JDBCAppender (Apache Log4j 1.2.17 API)
Date: 2012-05-06

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## org.apache.log4j.jdbc
Class JDBCAppender

    java.lang.Object
      org.apache.log4j.AppenderSkeleton
          org.apache.log4j.jdbc.JDBCAppender

All Implemented Interfaces:
  Appender, OptionHandler

    public class JDBCAppender

extends AppenderSkeleton
implements Appender

The JDBCAppender provides for sending log events to a database.

WARNING: This version of JDBCAppender is very likely to be completely replaced in the future. Moreoever, it does not log exceptions.

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 ways.

The `setSql(String sql)` sets the SQL statement to be used for logging -- this statement is sent to a `PatternLayout` (either created automaticly 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)

Overriding the `getLogStatement(org.apache.log4j.spi.LoggingEvent)` method allows more explicit control of the statement used for logging.

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.
- Override `getLogStatement(LoggingEvent event)` to produce specialized or dynamic statements. The default uses the sql option value.

Author:
  Kevin Steppe (ksteppe@pacbell.net)

Field Summary
`protected ArrayList` | `buffer` ArrayList holding the buffer of Logging Events.
`protected int` | `bufferSize` size of LoggingEvent buffer before writting to the database.
`protected Connection` | `connection` Connection used by default.
`protected String` | `databasePassword` User to use for default connection handling
`protected String` | `databaseURL` URL of the DB for default connection handling
`protected String` | `databaseUser` User to connect as for default connection handling
`protected ArrayList` | `removes` Helper object for clearing out the buffer
`protected 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").

Fields inherited from class org.apache.log4j.AppenderSkeleton
`closed, errorHandler, headFilter, layout, name, tailFilter, threshold`

Constructor Summary
`JDBCAppender()`

Method Summary
`void` | `append(LoggingEvent event)` Adds the event to the buffer.
`void` | `close()` Closes the appender, flushing the buffer first then closing the default connection if it is open.
`protected void` | `closeConnection(Connection con)` Override this to return the connection to a pool, or to clean up the resource.
`protected void` | `execute(String sql)` Override this to provide an alertnate method of getting connections (such as caching).
`void` | `finalize()` closes the appender before disposal
`void` | `flushBuffer()` loops through the buffer of LoggingEvents, gets a sql string from getLogStatement() and sends it to execute().
`int` | `getBufferSize()`
`protected Connection` | `getConnection()` Override this to link with your connection pooling system.
`boolean` | `getLocationInfo()` Gets whether the location of the logging request call should be captured.
`protected String` | `getLogStatement(LoggingEvent event)` By default getLogStatement sends the event to the required Layout object.
`String` | `getPassword()`
`String` | `getSql()` Returns pre-formated statement eg: insert into LogTable (msg) values ("%m")
`String` | `getURL()`
`String` | `getUser()`
`boolean` | `requiresLayout()` JDBCAppender requires a layout.
`void` | `setBufferSize(int newBufferSize)`
`void` | `setDriver(String driverClass)` Ensures that the given driver class has been loaded for sql connection creation.
`void` | `setLocationInfo(boolean flag)` The LocationInfo option takes a boolean value.
`void` | `setPassword(String password)`
`void` | `setSql(String s)`
`void` | `setURL(String url)`
`void` | `setUser(String user)`

Methods inherited from class org.apache.log4j.AppenderSkeleton
`activateOptions, addFilter, clearFilters, doAppend, getErrorHandler, getFilter, getFirstFilter, getLayout, getName, getThreshold, isAsSevereAsThreshold, setErrorHandler, setLayout, setName, setThreshold`

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

Methods inherited from interface org.apache.log4j.Appender
`addFilter, clearFilters, doAppend, getErrorHandler, getFilter, getLayout, getName, setErrorHandler, setLayout, setName`

Field Detail

### databaseURL

    protected String databaseURL

  URL of the DB for default connection handling

### databaseUser

    protected String databaseUser

  User to connect as for default connection handling

### databasePassword

    protected String databasePassword

  User to use for default connection handling

### connection

    protected 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 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 ArrayList buffer

  ArrayList holding the buffer of Logging Events.

### removes

    protected ArrayList removes

  Helper object for clearing out the buffer

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

### append

    public void append(LoggingEvent event)

  Adds the event to the buffer. When full the buffer is flushed.

  Specified by:
    `append` in class `AppenderSkeleton`

### getLogStatement

    protected String getLogStatement(LoggingEvent event)

  By default getLogStatement sends the event to the required Layout object. The layout will format the given pattern into a workable SQL string. Overriding this provides direct access to the LoggingEvent when constructing the logging statement.

### execute

    protected void execute(String sql)
                    throws 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:
    `SQLException`

### closeConnection

    protected void closeConnection(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 Connection getConnection()
                                throws 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:
    `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!

### finalize

    public void finalize()

  closes the appender before disposal

  Overrides:
    `finalize` in class `AppenderSkeleton`

### requiresLayout

    public boolean requiresLayout()

  JDBCAppender requires a layout.

  Specified by:
    `requiresLayout` in interface `Appender`

### setSql

    public void setSql(String s)

### getSql

    public String getSql()

  Returns pre-formated statement eg: insert into LogTable (msg) values ("%m")

### setUser

    public void setUser(String user)

### setURL

    public void setURL(String url)

### setPassword

    public void setPassword(String password)

### setBufferSize

    public void setBufferSize(int newBufferSize)

### getUser

    public String getUser()

### getURL

    public String getURL()

### getPassword

    public String getPassword()

### getBufferSize

    public int getBufferSize()

### setDriver

    public void setDriver(String driverClass)

  Ensures that the given driver class has been loaded for sql connection creation.

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