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Java第二十一天
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‎day21/IO流小结图.bmp

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‎day21/code/day21_IO/.classpath

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<?xml version="1.0" encoding="UTF-8"?>
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<classpath>
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<classpathentry kind="src" path="src"/>
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<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7"/>
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<classpathentry kind="output" path="bin"/>
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</classpath>

‎day21/code/day21_IO/.project

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<?xml version="1.0" encoding="UTF-8"?>
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<projectDescription>
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<name>day21_IO</name>
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<comment></comment>
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<projects>
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</projects>
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<buildSpec>
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<buildCommand>
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<name>org.eclipse.jdt.core.javabuilder</name>
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<arguments>
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</arguments>
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</buildCommand>
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</buildSpec>
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<natures>
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<nature>org.eclipse.jdt.core.javanature</nature>
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</natures>
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</projectDescription>

‎day21/code/day21_IO/.settings/org.eclipse.jdt.core.prefs

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eclipse.preferences.version=1
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org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
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org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.7
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org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
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org.eclipse.jdt.core.compiler.compliance=1.7
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org.eclipse.jdt.core.compiler.debug.lineNumber=generate
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org.eclipse.jdt.core.compiler.debug.localVariable=generate
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org.eclipse.jdt.core.compiler.debug.sourceFile=generate
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org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
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org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
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org.eclipse.jdt.core.compiler.source=1.7

‎day21/code/day21_IO/a.txt

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hello���

‎day21/code/day21_IO/bin/cn/itcast_01/CopyImageDemo.class

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‎day21/code/day21_IO/bin/cn/itcast_02/BufferedDemo.class

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‎day21/code/day21_IO/bin/cn/itcast_03/CopyMP4Demo.class

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‎day21/code/day21_IO/bin/cn/itcast_04/FileInputStreamDemo.class

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‎day21/code/day21_IO/bin/cn/itcast_04/StringDemo.class

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‎day21/code/day21_IO/bin/cn/itcast_05/StringDemo.class

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‎day21/code/day21_IO/bos.txt

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hello

‎day21/code/day21_IO/src/cn/itcast_01/CopyImageDemo.java

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package cn.itcast_01;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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/*
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* 需求：请把项目路径下的闭月羞花.bmp复制到项目路径下的林青霞.bmp中
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* 数据源：
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* 闭月羞花.bmp -- FileInputStream
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* 目的地：
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* 林青霞.bmp -- FileOutputStream
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*/
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public class CopyImageDemo {
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public static void main(String[] args) throws IOException {
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// 封装数据源
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FileInputStream fis = new FileInputStream("闭月羞花.bmp");
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// 封装目的地
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FileOutputStream fos = new FileOutputStream("林青霞.bmp");
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// 方式1
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// int by = 0;
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// while ((by = fis.read()) != -1) {
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// fos.write(by);
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// }
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// 方式2
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byte[] bys = new byte[1024];
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int len = 0;
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while ((len = fis.read(bys)) != -1) {
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fos.write(bys, 0, len);
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}
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// 释放资源
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fos.close();
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fis.close();
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}
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}

‎day21/code/day21_IO/src/cn/itcast_02/BufferedDemo.java

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package cn.itcast_02;
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import java.io.BufferedInputStream;
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import java.io.BufferedOutputStream;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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/*
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* 由于数组的方式一次比一个字节的方式快很多，所以，java本身在设计的时候，也考虑到了。
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* 就设计出了内置数组的缓冲区流。
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* 字节缓冲输入流
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* BufferedInputStream
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* 字节缓冲输出流
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* BufferedOutputStream
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*
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* 通过看构造方法，我们发现，缓冲流不能直接操作文件。
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* 是建立在基本的操作流之上的。
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* 所以，这种流也被称之为高级流。
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*/
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public class BufferedDemo {
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public static void main(String[] args) throws IOException {
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// 写数据
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// BufferedOutputStream(OutputStream out)
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// OutputStream out = new FileOutputStream("bos.txt");
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// BufferedOutputStream bos = new BufferedOutputStream(out);
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// BufferedOutputStream bos = new BufferedOutputStream(
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// new FileOutputStream("bos.txt"));
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// bos.write("hello".getBytes());
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// bos.close();
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// 读数据
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// BufferedInputStream(InputStream is)
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BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
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"bos.txt"));
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// 方式1
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int by = 0;
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while ((by = bis.read()) != -1) {
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System.out.print((char) by);
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}
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System.out.println("-----------------------");
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// 方式2
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bis = new BufferedInputStream(new FileInputStream("bos.txt"));
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byte[] bys = new byte[1024];
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int len = 0;
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while ((len = bis.read(bys)) != -1) {
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System.out.print(new String(bys, 0, len));
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}
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bis.close();
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}
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}

