blocks|key|1537633|text|我在Oracle中使用未关闭的ResultSets时遇到了问题，即使连接是关闭的。我得到的错误是|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1537634|"ORA-01000:+maximum+open+cursors+exceeded"|code-block|syntax|javascript|1537635|所以:永远关闭你的ResultSet！|1537636|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I've had problems with unclosed ResultSets in Oracle, even though the connection was closed. The error I got was 

<pre><code>"ORA-01000: maximum open cursors exceeded"
</code></pre>

So: Always close your ResultSet!

blocks|key|1752646|text|在这种情况下，Oracle将显示有关打开游标的错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1752647|根据：http://java.sun.com/javase/6/docs/api/java/sql/Statement.html|offset|length|1752648|看起来重用一条语句将关闭所有打开的结果集，关闭一条语句将关闭所有结果集，但我没有看到任何关于关闭连接将关闭它创建的任何资源的内容。|1752649|所有这些细节都留给了JDBC驱动程序提供程序。|1752650|显式地关闭所有内容总是最安全的。我们编写了一个util类，它使用try{+xxx+}+catch+(Throwable+{}+)包装所有内容，这样您就可以只调用Utils.close(rs)和Utils.close(stmt)等，而不必担心关闭扫描可能会抛出异常。|1752651|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/sql/Statement.html^0|0|3|1P|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@]|9|@$D|V|E|W|1|X]]|A|$]]|$1|F|3|G|5|6|7|Y|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|Z|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|10|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|S]]]]

Oracle will give you errors about open cursors in this case.

According to: <a href="http://java.sun.com/javase/6/docs/api/java/sql/Statement.html" rel="noreferrer">http://java.sun.com/javase/6/docs/api/java/sql/Statement.html</a>

it looks like reusing a statement will close any open resultsets, and closing a statement will close any resultsets, but i don't see anything about closing a connection will close any of the resources it created.

All of those details are left to the JDBC driver provider. 

Its always safest to close everything explicitly. We wrote a util class that wraps everything with try{ xxx } catch (Throwable {} so that you can just call Utils.close(rs) and Utils.close(stmt), etc without having to worry about exceptions that close scan supposedly throw.

blocks|key|1752781|text|在Java中，语句(而不是结果集)与Oracle中的游标相关。最好关闭您打开的资源，因为JVM和系统资源可能会发生意外行为。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1752782|此外，一些JDBC池化框架会汇集语句和连接，因此不关闭它们可能不会将这些对象标记为池中的空闲对象，从而导致框架中的性能问题。|1752783|通常，如果对象上有close()或destroy()方法，就有理由调用它，而忽略它则要自担风险。|1752784|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

In Java, Statements (not Resultsets) correlate to Cursors in Oracle. It is best to close the resources that you open as unexpected behavior can occur in regards to the JVM and system resources.

Additionally, some JDBC pooling frameworks pool Statements and Connections, so not closing them might not mark those objects as free in the pool, and cause performance issues in the framework.

In general, if there is a close() or destroy() method on an object, there's a reason to call it, and to ignore it is done so at your own peril.

blocks|key|1752849|text|只关闭连接而不关闭结果集的一个问题是，如果您的连接管理代码使用连接池，connection.close()会将连接放回池中。此外，某些数据库在服务器上有一个游标资源，除非显式关闭它，否则不会正确释放该资源。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1752850|entityMap^0|Z|I|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

One problem with ONLY closing the connection and not the result set, is that if your connection management code is using connection pooling, the <code>connection.close()</code> would just put the connection back in the pool. Additionally, some database have a cursor resource on the server that will not be freed properly unless it is explicitly closed.

blocks|key|1538019|text|您应该始终显式关闭所有JDBC资源。正如Aaron和John已经说过的，关闭连接通常只会将其返回到池中，并且并不是所有的JDBC驱动程序都以完全相同的方式实现。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1538020|下面是一个可以在finally块中使用的实用方法：|1538021|public+static+void+closeEverything(ResultSet+rs,+Statement+stmt,
++++++++Connection+con)+{
++++if+(rs+!=+null)+{
++++++++try+{
++++++++++++rs.close();
++++++++}+catch+(SQLException+e)+{
++++++++}
++++}
++++if+(stmt+!=+null)+{
++++++++try+{
++++++++++++stmt.close();
++++++++}+catch+(SQLException+e)+{
++++++++}
++++}
++++if+(con+!=+null)+{
++++++++try+{
++++++++++++con.close();
++++++++}+catch+(SQLException+e)+{
++++++++}
++++}
}|code-block|syntax|javascript|1538022|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You should always close all JDBC resources explicitly. As Aaron and John already said, closing a connection will often only return it to a pool and not all JDBC drivers are implemented exact the same way.

Here is a utility method that can be used from a finally block:

<pre><code>public static void closeEverything(ResultSet rs, Statement stmt,
 Connection con) {
 if (rs != null) {
 try {
 rs.close();
 } catch (SQLException e) {
 }
 }
 if (stmt != null) {
 try {
 stmt.close();
 } catch (SQLException e) {
 }
 }
 if (con != null) {
 try {
 con.close();
 } catch (SQLException e) {
 }
 }
}
</code></pre>

I've been doing code review (mostly using tools like FindBugs) of one of our pet projects and FindBugs marked following code as erroneous (pseudocode):

<pre><code>Connection conn = dataSource.getConnection();

try{
 PreparedStatement stmt = conn.prepareStatement();
 //initialize the statement
 stmt.execute();
 ResultSet rs = stmt.getResultSet();
 //get data
}finally{
 conn.close();
}
</code></pre>

The error was that this code might not release resources. I figured out that the ResultSet and Statement were not closed, so I closed them in finally:

<pre><code>finally{
 try{
 rs.close()
 }catch(SqlException se){
 //log it
 }
 try{
 stmt.close();
 }catch(SqlException se){
 //log it
 }
 conn.close();
}
</code></pre>

But I encountered the above pattern in many projects (from quite a few companies), and no one was closing ResultSets or Statements.

Did you have troubles with ResultSets and Statements not being closed when the Connection is closed? 

I found only <a href="http://www.theserverside.com/discussions/thread.tss?thread_id=41036" rel="noreferrer">this</a> and it refers to Oracle having problems with closing ResultSets when closing Connections (we use Oracle db, hence my corrections). java.sql.api says nothing in Connection.close() javadoc.

ResultSet not closed when connection closed?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我一直在对我们喜欢的一个项目和FindBugs进行代码审查(主要使用像FindBugs这样的工具)，并将以下代码标记为错误的(伪代码)：Connection conn = dataSource.getConnection();try{    PreparedStatement stmt = conn.prepareSt...

问连接关闭时ResultSet是否未关闭？
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