java新手笔记29 读取文件

1.读取文件

package com.yfs.javase;

import java.io.FileInputStream;

import java.io.FileReader;

import java.io.InputStream;

import java.io.Reader;

public class IODemo1 {

	/**

	 * 读取文件 显示

	 */

	public static void main(String[] args) throws Exception {

		//readFileSteame();

        readFileChar();

	}

	public static void readFileChar() throws Exception {

		//字节流

		Reader byte= new FileReader("FileDemo1.java");

		int data = byte.read();

		while(data != -1) {

			System.out.print((char)data);

			data = byte.read();

		}

		read.close();

	}

	public static void readFileSteame() throws Exception {

		//File file = new File("FileDemo1.java");//源头

		//输入流 源头 目的 连接 字节流

		//InputStream in = new FileInputStream(file) ;

		InputStream in = new FileInputStream("FileDemo1.java");

		//程序 目的

		int data = in.read();//读取文件数据

		while(data != -1){//读到-1 文件结束

			System.out.print((char)data);

			data = in.read();

		}

		in.close();

	}

}

2.输出流

package com.yfs.javase;

import java.io.File;

import java.io.FileOutputStream;

import java.io.FileWriter;

import java.io.OutputStream;

import java.io.Writer;

public class IODemo2 {

	/**

	 * 输出流

	 */

	public static void main(String[] args) throws Exception {

		//outDataSteame();

		outDataChar();

	}

	public static void outDataChar() throws Exception {

		Writer write = new FileWriter("outchar.txt");

		write.write('a');//处理一个字节

		write.write(5);

		write.write('中');//数据丢失

		write.close();

	}

	public static void outDataSteame() throws Exception {

		File file = new File("out.txt");

		//输出流

		OutputStream out = new FileOutputStream(file);

		out.write('a');//处理一个字节

		out.write(5);

		out.write('中');//数据丢失

		out.close();

	}

}

3.复制文件

package com.yfs.javase;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.Reader;

import java.io.Writer;

public class IODemo3 {

	/**

	 * 复制文件

	 */

	public static void main(String[] args) throws Exception {

		// copyFileStreame();

		copyFileChar();

	}

	public static void copyFileChar() throws Exception {

		Reader in = new FileReader("E:/img/index.gif");

		Writer out = new FileWriter("C:/pic1.gif");

		int data = in.read();

		while (data != -1) {

			out.write(data);

			data = in.read();

		}

		in.close();

		out.close();

		System.out.println("文件复制完成...");

	}

	public static void copyFileStreame() throws Exception {

		InputStream in = new FileInputStream("E:/img/index.gif");

		OutputStream out = new FileOutputStream("C:/pic.gif");

		int data = in.read();

		while (data != -1) {

			out.write(data);

			data = in.read();

		}

		in.close();

		out.close();

		System.out.println("文件复制完成...");

	}

}

4.缓冲流

package com.yfs.javase;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.Reader;

import java.io.Writer;

public class IODemo4 {

	/**

	 * 复制文件 缓冲流

	 */

	public static void main(String[] args) throws Exception {

		long start = System.currentTimeMillis();

		// copyFileStreame();

		//copyFile();

		//copyFile1();

		copyFile2();

		long end = System.currentTimeMillis();

		System.out.println("复制文件使用 " + (end - start) + " 毫秒");

	}

	public static void copyFile2() throws Exception {

		File source = new File("FileDemo1.java");

		InputStream in = new FileInputStream(source);

		File target = new File("C:/", source.getName());

		OutputStream out = new FileOutputStream(target);

		//自定义缓冲区

		byte[] data = new byte[1024  * 4];//1k

		int len = in.read(data);//len 读取的数据长度

	    while(len != -1 ) {//8

	    	out.write(data, 0, len);

	    	len = in.read(data);

	    }

		in.close();

		out.close();

	}

	public static void copyFile1() throws Exception {

		File source = new File("E:/EditPlus.zip");

		InputStream in = new FileInputStream(source);

		File target = new File("C:/", source.getName());

		OutputStream out = new FileOutputStream(target);

		//自定义缓冲区

		byte[] data = new byte[1024  * 4];//1k

		int len = in.read(data);//len 读取的数据长度

	    while(len != -1 ) {//8

	    	out.write(data, 0, len);

	    	len = in.read(data);

	    }

		in.close();

		out.close();

	}

	public static void copyFile() throws Exception {

		// 缓冲流

		File source = new File("E:/EditPlus.zip");

		InputStream in = new FileInputStream(source);

		File target = new File("C:/", source.getName());

		OutputStream out = new FileOutputStream(target);

		// 缓冲流套接在节点流

		BufferedInputStream bufin = new BufferedInputStream(in);

		BufferedOutputStream bufout = new BufferedOutputStream(out);

		int data = bufin.read();

		while (data != -1) {

			bufout.write(data);

			data = bufin.read();

		}

		in.close();

		out.close();

	}

	public static void copyFileStreame() throws Exception {

		File source = new File("E:/EditPlus.zip");

		InputStream in = new FileInputStream(source);

		File target = new File("C:/", source.getName());

		OutputStream out = new FileOutputStream(target);

		int data = in.read();

		while (data != -1) {

			out.write(data);

			data = in.read();

		}

		in.close();

		out.close();

	}

}

5.流转换

package com.yfs.javase;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.Reader;

import java.io.Writer;

public class IODemo5 {

	/**

	 * 流转换  字节流 -》 字符流

	 */

	public static void main(String[] args) throws Exception {

		InputStream in = new FileInputStream("FileDemo1.java");

		showFile(in);

	}

	public static void showFile(InputStream in) throws Exception {

		Reader read = new InputStreamReader(in);//流转换

		int data = read.read();

		while(data != -1) {

			System.out.print((char)data);

			data = read.read();

		}

		in.close();

	}

}