javaSE（15）(缓冲流、转换流和标准系统I0流)

字节缓冲流:package zz.itheima.bufferdstream;import java.io.BufferedInputStream;import java.io.FileInputStream;import java.io.FileNotFoundException;public class TestBufferedInputStream {    public static void main(String[] args) {        //测试字节缓冲流        /*java.io.BufferedInputStream    字节缓冲流(读)        public BufferedInputStream(InputStream in)  默认缓冲区是8k        public BufferedInputStream(InputStream out,  int size)可以自己指定缓冲区大小，单位字节        public int read()        public int read(byte[] b)        public void close()*/        //架管道        try {            BufferedInputStream bis = new BufferedInputStream(new FileInputStream("E:\\2.txt"));        } catch (FileNotFoundException e) {            e.printStackTrace();        }    }}字节缓冲流（写）:package zz.itheima.bufferdstream;import java.io.BufferedOutputStream;import java.io.FileOutputStream;import java.io.IOException;public class TestBufferedOutputStream {    public static void main(String[] args) {        //测试字节缓冲林（写）        /*java.io.BufferedOutputStream    字节缓冲流(写)         * public BufferedOutputStream(OutputStream out)   默认大小是8k        public BufferedOutputStream(OutputStream out,  int size)可以自己指定缓冲区大小，单位字节        public void write(int b)  参数是ASCII表中的码值，不是普通数字        public void write(byte[] b)        public void flush()          public void close() */        BufferedOutputStream bos = null;        try {            bos = new BufferedOutputStream(new FileOutputStream("E:\\2.txt"), 1024*16);            for (int i = 0; i <1024*16 + 1; i++) {                bos.write(97);            }        } catch (Exception e) {            e.printStackTrace();        } finally{            try {                bos.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }}字符缓冲流1：package zz.itheima.bufferdstream;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;public class TestBufferedWriter {    public static void main(String[] args) {        //测试字符缓冲流        //架管道        BufferedReader br = null;        BufferedWriter bw = null;        try {            bw = new BufferedWriter(new FileWriter("E:\\2.txt"));            bw.write("hel\r\nlo");            bw.write("world");            bw.flush();            br = new BufferedReader(new FileReader("E:\\2.txt"));            String val = br.readLine();            System.out.println(val);            String val1 = br.readLine();            System.out.println(val1);            String val2 = br.readLine();            System.out.println(val2);        } catch (Exception e) {            e.printStackTrace();        } finally{            try {                bw.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }    /**     * 测试结果：     *  hel        loworld        null     *      *      */}字符缓冲流2：package zz.itheima.bufferdstream;import java.io.BufferedWriter;import java.io.FileWriter;import java.io.IOException;public class TestBufferedWriter2 {    public static void main(String[] args) {        //测试字符缓冲流        BufferedWriter bw = null;        try {            int size = 1024*2;            bw = new BufferedWriter(new FileWriter("E:\\demo.txt"),size);            char[] temp = new char[size];            for (int i = 0; i < size; i++) {                temp[i] = 'a';            }            bw.write(temp);        } catch (IOException e) {            e.printStackTrace();        } finally{            try {                bw.flush();                bw.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }}使用字节缓冲流(拷贝一个视频文件)：package zz.itheima.bufferdstream;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;public class BufferedCopy {    public static void copy(){        long begin = System.currentTimeMillis();        //使用字节缓冲流(拷贝一个视频文件)                BufferedInputStream bis = null;                BufferedOutputStream bos = null;                try {                    bis = new BufferedInputStream(new FileInputStream("E:\\1.avi"));                    bos = new BufferedOutputStream(new FileOutputStream("D:\\1.avi"));                    byte[] temp = new byte[1024*1024*2];                    while (true) {                        int res = bis.read(temp);                        if (res==-1) {                            break;                        }else {                            bos.write(temp, 0, res);                        }                    }                } catch (Exception e) {                    e.printStackTrace();                } finally{                    try {                        bos.close();                        bis.close();                    } catch (IOException e) {                        e.printStackTrace();                    }                }        long end = System.currentTimeMillis();        System.out.println(end - begin);    }    public static void main(String[] args) {        copy();    }}测试字符编码：package zz.itheima.bufferdstream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;public