如何獲取在Java文件中最后寫入的位置？

Question

我想編寫一個循環日志文件：

public class CircularLogFile {
    public static final String LOG_FILE_NAME = "circular.log";
    public static final int LOG_FILE_SIZE_MAX = 256;

    public static void write(String line) throws IOException {
        //BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(logFileName, true));
        RandomAccessFile raf = new RandomAccessFile(LOG_FILE_NAME, "rw");
        System.out.println("file size: "+raf.length());
        System.out.println("file pointer: "+raf.getFilePointer());
        if (raf.length() >= LOG_FILE_SIZE_MAX && raf.getFilePointer() >= LOG_FILE_SIZE_MAX) {
            raf.seek(0);
        } else if (raf.length() >= LOG_FILE_SIZE_MAX && raf.getFilePointer() < LOG_FILE_SIZE_MAX) {
        } else if (raf.length() < LOG_FILE_SIZE_MAX) {
            raf.seek(raf.length());
        }

        raf.writeChars(line+"\n");

        raf.close();
    }

    public static void main(String[] args) throws IOException {
        int lineNumber = 0;

        while (true) {
            lineNumber++;
            write("This is Line "+lineNumber);
        }
    }
}

輸出：

This is Line 1400
s is Line 2
This is Line 3
This is Line 4
This is Line 5
This is Line 6
This is Line 7
This is Line 8
This is Line 9

不

This is Line 10
This is Line 11
This is Line 12
This is Line 4
This is Line 5
This is Line 6
This is Line 7
This is Line 8
This is Line 9

我想要上面的結果，但是我找不到文件中最后寫入的位置，如何獲得？

Answer 1

您想要的東西非常棘手，在我看來，它甚至可能不是處理它的最佳方法。 您正在使用和濫用文件I / O（昂貴且出於目標，有些困難）。

您是否正在處理如此大的文件，以致無法使用數據結構來解析文件並在刷新之前保留輸出？ 它將需要最少的計算並最小化I / O讀/寫，同時使其更易於使用