正确释放资源方法

1.只限于一个方法的资源

public static Properties loadProperties(String fileName)
throws IOException {
FileInputStream stream = new FileInputStream(fileName);
try {
Properties props = new Properties();
props.load(stream);
return props;
}
finally {
stream.close();
}
}

2.可靠的释放多个资源的方法

public void enumerateBar() throws SQLException {
Statement statement = null;
ResultSet resultSet = null;
Connection connection = getConnection();
try {
statement = connection.createStatement();
resultSet = statement.executeQuery("SELECT * FROM Bar");
// Use resultSet
}
finally {
try {
if (resultSet != null)
resultSet.close();
}
finally {
try {
if (statement != null)
statement.close();
}
finally {
connection.close();
}
}
}
}

private Connection getConnection() {
return null;
}

3.绑定连接的脆弱实现关闭

public class BoundedSet<T> {
private final Set<T> set = ...
private final Semaphore sem;

public BoundedHashSet(int bound) {
sem = new Semaphore(bound);
}

public boolean add(T o) throws InterruptedException {
sem.acquire();
boolean wasAdded = false;
try {
wasAdded = set.add(o);
return wasAdded;
}
finally {
if (!wasAdded)
sem.release();
}
}
}

参考ibm文章
http://www-128.ibm.com/developerworks/cn/java/j-jtp03216.html?ca=dwcn-newsletter-java