Package org.apache.log4j.jdbc

Class JDBCAppender

  • All Implemented Interfaces:
    Appender, OptionHandler
    public class JDBCAppender
extends AppenderSkeleton
implements Appender
    The JDBCAppender provides for sending log events to a database. It does not log exceptions.

    JDBCAppender shipping in 1.2.18.2 produces PreparedStatement instances. Thanks to the remarkable work of Vladimir Sitnikov JDBCAppender now interprets the SQL expression on the fly and inserts new events using PreparedStartement instances. Note that the table column types are restricted to those types compatible with Java's String.

    Versions 1.2.18.0 and prior are vulnerable to SQL injection attacks..

    Each append call adds to an ArrayList buffer. When the buffer is filled each log event is placed in a sql statement (configurable) and executed.

    BufferSize, db URL, User, & Password are configurable options in the standard log4j fashion.

    The setSql(String sql) sets the SQL statement to be used for logging -- this statement is sent to a PatternLayout (either created automatically by the appender or added by the user). Therefore by default all the conversion patterns in PatternLayout can be used inside of the statement. (see the test cases for examples).

    As mentioned earlier, the produced SQL is translated in an additional phase to use PreparedStatement.

    For use as a base class:

    • Override getConnection() to pass any connection you want. Typically this is used to enable application wide connection pooling.
    • Override closeConnection(Connection con) -- if you override getConnection make sure to implement closeConnection to handle the connection you generated. Typically this would return the connection to the pool it came from.
    • As of 1.2.18.1 getLogStatement(org.apache.log4j.spi.LoggingEvent) is no longer in use.
    Author:
    Kevin Steppe (ksteppe@pacbell.net)

    • Field Detail

      • databaseURL

        protected java.lang.String databaseURL
        URL of the DB for default connection handling

      • databaseUser

        protected java.lang.String databaseUser
        User to connect as for default connection handling

      • databasePassword

        protected java.lang.String databasePassword
        User to use for default connection handling

      • connection

        protected java.sql.Connection connection
        Connection used by default. The connection is opened the first time it is needed and then held open until the appender is closed (usually at garbage collection). This behavior is best modified by creating a sub-class and overriding the getConnection and closeConnection methods.

      • sqlStatement

        protected java.lang.String sqlStatement
        Stores the string given to the pattern layout for conversion into a SQL statement, eg: insert into LogTable (Thread, Class, Message) values ("%t", "%c", "%m").

        Be careful of quotes in your messages!

        Also see PatternLayout.

      • bufferSize

        protected int bufferSize
        size of LoggingEvent buffer before writting to the database. Default is 1.

      • buffer

        protected java.util.ArrayList<LoggingEvent> buffer
        ArrayList holding the buffer of Logging Events.

    • Constructor Detail

      • JDBCAppender

        public JDBCAppender()

    • Method Detail

      • getLocationInfo

        public boolean getLocationInfo()
        Gets whether the location of the logging request call should be captured.
        Returns:
        the current value of the LocationInfo option.
        Since:
        1.2.16

      • setLocationInfo

        public void setLocationInfo​(boolean flag)
        The LocationInfo option takes a boolean value. By default, it is set to false which means there will be no effort to extract the location information related to the event. As a result, the event that will be ultimately logged will likely to contain the wrong location information (if present in the log format).

        Location information extraction is comparatively very slow and should be avoided unless performance is not a concern.

        Parameters:
        flag - true if location information should be extracted.
        Since:
        1.2.16

      • execute

        protected void execute​(java.lang.String sql)
                throws java.sql.SQLException
        Override this to provide an alertnate method of getting connections (such as caching). One method to fix this is to open connections at the start of flushBuffer() and close them at the end. I use a connection pool outside of JDBCAppender which is accessed in an override of this method.
        Throws:
        java.sql.SQLException

      • closeConnection

        protected void closeConnection​(java.sql.Connection con)
        Override this to return the connection to a pool, or to clean up the resource.

        The default behavior holds a single connection open until the appender is closed (typically when garbage collected).

      • getConnection

        protected java.sql.Connection getConnection()
                                     throws java.sql.SQLException
        Override this to link with your connection pooling system.

        By default this creates a single connection which is held open until the object is garbage collected.

        Throws:
        java.sql.SQLException

      • close

        public void close()
        Closes the appender, flushing the buffer first then closing the default connection if it is open.
        Specified by:
        close in interface Appender

      • flushBuffer

        public void flushBuffer()
        loops through the buffer of LoggingEvents, gets a sql string from getLogStatement() and sends it to execute(). Errors are sent to the errorHandler.

        If a statement fails the LoggingEvent stays in the buffer!

      • requiresLayout

        public boolean requiresLayout()
        JDBCAppender requires a layout.
        Specified by:
        requiresLayout in interface Appender

      • setSql

        public void setSql​(java.lang.String s)

      • getSql

        public java.lang.String getSql()
        Returns pre-formated statement eg: insert into LogTable (msg) values ("%m")

      • setUser

        public void setUser​(java.lang.String user)

      • setURL

        public void setURL​(java.lang.String url)

      • setPassword

        public void setPassword​(java.lang.String password)

      • setBufferSize

        public void setBufferSize​(int newBufferSize)

      • getUser

        public java.lang.String getUser()

      • getURL

        public java.lang.String getURL()

      • getPassword

        public java.lang.String getPassword()

      • getBufferSize

        public int getBufferSize()

      • setDriver

        public void setDriver​(java.lang.String driverClass)
        Ensures that the given driver class has been loaded for sql connection creation.