‎day21/code/day21_IO/src/cn/itcast_03/CopyMP4Demo.java

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package cn.itcast_03;
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import java.io.BufferedInputStream;
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import java.io.BufferedOutputStream;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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/*
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* 数据源：
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* d:\\哥有老婆.mp4
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* 目的地：
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* 项目路径下copy.mp4
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*
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* 四种方式：
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* A:基本字节流一次读写一个字节 67023毫秒
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* B:基本字节流一次读写一个字节数组 共耗时：102毫秒
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* C:高效字节流一次读写一个字节 共耗时：650毫秒
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* D:高效字节流一次读写一个字节数组 共耗时：36毫秒
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*/
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public class CopyMP4Demo {
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public static void main(String[] args) throws IOException {
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long start = System.currentTimeMillis();
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// method1();
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// method2();
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// method3();
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method4();
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long end = System.currentTimeMillis();
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System.out.println("共耗时：" + (end - start) + "毫秒");
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}
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// 基本字节流一次读写一个字节
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public static void method1() throws IOException {
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FileInputStream fis = new FileInputStream("d:\\哥有老婆.mp4");
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FileOutputStream fos = new FileOutputStream("copy1.mp4");
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int by = 0;
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while ((by = fis.read()) != -1) {
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fos.write(by);
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}
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fos.close();
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fis.close();
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}
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// 基本字节流一次读写一个字节数组
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public static void method2() throws IOException {
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FileInputStream fis = new FileInputStream("d:\\哥有老婆.mp4");
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FileOutputStream fos = new FileOutputStream("copy2.mp4");
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byte[] bys = new byte[1024];
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int len = 0;
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while ((len = fis.read(bys)) != -1) {
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fos.write(bys, 0, len);
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}
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fos.close();
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fis.close();
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}
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// 高效字节流一次读写一个字节
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public static void method3() throws IOException {
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BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
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"d:\\哥有老婆.mp4"));
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BufferedOutputStream bos = new BufferedOutputStream(
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new FileOutputStream("copy3.mp4"));
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int by = 0;
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while ((by = bis.read()) != -1) {
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bos.write(by);
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}
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bos.close();
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bis.close();
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}
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// 高效字节流一次读写一个字节数组
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public static void method4() throws IOException {
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BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
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"d:\\哥有老婆.mp4"));
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BufferedOutputStream bos = new BufferedOutputStream(
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new FileOutputStream("copy4.mp4"));
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byte[] bys = new byte[1024];
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int len = 0;
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while ((len = bis.read(bys)) != -1) {
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bos.write(bys, 0, len);
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}
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bos.close();
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bis.close();
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}
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}

‎day21/code/day21_IO/src/cn/itcast_04/FileInputStreamDemo.java

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package cn.itcast_04;
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import java.io.FileInputStream;
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import java.io.IOException;
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/*
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* 字节流操作中文，不是特别的方便，所以我们要想办法改进。这个时候就引出了转换流。
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* 可以把字节流转换为字符流。
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* 字符流 = 字节流+编码表
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*/
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public class FileInputStreamDemo {
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public static void main(String[] args) throws IOException {
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FileInputStream fis = new FileInputStream("a.txt");
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// int by = 0;
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// while ((by = fis.read()) != -1) {
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// System.out.print((char) by);
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// }
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byte[] bys = new byte[1024];
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int len = 0;
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while ((len = fis.read(bys)) != -1) {
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System.out.print(new String(bys, 0, len));
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}
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fis.close();
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}
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}

