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Spring的JdbcTemplate使用，是否还需要手工或者aop指定关闭conn连接（ 使用JdbcTemplate是否需要关闭连接）...

分类: 文章 • 2025-05-12 13:18:40

JdbcTemplate类使用DataSource得到一个数据库连接。然后，他调用StatementCreator实例创建要执行的语句。下一步，他调用StatementCallBack完成。
一旦StatementCallBack返回结果，JdbcTemplate类完成所有必要清理工作关闭连接。如果StatementCreator或StatementCallBack抛出异常，JdbcTemplate类会捕获他们，并转换为Spring数据访问异常。

Spring的JdbcTemplate使用，是否还需要手工或者aop指定关闭conn连接（ 使用JdbcTemplate是否需要关闭连接）...



看一个JdbcTemplate里面的比较核心的一个方法：

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  1. //-------------------------------------------------------------------------
  2. // Methods dealing with prepared statements
  3. //-------------------------------------------------------------------------
  5. publicObject execute(PreparedStatementCreator psc, PreparedStatementCallback action)
  6. throwsDataAccessException {
  8. Assert.notNull(psc,"PreparedStatementCreator must not be null");
  9. Assert.notNull(action,"Callback object must not be null");
  10. if(logger.isDebugEnabled()) {
  11. String sql = getSql(psc);
  12. logger.debug("Executing prepared SQL statement"+ (sql !=null?" ["+ sql +"]":""));
  13. }
  15. Connection con = DataSourceUtils.getConnection(getDataSource());
  16. PreparedStatement ps =null;
  17. try{
  18. Connection conToUse = con;
  19. if(this.nativeJdbcExtractor !=null&&
  20. this.nativeJdbcExtractor.isNativeConnectionNecessaryForNativePreparedStatements()) {
  21. conToUse =this.nativeJdbcExtractor.getNativeConnection(con);
  22. }
  23. ps = psc.createPreparedStatement(conToUse);
  24. applyStatementSettings(ps);
  25. PreparedStatement psToUse = ps;
  26. if(this.nativeJdbcExtractor !=null) {
  27. psToUse =this.nativeJdbcExtractor.getNativePreparedStatement(ps);
  28. }
  29. Object result = action.doInPreparedStatement(psToUse);
  30. handleWarnings(ps);
  31. returnresult;
  32. }
  33. catch(SQLException ex) {
  34. // Release Connection early, to avoid potential connection pool deadlock
  35. // in the case when the exception translator hasn't been initialized yet.
  36. if(pscinstanceofParameterDisposer) {
  37. ((ParameterDisposer) psc).cleanupParameters();
  38. }
  39. String sql = getSql(psc);
  40. psc =null;
  41. JdbcUtils.closeStatement(ps);
  42. ps =null;
  43. DataSourceUtils.releaseConnection(con, getDataSource());
  44. con =null;
  45. throwgetExceptionTranslator().translate("PreparedStatementCallback", sql, ex);
  46. }
  47. finally{
  48. if(pscinstanceofParameterDisposer) {
  49. ((ParameterDisposer) psc).cleanupParameters();
  50. }
  51. JdbcUtils.closeStatement(ps);
  52. DataSourceUtils.releaseConnection(con, getDataSource());
  53. }
  54. }

显然，我们在finally里面看到了关闭调用，在看看这个关闭调用方法内部：
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  1. /**
  2. * Close the given Connection, obtained from the given DataSource,
  3. * if it is not managed externally (that is, not bound to the thread).
  4. * @param con the Connection to close if necessary
  5. * (if this is <code>null</code>, the call will be ignored)
  6. * @param dataSource the DataSource that the Connection was obtained from
  7. * (may be <code>null</code>)
  8. * @see #getConnection
  9. */
  10. publicstaticvoidreleaseConnection(Connection con, DataSource dataSource) {
  11. try{
  12. doReleaseConnection(con, dataSource);
  13. }
  14. catch(SQLException ex) {
  15. logger.debug("Could not close JDBC Connection", ex);
  16. }
  17. catch(Throwable ex) {
  18. logger.debug("Unexpected exception on closing JDBC Connection", ex);
  19. }
  20. }
  22. /**
  23. * Actually close the given Connection, obtained from the given DataSource.
  24. * Same as {@link #releaseConnection}, but throwing the original SQLException.
  25. * <p>Directly accessed by {@link TransactionAwareDataSourceProxy}.
  26. * @param con the Connection to close if necessary
  27. * (if this is <code>null</code>, the call will be ignored)
  28. * @param dataSource the DataSource that the Connection was obtained from
  29. * (may be <code>null</code>)
  30. * @throws SQLException if thrown by JDBC methods
  31. * @see #doGetConnection
  32. */
  33. publicstaticvoiddoReleaseConnection(Connection con, DataSource dataSource)throwsSQLException {
  34. if(con ==null) {
  35. return;
  36. }
  38. if(dataSource !=null) {
  39. ConnectionHolder conHolder = (ConnectionHolder) TransactionSynchronizationManager.getResource(dataSource);
  40. if(conHolder !=null&& connectionEquals(conHolder, con)) {
  41. // It's the transactional Connection: Don't close it.
  42. conHolder.released();
  43. return;
  44. }
  45. }
  47. // Leave the Connection open only if the DataSource is our
  48. // special SmartDataSoruce and it wants the Connection left open.
  49. if(!(dataSourceinstanceofSmartDataSource) || ((SmartDataSource) dataSource).shouldClose(con)) {
  50. logger.debug("Returning JDBC Connection to DataSource");
  51. con.close();
  52. }
  53. }

主要下面这几行代码:
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  1. // Leave the Connection open only if the DataSource is our
  2. // special SmartDataSoruce and it wants the Connection left open.
  3. if(!(dataSourceinstanceofSmartDataSource) || ((SmartDataSource) dataSource).shouldClose(con)) {
  4. logger.debug("Returning JDBC Connection to DataSource");
  5. con.close();
  6. }

哦，可以看到大部分情况下是自动关闭，除非你使用的SmartDataSource，且SmartDataSource指定了允许关闭。


有些时候，你引入了JdbcTemplate或者DaoSupport，但是有时还需要自己额外的拿到conn进行操作，如下：
jdbcTemplate.getDataSource().getConnection()
那么，你应该就需要关闭连接了

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