPollingMessage;

public final class Client {

	private Client() {
	}

	public static void main(String args[]) throws Exception {
		//read the request payload
		File input = new File(
				"/RequestPhysicalInventory_FLOW_PIPeR_MPI3.1.xml");
		//set the uri which we will send request and the http method is post
		PostMethod post = new PostMethod(
				"http://10.10.27.74:7001/ManagePhysicalInventoryConsumerProject/ManagePhysicalInventoryConsumerProxyService ");
		post.addRequestHeader("Accept", "text/xml");
		RequestEntity entity = new FileRequestEntity(input, "text/xml; charset=ISO-8859-1");
		post.setRequestEntity(entity);
		HttpClient httpclient = new HttpClient();
		//execute the post method and get the response status code
		int result = httpclient.executeMethod(post);
		System.out.println("Response status code: " + result);
		System.out.println("Response body: ");
		//print the body of response
		System.out.println(post.getResponseBodyAsString());

		//invoke the method to convert the xml to a pojo
		RequestPhysicalInventoryPollingMessage message = xml2pojo(post
				.getResponseBodyAsString());
		System.out.println("interval:" + message.getInterval());
		System.out.println("from:" + message.getFrom());
		System.out.println("to:" + message.getTo());
		System.out.println("pollinguri:" + message.getPollingurl());
	}
	//convert the xml to a pojo
	public static RequestPhysicalInventoryPollingMessage xml2pojo(String xml)
			throws JAXBException {
		JAXBContext jaxbContext;
		//set the pojo in a new instance of JaxbContext
		jaxbContext = JAXBContext
				.newInstance(RequestPhysicalInventoryPollingMessage.class);
		
		Unmarshaller um = jaxbContext.createUnmarshaller();
		ByteArrayInputStream is = new ByteArrayInputStream(xml.getBytes());
		/*
		 * this method has no parameter as String,so we must get the bytes from a String,and create a ByteArrayInputStream
		 * by the bytes.
		 */
		RequestPhysicalInventoryPollingMessage message = (RequestPhysicalInventoryPollingMessage) um
				.unmarshal(is);
		return message;
	}

}

因为英语很烂，不知道用英语写的注释有没有写错。。。中文重新说明下:
RequestPhysicalInventoryPollingMessage message = (RequestPhysicalInventoryPollingMessage) um
.unmarshal(is);
这个方法：unmarshal() ，他不能接受String类型的参数（个人很不理解，为什么jaxb不去实现简单的把xml写在String中的POJO转化）。所以如果现在有一个String，内容是xml，就必须先调用这个String的getBytes()方法，然后用得到的byte[]去创建一个ByteArrayInputStream。然后把这个InputStream作为参数调用unmarshal().

执行代码结果如下：

Response status code: 200
Response body: 
<?xml version="1.0" encoding="UTF-8"?>
<RequestPhysicalInventoryPollingMessage><interval>-1</interval><from>http://www.altova.com</from><to>http://www.altova.com</to><pollingurl>http://10.10.27.74:7001/ManagePhysicalInventoryConsumerProject/ManagePhysicalInventoryConsumerProxyService/String</pollingurl></RequestPhysicalInventoryPollingMessage>
interval:-1
from:http://www.altova.com
to:http://www.altova.com
pollinguri:http://10.10.27.74:7001/ManagePhysicalInventoryConsumerProject/ManagePhysicalInventoryConsumerProxyService/String