RandomAccessFile（一）

1、向文件中插入内容案例1
原文件
12345678
插入后
123abcsdfsa45678

import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;import java.io.RandomAccessFile;public class AccessFileUtils {    /**     * 向文件中插入内容案例1     * @param insertIndex     * @param content     * @param file     * 1234567   123abc4567     */    public static void main(String[] args) {        File file = new File("C:\\Users\\Administrator\\Desktop\\ABC.txt");        int insertIndex = 3;        String counte = "abcsdfsa";        play01(file, insertIndex, counte);    }    public static void play01(File file, int insertIndex, String counte){        try {            RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");            randomAccessFile.seek(insertIndex);            byte[] bytes = new byte[1024];            int currentcounte = 0;            String tempString = "";            while((currentcounte = randomAccessFile.read(bytes)) != -1){                tempString += new String(bytes, 0, currentcounte);            }            randomAccessFile.seek(insertIndex + counte.length());            randomAccessFile.writeBytes(tempString);            randomAccessFile.seek(insertIndex);            randomAccessFile.writeBytes(counte);        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

2、向文件中插入内容案例2

public static void insertContent2(File file, int insertIndex, String content){        try {            RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");            //判断如果插入位置不在文件长度范围内，则无效，直接return            if(insertIndex < 0 || insertIndex > randomAccessFile.length()){                System.out.println("插入位置无效");                return;            }            //randomAccessFile.length() 9            //bytes.length 2            //i 8            //i - bytes.length 6            //1234567            byte[] bytes = content.getBytes();            randomAccessFile.setLength(randomAccessFile.length() + bytes.length);            for(long i = randomAccessFile.length() - 1; i > bytes.length + insertIndex; i--){                randomAccessFile.seek(i - bytes.length);                byte temp = randomAccessFile.readByte();                randomAccessFile.seek(i);                randomAccessFile.writeByte(temp);            }            randomAccessFile.seek(insertIndex);            randomAccessFile.write(bytes);            randomAccessFile.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }

3、向文件中插入内容案例3:涉及中文字符

public static void insertContent3(File file, int insertIndex, String content){        try {            RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");            //判断如果插入位置不在文件长度范围内，则无效，直接return            if(insertIndex < 0 || insertIndex > randomAccessFile.length()){                System.out.println("插入位置无效");                return;            }            randomAccessFile.seek(insertIndex);            byte[] bytes = new byte[1024];            int currentCount = 0;            File tempFile = File.createTempFile("CopyTempFile", "txt", new File("E:"));            RandomAccessFile tempRandomAccessFile = new RandomAccessFile(tempFile, "rw");            while((currentCount = randomAccessFile.read(bytes)) != -1){                tempRandomAccessFile.write(bytes, 0, currentCount);            }            randomAccessFile.seek(insertIndex);            randomAccessFile.writeBytes(content);            randomAccessFile.seek(insertIndex + content.getBytes().length);            tempRandomAccessFile.seek(0);            while((currentCount = tempRandomAccessFile.read(bytes)) != -1){                randomAccessFile.write(bytes, 0, currentCount);            }            randomAccessFile.close();            tempRandomAccessFile.close();            tempFile.deleteOnExit();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }