JAVA 读取最后一行 删除最后一行 覆盖最后一行

注：有的地方视情况而定，比如nextend = start+len-1， 如果是空文件就会出错了可以把-1 去掉

读取末行操作：

    public static String readendline(String filename) throws Exception {  
      
            RandomAccessFile file0 = new RandomAccessFile(filename, "r");  
            long start = file0.getFilePointer();  
            long len = file0.length();  
            long nextend = start + len - 1;  
            file0.seek(nextend);  
            byte buf[] = new byte[1];  
            int i = -1;  
            String linestr = null;  
            while (nextend > start) {  
                i = file0.read(buf, 0, 1);  
                if (buf[0] == '\n') {  
                    if ((linestr = file0.readLine()) != null) {  
                         System.out.println("endline:" + linestr);  
                        break;  
                    }  
      
                }  
                nextend--;  
                file0.seek(nextend);  
            }  
      
            file0.close();  
            return linestr;  
      
        }  
    }  

写末行，覆盖末行操作：

	public static void writeendline(String filepath, String string)
			throws Exception {

		RandomAccessFile file = new RandomAccessFile(filepath, "rw");
		long len = file.length();
		long start = file.getFilePointer();
		long nextend = start + len - 1;
		byte[] buf = new byte[1];
		file.seek(nextend);
		file.read(buf, 0, 1);

		if (buf[0] == '\n')

			file.writeBytes(string);
		else
			
			file.writeBytes("\r\n"+string);
		
		file.close();

	}

	public static void rewriteendline(String filepath, String string)
			throws Exception {

		RandomAccessFile file = new RandomAccessFile(filepath, "rw");
		long len = file.length();
		long start = file.getFilePointer();
		long nextend = start + len - 1;

		int i = -1;
		file.seek(nextend);
		byte[] buf = new byte[1];

		while (nextend > start) {

			i = file.read(buf, 0, 1);
			if (buf[0] == '\r') {
				file.setLength(nextend - start);
				break;
			}
			nextend--;
			file.seek(nextend);

		}
		file.close();
		writeendline(filepath, string);

	}