java自动关闭资源

1.6和之前是这样的，但这样的缺点是finally中也可能报错（如关闭流）：

BufferedReader br = null;
		try {
			br = new BufferedReader(new FileReader(""));
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (br != null)
				br.close();
		}

1.7新增try-with-resources 语句：

try (BufferedReader br = new BufferedReader(new FileReader(""))) {
			br.readLine();
		}

1.7中只要实现了AutoCloseable或Closeable接口的类或接口，均可以使用try-with-resource来实现异常处理和资源关闭。

public abstract class Reader implements Readable, Closeable

public interface Closeable extends AutoCloseable