java 文件操作一

文件拷贝

字节流：

package com.ldd.second.wenjian;

import sun.rmi.runtime.Log;

import java.io.*;
import java.util.Scanner;
import java.util.logging.Logger;

/**
 * @author ldd
 * @version 1.0.0
 * @create 2018.5.4
 * @decription InputStream
 * <p>
 * Constructors
 * Constructor and Description
 *
 * InputStream()
 * Method Summary
 * Methods
 * Modifier and Type	Method and Description
 *
 * int	available()
 * Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.
 *
 * void	close()
 * Closes this input stream and releases any system resources associated with the stream.
 * void	mark(int readlimit)
 * Marks the current position in this input stream.
 * boolean	markSupported()
 * Tests if this input stream supports the mark and reset methods.
 *
 * abstract int	read()
 * Reads the next byte of data from the input stream.
 *
 * int	read(byte[] b)
 * Reads some number of bytes from the input stream and stores them into the buffer array b.
 *
 * int	read(byte[] b, int off, int len)
 * Reads up to len bytes of data from the input stream into an array of bytes.
 *
 * void	reset()
 * Repositions this stream to the position at the time the mark method was last called on this input stream.
 *
 * long	skip(long n)
 * Skips over and discards n bytes of data from this input stream.
 * Methods inherited from class java.lang.Object
 *
 * clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 */
public class FileByteCopy {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入源文件路径");
        String srcPath = sc.next();
        System.out.println("请输入源文件路径是：" + srcPath);
        System.out.println("请输入目标文件路径");
        String destPath = sc.next();
        System.out.println("请输入目标文件路径是 ：" + destPath);
        try {
            copyFile(srcPath, destPath);
            Logger.getLogger("finished", "copy");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 利用字节流来实现文件的复制(字节流可以处理一切数据)
     *
     * @param srcPath  : 源文件路径
     * @param destPath : 目标文件路径
     * @throws Exception
     */
    public static void copyFile(String srcPath, String destPath) throws Exception {
        //构建源文件和目标文件的File对象
        File src = new File(srcPath);
        File dest = new File(destPath);
        //如果源文件不存在,抛出异常
        if (!src.exists()) {
            throw new IOException("文件不存在!");
        }
        //如果目标文件父路径不存在,创建父路径
        if (!dest.getParentFile().exists()) {
            dest.getParentFile().mkdirs();
        }
        //实例化输入流和输出流
        InputStream is = new FileInputStream(src);
        OutputStream os = new FileOutputStream(dest);
        //定义缓冲字节数组,用来接收读取的内容
        byte buf[] = new byte[1024];
        int len = 0;
        while ((len = is.read(buf)) != -1) {
            os.write(buf, 0, len);
            os.flush();
        }
        //关闭流
        os.close();
        is.close();
    }
}

字符流：

package com.ldd.second.wenjian;

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;

/**
 * @author liudongdong19
 * @create 2018.5.4
 * <p>
 * Constructor and Description
 * <p>
 * FileReader(File file)
 * Creates a new FileReader, given the File to read from.
 * <p>
 * FileReader(FileDescriptor fd)
 * Creates a new FileReader, given the FileDescriptor to read from.
 * <p>
 * FileReader(String fileName)
 * Creates a new FileReader, given the name of the file to read from.
 * Method Summary
 * Methods inherited from class java.io.InputStreamReader
 * <p>
 * close, getEncoding, read, read, ready
 * Methods inherited from class java.io.Reader
 * mark, markSupported, read, read, reset, skip
 * <p>
 * Methods inherited from class java.lang.Object
 * <p>
 * clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 */
public class FileCharCopy {
    public static void main(String[] args) {
        FileCharCopy f = new FileCharCopy();
        try {

            /**
             * 这里遇到一个错误关于文件路径
             * window 下 a.txt 文件的.txt 后缀默认是没有的
             * */
            f.copy("D:\\File\\1.txt", "D:\\File\\2.txt");
            System.out.println("copy end");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * @param f1 源文件路径
     * @param f2 目标文件路径
     * @function 实现文件字符流拷贝
     */
    public void copy(String f1, String f2) throws Exception {
        FileReader fr = new FileReader(new File(f1));
        FileWriter fw = new FileWriter(new File(f2), false);
        char[] chars = new char[1024];
        int len = fr.read(chars);
        while (len != -1) {
            fw.write(chars, 0, len);
            fw.flush();
            len = fr.read(chars);
        }

        fr.close();
        fw.close();
    }
}