更多 Java 基础知识方面的文章，请参见文集《Java 基础知识》
resource
A resource is an object that must be closed after the program is finished with it.
resource 是一个对象，需要在程序结束前将其关闭。
Java7 之前，如何关闭资源
使用 finally 来确保资源会被关闭。
例如：
public static void main(String[] args) throws Exception {
InputStream bin = new BufferedInputStream(new FileInputStream("a.txt"));
try {
int c;
while ((c = bin.read()) != -1) {
System.out.print((char) c);
}
} finally {
bin.close();
}
}
Java7 开始提供 TWR 语法 Try With Resource
The try-with-resources statement ensures that each resource is closed at the end of the statement.
TWR 语法确保了资源会被自动释放。
Any object that implements java.lang.AutoCloseable, which includes all objects which implement java.io.Closeable
, can be used as a resource.
资源的类需要实现AutoCloseable接口。
例如 BufferedInputStream，它的父类 InputStream 实现了 Closeable 接口：
public abstract class InputStream implements Closeable
The
Closeableinterface extends theAutoCloseableinterface.
因此可以通过如下方式使用 BufferedInputStream：
无论是否出现 Exception，bin 都会在 Try 语句块结束时自动释放。
public static void main(String[] args) throws Exception {
try (InputStream bin = new BufferedInputStream(new FileInputStream("a.txt"))) {
int c;
while ((c = bin.read()) != -1) {
System.out.print((char) c);
}
}
}
