Hello Rob, Thanks. I wrote this before I knew about the “try-with” feature, but will look into it. I see that an issue with my current code is that the connection won’t be closed if an error is thrown.
Best regards, Dan From: Rob Sargent <rsarg...@xmission.com> Sent: Thursday, July 31, 2025 11:22 PM To: Tomcat Users List <users@tomcat.apache.org> Cc: Tomcat Users List <users@tomcat.apache.org> Subject: Re: How to access a REST service Daniel, You might take a look at java’s “ try with” construct The try-with-resources Statement (The Java™ Tutorials > Essential Java Classes > Exceptions) docs.oracle.com -------------------------------------------------------------------------------------------------------------- NkdkJdXPPEBannerStart Be Careful With This Message From (Rob Sargent <rsarg...@xmission.com>)<https://godaddy1.cloud-protect.net/email-details/?k=k1&payload=53616c7465645f5f43cdb6b8a8a52fa3034cb686bdec16527bc6702454bf60bc53c293e94b791a875d6eef29456ccde42b0f1f2e37268fc23df4e1a4c20f59fbfd081ad91e2206beca270f4502ddce16efdf9c0027285e07a7ead6a0d71b2f7cc67a347c0cc24f535337c9f1799502fdd6fe0419af566980908394dacbaa83d51a09ff16e0358c73c1ae9661daf2f8d969452b484810e64edad60cae5b674bc26056eb22d41f2a4d1e4cdcc1124a1e67d2a3aa0ed3c5f949128180ed87e8b5f6c8a8fc40cb5925515b14d3fa45c2c3198a8fa11c0ff352ea71fde364d47d4aff649892e45b646ae1d29f30e4a6f2352b> Learn More<https://godaddy1.cloud-protect.net/email-details/?k=k1&payload=53616c7465645f5f43cdb6b8a8a52fa3034cb686bdec16527bc6702454bf60bc53c293e94b791a875d6eef29456ccde42b0f1f2e37268fc23df4e1a4c20f59fbfd081ad91e2206beca270f4502ddce16efdf9c0027285e07a7ead6a0d71b2f7cc67a347c0cc24f535337c9f1799502fdd6fe0419af566980908394dacbaa83d51a09ff16e0358c73c1ae9661daf2f8d969452b484810e64edad60cae5b674bc26056eb22d41f2a4d1e4cdcc1124a1e67d2a3aa0ed3c5f949128180ed87e8b5f6c8a8fc40cb5925515b14d3fa45c2c3198a8fa11c0ff352ea71fde364d47d4aff649892e45b646ae1d29f30e4a6f2352b> Potential Impersonation The sender's identity could not be verified and someone may be impersonating the sender. 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NkdkJdXPPEBannerEnd Daniel, You might take a look at java’s “ try with” construct The try-with-resources Statement (The Java™ Tutorials > Essential Java Classes > Exceptions)<https://urldefense.proofpoint.com/v2/url?u=https-3A__docs.oracle.com_javase_tutorial_essential_exceptions_tryResourceClose.html&d=DwMFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=AbCalLxzopgQUG9LLcXdB80OM-GtDfItX76RMxNYqz4&m=-hacTP6KVKuoWm9UAmO35pU3860b8Zy2BhScJ-KwihYqxah3UKba5boSuGVBsRx0&s=mNhXT4swanwGi8JqA0d0saa_QrNH6RP9EBEnFjz-kE0&e=> docs.oracle.com<https://urldefense.proofpoint.com/v2/url?u=https-3A__docs.oracle.com_javase_tutorial_essential_exceptions_tryResourceClose.html&d=DwMFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=AbCalLxzopgQUG9LLcXdB80OM-GtDfItX76RMxNYqz4&m=-hacTP6KVKuoWm9UAmO35pU3860b8Zy2BhScJ-KwihYqxah3UKba5boSuGVBsRx0&s=mNhXT4swanwGi8JqA0d0saa_QrNH6RP9EBEnFjz-kE0&e=> [favicon.ico]<https://urldefense.proofpoint.com/v2/url?u=https-3A__docs.oracle.com_javase_tutorial_essential_exceptions_tryResourceClose.html&d=DwMFaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=AbCalLxzopgQUG9LLcXdB80OM-GtDfItX76RMxNYqz4&m=-hacTP6KVKuoWm9UAmO35pU3860b8Zy2BhScJ-KwihYqxah3UKba5boSuGVBsRx0&s=mNhXT4swanwGi8JqA0d0saa_QrNH6RP9EBEnFjz-kE0&e=> -------------------------------------------------------------------------------------------------------------- Here is a fragment of the code from the file HolidaysRESTJSONResource.jar. -------------------------------------------------------------------------- public class HolidaysRESTJSONResource { DataSource dataSource; public HolidaysRESTJSONResource() { dataSource = DataSourceSingleton.getInstance().dataSource; } @GET @Path("/countries") @Produces(MediaType.APPLICATION_JSON) public String getJsonCountries() { ... Connection connection; try { connection = dataSource.getConnection(); TempDataStorage.countryList = GetCountryList.doIt(connection); connection.close(); ... } -------------------------------------------------------------------------- The constructor for HolidaysRESTJSONResource creates a DataSource by creating an instance of the following DataSourceSingleton class and retrieving the value of the DataSource instance variable. I borrowed this code from somewhere. It seems to work. The MySql database is called "holidays". -------------------------------------------------------------------------- public class DataSourceSingleton { private static DataSourceSingleton instance = null; public DataSource dataSource = null; private DataSourceSingleton() { try { InitialContext ctx = new InitialContext(); dataSource = (DataSource) ctx.lookup("jdbc/holidays"); } catch (NamingException e) { System.out.println(e); } } public static DataSourceSingleton getInstance() { if (instance == null) { instance = new DataSourceSingleton(); } return instance; } } -------------------------------------------------------------------------- Back in HolidaysRESTJSONResource, in the method getJsonCountries(), the DataSource object, called "dataSource", is used to create the connection object, and this is used in a method call GetCountryList.doIt() to retrieve a list of countries from the database. Then this connection object is closed. I think that this is all that is needed to prevent memory leaks. Is this correct? I do this for every such method call that accesses the database. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org<mailto:users-unsubscr...@tomcat.apache.org> For additional commands, e-mail: users-h...@tomcat.apache.org<mailto:users-h...@tomcat.apache.org> --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org<mailto:users-unsubscr...@tomcat.apache.org> For additional commands, e-mail: users-h...@tomcat.apache.org<mailto:users-h...@tomcat.apache.org>
