Java文件读写IO/NIO及性能比较总结

来源：互联网发布：梦回唐朝知乎编辑：程序博客网时间：2024/06/06 07:06
package com.io.test;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.InputStreamReader;import java.io.OutputStream;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;/** * 文件读取 * 1、按字节读取文件 * 2、按字符读取文件 * 3、按行读取文件 * @author bofei * */public class FileOperate {    private static final String FILE_PATH = "D:/work/3.gz";        //字节   /* public static void readFileByByte(String filePath) {        File file = new File(FILE_PATH);        InputStream ins = null;        try {            ins = new FileInputStream(file);            int temp;            while ((temp = ins.read()) !=-1) {                System.out.write(temp);//                System.out.print(temp);            }        } catch (IOException e) {            e.printStackTrace();        } finally {            if (ins !=null ) {                try {                    ins.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }        //字符    public static void readFileByCharacter(String filePath) {        File file = new File(FILE_PATH);        FileReader reader = null;        try {            reader = new FileReader(file);            int temp;            while ((temp = reader.read()) != -1) {                //if (((char)temp) != '\r') {                    System.out.print((char)temp);               // }            }        } catch (IOException e) {            e.printStackTrace();        } finally {            if (reader != null) {                try {                    reader.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }        //行    public static void readFileByLine(String filePath) {        File file = new File(filePath);        BufferedReader buf =null;        try {            buf = new BufferedReader(new FileReader(file));            String temp =null;            while ((temp = buf.readLine()) != null) {                System.out.println(temp);            }        } catch (IOException e) {            e.printStackTrace();        } finally {            if (buf != null) {                try {                    buf.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }*/            //以字节为单位读写文件内容    public static void readFileByByte(String filePath) {        File file = new File(filePath);        InputStream ins = null;        OutputStream outs = null;        try {            ins = new FileInputStream(file);            outs = new FileOutputStream("d:/work/readFileByByte.txt");            int temp;            while ((temp = ins.read()) != -1) {                outs.write(temp);            }        } catch (IOException e) {            e.printStackTrace();        } finally {            if (ins != null && outs !=null) {                try {                    ins.close();                    outs.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }        //以字符为单位读写内容    public static void readFileByCharactor(String filePath) {        File file = new File(filePath);        FileReader reader = null;        FileWriter writer = null;        try {            reader = new FileReader(file);            writer = new FileWriter("d:/work/readFileByCharactor.txt");            int temp;            while ((temp = reader.read()) != -1) {//                System.out.print(((char)temp);                writer.write(temp);            }        } catch (IOException e) {            e.printStackTrace();        } 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    public static void readFileByLine(String filePath) {        File file = new File(filePath);        BufferedReader bufReader = null;        BufferedWriter bufWriter = null;        InputStreamReader isr =null;        try {            bufReader = new BufferedReader(new InputStreamReader(new FileInputStream(file), "GBK"));            bufWriter = new BufferedWriter(new FileWriter("d:/work/readFileByLine.gz"));            String temp = null;            while ((temp = bufReader.readLine()) != null) {//                System.out.println(temp);                bufWriter.write(temp);                bufWriter.newLine();//                bufWriter.newLine();//                bufWriter.write(new String(temp.getBytes("GBK"),"utf-8") + "\n");            }        } catch (IOException e) {            e.printStackTrace();        } finally {            if (bufReader != null && bufWriter !=null) {                try {                    bufReader.close();                    bufWriter.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }    //使用 nio ByteBuffer 字节将文件输出到另一个文件    public static void readFileByByteBuffer(String filePath) {        FileInputStream in = null;        FileOutputStream out = null;        try {            //获取源文件和目标输出文件的输入输出流            in = new FileInputStream(filePath);            out = new FileOutputStream("d:/work/readFileByByteBuffer.gz");            //获取 输入 和输出通道            FileChannel fcIn = in.getChannel();            FileChannel fcOut = out.getChannel();            ByteBuffer buffer = ByteBuffer.allocate(1024);            while (true) {                // clear方法重设缓冲区，使他可以接受读入的数据                buffer.clear();                //从输入通道中将数据读取缓冲区                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份通道                buffer.flip();                fcOut.write(buffer);            }                    } catch (IOException e) {            e.printStackTrace();        } finally {            if (in !=null && out !=null) {                try {                    in.close();                    out.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }    public static void main(String[] args) {        long start=System.currentTimeMillis();//        readFileByByte(FILE_PATH); // 9078//        readFileByCharactor(FILE_PATH); // 528//        readFileByLine(FILE_PATH);         // 94 187 697(80M) 4097(228M) 23953(660M)        readFileByByteBuffer(FILE_PATH); // 180 125 391(80M) 3031(228m) 3621(660M)        long end =System.currentTimeMillis();        System.out.println("time: " + (end - start));    }}
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