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。