Android NIO学习之文件拷贝

public static long forChannel(File f1, File f2) throws Exception {
   long time = new Date().getTime();
   int size = 2*1024; FileInputStream in = new FileInputStream(f1);
   FileOutputStream out = new FileOutputStream(f2); FileChannel inC = in.getChannel();
   FileChannel outC = out.getChannel(); ByteBuffer buffer = null;
   int count = size;
   while (inC.position() != inC.size()) {
    if ((inC.size() - inC.position()) < size) {
     count = (int) (inC.size() - inC.position());
    }
    buffer = ByteBuffer.allocateDirect(count);
    
    inC.read(buffer);
    
    buffer.flip();
    
    outC.write(buffer);
    
    outC.force(false);
   }
   inC.close();
   outC.close();
   
   in.close();
   out.flush();
   out.close();
   return new Date().getTime() - time;
  }
  
  public static long forChannelOne(File f1, File f2) throws IOException {
   long time = new Date().getTime();
   int size = 2 * 1024;// 2097152;
   FileInputStream in = new FileInputStream(f1);
   FileOutputStream out = new FileOutputStream(f2); FileChannel fcin = in.getChannel();
   FileChannel fcout = out.getChannel(); ByteBuffer buffer = ByteBuffer.allocate(size); // 分配2KB作为缓冲区
 while (true) {
    buffer.clear(); // 每次使用必须置空缓冲区  int r = fcin.read(buffer);
  if (r == -1) {
     break;
    }  buffer.flip(); // 写入前使用flip这个方法
  fcout.write(buffer);
   } fcin.close();
   fcout.close(); in.close();
   out.flush();
   out.close();
   return new Date().getTime() - time;
  }  public static long forJava(File f1, File f2) throws Exception {
   long time = new Date().getTime();
   int size = 2 * 1024;// 2097152;
   FileInputStream in = new FileInputStream(f1);
   FileOutputStream out = new FileOutputStream(f2); byte[] buffer = new byte[size];
   int ins;
   while ((ins = in.read(buffer)) != -1) {
    out.write(buffer, 0, ins);
   } in.close();
   out.flush();
   out.close();
   return new Date().getTime() - time;
  }  public static long forTransfer(File f1, File f2) throws Exception {
   long time = new Date().getTime();
   int size = 2 * 1024;// 2k == 2097152;
   FileInputStream in = new FileInputStream(f1);
   FileOutputStream out = new FileOutputStream(f2); FileChannel inC = in.getChannel();
   FileChannel outC = out.getChannel(); int count = size;
   while (inC.position() != inC.size()) {
    if ((inC.size() - inC.position()) < size) {
     count = (int) (inC.size() - inC.position());
    }
    inC.transferTo(inC.position(), count, outC);
    inC.position(inC.position() + count);
   }
   inC.close();
   outC.close();
   return new Date().getTime() - time;
  }public void test(){
   String infile = "/sdcard/testUTF.txt"; //8k
   String outfile = "/sdcard/testUTF8.txt";
   File f1 = new File(infile);
   File f2 = new File(outfile);
   try {
 //   Log.v("TAG", "" + Student.forJava(f1, f2));//31
 //   Log.v("TAG", "" + Student.forTransfer(f1, f2));//28
    Log.v("TAG", "" + Student.forChannelOne(f1, f2));//22
 //   Log.v("TAG", "" + Student.forChannel(f1, f2));//15
   } catch (Exception e) {
    e.printStackTrace();
   }