‎day21/code/day21_IO/src/cn/itcast_04/StringDemo.java

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package cn.itcast_04;
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import java.util.Arrays;
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/*
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* 它可以自己把两个字节拼成一个汉字
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* 第一个字节肯定是负数。第二个可能是正数，大部分是负数。
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*/
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public class StringDemo {
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public static void main(String[] args) {
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// hello你好
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// String s = "hello";
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// byte[] bys = s.getBytes();
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// // [104, 101, 108, 108, 111]
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// System.out.println(Arrays.toString(bys));
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String ss = "我爱你林青霞";
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byte[] bys = ss.getBytes();
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// [-50, -46, -80, -82, -60, -29, -63, -42, -57, -32, -49, -68]
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System.out.println(Arrays.toString(bys));
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}
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}

‎day21/code/day21_IO/src/cn/itcast_05/StringDemo.java

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package cn.itcast_05;
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import java.io.UnsupportedEncodingException;
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import java.util.Arrays;
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/*
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* String s = "你好";
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*
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* 编码：
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* 把你能够看懂的变成你看不懂
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* 解码：
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* 把你看不懂变成你能看懂的
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*
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* 谍战片：潜伏,回家看看去
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* 今天晚上老地方见 -- 1011110000111 -- 十进制 -- 找个小本子 -- 找字符
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*/
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public class StringDemo {
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public static void main(String[] args) throws UnsupportedEncodingException {
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String s = "你好";
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// public byte[] getBytes()
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// byte[] bys = s.getBytes();
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// [-60, -29, -70, -61]
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// public byte[] getBytes(String charsetName)
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byte[] bys = s.getBytes("GBK");
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// [-60, -29, -70, -61]
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// byte[] bys = s.getBytes("UTF-8");
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// [-28, -67, -96, -27, -91, -67]
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System.out.println(Arrays.toString(bys));
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// String(byte[] bytes)
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// String ss = new String(bys);
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// public String(byte[] bytes, String charsetName)
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String ss = new String(bys, "GBK");
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// String ss = new String(bys, "UTF-8");
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System.out.println(ss);
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}
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}

‎day21/code/day21_IO/林青霞.bmp

2.24 MB
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‎day21/code/day21_IO/闭月羞花.bmp

2.24 MB
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‎day21/code/day21_IO2/.classpath

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<?xml version="1.0" encoding="UTF-8"?>
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<classpath>
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<classpathentry kind="src" path="src"/>
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<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7"/>
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<classpathentry kind="output" path="bin"/>
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</classpath>

‎day21/code/day21_IO2/.project

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<?xml version="1.0" encoding="UTF-8"?>
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<projectDescription>
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<name>day21_IO2</name>
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<comment></comment>
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<projects>
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</projects>
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<buildSpec>
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<buildCommand>
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<name>org.eclipse.jdt.core.javabuilder</name>
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<arguments>
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</arguments>
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</buildCommand>
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</buildSpec>
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<natures>
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<nature>org.eclipse.jdt.core.javanature</nature>
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</natures>
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</projectDescription>

‎day21/code/day21_IO2/.settings/org.eclipse.jdt.core.prefs

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eclipse.preferences.version=1
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org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
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org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.7
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org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
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org.eclipse.jdt.core.compiler.compliance=1.7
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org.eclipse.jdt.core.compiler.debug.lineNumber=generate
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org.eclipse.jdt.core.compiler.debug.localVariable=generate
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org.eclipse.jdt.core.compiler.debug.sourceFile=generate
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org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
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org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
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org.eclipse.jdt.core.compiler.source=1.7

‎day21/code/day21_IO2/Copy.java

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package cn.itcast_01;
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import java.io.FileInputStream;
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import java.io.IOException;
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import java.io.InputStreamReader;
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/*
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* InputStreamReader(InputStream in)
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* InputStreamReader(InputStream in, String charsetName)
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*/
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public class InputStreamReaderDemo {
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public static void main(String[] args) throws IOException {
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// 创建对象
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InputStreamReader isr = new InputStreamReader(new FileInputStream(
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"isr.txt"));
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// 一次读取一个字符
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// int ch = 0;
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// while ((ch = isr.read()) != -1) {
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// System.out.print((char) ch);
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// }
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// 一次读取一个字符数组
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char[] chs = new char[1024];
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int len = 0;
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while ((len = isr.read(chs)) != -1) {
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System.out.print(new String(chs, 0, len));
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}
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// 释放资源
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isr.close();
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}
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}

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