java 從檔案末尾開始讀取檔案內容
阿新 • • 發佈:2018-12-31
/**
* 從檔案末尾開始讀取檔案,並逐行列印
* @param filename file path
* @param charset character
*/
public static void readFileFromEnd(String filename, String charset) {
RandomAccessFile rf = null;
try {
rf = new RandomAccessFile(filename, "r");
long fileLength = rf.length();
long start = rf.getFilePointer();// 返回此檔案中的當前偏移量
long readIndex = start + fileLength -1;
String line;
rf.seek(readIndex);// 設定偏移量為檔案末尾
int c = -1;
while (readIndex > start) {
c = rf.read();
String readText = null;
if (c == '\n' || c == '\r' ) {
line = rf.readLine();
if (line != null) {
readText = new String(line.getBytes("ISO-8859-1"), charset);
} else {
System.out.println("read line : " + line);
}
readIndex--;
}
readIndex--;
rf.seek(readIndex);
if (readIndex == 0) {// 當檔案指標退至檔案開始處,輸出第一行
readText = rf.readLine();
}
if (readText != null) {
System.out.println(readText);
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (rf != null)
rf.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}