1

我有一个 Java Web 服务器。当我在它空闲了一夜后访问它时，我得到以下异常：“语句已关闭，没有进一步的内部信息可用”。

为了调试这个，我在代码中添加了一个检查：

        try 
        {
            if (stmt.isClosed())
                throw new Exception("Aha!");
            stmt.setString(1, lemma);
            rs = stmt.executeQuery();   
        } 
        catch (SQLException e)  {
            e.printStackTrace();
        }

但是，我没有看到异常“啊哈！”，我看到了这个异常：

statement has been closed, no further internal information available
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 82,918,766 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122)
    at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3056)
    at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2942)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3485)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1960)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2114)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2696)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2105)
    at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2264)
    at eu.excitementproject.eop.core.component.lexicalknowledge.similarity.AbstractSimilarityLexicalResource.getRulesForSide(AbstractSimilarityLexicalResource.java:122)
    ... 69 more
Caused by: java.net.SocketException: Software caused connection abort: recv failed
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.read(Unknown Source)
    at java.net.SocketInputStream.read(Unknown Source)
    at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)
    at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)
    at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)
    at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2500)
    at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2953)
    ... 77 more

这是什么意思，我该如何防止这种情况发生？

4

1 回答 1

2

可能会发生连接关闭但语句保持打开的情况。在这种情况下，对 Statement.isClosed() 的调用将返回 false，但仍会抛出异常。

尝试

if (stmt.isClosed() || stmt.getConnection().isClosed())
    throw new Exception("Aha!");
于 2013-05-07T18:47:09.750 回答