java中发送http请求的方法

package org.jeecgframework.test.demo;
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.Socket;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;  

import java.util.Set;
import java.util.SortedMap;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;  

public class HttpClientHelper {
    /**
     * @Description:使用HttpURLConnection发送post请求
     * @author:liuyc
     * @time:2016年5月17日 下午3:26:07
     */
    public static String sendPost(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        // 构建请求参数
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> e : params.entrySet()) {
                sbParams.append(e.getKey());
                sbParams.append("=");
                sbParams.append(e.getValue());
                sbParams.append("&");
            }
        }
        HttpURLConnection con = null;
        OutputStreamWriter osw = null;
        BufferedReader br = null;
        // 发送请求
        try {
            URL url = new URL(urlParam);
            con = (HttpURLConnection) url.openConnection();
            con.setRequestMethod("POST");
            con.setDoOutput(true);
            con.setDoInput(true);
            con.setUseCaches(false);
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            if (sbParams != null && sbParams.length() > 0) {
                osw = new OutputStreamWriter(con.getOutputStream(), charset);
                osw.write(sbParams.substring(0, sbParams.length() - 1));
                osw.flush();
            }
            // 读取返回内容
            resultBuffer = new StringBuffer();
            int contentLength = Integer.parseInt(con.getHeaderField("Content-Length"));
            if (contentLength > 0) {
                br = new BufferedReader(new InputStreamReader(con.getInputStream(), charset));
                String temp;
                while ((temp = br.readLine()) != null) {
                    resultBuffer.append(temp);
                }
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (osw != null) {
                try {
                    osw.close();
                } catch (IOException e) {
                    osw = null;
                    throw new RuntimeException(e);
                } finally {
                    if (con != null) {
                        con.disconnect();
                        con = null;
                    }
                }
            }
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                } finally {
                    if (con != null) {
                        con.disconnect();
                        con = null;
                    }
                }
            }
        }  

        return resultBuffer.toString();
    }  

    /**
     * @Description:使用HttpClient发送post请求
     * @author:liuyc
     * @time:2016年5月17日 下午3:28:23
     */
    public static String httpClientPost(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        HttpClient client = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(urlParam);
        // 构建请求参数
        List<NameValuePair> list = new ArrayList<NameValuePair>();
        Iterator<Entry<String, Object>> iterator = params.entrySet().iterator();
        while (iterator.hasNext()) {
            Entry<String, Object> elem = iterator.next();
            list.add(new BasicNameValuePair(elem.getKey(), String.valueOf(elem.getValue())));
        }
        BufferedReader br = null;
        try {
            if (list.size() > 0) {
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, charset);
                httpPost.setEntity(entity);
            }
            HttpResponse response = client.execute(httpPost);
            // 读取服务器响应数据
            resultBuffer = new StringBuffer();
            br = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
            String temp;
            while ((temp = br.readLine()) != null) {
                resultBuffer.append(temp);
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                }
            }
        }
        return resultBuffer.toString();
    }  

    //请求xml组装
    public static String getRequestXml(SortedMap<String,Object> parameters){
          StringBuffer sb = new StringBuffer();
          sb.append("<xml>");
          Set es = parameters.entrySet();
          Iterator it = es.iterator();
          while(it.hasNext()) {
              Map.Entry entry = (Map.Entry)it.next();
              String key = (String)entry.getKey();
              String value = (String)entry.getValue();
              if ("attach".equalsIgnoreCase(key)||"body".equalsIgnoreCase(key)||"sign".equalsIgnoreCase(key)) {
                  sb.append("<"+key+">"+"<![CDATA["+value+"]]></"+key+">");
              }else {
                  sb.append("<"+key+">"+value+"</"+key+">");
              }
          }
          sb.append("</xml>");
          return sb.toString();
      }
    //生成签名
    public static String createSign(String characterEncoding,SortedMap<String,Object> parameters){
          StringBuffer sb = new StringBuffer();
          Set es = parameters.entrySet();
          Iterator it = es.iterator();
          while(it.hasNext()) {
              Map.Entry entry = (Map.Entry)it.next();
              String k = (String)entry.getKey();
              Object v = entry.getValue();
              if(null != v && !"".equals(v)
                      && !"sign".equals(k) && !"key".equals(k)) {
                  sb.append(k + "=" + v + "&");
              }
          }
          sb.append("key=" + "");
          String sign = MD5.md5(sb.toString()).toUpperCase();
          return sign;
      }
    //请求方法
    public static String httpsRequest(String requestUrl, String requestMethod, String data) {
          try {  

