使用HttpClient 发送get、post请求，及其解析xml返回数据

一、关于HttpClient的使用：

可以参考这个博客地址，这里有详细的介绍，需要的可以先看一下：

地址是：http://blog.csdn.net/wangpeng047/article/details/19624529

二、项目中用到HttpClient 去请求一个地址，但是用get请求如果参数过多，不同的浏览器会导致不同程度的参数丢失，所以还应该要有post的请求的方式，在加上post请求方式的后，发现不能用原来解析get请求的方式来解析服务器返回的数据，经多方查找资料最终找到了解决方案，故记之；

代码如下：

 package com.shusheng.util;

 import java.io.IOException;
 import java.io.InputStream;
 import java.io.UnsupportedEncodingException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;

 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;

 import org.apache.http.HttpEntity;
 import org.apache.http.HttpResponse;
 import org.apache.http.NameValuePair;
 import org.apache.http.client.ClientProtocolException;
 import org.apache.http.client.HttpClient;
 import org.apache.http.client.entity.UrlEncodedFormEntity;
 import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.client.methods.HttpGet;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.DefaultHttpClient;
 import org.apache.http.impl.client.HttpClients;
 import org.apache.http.message.BasicNameValuePair;
 import org.apache.http.util.EntityUtils;
 import org.dom4j.DocumentException;
 import org.dom4j.DocumentHelper;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.NodeList;
 import org.xml.sax.SAXException;

 public class SendSmsMessage {
     //验证用户信息
     private static final String username = "username";
     private static final String password = "password";
     //字符编码及其他参数
     private static final String charset = "utf-8";
     private static final String url = "http://127.0.0.1:8080/WebAPI/dtest.actioin";
     /*
      * 因请求返回的数据中只需要code和result两个字段的信息，因此方法只返回一个存有这两个值的map
     */
     //get方式请求
     public static Map<String,String> sendMessageByGet(String content,String phones){
         Map<String,String> map = new HashMap<String, String>();
         HttpClient httpClient = new DefaultHttpClient();
         String fullUrl = url + "?user="+username+"&pwd="+password+"&mobiles="+phones+"&contents="+content;
         HttpGet httpGet = new HttpGet(fullUrl);
         try {
             HttpResponse response = httpClient.execute(httpGet);
             HttpEntity entity = response.getEntity();
             if (null != entity) {
                 InputStream in = entity.getContent();//将返回的内容流入输入流内
                 // 创建一个Document解析工厂
                 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                 DocumentBuilder builder = factory.newDocumentBuilder();
                 // 将输入流解析为Document
                 Document document = builder.parse(in);//用输入流实例化Document

                 Element rootElement = document.getDocumentElement();

                 NodeList codeNode = rootElement.getElementsByTagName("Code");
                 map.put("Code", codeNode.item(0).getTextContent());        

                 NodeList resultNode = rootElement.getElementsByTagName("Result");
                 map.put("Result", resultNode.item(0).getTextContent());

             }
         } catch (ClientProtocolException e) {
             e.printStackTrace();
         } catch (IllegalStateException e) {
             e.printStackTrace();
         } catch (DOMException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } catch (ParserConfigurationException e) {
             e.printStackTrace();
         } catch (SAXException e) {
             e.printStackTrace();
         }
         return map;
     }

     //post方式请求
     public static Map<String,String> sendMessageByPost(String content,String phones){
         Map<String,String> map = new HashMap<String, String>();
         // 创建默认的httpClient实例.
         CloseableHttpClient httpclient = HttpClients.createDefault();
         // 创建httppost
         HttpPost httppost = new HttpPost(url);
         // 创建参数队列
         List<NameValuePair> formparams = new ArrayList<NameValuePair>();
         formparams.add(new BasicNameValuePair("user", username));
         formparams.add(new BasicNameValuePair("pwd", password));
         formparams.add(new BasicNameValuePair("mobiles", phones));
         formparams.add(new BasicNameValuePair("contents", content)); 

         UrlEncodedFormEntity uefEntity;
         try{
             uefEntity = new UrlEncodedFormEntity(formparams, charset);
             httppost.setEntity(uefEntity);
             System.out.println("executing request " + httppost.getURI());
             CloseableHttpResponse response = httpclient.execute(httppost);
             try{
                 HttpEntity entity = response.getEntity();
                 if (entity != null) {
                     //将返回的数据直接转成String
                     String str = EntityUtils.toString(entity, "UTF-8") ;
                     System.out.println("--------------------------------------");
                     //注意这里不能写成EntityUtils.toString(entity, "UTF-8"),因为EntityUtils只能调用一次，否则会报错：java.io.IOException: Attempted read from closed stream
                     System.out.println("Response content: " + str);
                     System.out.println("--------------------------------------");  

                     //这里用str作为参数获得 Document 对象
                     org.dom4j.Document document = DocumentHelper.parseText(str);
                     org.dom4j.Element rootElement = document.getRootElement();

                     String code = rootElement.element("Code").getText();
                     String result = rootElement.element("Result").getText();
                     map.put("Code", code);
                     map.put("Result", result);
                 }
             }catch (DocumentException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }finally{
                 response.close();
             }

         } catch (ClientProtocolException e) {
             e.printStackTrace();
         } catch (UnsupportedEncodingException e1) {
             e1.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }finally{
              // 关闭连接,释放资源
             try {
                 httpclient.close();
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }

         return map ;
     }

     //验证手机号方法
     public static boolean checkPhoneNo(String phone){
         if(phone==null || phone.trim().equals("")){
             return false;
         }
         String regExp = "^[1]([3][0-9]{1}|59|58|88|89)[0-9]{8}$";
         Pattern p = Pattern.compile(regExp);
         Matcher m = p.matcher(phone);
         return m.find();
     }

     public static void main(String args[]){
         //System.out.println(checkPhoneNo(null));
         sendMessageByPost("【post请求】测试20151117_006","[正确手机号]");
     }
 }

这里贴一下服务器的返回String类型的xml数据：

 <?xml version="1.0" encoding="utf-8"?>
 <APIResult xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://tempuri.org/">
 <Code>12270</Code>
 <Result>短信提交成功</Result>
 </APIResult>

三、以上代码也可以看做是用java解析返回类型为xml的数据的方法；通过inputstream或者String 创建Document对象，然后通过该对象来解析每个分支的数据；上面代码中，如果在pos方式请求方法里用get方法那种解析xml的方式(即使用InputStream)会报错：java.io.IOException: Attempted read from closed stream；因此才使用String来创建Document的方式解析post请求返回的xml数据。有需要可以自己测试下，反正是个单独的类调试非常方便。

以上内容来自工作中遇到的问题以及上网查询所得，记以温之。