Java 输入流中的read(byte[] b)方法详解

public int read(byte[] b)
  throws IOException

ServerSocket server = new ServerSocket(port)
Socket client = server.accept();
BufferedInputStream bis = new BufferedInputStream(client.getInputStream);

byte[] box = new byte[1024];
int len = 0;
while(-1!=(len = bis.read(box))) {
 System.out.println(len);
 String msg = new String(box, 0, len);
}语句1;语句二;

public class Test{
 public static void main(String[] args) throws Exception {
 UseTimeTool.getInstance().start();
 FileInputStream fis = new FileInputStream("D:\\1.mp3");
 FileOutputStream fos = new FileOutputStream("D:\\1copy.mp3");
 //(PS:一下3个大家分开来写和测试,为了方便我都列出来了)
 /*--------------不使用缓冲--------------*/
 //如果不缓冲,花了差不多14"秒"
 int len = -1;
 while ((len = fis.read()) != -1) {
  //这里就不是长度的问题了,而是读取的字节"内容",读到一个写一个,相当慢.
  System.out.println("len : "+ len); 
  fos.write(len);
 }
 /*--------------使用缓冲--------------*/
 //缓冲方法复制歌曲用了不到20"毫秒"
 //创建一个长度为1024的字节数组,每次都读取5kb,目的是缓存,如果不用缓冲区,用fis.read(),就会效率低,一个一个读字节,缓冲区是一次读5000个
 byte[] bytes = new byte[1024*5];
 //每次都是从读取流中读取(5k)长度的数据,然后再写到文件去(5k的)数据,注意,每次读取read都会不同,是获取到下一个,直到后面最后一个.
 while (fis.read(bytes)!=-1) {
  //write是最追加到文件后面,所以直接每次添5K.
  fos.write(bytes); 
 }
 /*--------------解释len--------------*/
 //告诉你为什么用len
 byte[] bytes = new byte[1024*5];
 int len = -1;
 //解释这个fis.read(bytes)的意思:从读取流"读取数组长度"的数据(打印len可知),并放入数组
 while ((len = fis.read(bytes,0,1024)) != -1) {
  //虽然数组长度的*5,但是这里我们设置了1024所以每次输出1024
  System.out.println("len : "+ len);
  //因为每次得到的是新的数组,所以每次都是新数组的"0-len"
  fos.write(bytes,0,len);
 }
 fis.close();
 fos.close();
 UseTimeTool.getInstance().stop();
 }
}

class UseTimeTool {
 private static UseTimeTool utt = new UseTimeTool();
 private UseTimeTool() {
 }
 public static UseTimeTool getInstance() {
 return utt;
 }
 private long start;
 public void start() {
 start = System.currentTimeMillis();
 }
 public void stop() {
 long end = System.currentTimeMillis();
 System.out.println("所用時間 : " + (end - start) + "毫秒");
 }
}

public class Test{
 public static void main(String[] args) throws Exception {
 UseTimeTool.getInstance().start();
 FileInputStream fis = new FileInputStream("D:\\a.txt");
 FileOutputStream fos = new FileOutputStream("D:\\acopy.txt");

byte[] bytes = new byte[1024*5];
 while (fis.read(bytes)!=-1) {
  fos.write(bytes); 
 }

byte[] bytes = new byte[1024*5];
 int len = -1;
 while ((len = fis.read(bytes,0,1024)) != -1) {
  fos.write(bytes,0,len);
 }