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What this is

This file is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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The source code

 * Copyright (C) The Apache Software Foundation. All rights reserved.

package com.klopotek.utils.log;

import java.sql.*;
import java.util.*;
import org.apache.log4j.*;
import org.apache.log4j.helpers.*;
import org.apache.log4j.spi.*;

The JDBCAppender, writes messages into a database

The JDBCAppender is configurable at runtime by setting options in two alternatives :

1. Use a configuration-file

Define the options in a file (example) and call a PropertyConfigurator.configure(filename) in your code.

2. Use the methods of JDBCAppender to do it

Call JDBCAppender::setOption(JDBCAppender.xxx_OPTION, String value) to do it analogically without a configuration-file (example)

All available options are defined as static String-constants in JDBCAppender named xxx_OPTION.

Here is a description of all available options :

1. Database-options to connect to the database

- URL_OPTION : a database url of the form jdbc:subprotocol:subname

- USERNAME_OPTION : the database user on whose behalf the connection is being made

- PASSWORD_OPTION : the user's password

2. Connector-option to specify your own JDBCConnectionHandler

- CONNECTOR_OPTION : a classname which is implementing the JDBCConnectionHandler-interface

This interface is used to get a customized connection.

If in addition the database-options are given, these options will be used as arguments for the JDBCConnectionHandler-interface to get a connection.

Else if no database-options are given, the JDBCConnectionHandler-interface is called without them.

Else if this option is not defined, the database-options are required to open a connection by the JDBCAppender.

3. SQL-option to specify a static sql-statement which will be performed with every occuring message-event

- SQL_OPTION : a sql-statement which will be used to write to the database

Use the variable @MSG@ on a location in the statement, which has to be dynamically replaced by the message-text.

If you give this option, the table-option and columns-option will be ignored !

4. Table-option to specify a table contained by the database

- TABLE_OPTION : the table in which the logging will be done

5. Columns-option to describe the important columns of the table (Not nullable columns are mandatory to describe!)

- COLUMNS_OPTION : a formatted list of column-descriptions

Each column description consists of

- the name of the column (required)

- a logtype which is a static constant of class LogType (required)

- and a value which depends by the LogType (optional/required, depending by logtype)

Here is a description of the available logtypes of class {@link LogType} and how to handle the value:

o MSG = a value will be ignored, the column will get the message. (One columns need to be of this type!)

o STATIC = the value will be filled into the column with every logged message. (Ensure that the type of value can be casted into the sql-type of the column!)

o ID = value must be a classname, which implements the JDBCIDHandler-interface.

o TIMESTAMP = a value will be ignored, the column will be filled with a actually timestamp with every logged message.

o EMPTY = a value will be ignored, the column will be ignored when writing to the database (Ensure to fill not nullable columns by a database trigger!)

If there are more than one column to describe, the columns must be separated by a Tabulator-delimiter (unicode0008) !

The arguments of a column-description must be separated by the delimiter '~' !

(Example : name1~logtype1~value1 name2~logtype2~value2...)

6. Layout-options to define the layout of the messages (optional)

- _ : the layout wont be set by a xxx_OPTION

See the configuration-file and code examples below...

The default is a layout of the class {@link org.apache.log4j.PatternLayout} with the pattern=%m which representate only the message.

7. Buffer-option to define the size of the message-event-buffer (optional)

- BUFFER_OPTION : define how many messages will be buffered until they will be updated to the database.

The default is buffer=1, which will do a update with every happened message-event.

8. Commit-option to define a auto-commitment

- COMMIT_OPTION : define whether updated messages should be committed to the database (Y) or not (N).

The default is commit=Y.

The sequence of some options is important :

1. Connector-option OR/AND Database-options

Any database connection is required !

2. (Table-option AND Columns-option) OR SQL-option

Anything of that is required ! Whether where to write something OR what to write somewhere...;-)

3. All other options can be set at any time...

The other options are optional and have a default initialization, which can be customized.

Here is a configuration-file example, which can be used as argument for the PropertyConfigurator : configfile_example.txt

Here is a code-example to configure the JDBCAppender with a configuration-file :

Here is a another code-example to configure the JDBCAppender without a configuration-file :

