I'm using Spring JDBC and I've got this test method to connect to PostgreSQL DB (It's a example code, this isn't the original code):
public void toConnect() {
final String sql = "SELECT 1";
template.execute(sql);
}
If I catch the DataAccessException, and I call method getCause() the program trigger the PLSQException anyway (though finally printing the message that I set in the catch).
public void toConnect() throws CGConnException {
final String sql = "SELECT 1";
try {
template.execute(sql);
} catch (DataAccessException e) {
throw new CGConnException("CG : Error DataBase connection. - ", e.getCause());
}
}
The problem is than I can't handle the exception and I want than only print the Message of the catch, without the exception details.
If it's run with an error on config parameters or the PostgreSQL database is down, a PSQLException is generated and that is great but I need to control this exception. However JdbcTemplate.execute(sql) method throws a DataAccessException, therefore, doesn't possibly catch the PSQLException on try/catch block (or I don't know how to do). So, when run the program always appears the stack trace in the console:
2021-05-02 03:10:14.052 ERROR 73837 --- [ main] .PostgresClientTestConnectionApplication : Error : CG : Error DataBase connection.
In this case, I need to print only a log as "Connection Error" or something similar as the example above.
Thank you in advance.
Actually there is no mistake. The exception is handled and the program finally correctly when is catch it.
try {
template.execute(sql);
logger.error("Connection Successful . . .");
} catch (Exception e) {
logger.error("Error connection" + e.getMessage());
throw new CGConnException("CG : Error DataBase connection. - ", e);
}
In the run console it's print the associate stack trace because Spring internal classes to do it, but don't mean than we are doing something wrong or than no handle the exception.
Related
I have the below statements in my code which violates some Sonar Rules.
LOG.info("Fetched: {}", mapper.writeValueAsString(requests));
This one shows Invoke method(s) only conditionally for mapper.writeValueAsString(requests).
}catch (Exception e) {
LOG.error("Exception occurred while trying to fetch requests", e);
throw new GenericException(Error.FETCH_REQUEST_ERR_001.name(), e.getMessage(), Error.FETCH_REQUEST_ERR_001.value());
}
This one shows Either log this exception and handle it, or rethrow it with some contextual information. rule violation.
Any idea on how to resolve these. Appreciate any help.
I use IntelliJ and in a similar situation as yours SonarLint plugin accepted the following fix for me:
if(LOG.isInfoEnabled() && mapper != null){
LOG.info("Fetched: {}", mapper.writeValueAsString(requests)); // Your code
}
I am writing a RESTful web service using spring 3 and I noticed that when I implemented my DAO's (I am using spring-jdbc for database access), the exceptions that get thrown are pretty generic, so i am not able to identify if the exception occurred because my database is down or my query failed.
sample code:
try {
Q q = jdbcTemplate.queryForObject(MY_QUERY, new Object[]{id}, new MyMapper());
return q;
} catch (DataAccessException e) {
// What is this exception ? database down ? query failed ?
}
Unless I know what exception is this during runtime, I can't send back reasonable error message to service client.
Any help is appreciated. Thanks
You shouldn't be trying to catch every single possible exception; code so that you don't run into the possibility of multiple user or programmer error type exceptions. Generally there are three type of exceptions that occur in every DAO regardless of what you do. (1) your database is down... imo if this is the issue you've got bigger problems. (2) user authentication error which is easy enough to catch and deal with (however you should probably be handling that situation on your RESTful front-end. (3) improper data. If you have bad data, just send the attempted data back and the reason for the exception.
try {
Q q = jdbcTemplate.queryForObject(MY_QUERY, new Object[]{id}, new MyMapper());
return q;
} catch (DataAccessException e) {
throw new DaoException("Could not retrieve q with ID: " + qID, e);
}
The method queryForObject only throws DataAccessException or IncorrectResultSizeDataAccessException. You shouldn't catch exception due to database connection failure at this level. However, in your DAO class, you normally have code to establish the dataSource which can be injected by Spring's IoC container. That part of code will throw exception if the database connection fails. You should catch DB failure exception there.
Currently i am using spring declarative transaction manager in my application. During DB operations if any constraint violated i want to check the error code against the database. i mean i want to run one select query after the exception happened. So i am catching the DataIntegrityViolationException inside my Catch block and then i am trying to execute one more error code query. But that query is not get executed . I am assuming since i am using the transaction manager if any exception happened the next query is not getting executed. Is that right?. i want to execute that error code query before i am returning the results to the client. Any way to do this?