class TestEncoding {    public static void main(String[] args) throws Exception {        //测试utf-8编码的文本文件的读写                //在工程中新建一个文本文件                //点右键通过属性改为utf-8                //录入几个汉字        //FileReader默认采用GBK编码,因此对于utf-8格式的文本会出现乱码        FileReader fr = null;        File f = null;        try {             f = new File("demo.txt");             fr = new FileReader(f);            char[] temp = new char[(char)f.length()];            fr.read(temp);            System.out.println(new String(temp));        } catch (FileNotFoundException e) {            e.printStackTrace();        } finally{            try {                fr.close();            } catch (IOException e) {                e.printStackTrace();            }        }        //InputStreamReader可以自己设置编码，格式要与文本文件的编码格式一致即可，不会出现乱码        InputStreamReader isr = null;        try {            isr = new InputStreamReader(new FileInputStream(f),"utf-8");            char[] temp = new char[(int)f.length()];            isr.read(temp);            System.out.println(new String(temp));        } catch (Exception e) {            e.printStackTrace();        } finally{            isr.close();        }        //FileWriter类默认使用GBK进行编码，如果文件是utf-8格式的，就会出现乱码                FileWriter fw=new FileWriter(f);                fw.write("张三");                fw.close();                //OutputStreamWriter类可以自己指定编码，需要跟文件的编码保持一致，就不会出现乱码                OutputStreamWriter osw=new OutputStreamWriter(new FileOutputStream(f),"utf-8");                osw.write("张三");                osw.close();    }}对字符串进行转码：package zz.itheima.bufferdstream;import java.io.File;import java.io.FileInputStream;import java.io.FileReader;public class TestStringEncoding {    public static void main(String[] args) throws Exception{        //对某个字符串进行转码        //使用基本字节输入流读取utf-8格式的文本        File f = new File("demo.txt");        FileInputStream fis = new FileInputStream(f);        byte[] temp = new byte[(int)f.length()];        fis.read(temp);        System.out.println(new String(temp,"utf-8"));        fis.close();        //使用基本字符输入流读取utf-8格式的文本        File f1=new File("demo.txt");        FileReader fr=new FileReader(f1);        char[] t=new char[(int)f.length()];        fr.read(t);        String val=new String(t);        System.out.println(new String(val.getBytes(),"utf-8"));        fr.close();        //如果得到的字符串乱码怎么处理        String s = "美好！";        System.out.println(new String(s.getBytes(),"utf-8"));    }}系统标准的输入输出流：package zz.itheima.bufferdstream;import java.io.InputStream;import java.io.PrintStream;public class TestSystem {    //系统标准的输入输出流    public static void main(String[] args) throws Exception{        // System.in   System.out,        InputStream is = System.in;        int val = is.read();        PrintStream ps = System.out;        ps.write(val);        ps.flush();        ps.close();    }}例子一：package zz.itheima.bufferdstream;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileReader;import java.io.FileWriter;import java.util.Scanner;public class Demo1 {    public static void main(String[] args) throws Exception{        /*用户在控制台循环录入姓名和年龄，然后存到一个文本文件中，一人占一行，        直到quit退出，然后把文件中的每一行都输出到控制台(字符缓冲流特有方法)*/        BufferedReader br = new BufferedReader(new FileReader("E:\\2.txt"));        BufferedWriter bw = new BufferedWriter(new FileWriter("E:\\2.txt"));        String flag ;        do {            Scanner sc = new Scanner(System.in);            System.err.println("请输入姓名");            String name = sc.nextLine();            System.out.println("请输入年龄：");            String  age = sc.nextLine();            bw.write(name +"\t" +age);            bw.newLine();            System.out.println("是否继续？");            flag = sc.next();        } while (flag.equalsIgnoreCase("y"));        bw.close();        while (true) {            String res = br.readLine();            if (res==null) {                break;            }else {                bw.write(res);            }        }    }}例子二：package zz.itheima.bufferdstream;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileReader;import java.io.FileWriter;public class Demo2 {    public static void main(String[] args)throws Exception {        //练习：读取一个Java源文件，输出代码有多少行？然后把该文件的代码写入到另一个文本文件中        BufferedReader br = null;        BufferedWriter bw = null;        int count = 0;        try {            br = new BufferedReader(new FileReader("D:\\1.java"));            bw = new BufferedWriter(new FileWriter("E:\\2.txt"));            while (true) {                String val  = br.readLine();                if (val==null) {                    break;                }else {                    count++;                    bw.write(val);                    bw.newLine();                }            }        } catch (Exception e) {            e.printStackTrace();        } finally{            bw.close();            bw.close();        }        System.out.println(count);    }}