Author : Thomas Fenner

@since 1.0 */ public class JDBCAppender extends AppenderSkeleton { /** A database-option to to set a database url of the form jdbc:subprotocol:subname. */ public static final String URL_OPTION = "url"; /** A database-option to set the database user on whose behalf the connection is being made. */ public static final String USERNAME_OPTION = "username"; /** A database-option to set the user's password. */ public static final String PASSWORD_OPTION = "password"; /** A table-option to specify a table contained by the database */ public static final String TABLE_OPTION = "table"; /** A connector-option to specify your own JDBCConnectionHandler */ public static final String CONNECTOR_OPTION = "connector"; /** A columns-option to describe the important columns of the table */ public static final String COLUMNS_OPTION = "columns"; /** A sql-option to specify a static sql-statement which will be performed with every occuring message-event */ public static final String SQL_OPTION = "sql"; /** A buffer-option to define the size of the message-event-buffer */ public static final String BUFFER_OPTION = "buffer"; /** A commit-option to define a auto-commitment */ public static final String COMMIT_OPTION = "commit"; //Variables to store the options values setted by setOption() : private String url = null; private String username = null; private String password = null; private String table = null; private String connection_class = null; private String sql = null; private boolean docommit = true; private int buffer_size = 1; private JDBCConnectionHandler connectionHandler = null; //This buffer stores message-events. //When the buffer_size is reached, the buffer will be flushed and the messages will updated to the database. private ArrayList buffer = new ArrayList(); //Database-connection private Connection con = null; //This class encapsulate the logic which is necessary to log into a table private JDBCLogger jlogger = new JDBCLogger(); //Flags : //A flag to indicate a established database connection private boolean connected = false; //A flag to indicate configuration status private boolean configured = false; //A flag to indicate that everything is ready to get append()-commands. private boolean ready = false; /** If program terminates close the database-connection and flush the buffer */ public void finalize() { close(); super.finalize(); } /** Internal method. Returns a array of strings containing the available options which can be set with method setOption() */ public String[] getOptionStrings() { // The sequence of options in this string is important, because setOption() is called this way ... return new String[]{CONNECTOR_OPTION, URL_OPTION, USERNAME_OPTION, PASSWORD_OPTION, SQL_OPTION, TABLE_OPTION, COLUMNS_OPTION, BUFFER_OPTION, COMMIT_OPTION}; } /** Sets all necessary options */ public void setOption(String _option, String _value) { _option = _option.trim(); _value = _value.trim(); if(_option == null || _value == null) return; if(_option.length() == 0 || _value.length() == 0) return; _value = _value.trim(); if(_option.equals(CONNECTOR_OPTION)) { if(!connected) connection_class = _value; } else if(_option.equals(URL_OPTION)) { if(!connected) url = _value; } else if(_option.equals(USERNAME_OPTION)) { if(!connected) username = _value; } else if(_option.equals(PASSWORD_OPTION)) { if(!connected) password = _value; } else if(_option.equals(SQL_OPTION)) { sql = _value; } else if(_option.equals(TABLE_OPTION)) { if(sql != null) return; table = _value; } else if(_option.equals(COLUMNS_OPTION)) { if(sql != null) return; String name = null; int logtype = -1; String value = null; String column = null; String arg = null; int num_args = 0; int num_columns = 0; StringTokenizer st_col; StringTokenizer st_arg; //Columns are TAB-separated st_col = new StringTokenizer(_value, " "); num_columns = st_col.countTokens(); if(num_columns < 1) { errorHandler.error("JDBCAppender::setOption(), Invalid COLUMN_OPTION value : " + _value + " !"); return; } for(int i=1; i<=num_columns; i++) { column = st_col.nextToken(); //Arguments are ~-separated st_arg = new StringTokenizer(column, "~"); num_args = st_arg.countTokens(); if(num_args < 2) { errorHandler.error("JDBCAppender::setOption(), Invalid COLUMN_OPTION value : " + _value + " !"); return; } for(int j=1; j<=num_args; j++) { arg = st_arg.nextToken(); if(j == 1) name = arg; else if(j == 2) { try { logtype = Integer.parseInt(arg); } catch(Exception e) { logtype = LogType.parseLogType(arg); } if(!LogType.isLogType(logtype)) { errorHandler.error("JDBCAppender::setOption(), Invalid COLUMN_OPTION LogType : " + arg + " !"); return; } } else if(j == 3) value = arg; } if(!setLogType(name, logtype, value)) return; } } else if(_option.equals(BUFFER_OPTION)) { try { buffer_size = Integer.parseInt(_value); } catch(Exception e) { errorHandler.error("JDBCAppender::setOption(), Invalid BUFFER_OPTION value : " + _value + " !"); return; } } else if(_option.equals(COMMIT_OPTION)) { docommit = _value.equals("Y"); } if(_option.equals(SQL_OPTION) || _option.equals(TABLE_OPTION)) { if(!configured) configure(); } } /** Internal method. Returns true, you may define your own layout... */ public boolean requiresLayout() { return true; } /** Internal method. Close the database connection & flush the buffer. */ public void close() { flush_buffer(); if(connection_class == null) { try{con.close();}catch(Exception e){errorHandler.error("JDBCAppender::close(), " + e);} } this.closed = true; } /** You have to call this function for all provided columns of your log-table ! */ public boolean setLogType(String _name, int _logtype, Object _value) { if(sql != null) return true; if(!configured) { if(!configure()) return false; } try { jlogger.setLogType(_name, _logtype, _value); } catch(Exception e) { errorHandler.error("JDBCAppender::setLogType(), " + e); return false; } return true; } /** Internal method. Appends the message to the database table. */ public void append(LoggingEvent event) { if(!ready) { if(!ready()) { errorHandler.error("JDBCAppender::append(), Not ready to append !"); return; } } buffer.add(event); if(buffer.size() >= buffer_size) flush_buffer(); } /** Internal method. Flushes the buffer. */ public void flush_buffer() { try { int size = buffer.size(); if(size < 1) return; for(int i=0; i
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