我试图用tomcat运行我的应用程序,我第一次调试/运行应用程序,它的工作很好。但是当我试图第二次运行时,我得到错误"XJ040"。
"Failed to start database 'C:Documents and Settingsvitaly87.netbeans- derbyarticals' with class loader WebappClassLoader
context: /WebApplication1
delegate: false
repositories:
我认为这个问题是因为关闭连接时出了问题。因为当我停止服务器时,问题就会消失,直到第二次运行。
这里的代码:
private Connection connect = null;
//private Statement stmt = null;
private PreparedStatement preparedStatement = null;
private ResultSet resultSet = null;
public ArrayList<story> stories=new ArrayList<story>();
void getStories(String version) throws SQLException{
try{
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
}catch(ClassNotFoundException e){
System.out.println(e);
}
connect = DriverManager.getConnection( "jdbc:derby:C:\Documents and Settings\vitaly87\.netbeans-derby\articals", "admin", "admin");
// statement = connect.createStatement();
int ArticlesId= Integer.parseInt(version);
preparedStatement = connect.prepareStatement("SELECT * FROM admin.articles where id>"+ArticlesId+"");
resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {
stories.add(new story(resultSet.getString("title"),resultSet.getString("date"),resultSet.getString("text")));
}
close();
}
//close connection
private void close() {
try {
if (resultSet != null) {
resultSet.close();
}
if (connect != null) {
connect.close();
}
} catch (Exception e) {
}
thanks for help
最好总是关闭最后的连接
connect = DriverManager.getConnection(...)
try
{
// use connection
}
finally
{
try
{
connect.close()
}
catch (SQLException e)
{
// log e
}
}
在你的代码中,如果你有一个异常,连接将不会被关闭,例如在parseInt(version)或exequteQuery()
同样在你的情况下,我不认为关闭结果集是必要的,因为你正在关闭连接。
try {
if (resultSet != null) {
resultSet.close();
}
if (connect != null) {
connect.close();
}
} catch (Exception e) {
}
是有问题的,因为1。如果resultSet.close()抛出异常,则连接永远不会关闭。在此方法中不会看到抛出任何异常。我建议至少记录捕获到的异常