message: perf: use StringBuffer in Java HTTP API
  by chenjiaqi
diff: @@ -2,6 +2,7 @@ package jgsc;
  import java.io.*;
  import java.net.*;
  +import java.lang.*;
  import java.net.URLEncoder;
  import java.net.URLDecoder;
  import java.io.UnsupportedEncodingException;
  @@ -37,7 +38,7 @@ public class GstoreConnector {
  //this may help to reduce the GC cost
  public String sendGet(String param) {
  String url = "http://" + this.serverIP + ":" + this.serverPort;
  - String result = "";
  + StringBuffer result = new StringBuffer();
  BufferedReader in = null;
  System.out.println("parameter: "+param);
  @@ -82,7 +83,7 @@ public class GstoreConnector {
  while ((line = in.readLine()) != null) {
  //PERFORMANCE: this can be very costly if result is very large, because many temporary Strings are produced
  //In this case, just print the line directly will be much faster
  - result += line;
  + result.append(line);
  //System.out.println("get data size: " + line.length());
  //System.out.println(line);
  }
  @@ -103,7 +104,7 @@ public class GstoreConnector {
  e2.printStackTrace();
  }
  }
  - return result;
  + return result.toString();
  }
  //NOTICE: no need to connect now, HTTP connection is kept by default
  