SQLNonTransientConnectionException：在与 Derby 数据库交互时，在我的应用程序中没有当前连接

Question

我在应用程序中实现了 derby 数据库来保存数据，并且在 Derby 数据库中检索结果集形式 select 查询时遇到此异常。 要建立连接，我使用连接字符串：

我使用此方法建立连接：

我在类 Connection.java 中声明此方法：

 public synchronized Connection createConnection() throws Exception {

        Connection rescon = null;

        try {
            if (this.dbuser == null) {
                rescon = DriverManager.getConnection(this.URI + ";create=true");
                } else {
                rescon = DriverManager.getConnection(this.URI + ";create=true",
                        this.dbuser, this.dbpass);
            }
            // new connection in connection pool created
        } catch (SQLException e) {
            final String stackNum = Utility.exceptionHandler(e);
            throw new Exception("Exception get during Connection - " + e.getMessage());
        }
        return rescon;
    }

我将此方法用作并创建连接，在使用字符串的牵引期间创建连接：

private Connection objConnection = null;
objConnectionpool = new Connection("jdbc:derby:" + Folder.getAbsolutePath() +        "/myapplication" + sFileName, null, null, "org.apache.derby.jdbc.EmbeddedDriver");
objConnection =  objConnectionpool.createNewConnection();

我在执行查询时遇到异常：

sQuery = "select value,reason from " + TableNm + " where fileName ='" + FileName + "' AND type='"+Type+"' AND status ='remaining'"; 

在处理和与 Derby 数据库交互期间，我们也可能会更新从数据库获取数据：

插入数据库之前，我将 setAutoCommit 执行为 false

objConnection.setAutoCommit(false);

在插入后

ps = objConnection.prepareStatement(sQuery);
rs = ps.executeQuery();
objConnection.commit();
objConnection.setAutoCommit(true);

：我收到异常为

java.sql.SQLNonTransientConnectionException: No current connection.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.noCurrentConnection(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.checkIfClosed(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.setupContextStack(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown Source)
    at com.myapplication.c.aw.a(Unknown Source)
    at com.myapplication.c.aw.a(Unknown Source)
    at com.myapplication.main.avd.run(Unknown Source)
Caused by: java.sql.SQLException: No current connection.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
    ... 11 more

Answer 1

通过谷歌找到这个。

我遇到了同样的问题，并在此示例应用程序中找到了答案： http:// /db.apache.org/derby/docs/10.4/devguide/rdevcsecure26537.html

//强制垃圾回收卸载EmbeddedDriver
// 这样 Derby 就可以重新开始
系统.gc();

现在工作完美。