java io流复制文件简单实例

java io流复制文件简单实例

实例1：

package com.io;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

import javax.xml.soap.SAAJResult;

public class IoDemo2 {
	public static void main(String[] args) {
		
		File file = new File("E://ABCJava//ZYQ//20191014.txt");
		BufferedInputStream input = null;
		
		File file2 = new File("D://QQQ//20191014.txt");
		BufferedOutputStream output = null;
		
		try {
			input = new BufferedInputStream(new FileInputStream(file));
			output = new BufferedOutputStream(new FileOutputStream(file2));
			
			byte[] buffer = new byte[4096];
			int len = 0;
			
			if(file2.exists()){
				System.out.println("文件已存在，是否覆盖 Y|N");
				Scanner in = new Scanner(System.in);
				String x = in.next();
				if(x.equals("Y") ){
					System.out.println("已覆盖");
				}else{
					System.out.println("覆盖失败");
				}
				
			}else{
				while((len=input.read(buffer))!=-1){
					output.write(buffer,0,len);
					output.flush();
				}
			}
			output.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

实例2：

package com.date;

import java.io.File;
import java.io.IOException;

public class IODemo {
	public static void main(String[] args){
		
		File file = new File("E://ABCJava//ZYQ");
		
		if(!file.exists()){
			file.mkdir();
		}else{
			System.out.println("目录文件已存在");
		}
		
		if(file.isDirectory()){
			System.out.println("是目录");
		}
		
		File file1 = new File(file,"20191014.txt");
		if(!file1.exists()){
			try {
				file1.createNewFile();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}else{
			System.out.println("文件已存在");
		}
	}
}

实例3：

package com.date;

import java.io.FileReader;
import java.io.FileWriter;
import java.io.Reader;
import java.io.Writer;

public class StreamDemo {
	public static void main(String[] args) {

		long startTime = System.currentTimeMillis();
		Reader reader = null;
		Writer writer = null;

		try {
			reader = new FileReader("E://ABCJava//ZYQ//20191014.txt");
			writer = new FileWriter("D://QQQ//20191014.txt");

			char[] buffer = new char[2048];
			int len = 0;
			while ((len = reader.read(buffer)) != -1) {
				writer.write(buffer, 0, len);
			}
			reader.close();
			writer.close();

			long endTime = System.currentTimeMillis();
			System.out.println("文件复制成功");
			System.out.println("耗时：" + (endTime - startTime));
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}

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