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");     } }