Java之IO（二）缓冲流、转换流

package com.shuhuadream.buffer;import java.io.BufferedInputStream;import java.io.Closeable;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import com.shuhuadream.inputstream.IOHelper;/** * 处理流的好处： * 处理流必须在节点流的基础之上，增加了效率，提高了性能，扩大的功能。 *  * 1.缓冲流 *     缓冲字节流 *         BufferedInputStream *         BufferedOutputStream *     缓冲字符流 *         BufferedReader *         BufferedWriter *处理流内部包含了节点流，节点流决定了与其沟通的外部设备，而处理流则增加了其功能。 *      * 缓冲流的好处： *    缓冲流内部包含一个缓冲区域，默认8kb，每一次程序调用read方法其实都是从缓冲区域当中读取内容，如果读取失败 *    就说明缓冲区域当中没有内容，那么就从数据源当中读取内容，然后会尽可能读取更多的字节放入到缓冲区域当中， *    最后缓冲区域当中的内容，会全部返回给程序。 * 从缓冲区读取数据会比直接从数据源读取数据的速度快，效率也更高，性能更好。 *  * 处理流处理数据和节点流处理数据的方法基本上完全相同。 * */public class Demo01 {public static void main(String[] args) {//1.选择流FileInputStream fis  = null;BufferedInputStream bis = null;try {fis = new FileInputStream(new File("d:\\d.txt")); bis = new BufferedInputStream(fis);// 2.创建缓存字节数组 byte[]buf = new byte[1024];// 3.定义变量，实际保存的字节数 int hasRead = 0;// 4.循环读取 while ((hasRead = bis.read(buf))!=-1) {// 5.操作字节数组 String msg = new String(buf, 0,hasRead); System.out.println(msg);}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {//6.关闭流IOHelper.closeIO(new Closeable[]{fis,bis});}}}

package com.shuhuadream.buffer;import java.io.BufferedOutputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import com.shuhuadream.inputstream.IOHelper;public class Demo02 {public static void main(String[] args) {//1.选择流BufferedOutputStream bos = null;try {bos = new BufferedOutputStream(new FileOutputStream("readme.txt"));//2.准备数据源String msg = "床前明月光，疑是地上霜。\n举头望明月，低头思故乡。";byte[] data = msg.getBytes();//3.使用输出流写入数据bos.write(data);//4.刷新流bos.flush();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {//5.关闭流IOHelper.closeIO(bos);}}}

package com.shuhuadream.buffer;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.Closeable;import java.io.File;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import com.shuhuadream.inputstream.IOHelper;/**了解： * BufferedReader * BufferedWriter * */public class Demo03 {public static void main(String[] args) {File srcFile = new File("C:\\Users\\Administrator\\Desktop\\2017-08-16\\country.txt");File destFile = new File("country.txt");copyFile(srcFile, destFile);}public static void copyFile(File srcFile,File destFile){//1.BufferedReader br = null;BufferedWriter bw = null;try {br = new BufferedReader(new FileReader(srcFile));bw = new BufferedWriter(new FileWriter(destFile));//2.String line = "";//3while (true) {line = br.readLine();if (line==null) {break;}bw.write(line);bw.newLine();   //换行}//5bw.flush();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {IOHelper.closeIO(new Closeable[]{br,bw});}}}

package com.shuhuadream.buffer;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.Closeable;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import com.shuhuadream.inputstream.IOHelper;import com.shuhuadream.inputstream.Test01;// 缓冲流复制文件public class Test02 {public static void main(String[] args) {File srcFile = new File("D:\\360Downloads\\2.文件流和缓冲流.avi");File destFile1 = new File("D:\\360\\节点流复制文件.avi");long time1 = System.currentTimeMillis();Test01.copyFile(srcFile, destFile1);long time2 = System.currentTimeMillis();System.out.println("使用节点流复制文件消耗了："+(time2-time1)+"毫秒");File destFile2 = new File("D:\\360\\处理流复制文件.avi");long time3 = System.currentTimeMillis();copyFile(srcFile, destFile2);long time4 = System.currentTimeMillis();System.out.println("使用处理流复制文件消耗了："+(time4-time3)+"毫秒");}public static void copyFile(File srcFile ,File destFile){//1.BufferedInputStream bis = null;BufferedOutputStream bos = null;try {bis = new BufferedInputStream(new FileInputStream(srcFile));bos = new BufferedOutputStream(new FileOutputStream(destFile));//2.byte[]buf = new byte[1024];//3int hasRead = 0;//4.while ((hasRead = bis.read(buf))!=-1) {//5bos.write(buf, 0, hasRead);}//6.bos.flush();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {IOHelper.closeIO(new Closeable[]{bis,bos});}}}

