java使用randomaccessfile在文件任意位置写入数据

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");
    }
}