java io 流 效率

作者：roger51

http://roger51.javaeye.com/blog/105498

import java.io.*;

public class IOTest {

public static void main(String[] args){

             IOTest io = new IOTest();

             try{

             long startTime = System.currentTimeMillis();

             io.readWrite("c:/temp/1.txt","c:/temp/2.txt");     

             long endTime = System.currentTimeMillis();

             System.out.println("Time taken for reading and writing using default behaviour : "

                                                           + (endTime - startTime) + " milli seconds" );

 

             long startTime1 = System.currentTimeMillis();

             io.readWriteBuffer("c:/temp/1.txt","c:/temp/2.txt");            

             long endTime1 = System.currentTimeMillis();

             System.out.println("Time taken for reading and writing using buffered streams : "

                                                           + (endTime1 - startTime1) + " milli seconds" );

 

             long startTime2 = System.currentTimeMillis();

             io.readWriteArray("c:/temp/1.txt","c:/temp/2.txt");              

             long endTime2 = System.currentTimeMillis();

             System.out.println("Time taken for reading and writing using custom buffering : "

                                                           + (endTime2 - startTime2) + " milli seconds" );

             }catch(IOException e){ e.printStackTrace();}

}

public static void readWrite(String fileFrom, String fileTo) throws IOException{

             InputStream in = null;

             OutputStream out = null;

             try{

                          in = new FileInputStream(fileFrom);

                          out = new FileOutputStream(fileTo);

                          while(true){

                                          int bytedata = in.read();

                                          if(bytedata == -1)

                                          break;

                                          out.write(bytedata);

                          }

             }

             finally{

              if(in != null)

                          in.close();

              if(out !=null)

                          out.close();

             }

}

public static void readWriteBuffer(String fileFrom, String fileTo) throws IOException{

             InputStream inBuffer = null;

             OutputStream outBuffer = null;

             try{

                          InputStream in = new FileInputStream(fileFrom);

                          inBuffer = new BufferedInputStream(in);

                          OutputStream out = new FileOutputStream(fileTo);

                          outBuffer = new BufferedOutputStream(out);

                          while(true){

                                          int bytedata = inBuffer.read();

                                          if(bytedata == -1)

                                          break;

                                          out.write(bytedata);

                          }

             }

             finally{

              if(inBuffer != null)

                          inBuffer.close();

              if(outBuffer !=null)

                          outBuffer.close();

             }

}           

public static void readWriteArray(String fileFrom, String fileTo) throws IOException{

             InputStream in = null;

             OutputStream out = null;

             try{

                          in = new FileInputStream(fileFrom);

                          out = new FileOutputStream(fileTo);

                          int availableLength = in.available();

                          byte[] totalBytes = new byte[availableLength];

                          int bytedata = in.read(totalBytes);

                          out.write(totalBytes);

                             

             }

             finally{

              if(in != null)

                          in.close();

              if(out !=null)

                          out.close();

             }

}           

}