#Override
#Transactional
public LineOfBusinessResponse create(
CreateLineOfBusiness createLineOfBusiness)
throws GenericUpcException {
logger.info("Start of createLineOfBusinessEntity()");
LineOfBusinessEntity lineOfBusinessEntity =
setLineOfBusinessEntityProperties(createLineOfBusiness);
try {
lineOfBusinessDao.create(lineOfBusinessEntity);
return setUpcLineOfBusinessResponseProperties(lineOfBusinessEntity);
}
// Some db constraints is failed
catch (DataIntegrityViolationException dav) {
String errorMessage =
errorCodesBd.findErrorCodeByErrorMessage(dav.getMessage());
throw new GenericUpcException(errorMessage);
}
// General Exceptions handling
catch (Exception exc) {
logger.debug("<<<<Coming inside General >>>>");
System.out.print("<<<<Coming inside General >>>>");
throw new GenericUpcException(exc.getMessage());
}
}
public String findErrorCodeByErrorMessage(String errorMessage)throws GenericUpcException {
try{
int first=errorMessage.indexOf("[",errorMessage.indexOf("constraint"));
int last=errorMessage.indexOf("]",first);
String errorCode=errorMessage.substring(first+1, last);
//return errorCodesDao.find(errorCode);
return errorCode;
}
catch(Exception e)
{
throw new GenericUpcException(e.getMessage());
}
}
Please help me.
I don't think problem you're describing has anything to do with Transaction management. If DataIntegrityViolationException happens within your try() block you code within catch() should execute. Perhaps exception different from DataIntegrityViolationException happens or your findErrorCodeByErrorMessage() throwing another exception. In general, Transaction logic would be applied only once you return from your method call, until then you could do whatever you like using normal Java language constructs. I suggest you put breakpoint in your error error handler or some debug statements to see what's actually happening.
I have an issue with VS2010 where the debugger stops with an Unhandled Exception. However, the exception is definitely handled. In fact, if I put code in the catch block, I'll hit it when I press F5. In Debug -> Exceptions, I definitely do not have the "Thrown" checkbox checked, so IMO there is absolutely no reason for the unhandled exception dialog to pop up...
I can't post the exact code, but will work on a sample soon. The basic idea behind the offending code section is that I have a thread that talks to hardware, and if I have an error talking to it, then I throw a HardwareException. The thread is launched with BeginInvoke, and the exception is caught in the callback handler when I call EndInvoke.
When the exception is thrown in the debugger, I get a messagebox that says 'HardwareException not handled by user code". But it is!!!
EDIT -- Well, this is driving me crazy. I've got sample code that is representative of the code I have in my application, and it looks like this:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.Remoting.Messaging;
using System.Threading;
namespace ConsoleApplication1
{
public class HardwareException : ApplicationException
{
public HardwareException( string message) : base(message) {}
}
class Program
{
delegate void HardwareTestDelegate();
static void Main(string[] args)
{
HardwareTestDelegate d = new HardwareTestDelegate( HardwareTestThread);
d.BeginInvoke( HardwareTestComplete, null);
while( true);
}
static void HardwareTestThread()
{
throw new HardwareException( "this is a test");
}
static void HardwareTestComplete( IAsyncResult iar)
{
try {
AsyncResult ar = (AsyncResult)iar;
HardwareTestDelegate caller = (HardwareTestDelegate)ar.AsyncDelegate;
caller.EndInvoke( iar);
} catch( Exception ex) {
Console.WriteLine( "Should see this line without getting an unhandled exception message in the IDE");
}
}
}
}
I throw my HardwareException from the thread, and then handle the exception when EndInvoke is called. I guess Murphy was right, because when I run this sample code, it does what I expect -- i.e. no unhandled exception error message pops up in the IDE!
Here is the response from Microsoft, case 111053102422121. Allen Weng writes the following:
Analysis:
For your information, CLR will re-throw the exception inside the callback when you call EndInvoke(). Below is a simplified version of EndInvoke():
public object EndInvoke(IAsyncResult asyncResult)
{
using (new MultithreadSafeCallScope())
{
ThreadMethodEntry entry = asyncResult as ThreadMethodEntry;
............
if (entry.exception != null)
{
throw entry.exception;
}
}
}
The exception will be handled in the call back function or in the asynchronous method if an exception handler is provided. This is how it works without a debugger attached.
