java应用程序向服务器发送request请求，并接受响应

下面代码是别人写的，经测试很好用

//get形式发生请求

public static String sendGet(String url,String param){
  String result = "";
  BufferedReader in = null;
  try{
   String urlNameString = url+"?"+param;
   URL realUrl = new URL(urlNameString);
   //发送请求
   URLConnection connection  = realUrl.openConnection();
   connection.setRequestProperty("accept","*/*");
   connection.setRequestProperty("connection","Keep-Alive");
   connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");

   //这句话只会建立一个连接，并不会把请求发出去
   connection.connect();
   //接受响应
   Map<String,List<String>> map = connection.getHeaderFields();
   for(String key:map.keySet()){
    System.out.println(key+"="+map.get(key));
   }
   in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
   String line = null;
   while((line = in.readLine()) != null){
    result +=line;
   }
  }catch(Exception e){
   System.out.println("发送get请求出现错误！"+e);
   e.printStackTrace();
  }
  finally{
   try {
    if(in != null){
     in.close();
    }
   } catch (Exception e2) {
    // TODO: handle exception
    e2.printStackTrace();
   }
  }
  return result;
 }

//post发送

public static String sendPost(String url,String param){
  PrintWriter out = null;
  BufferedReader in = null;
  String result = "";
  try{
   URL realUrl = new URL(url);
     
   URLConnection conn = realUrl.openConnection();
   conn.setRequestProperty("accept","*/*");
   conn.setRequestProperty("connection","Keep-Alive");
   conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
   //post请求必写
   conn.setDoOutput(true);
   conn.setDoInput(true);
   out = new PrintWriter(conn.getOutputStream());
   out.println(param);
   out.flush();
   //conn.getInputStream()这句话会真正的发出请求
   in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
   String line = null;
   while((line = in.readLine()) != null){
    result +=line;
   }
  }catch(Exception e){
   System.out.println("发送POST请求出错！");
   e.printStackTrace();
  }
  finally{
   try{
    if(out != null)
     out.close();
    if(in != null)
     in.close();
   }catch(IOException ex){
    ex.printStackTrace();
   }
  }
  return result;
 }