BufferedInputStream的数据成员buf是一个位数组,默认为2048字节。当读取数据来源时,例如文件,BufferedInputStream会尽量将buf填满。当使用read()方法时,实际上是先读取buf中的数据,而不是直接对数据来源作读取。当buf中的数据不足时,BufferedInputStream才会再实现给定的InputStream对象的read()方法,从指定的装置中提取数据。 BufferedOutputStream的数据成员buf也是一个位数组,默认为512字节。当使用write()方法写入数据时实际上会先将数据写到buf中,当buf已满时才会实现给定的OutputStream对象的write()方法,将buf数据写到目的地,而不是每次都对目的地作写入的动作。
BufferedOutputStream流写出数据时一定要调用flush()方法才算完成所有流写出
demo如下
package ysu.hxy;
import java.io.*;
public class BufferedStreamDemo
{
public static void main(String[] args)
{
try
{
byte[] data = new byte[1];
File srcFile = new File(args[0]);
File desFile = new File(args[1]);
BufferedInputStream bufferedInputStream =
new BufferedInputStream(new FileInputStream(srcFile));
BufferedOutputStream bufferedOutputStream =
new BufferedOutputStream(new FileOutputStream(desFile));
System.out.println("复制文件:"+srcFile.length()+"字节");
while(bufferedInputStream.read(data)!=-1)
{
bufferedOutputStream.write(data);
}
//将缓冲区中的数据全部写出
bufferedOutputStream.flush();
//关闭流
bufferedInputStream.close();
bufferedOutputStream.close();
System.out.println("复制完成");
}
catch(ArrayIndexOutOfBoundsException e)
{
System.out.println("using:java UseFileStream src des");
e.printStackTrace();
}
catch(IOException e)
{
e.printStackTrace();
}
}
};
package ysu.hxy;
import java.io.*;
public class BufferedStreamDemo
{
public static void main(String[] args)
{
try
{
byte[] data = new byte[1];
File srcFile = new File(args[0]);
File desFile = new File(args[1]);
BufferedInputStream bufferedInputStream =
new BufferedInputStream(new FileInputStream(srcFile));
BufferedOutputStream bufferedOutputStream =
new BufferedOutputStream(new FileOutputStream(desFile));
System.out.println("复制文件:"+srcFile.length()+"字节");
while(bufferedInputStream.read(data)!=-1)
{
bufferedOutputStream.write(data);
}
//将缓冲区中的数据全部写出
bufferedOutputStream.flush();
//关闭流
bufferedInputStream.close();
bufferedOutputStream.close();
System.out.println("复制完成");
}
catch(ArrayIndexOutOfBoundsException e)
{
System.out.println("using:java UseFileStream src des");
e.printStackTrace();
}
catch(IOException e)
{
e.printStackTrace();
}
}
};