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## org.springframework.jdbc.datasource
Class IsolationLevelDataSourceAdapter

    java.lang.Object
      org.springframework.jdbc.datasource.DelegatingDataSource
          org.springframework.jdbc.datasource.UserCredentialsDataSourceAdapter
              org.springframework.jdbc.datasource.IsolationLevelDataSourceAdapter

All Implemented Interfaces:
  Wrapper, CommonDataSource, DataSource, InitializingBean

Direct Known Subclasses:
  WebSphereDataSourceAdapter

    public class IsolationLevelDataSourceAdapter

extends UserCredentialsDataSourceAdapter

An adapter for a target `DataSource`, applying the current Spring transaction's isolation level (and potentially specified user credentials) to every `getConnection` call. Also applies the read-only flag, if specified.

Can be used to proxy a target JNDI DataSource that does not have the desired isolation level (and user credentials) configured. Client code can work with this DataSource as usual, not worrying about such settings.

Inherits the capability to apply specific user credentials from its superclass `UserCredentialsDataSourceAdapter`; see the latter's javadoc for details on that functionality (e.g. `UserCredentialsDataSourceAdapter.setCredentialsForCurrentThread(java.lang.String, java.lang.String)`).

WARNING: This adapter simply calls `Connection.setTransactionIsolation(int)` and/or `Connection.setReadOnly(boolean)` for every Connection obtained from it. It does, however, not reset those settings; it rather expects the target DataSource to perform such resetting as part of its connection pool handling. Make sure that the target DataSource properly cleans up such transaction state.

Since:
  2.0.3
Author:
  Juergen Hoeller
See Also:
  `setIsolationLevel(int)`, `setIsolationLevelName(java.lang.String)`, `UserCredentialsDataSourceAdapter.setUsername(java.lang.String)`, `UserCredentialsDataSourceAdapter.setPassword(java.lang.String)`

Constructor Summary
`IsolationLevelDataSourceAdapter()`

Method Summary
`protected Connection` | `doGetConnection(String username, String password)` Applies the current isolation level value and read-only flag to the returned Connection.
`protected Integer` | `getCurrentIsolationLevel()` Determine the current isolation level: either the transaction's isolation level or a statically defined isolation level.
`protected Boolean` | `getCurrentReadOnlyFlag()` Determine the current read-only flag: by default, the transaction's read-only hint.
`protected Integer` | `getIsolationLevel()` Return the statically specified isolation level, or `null` if none.
`void` | `setIsolationLevel(int isolationLevel)` Specify the default isolation level to use for Connection retrieval, according to the JDBC `Connection` constants (equivalent to the corresponding Spring `TransactionDefinition` constants).
`void` | `setIsolationLevelName(String constantName)` Set the default isolation level by the name of the corresponding constant in `TransactionDefinition`, e.g.

Methods inherited from class org.springframework.jdbc.datasource.UserCredentialsDataSourceAdapter
`getConnection, getConnection, removeCredentialsFromCurrentThread, setCredentialsForCurrentThread, setPassword, setUsername`

Methods inherited from class org.springframework.jdbc.datasource.DelegatingDataSource
`afterPropertiesSet, getLoginTimeout, getLogWriter, getTargetDataSource, isWrapperFor, setLoginTimeout, setLogWriter, setTargetDataSource, unwrap`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### IsolationLevelDataSourceAdapter

    public IsolationLevelDataSourceAdapter()

Method Detail

### setIsolationLevelName

    public final void setIsolationLevelName(String constantName)
                                     throws IllegalArgumentException

  Set the default isolation level by the name of the corresponding constant in `TransactionDefinition`, e.g. "ISOLATION_SERIALIZABLE".

  If not specified, the target DataSource's default will be used. Note that a transaction-specific isolation value will always override any isolation setting specified at the DataSource level.

  Parameters:
    `constantName` - name of the constant
  Throws:
    `IllegalArgumentException`
  See Also:
    `TransactionDefinition.ISOLATION_READ_UNCOMMITTED`, `TransactionDefinition.ISOLATION_READ_COMMITTED`, `TransactionDefinition.ISOLATION_REPEATABLE_READ`, `TransactionDefinition.ISOLATION_SERIALIZABLE`, `setIsolationLevel(int)`

### setIsolationLevel

    public void setIsolationLevel(int isolationLevel)

  Specify the default isolation level to use for Connection retrieval, according to the JDBC `Connection` constants (equivalent to the corresponding Spring `TransactionDefinition` constants).

  If not specified, the target DataSource's default will be used. Note that a transaction-specific isolation value will always override any isolation setting specified at the DataSource level.

  See Also:
    `Connection.TRANSACTION_READ_UNCOMMITTED`, `Connection.TRANSACTION_READ_COMMITTED`, `Connection.TRANSACTION_REPEATABLE_READ`, `Connection.TRANSACTION_SERIALIZABLE`, `TransactionDefinition.ISOLATION_READ_UNCOMMITTED`, `TransactionDefinition.ISOLATION_READ_COMMITTED`, `TransactionDefinition.ISOLATION_REPEATABLE_READ`, `TransactionDefinition.ISOLATION_SERIALIZABLE`, `TransactionDefinition.getIsolationLevel()`, `TransactionSynchronizationManager.getCurrentTransactionIsolationLevel()`

### getIsolationLevel

    protected Integer getIsolationLevel()

  Return the statically specified isolation level, or `null` if none.

### doGetConnection

    protected Connection doGetConnection(String username,
                                         String password)
                                  throws SQLException

  Applies the current isolation level value and read-only flag to the returned Connection.

  Overrides:
    `doGetConnection` in class `UserCredentialsDataSourceAdapter`
  Parameters:
    `username` - the username to use
    `password` - the password to use
  Returns:
    the Connection
  Throws:
    `SQLException`
  See Also:
    `getCurrentIsolationLevel()`, `getCurrentReadOnlyFlag()`

### getCurrentIsolationLevel

    protected Integer getCurrentIsolationLevel()

  Determine the current isolation level: either the transaction's isolation level or a statically defined isolation level.

  Returns:
    the current isolation level, or `null` if none
  See Also:
    `TransactionSynchronizationManager.getCurrentTransactionIsolationLevel()`, `setIsolationLevel(int)`

### getCurrentReadOnlyFlag

    protected Boolean getCurrentReadOnlyFlag()

  Determine the current read-only flag: by default, the transaction's read-only hint.

  Returns:
    whether there is a read-only hint for the current scope
  See Also:
    `TransactionSynchronizationManager.isCurrentTransactionReadOnly()`

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