When you run it in VS.NET, the debugger seems checking only the presence of the exception handler in the asynchronous method. If there is no such handler, the debugger would think the exception is not handled and pop up an error message notifying you of this.
Suggestion:
The application should work as expected when you run it stand alone. If the error message is annoying in debugging for you, you can disable it by unchecking “User unhandled” for “Common Language Runtime Exceptions”in the Exception dialog box (Debug|Exceptions or press CTRL+ATL+E). Or you can add try/catch in the asynchronous method. In the latter case, the exception is set to null and won’t be re-thrown in EndInvoke().
I'm having this same problem, so I'll post this possible workaround for posterity's sake:
In your code that throws an exception into the .NET code (HardwareTestThread() in the example above,) catch the exception that's being thrown and wrap it in some esoteric .NET exception type for which you can disable the "user-unhandled" option in the Debug>Exceptions dialog. For my case, I needed to allow an IOException to propagate through some .NET code back to my code, so I just caught the IOException and wrapped in an AppDomainUnloadedException before letting it propagate through the .NET code back to my catch block. I chose AppDomainUnloadedException because user-unhandled is unchecked for it by default and it's in the System.dll assembly, so it was already being imported in my project, though any exception should work, so long as you disable the "user-unhandled" option for it and you don't care that the debugger won't break on that type of exception in the future.
Here's my code that wraps the IOException I was needing to propagate:
public override int Read(byte[] buffer, int offset, int count)
{
try { return innerStream.Read(buffer, offset, count); }
catch (IOException ex) { throw new AppDomainUnloadedException("Exception from innerStream: " + ex.Message, ex); }
}
And here's my code where I'm catching it on the other side of the .NET code it needed to propagate through:
try { bytesRead = sslStream.Read(buffer, offset, count); }
catch (Exception ex) { /* ex handled here. */ }
We are running a websphere commerce site with an oracle DB and facing an issue where we are running out of db connections.
We are using a JDBCHelper singleton for getting the prepared statements and cosing the connections.
public static JDBCHelper getJDBCHelper() {
if (theObject == null){
theObject = new JDBCHelper();
}
return theObject;
}
public void closeResources(Connection con, PreparedStatement pstmt, ResultSet rs){
try{
if(rs!=null){ rs.close();}
}catch(SQLException e){
logger.info("Exception closing the resultset");
}try{
if(pstmt!=null) { pstmt.close(); }
}catch(SQLException e){
logger.info("Exception closing the preparedstatement");
}try{
if(con!=null){ con.close(); }
}catch(SQLException e){
logger.info("Exception closing the connection");
}
}
However when we try getting the connection using a prepStmt.getConnection() for passing to the close resources after execution it throws an sql exception. Any idea why? Does the connection get closed immediately after execution? And is there something wrong in our use of the singleton JDBCHelper?
EDIT
Part of the code which makes the prepared statement,executes and closes the connection
PreparedStatement pstmt = jdbcHelper.getPreparedStatement(query);
try{
//rest of the code
int brs = pstmt.executeUpdate();
}
finally{
try {
jdbcHelper.closeResources(pstmt.getConnection(),pstmt);
} catch (SQLException e1) {
logger.logp(Level.SEVERE,CLASS_NAME,methodName,"In the finally block - Could not close connection", e1);
}
}
Your connection will most likely come from a pool, and closing it actually will return the connection to the pool (under the covers). I think posting the code which gets the connection, uses it and closes it via JDBCHelper will be of more use.
Re. your singleton, I'm not sure why you're using this, since it doesn't appear to have anything to warrant it being a singleton. Check out Apache Commons DbUtils which does this sort of stuff and more besides.
This code seems to be written for single threaded operation only, as it's lacking any synchronisation code. The getJdbcHelper() method for instance is likely to create two JdbcHelpers. If I'm not mistaken there's even no guarantee that a second thread will see theObject, long after a primary thread has created it. Although they usually will, by virtue of the architecture the JVM runs on.
If you're running this inside a web server you're likely to be running into race issues, where two threads are modifying your connection at the same time. Unless you rolled your own connection pool or something.
Brian is right, use one of the freely available libraries that solve this (hard) problem for you.