readLine的两种用法

StringBuffer sbuf = new StringBuffer();
					InputStream is = new FileInputStream(fileName);
					BufferedReader reader = new BufferedReader(new InputStreamReader(is, "GBK"));
					String line = reader.readLine();
while (null != line) {
						sbuf.append(line).append("\n");
line = reader.readLine();
					}
					// 关闭reader就行了，is.close()不必
					reader.close();

StringBuffer sbuf = new StringBuffer();
					InputStream is = new FileInputStream(fileName);
					BufferedReader reader = new BufferedReader(new InputStreamReader(is, "GBK"));
					String line ="";
while ((line = reader.readLine())!=null) {
						sbuf.append(line).append("\n");
					}
					reader.close();