              URL url = new URL(requestUrl);
              HttpURLConnection conn = (HttpURLConnection) url.openConnection();  

              conn.setDoOutput(true);
              conn.setDoInput(true);
              conn.setUseCaches(false);
              // 设置请求方式（GET/POST）
              conn.setRequestMethod(requestMethod);
              conn.setRequestProperty("content-type", "application/json");
             // conn.setRequestProperty("content-type", "text/xml;charset=utf-8");
              // 当outputStr不为null时向输出流写数据
              if (null != data) {
                  OutputStream outputStream = conn.getOutputStream();
                  // 注意编码格式
                  outputStream.write(data.getBytes("UTF-8"));
                  outputStream.close();
              }
              // 从输入流读取返回内容
              InputStream inputStream = conn.getInputStream();
              InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
              BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
              String str = null;
              StringBuffer buffer = new StringBuffer();
              while ((str = bufferedReader.readLine()) != null) {
                  buffer.append(str);
              }
              // 释放资源
              bufferedReader.close();
              inputStreamReader.close();
              inputStream.close();
              inputStream = null;
              conn.disconnect();
              return buffer.toString();
          } catch (ConnectException ce) {
              System.out.println("连接超时：{}"+ ce);
          } catch (Exception e) {
              System.out.println("https请求异常：{}"+ e);
          }
          return null;
      }
    public static void main(String[] args) {
        String requestUrl,requestMethod,outputStr;
        requestUrl="（此处填写你要请求的url地址）";
        requestMethod="POST";
        outputStr="<xml>"+
                    "<appid><![CDATA[wx2421b1c4370ec43b]]></appid>"+
                    "<mch_id><![CDATA[10000100]]></mch_id>"+
                    "<device_info><![CDATA[1]]></device_info>"+
                    "<nonce_str><![CDATA[5d2b6c2a8db53831f7eda20af46e531c]]></nonce_str>"+
                    "<sign><![CDATA[6245928B869A39BC75A421200A74002E]]></sign>"+
                    "<result_code><![CDATA[SUCCESS]]></result_code>"+
                    "<return_code><![CDATA[SUCCESS]]></return_code>"+
                    "<err_code><![CDATA[1004400740201409030005092168]]></err_code>"+
                    "<err_code_des><![CDATA[1004400740201409030005092168]]></err_code_des>"+
                    "<openid><![CDATA[oUpF8uMEb4qRXf22hE3X68TekukE]]></openid>"+
                    "<is_subscribe><![CDATA[Y]]></is_subscribe>"+
                    "<trade_type><![CDATA[JSAPI]]></trade_type>"+
                    "<bank_type><![CDATA[CFT]]></bank_type>"+
                    "<total_fee><![CDATA[1]]></total_fee>"+
                    "<fee_type><![CDATA[CNY]]></fee_type>"+
                    "<cash_fee><![CDATA[168]]></cash_fee>"+
                    "<cash_fee_type><![CDATA[1004400740201409030005092168]]></cash_fee_type>"+
                    "<transaction_id><![CDATA[1004400740201409030005092168]]></transaction_id>"+
                    "<out_trade_no><![CDATA[137999992017032919767558710]]></out_trade_no>"+
                    "<time_end><![CDATA[20140903131540]]></time_end>"+
                    "<trade_state><![CDATA[1]]></trade_state>"+
                    "<attach><![CDATA[支付测试]]></attach>"+
                    "</xml>";

　　　　//错误的json请求
      　　// String data = "[{\"id\":1,\"name\":\"o2o_V3.0新版发布\",\"content\":\"o2o_V3.0新版发布\",\"time\":\"2015-05-11 03:12:51\"}]";
        String data = "{\"id\":1,\"name\":\"o2o_V3.0新版发布\",\"content\":\"o2o_V3.0新版发布\",\"time\":\"2015-05-11 03:12:51\"}";
        String xml=httpsRequest(requestUrl,requestMethod,data);
        System.out.println(xml);
        //System.out.println(outputStr);
    }

}  

请求的时候只需要调用这个类中的httpsRequest方法，requestUrl代表的就是请求的url地址，requestMethod代表的是以Post或者Get方法请求方式，data就是请求的参数；