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DataSource (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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javax.sql
Interface DataSource

public interface DataSource

A factory for connections to the physical data source that this DataSource object represents. An alternative to the DriverManager facility, a DataSource object is the preferred means of getting a connection. An object that implements the DataSource interface will typically be registered with a naming service based on the JavaTM Naming and Directory (JNDI) API.

The DataSource interface is implemented by a driver vendor. There are three types of implementations:

  1. Basic implementation -- produces a standard Connection object
  2. Connection pooling implementation -- produces a Connection object that will automatically participate in connection pooling. This implementation works with a middle-tier connection pooling manager.
  3. Distributed transaction implementation -- produces a Connection object that may be used for distributed transactions and almost always participates in connection pooling. This implementation works with a middle-tier transaction manager and almost always with a connection pooling manager.

A DataSource object has properties that can be modified when necessary. For example, if the data source is moved to a different server, the property for the server can be changed. The benefit is that because the data source's properties can be changed, any code accessing that data source does not need to be changed.

A driver that is accessed via a DataSource object does not register itself with the DriverManager. Rather, a DataSource object is retrieved though a lookup operation and then used to create a Connection object. With a basic implementation, the connection obtained through a DataSource object is identical to a connection obtained through the DriverManager facility.

Since:
1.4

Method Summary
 Connection getConnection()
          Attempts to establish a connection with the data source that this DataSource object represents.
 Connection getConnection(String username, String password)
          Attempts to establish a connection with the data source that this DataSource object represents.
 int getLoginTimeout()
          Gets the maximum time in seconds that this data source can wait while attempting to connect to a database.
 PrintWriter getLogWriter()
          Retrieves the log writer for this DataSource object.
 void setLoginTimeout(int seconds)
          Sets the maximum time in seconds that this data source will wait while attempting to connect to a database.
 void setLogWriter(PrintWriter out)
          Sets the log writer for this DataSource object to the given java.io.PrintWriter object.
 

Method Detail

getConnection

public Connection getConnection()
                         throws SQLException

Attempts to establish a connection with the data source that this DataSource object represents.

Returns:
a connection to the data source
Throws:
SQLException - if a database access error occurs

getConnection

public Connection getConnection(String username,
                                String password)
                         throws SQLException

Attempts to establish a connection with the data source that this DataSource object represents.

Parameters:
username - the database user on whose behalf the connection is being made
password - the user's password
Returns:
a connection to the data source
Throws:
SQLException - if a database access error occurs

getLogWriter

public PrintWriter getLogWriter()
                         throws SQLException

Retrieves the log writer for this DataSource object.

The log writer is a character output stream to which all logging and tracing messages for this data source will be printed. This includes messages printed by the methods of this object, messages printed by methods of other objects manufactured by this object, and so on. Messages printed to a data source specific log writer are not printed to the log writer associated with the java.sql.Drivermanager class. When a DataSource object is created, the log writer is initially null; in other words, the default is for logging to be disabled.

Returns:
the log writer for this data source or null if logging is disabled
Throws:
SQLException - if a database access error occurs
See Also:
setLogWriter(java.io.PrintWriter)

setLogWriter

public void setLogWriter(PrintWriter out)
                  throws SQLException

Sets the log writer for this DataSource object to the given java.io.PrintWriter object.

The log writer is a character output stream to which all logging and tracing messages for this data source will be printed. This includes messages printed by the methods of this object, messages printed by methods of other objects manufactured by this object, and so on. Messages printed to a data source- specific log writer are not printed to the log writer associated with the java.sql.Drivermanager class. When a DataSource object is created the log writer is initially null; in other words, the default is for logging to be disabled.

Parameters:
out - the new log writer; to disable logging, set to null
Throws:
SQLException - if a database access error occurs
See Also:
getLogWriter()

setLoginTimeout

public void setLoginTimeout(int seconds)
                     throws SQLException

Sets the maximum time in seconds that this data source will wait while attempting to connect to a database. A value of zero specifies that the timeout is the default system timeout if there is one; otherwise, it specifies that there is no timeout. When a DataSource object is created, the login timeout is initially zero.

Parameters:
seconds - the data source login time limit
Throws:
SQLException - if a database access error occurs.
See Also:
getLoginTimeout()

getLoginTimeout

public int getLoginTimeout()
                    throws SQLException
Gets the maximum time in seconds that this data source can wait while attempting to connect to a database. A value of zero means that the timeout is the default system timeout if there is one; otherwise, it means that there is no timeout. When a DataSource object is created, the login timeout is initially zero.

Returns:
the data source login time limit
Throws:
SQLException - if a database access error occurs.
See Also:
setLoginTimeout(int)
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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.