缓冲流

缓冲流

缓冲流：

 　　读取数据大量的文件时 ，读取的速度慢， java提供了一套缓冲流，提高IO流的效率。分为字节缓冲流和字符缓冲流。

★字节缓冲流：

　　　　缓冲输出流：BufferedOutputStream　　缓冲输入流：BufferesInputStream

BufferedOutputStream：

 

/*
 * 字节输出流的缓冲流  作用  提高效率
 * 继承OutputStream
 * 构造方法 new BufferedOutputStream(OutputStream out);
 * 
 * */
public class BufferedOutputStreamDemo { public static void main(String[] args) throws Exception { // 1创建字节输出流 绑定文件 //FileOutputStream fos =new FileOutputStream("c:\\buffer"); BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("c:\\buffer")); bos.write(65);//自动查码表 utf-8 0 1 //输出字符串 byte[] b= "hello world".getBytes(); bos.write(b); //截取 bos.write(b, 3, 2); bos.close(); } }

 

BufferesInputStream：

/*
 *   字节输入流的缓冲流  
 *   继承InputStream
 *   构造方法
 * 
 * */
public class BufferedInputStreamDemo { public static void main(String[] args) throws Exception { //1 创建字节输入流的缓冲流对象 BufferedInputStream b = new BufferedInputStream(new FileInputStream("c:\\buffer")); byte[] bs = new byte[1024]; b.close(); int len = 0; while((len=b.read(bs))!=-1){ System.out.print(new String(bs,0,len)); } } }

★字符缓冲流，用于文本数据的高速写入

　　缓冲输入流BufferedReader　　缓冲输出流BufferedWrite

BufferedReader

public class BufferedReaderDemo {
    public static void main(String[] args) throws Exception { //创建字符输入缓冲流对象 BufferedReader bu =new BufferedReader(new FileReader("c:\\bu.txt")); String len = null; while((len=bu.readLine())!=null){ System.out.println(len); } bu.close(); } }

BufferedWrite

/*字符输出缓冲流
 * write();
 *  构造方法 BufferedWriter(Writer w);
 *  new line() 写换行    \r\n
 *            linux   \n
 * */
public class BufferedWriterDemo { public static void main(String[] args) throws IOException { //创建字符输出流 封装文件 FileWriter fWriter = new FileWriter("c://bu.txt"); BufferedWriter bufferedWriter = new BufferedWriter(fWriter); bufferedWriter.write("您好"); bufferedWriter.newLine();//换行 bufferedWriter.write(100); bufferedWriter.flush(); bufferedWriter.write("床前明月光"); bufferedWriter.close(); } }

文件缓冲流的复制方式：

/*
 *  文件的复制方式
 *  1 字节流读写单个字节
 *  2 字节流读写字节数组   2405ms
 *  3 字节流缓冲区 读写单个字节   4855ms
 *  4 字节流缓冲区读写字节数组  697ms
 * */
public class Copy { public static void main(String[] args) throws Exception { long timeStart = System.currentTimeMillis(); copy4(new File("c:\\liu.mp4"), new File("d:\\liu.mp4")); long end = System.currentTimeMillis(); System.out.println(end-timeStart); } // 4 字节流缓冲区读写字节数组 public static void copy4(File src,File desc) throws Exception{ BufferedInputStream bu = new BufferedInputStream(new FileInputStream(src)); BufferedOutputStream ou = new BufferedOutputStream(new FileOutputStream(desc)); int len = 0; byte[] b=new byte[1024*10]; while((len=bu.read(b))!=-1){ ou.write(b,0,len); } ou.close(); bu.close(); } //3 字节流缓冲区 读写单个字节 public static void copy3(File src,File desc) throws Exception{ BufferedInputStream bu = new BufferedInputStream(new FileInputStream(src)); BufferedOutputStream ou = new BufferedOutputStream(new FileOutputStream(desc)); int len = 0; while((len=bu.read())!=-1){ ou.write(len); } ou.close(); bu.close(); } //2 字节流读写字节数组 public static void copy2(File src,File desc) throws Exception{ FileInputStream fis = new FileInputStream(src); FileOutputStream fos = new FileOutputStream(desc); int len = 0; byte[] b =new byte[1024*10]; while((len=fis.read(b))!=-1){ fos.write(b,0,len); } fos.close(); fis.close(); } //1 字节流读写单个字节 public static void copy1(File src,File desc) throws Exception{ FileInputStream fis = new FileInputStream(src); FileOutputStream fos = new FileOutputStream(desc); int len = 0; while((len=fis.read())!=-1){ fos.write(len); } fos.close(); fis.close(); } }

转载于:https://www.cnblogs.com/cuichaobo/p/10681326.html