文件读写回顾

文件读写方法
1、字节读写（InputStream/OutputStream）
2、字符读取（FileReader/FileWriter）
3、行读取（BufferedReader/BufferedWriter）

package com.waddell.basic;  

import java.io.BufferedReader;  
import java.io.BufferedWriter;  
import java.io.File;  
import java.io.FileInputStream;  
import java.io.FileOutputStream;  
import java.io.FileReader;  
import java.io.FileWriter;  
import java.io.IOException;  
import java.io.InputStream;  
import java.io.OutputStream;  
import java.nio.ByteBuffer;  
import java.nio.channels.FileChannel;  


public class FileOperate {  

    private static final String FILE_PATH = "d:/work/jipinwodi.txt";  

    /** 
     * 以字节为单位读写文件内容 
     *  
     * @param filePath 
     *            ：需要读取的文件路径 
     */  
    public static void readFileByByte(String filePath) {  
        File file = new File(filePath);  
        // InputStream:此抽象类是表示字节输入流的所有类的超类。  
        InputStream ins = null;  
        OutputStream outs = null;  
        try {  
            // FileInputStream:从文件系统中的某个文件中获得输入字节。  
            ins = new FileInputStream(file);  
            outs = new FileOutputStream("d:/work/readFileByByte.txt");  
            int temp;  
            // read():从输入流中读取数据的下一个字节。  
            while ((temp = ins.read()) != -1) {  
                outs.write(temp);  
            }  
        } catch (Exception e) {  
            e.getStackTrace();  
        } finally {  
            if (ins != null && outs != null) {  
                try {  
                    outs.close();  
                    ins.close();  
                } catch (IOException e) {  
                    e.getStackTrace();  
                }  
            }  
        }  
    }  

    /** 
     * 以字符为单位读写文件内容 
     *  
     * @param filePath 
     */  
    public static void readFileByCharacter(String filePath) {  
        File file = new File(filePath);  
        // FileReader:用来读取字符文件的便捷类。  
        FileReader reader = null;  
        FileWriter writer = null;  
        try {  
            reader = new FileReader(file);  
            writer = new FileWriter("d:/work/readFileByCharacter.txt");  
            int temp;  
            while ((temp = reader.read()) != -1) {  
                writer.write((char)temp);  
            }  
        } catch (IOException e) {  
            e.getStackTrace();  
        } finally {  
            if (reader != null && writer != null) {  
                try {  
                    reader.close();  
                    writer.close();  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
    }  

    /** 
     * 以行为单位读写文件内容 
     *  
     * @param filePath 
     */  
    public static void readFileByLine(String filePath) {  
        File file = new File(filePath);  
        // BufferedReader:从字符输入流中读取文本，缓冲各个字符，从而实现字符、数组和行的高效读取。  
        BufferedReader bufReader = null;  
        BufferedWriter bufWriter = null;  
        try {  
            // FileReader:用来读取字符文件的便捷类。  
            bufReader = new BufferedReader(new FileReader(file));  
            bufWriter = new BufferedWriter(new FileWriter("d:/work/readFileByLine.txt"));  
            // buf = new BufferedReader(new InputStreamReader(new  
            // FileInputStream(file)));  
            String temp = null;  
            while ((temp = bufReader.readLine()) != null) {  
                bufWriter.write(temp+"\n");  
            }  
        } catch (Exception e) {  
            e.getStackTrace();  
        } finally {  
            if (bufReader != null && bufWriter != null) {  
                try {  
                    bufReader.close();  
                    bufWriter.close();  
                } catch (IOException e) {  
                    e.getStackTrace();  
                }  
            }  
        }  
    }  

    /** 
     * 使用Java.nio ByteBuffer字节将一个文件输出至另一文件 
     *  
     * @param filePath 
     */  
    public static void readFileByBybeBuffer(String filePath) {  
        FileInputStream in = null;  
        FileOutputStream out = null;  
        try {  
            // 获取源文件和目标文件的输入输出流    
            in = new FileInputStream(filePath);  
            out = new FileOutputStream("d:/work/readFileByBybeBuffer.txt");  
            // 获取输入输出通道  
            FileChannel fcIn = in.getChannel();  
            FileChannel fcOut = out.getChannel();  
            ByteBuffer buffer = ByteBuffer.allocate(1024);  
            while (true) {  
                // clear方法重设缓冲区，使它可以接受读入的数据  
                buffer.clear();  
                // 从输入通道中将数据读到缓冲区  
                int r = fcIn.read(buffer);  
                if (r == -1) {  
                    break;  
                }  
                // flip方法让缓冲区可以将新读入的数据写入另一个通道    
                buffer.flip();  
                fcOut.write(buffer);  
            }  

        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            if (in != null && out != null) {  
                try {  
                    in.close();  
                    out.close();  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
    }  

    public static long getTime(){  
        return System.currentTimeMillis();  
    }  

    public static void main(String args[]) {  
        long time1 = getTime() ;  
        // readFileByByte(FILE_PATH);// 8734,8281,8000,7781,8047  
        // readFileByCharacter(FILE_PATH);// 734, 437, 437, 438, 422  
        // readFileByLine(FILE_PATH);// 110, 94,  94,  110, 93  
        readFileByBybeBuffer(FILE_PATH);// 125, 78,  62,  78, 62  
        long time2 = getTime() ;  
        System.out.println(time2-time1);  
    }  
}