Examples of org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy

Package org.springframework.jdbc.datasource

Examples of org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy

org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy
Proxy for a target DataSource, fetching actual JDBC Connections lazily, i.e. not until first creation of a Statement. Connection initialization properties like auto-commit mode, transaction isolation and read-only mode will be kept and applied to the actual JDBC Connection as soon as an actual Connection is fetched (if ever). Consequently, commit and rollback calls will be ignored if no Statements have been created.
This DataSource proxy allows to avoid fetching JDBC Connections from a pool unless actually necessary. JDBC transaction control can happen without fetching a Connection from the pool or communicating with the database; this will be done lazily on first creation of a JDBC Statement.
If you configure both a LazyConnectionDataSourceProxy and a TransactionAwareDataSourceProxy, make sure that the latter is the outermost DataSource. In such a scenario, data access code will talk to the transaction-aware DataSource, which will in turn work with the LazyConnectionDataSourceProxy.
Lazy fetching of physical JDBC Connections is particularly beneficial in a generic transaction demarcation environment. It allows you to demarcate transactions on all methods that could potentially perform data access, without paying a performance penalty if no actual data access happens.
This DataSource proxy gives you behavior analogous to JTA and a transactional JNDI DataSource (as provided by the J2EE server), even with a local transaction strategy like DataSourceTransactionManager or HibernateTransactionManager. It does not add value with Spring's JtaTransactionManager as transaction strategy.
Lazy fetching of JDBC Connections is also recommended for read-only operations with Hibernate, in particular if the chances of resolving the result in the second-level cache are high. This avoids the need to communicate with the database at all for such read-only operations. You will get the same effect with non-transactional reads, but lazy fetching of JDBC Connections allows you to still perform reads in transactions.
NOTE: This DataSource proxy needs to return wrapped Connections to handle lazy fetching of an actual JDBC Connection. Therefore, the returned Connections cannot be cast to a native JDBC Connection type like OracleConnection, or to a connection pool implementation type. Use a corresponding NativeJdbcExtractor to retrieve the native JDBC Connection. @author Juergen Hoeller @since 1.1.4 @see ConnectionProxy @see DataSourceTransactionManager @see org.springframework.orm.hibernate3.HibernateTransactionManager @see org.springframework.jdbc.support.nativejdbc.NativeJdbcExtractor

    }
  }


  public void testClobStringTypeWithSynchronizedConnection() throws Exception {
    DataSource dsTarget = new DriverManagerDataSource();
    DataSource ds = new LazyConnectionDataSourceProxy(dsTarget);


    lobHandler.getClobAsString(rs, 1);
    lobHandlerControl.setReturnValue("content", 2);
    lobCreator.setClobAsString(ps, 1, "content");
    lobCreatorControl.setVoidCallable(1);

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    assertTrue("JTA synchronizations not active", !TransactionSynchronizationManager.isSynchronizationActive());
  }


  public void testTransactionCommitWithNonExistingDatabaseAndLazyConnection() throws Exception {
    DriverManagerDataSource dsTarget = new DriverManagerDataSource();
    final LazyConnectionDataSourceProxy ds = new LazyConnectionDataSourceProxy();
    ds.setTargetDataSource(dsTarget);
    ds.setDefaultAutoCommit(true);
    ds.setDefaultTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
    //ds.setDefaultTransactionIsolationName("TRANSACTION_READ_COMMITTED");


    LocalSessionFactoryBean lsfb = new LocalSessionFactoryBean();
    lsfb.setDataSource(ds);
    Properties props = new Properties();

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                }
            }
        });
        
        // Springframework provided proxies that make working with transactions much easier
        LazyConnectionDataSourceProxy lazyProxy = new LazyConnectionDataSourceProxy(dataSource);
        
        setInstance(dsName, lazyProxy);
    }

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  }


  @Test
  public void testTransactionCommitWithNonExistingDatabaseAndLazyConnection() throws Exception {
    DriverManagerDataSource dsTarget = new DriverManagerDataSource();
    final LazyConnectionDataSourceProxy ds = new LazyConnectionDataSourceProxy();
    ds.setTargetDataSource(dsTarget);
    ds.setDefaultAutoCommit(true);
    ds.setDefaultTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
    //ds.setDefaultTransactionIsolationName("TRANSACTION_READ_COMMITTED");


    LocalSessionFactoryBean lsfb = new LocalSessionFactoryBean();
    lsfb.setDataSource(ds);
    Properties props = new Properties();

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  }


  @Test
  public void testTransactionCommitWithNonExistingDatabaseAndLazyConnection() throws Exception {
    DriverManagerDataSource dsTarget = new DriverManagerDataSource();
    final LazyConnectionDataSourceProxy ds = new LazyConnectionDataSourceProxy();
    ds.setTargetDataSource(dsTarget);
    ds.setDefaultAutoCommit(true);
    ds.setDefaultTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
    //ds.setDefaultTransactionIsolationName("TRANSACTION_READ_COMMITTED");


    LocalSessionFactoryBean lsfb = new LocalSessionFactoryBean();
    lsfb.setDataSource(ds);
    Properties props = new Properties();

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    }
  }


  public DataSource getDataSource(String uri) {
    HiveBasicDataSource ds = new HiveBasicDataSource(uri);
    LazyConnectionDataSourceProxy dataSourceProxy = new LazyConnectionDataSourceProxy(ds);
    dataSourcesToClose.add(ds);
    return dataSourceProxy;
  }

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                        dataSourceToUse = pp.postProcess(dataSourceToUse);
                    }
                }
            }


            dataSources.put(descriptor.getIdentity(), new LazyConnectionDataSourceProxy(
                    dataSourceToUse));
        }
    }

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