解决RandomAccessFile.readLine()读取中文乱码

/**
	 * 倒叙读取文集最后30行
	 * @param filename
	 * @return
	 */
	public static String read(String filename) {
		String runMessage="";
		RandomAccessFile rf = null;
		try {
			rf = new RandomAccessFile(filename, "r");
			long len = rf.length();
			long start = rf.getFilePointer();
			long nextend = start + len;
			String line;
			rf.seek(nextend);
			int c = -1;
			int x = 0;
			while ((nextend > start) & (x < 30)) {
				c = rf.read();
				if (c == '\n' || c == '\r') {
					line = rf.readLine();
					if (line != null) {
						//System.out.println(line);
						runMessage+=new String(line)+"<br>";
					} else {
						System.out.println(line);// 输出为null，能够注释掉
					}
					nextend--;
					x++;
				}
				nextend--;
				rf.seek(nextend);
				if (nextend == 0) {// 当文件指针退至文件开始处，输出第一行
					System.out.println(rf.readLine());
					runMessage+=rf.readLine()+"<br>";
				}
			}
			//System.out.println(runMessage);
			runMessage=new String(runMessage.getBytes("8859_1"),"gb2312");//解决中文乱码
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if (rf != null)
					rf.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return runMessage;
	}