Java uses randomaccessfile to write data anywhere in the file

复制代码代码如下:

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.RandomAccessFile;

public class InsertContent {

public static void insert(String fileName, long pos, String insertContent) throws IOException{

File file = File.createTempFile("tmp", null);

file.deleteOnExit();

RandomAccessFile raf = new RandomAccessFile(fileName, "rw");

FileInputStream fileInputStream = new FileInputStream(file);

FileOutputStream fileOutputStream = new FileOutputStream(file);

raf.seek(pos);

byte[] buff = new byte[64];

int hasRead = 0;

while((hasRead = raf.read(buff)) > 0){

fileOutputStream.write(buff);

}

raf.seek(pos);

raf.write(insertContent.getBytes());

//追加文件插入点之后的内容

while((hasRead = fileInputStream.read(buff)) > 0){

raf.write(buff, 0, hasRead);

}

raf.close();

fileInputStream.close();

fileOutputStream.close();

}

public static void main(String[] args) throws IOException {

insert("F:/AttendanceActivity.java", 57, "插入的内容rn");

}

}