import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpClient {
 //發送一個GET請求
 public static String get(String path) throws Exception{
  HttpURLConnection httpConn=null;
  BufferedReader in=null;
  try {
   URL url=new URL(path);
   httpConn=(HttpURLConnection)url.openConnection();

   //讀取響應
   if(httpConn.getResponseCode()==HttpURLConnection.HTTP_OK){
    StringBuffer content=new StringBuffer();
    String tempStr="";
    in=new BufferedReader(new InputStreamReader(httpConn.getInputStream()));
    while((tempStr=in.readLine())!=null){
     content.append(tempStr);
    }
    return content.toString();
   }else{
    throw new Exception("請求出現了問題!");
   }
  } catch (IOException e) {
   e.printStackTrace();
  }finally{
   in.close();
   httpConn.disconnect();
  }
  return null;
 }
 //發送一個GET請求,參數形式key1=value1&key2=value2...
 public static String post(String path,String params) throws Exception{
  HttpURLConnection httpConn=null;
  BufferedReader in=null;
  PrintWriter out=null;
  try {
   URL url=new URL(path);
   httpConn=(HttpURLConnection)url.openConnection();
   httpConn.setRequestMethod("POST");
   httpConn.setDoInput(true);
   httpConn.setDoOutput(true);

   //發送post請求參數
   out=new PrintWriter(httpConn.getOutputStream());
   out.println(params);
   out.flush();

   //讀取響應
   if(httpConn.getResponseCode()==HttpURLConnection.HTTP_OK){
    StringBuffer content=new StringBuffer();
    String tempStr="";
    in=new BufferedReader(new InputStreamReader(httpConn.getInputStream()));
    while((tempStr=in.readLine())!=null){
     content.append(tempStr);
    }
    return content.toString();
   }else{
    throw new Exception("請求出現了問題!");
   }
  } catch (IOException e) {
   e.printStackTrace();
  }finally{
   in.close();
   out.close();
   httpConn.disconnect();
  }
  return null;
 }

 public static void main(String[] args) throws Exception {
  //String resMessage=HttpClient.get("http://localhost:3000/hello?hello=hello get");
  String resMessage=HttpClient.post("http://localhost:3000/hello", "hello=hello post");
  System.out.println(resMessage);
 }

}