package com.shuhuadream.demo03;import java.io.UnsupportedEncodingException;//转换流/* * 转换流作用：把字节流转换为字符流，可以解决出现的因为编码和解码造成的乱码问题 * InputStreamReader * OutputStreamWriter *  * 编码：字符--编码字符集-----二进制 * 解码：二进制---解码字符集----字符 *  * 在处理文件时，如果文件的字符格式和编译器处理格式不一样，会出现乱码问题。 *  * 出现乱码问题的原因： * 1.编码和解码字符集不一致造成的乱码 * 2.字节的缺失，长度的丢失 *  * 大部分情况下，出现乱码问题是因为中国汉字，因为中国汉字在不同的字符编码当中占据的字节数不相同， * 但是都占据多个字节，而英文没有这个问题。 */public class Demo01 {public static void main(String[] args) {//cover();String msg = "是中国人就转起来！！";byte[] data = msg.getBytes();String result = new String(data, 0, 5);System.out.println(result);}public static void cover(){String msg = "稻花香里说丰年，听取蛙声一片，呱呱呱！！！";//字符串编码的过程，使用编译器默认的格式进行编码byte[] data = msg.getBytes();//解码String result = new String(data, 0, data.length);System.out.println(result);//使用特定的编码集进行编码try {byte[] darr = msg.getBytes("utf-8");result = new String(darr,0,darr.length);System.out.println(result);} catch (UnsupportedEncodingException e) {e.printStackTrace();}}}

package com.shuhuadream.demo03;import java.io.BufferedReader;import java.io.Closeable;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStreamReader;import java.io.UnsupportedEncodingException;import com.shuhuadream.inputstream.IOHelper;// InputStreamReader :转换输入流--》将字节输入流转换成字符输入流// 作用：为了防止文件使用字符输入流处理时出现乱码问题。public class Demo02 {public static void main(String[] args) {File file = new File("C:\\Users\\Administrator\\Desktop\\2017-08-16\\chat.txt");FileInputStream fis = null;InputStreamReader isr = null;BufferedReader reader = null;try { fis = new FileInputStream(file); isr = new InputStreamReader(fis,"utf-8"); reader = new BufferedReader(isr); String line = "";while ((line = reader.readLine())!=null) {System.out.println(line);}} catch (UnsupportedEncodingException e) {e.printStackTrace();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {IOHelper.closeIO(new Closeable[]{fis,isr,reader});}}}

package com.shuhuadream.demo03;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.Closeable;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import java.io.UnsupportedEncodingException;import com.shuhuadream.inputstream.IOHelper;/** * 转换流复制文件 * */public class Demo03 {public static void main(String[] args) {File srcFile = new File("C:\\Users\\Administrator\\Desktop\\2017-08-16\\chat.txt");File destFile = new File("chat.txt");copyFile(srcFile, destFile, "UTF-8");}public static void copyFile(File srcFile,File destFile,String charsetName){//1.选择流BufferedReader br = null;BufferedWriter bw = null;try {br = new BufferedReader(new InputStreamReader(new FileInputStream(srcFile), charsetName));bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(destFile),charsetName));//2String line = null;//3while ((line = br.readLine())!=null) {bw.write(line);bw.newLine();}//4bw.flush();} catch (UnsupportedEncodingException e) {e.printStackTrace();} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {IOHelper.closeIO(new Closeable[]{br,bw});}}}