IO基础（2）-IO缓冲流及其他流用法

一、缓冲流

• 为了提高数据读写的速度，JavaAPI提供了带缓冲功能的流类，在使用这些流类时，会创建一个内部缓冲区数组

• 根据数据操作单位可以把缓冲流分为：

     BufferedInputStream和BufferedOutputStream

     BufferedReader和BufferedWriter

• 缓冲流要“套接”在相应的节点流之上，对读写的数据提供了缓冲的功能，提高了读写的效率，同时增加了一些新的方法

• 对于输出的缓冲流，写出的数据会先在内存中缓存，使用flush()将会使内存中的数据立刻写出

import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import org.junit.Test;/* * 抽象基类节点流（文件流）                                缓冲流（处理流的一种,可以提升文件操作的效率） * InputStreamFileInputStreamBufferedInputStream * OutputStreamFileOutputStreamBufferedOutputStream  (flush()) * ReaderFileReaderBufferedReader  (readLine()) * WriterFileWriterBufferedWriter  (flush()) */public class TestBuffered {@Testpublic void testBufferedReader(){BufferedReader br = null;BufferedWriter bw = null;try {File file = new File("dbcp.txt");File file1 = new File("dbcp3.txt");FileReader fr = new FileReader(file);FileWriter fw = new FileWriter(file1);br = new BufferedReader(fr);bw = new BufferedWriter(fw);//char[] c = new char[1024];//int len;//while((len = br.read(c))!= -1){//String str = new String(c, 0, len);//System.out.print(str);//}String str;while((str = br.readLine()) != null){//System.out.println(str);bw.write(str + "\n");//bw.newLine();bw.flush();}}catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{if(bw != null){try {bw.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(br != null){try {br.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}@Testpublic void testCopyFile(){long start = System.currentTimeMillis();//String src = "C:\\Users\\shkstart\\Desktop\\1.avi";//String dest = "C:\\Users\\shkstart\\Desktop\\3.avi";String src = "C:\\Users\\shkstart\\Desktop\\实验.doc";String dest = "C:\\Users\\shkstart\\Desktop\\实验1.doc";copyFile(src,dest);long end = System.currentTimeMillis();System.out.println("花费的时间为：" + (end - start));//746}//使用缓冲流实现文件的复制的方法public void copyFile(String src,String dest){BufferedInputStream bis = null;BufferedOutputStream bos = null;try {//1.提供读入、写出的文件File file1 = new File(src);File file2 = new File(dest);//2.想创建相应的节点流：FileInputStream、FileOutputStreamFileInputStream fis = new FileInputStream(file1);FileOutputStream fos = new FileOutputStream(file2);//3.将创建的节点流的对象作为形参传递给缓冲流的构造器中bis = new BufferedInputStream(fis);bos = new BufferedOutputStream(fos);//4.具体的实现文件复制的操作byte[] b = new byte[1024];int len;while((len = bis.read(b)) != -1){bos.write(b, 0, len);bos.flush();}}catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{//5.关闭相应的流if(bos != null){try {bos.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(bis != null){try {bis.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}//使用BufferedInputStream和BufferedOutputStream实现非文本文件的复制@Testpublic void testBufferedInputOutputStream(){BufferedInputStream bis = null;BufferedOutputStream bos = null;try {//1.提供读入、写出的文件File file1 = new File("1.jpg");File file2 = new File("2.jpg");//2.想创建相应的节点流：FileInputStream、FileOutputStreamFileInputStream fis = new FileInputStream(file1);FileOutputStream fos = new FileOutputStream(file2);//3.将创建的节点流的对象作为形参传递给缓冲流的构造器中bis = new BufferedInputStream(fis);bos = new BufferedOutputStream(fos);//4.具体的实现文件复制的操作byte[] b = new byte[1024];int len;while((len = bis.read(b)) != -1){bos.write(b, 0, len);bos.flush();}}catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{//5.关闭相应的流if(bos != null){try {bos.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(bis != null){try {bis.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}}

二、转换流

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.io.UnsupportedEncodingException;import org.junit.Test;public class TestOtherStream {/* * 标准的输入输出流： * 标准的输出流：System.out * 标准的输入流：System.in *  * 题目： * 从键盘输入字符串，要求将读取到的整行字符串转成大写输出。然后继续进行输入操作， * 直至当输入“e”或者“exit”时，退出程序。 */@Testpublic void test2(){BufferedReader br = null;try {InputStream is = System.in;InputStreamReader isr = new InputStreamReader(is);br = new BufferedReader(isr);String str;while(true){System.out.println("请输入字符串：");str = br.readLine();if(str.equalsIgnoreCase("e") || str.equalsIgnoreCase("exit")){break;}String str1 = str.toUpperCase();System.out.println(str1);}} catch (IOException e) {e.printStackTrace();}finally{if(br != null){try {br.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}/* * 如何实现字节流与字符流之间的转换： * 转换流：InputStreamReader  OutputStreamWriter * 编码：字符串  --->字节数组 * 解码：字节数组--->字符串 */@Testpublic void test1(){BufferedReader br = null;BufferedWriter bw = null;try {//解码File file = new File("dbcp.txt");FileInputStream fis = new FileInputStream(file);InputStreamReader isr = new InputStreamReader(fis, "GBK");br = new BufferedReader(isr);//编码File file1 = new File("dbcp4.txt");FileOutputStream fos = new FileOutputStream(file1);OutputStreamWriter osw = new OutputStreamWriter(fos, "GBK");bw = new BufferedWriter(osw);String str;while((str = br.readLine()) != null){bw.write(str);bw.newLine();bw.flush();}}catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{if(bw != null){try {bw.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}if(br != null){try {br.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}}