/*
* 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.*;
/**
This class encapsulate the logic which is necessary to log into a table.
Used by JDBCAppender
<p><b>Author : </b><A HREF="mailto:t.fenner@klopotek.de">Thomas Fenner</A></p>
@since 1.0
*/
public class JDBCLogger
{
//All columns of the log-table
private ArrayList logcols = null;
//Only columns which will be provided by logging
private String column_list = null;
//Number of all columns
private int num = 0;
//Status for successful execution of method configure()
private boolean isconfigured = false;
//Status for ready to do logging with method append()
private boolean ready = false;
//This message will be filled with a error-string when method ready() failes, and can be got by calling getMsg()
private String errormsg = "";
private Connection con = null;
private Statement stmt = null;
private ResultSet rs = null;
private String table = null;
//Variables for static SQL-statement logging
private String sql = null;
private String new_sql = null;
private String new_sql_part1 = null;
private String new_sql_part2 = null;
private static final String msg_wildcard = "@MSG@";
private int msg_wildcard_pos = 0;
/**
Writes a message into the database table.
Throws an exception, if an database-error occurs !
*/
public void append(String _msg) throws Exception
{
if(!ready) if(!ready()) throw new Exception("JDBCLogger::append(), Not ready to append !");
if(sql != null)
{
appendSQL(_msg);
return;
}
LogColumn logcol;
rs.moveToInsertRow();
for(int i=0; i<num; i++)
{
logcol = (LogColumn)logcols.get(i);
if(logcol.logtype == LogType.MSG)
{
rs.updateObject(logcol.name, _msg);
}
else if(logcol.logtype == LogType.ID)
{
rs.updateObject(logcol.name, logcol.idhandler.getID());
}
else if(logcol.logtype == LogType.STATIC)
{
rs.updateObject(logcol.name, logcol.value);
}
else if(logcol.logtype == LogType.TIMESTAMP)
{
rs.updateObject(logcol.name, new Timestamp((new java.util.Date()).getTime()));
}
}
rs.insertRow();
}
/**
Writes a message into the database using a given sql-statement.
Throws an exception, if an database-error occurs !
*/
public void appendSQL(String _msg) throws Exception
{
if(!ready) if(!ready()) throw new Exception("JDBCLogger::appendSQL(), Not ready to append !");
if(sql == null) throw new Exception("JDBCLogger::appendSQL(), No SQL-Statement configured !");
if(msg_wildcard_pos > 0)
{
new_sql = new_sql_part1 + _msg + new_sql_part2;
}
else new_sql = sql;
try
{
stmt.executeUpdate(new_sql);
}
catch(Exception e)
{
errormsg = new_sql;
throw e;
}
}
/**
Configures this class, by reading in the structure of the log-table
Throws an exception, if an database-error occurs !
*/
public void configureTable(String _table) throws Exception
{
if(isconfigured) return;
//Fill logcols with META-informations of the table-columns
stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE);
rs = stmt.executeQuery("SELECT * FROM " + _table + " WHERE 1 = 2");
LogColumn logcol;
ResultSetMetaData rsmd = rs.getMetaData();
num = rsmd.getColumnCount();
logcols = new ArrayList(num);
for(int i=1; i<=num; i++)
{
logcol = new LogColumn();
logcol.name = rsmd.getColumnName(i).toUpperCase();
logcol.type = rsmd.getColumnTypeName(i);
logcol.nullable = (rsmd.isNullable(i) == rsmd.columnNullable);
logcol.isWritable = rsmd.isWritable(i);
if(!logcol.isWritable) logcol.ignore = true;
logcols.add(logcol);
}
table = _table;
isconfigured = true;
}
/**
Configures this class, by storing and parsing the given sql-statement.
Throws an exception, if somethings wrong !
*/
public void configureSQL(String _sql) throws Exception
{
if(isconfigured) return;
if(!isConnected()) throw new Exception("JDBCLogger::configureSQL(), Not connected to database !");
if(_sql == null || _sql.trim().equals("")) throw new Exception("JDBCLogger::configureSQL(), Invalid SQL-Statement !");
sql = _sql.trim();
stmt = con.createStatement();
msg_wildcard_pos = sql.indexOf(msg_wildcard);
if(msg_wildcard_pos > 0)
{
new_sql_part1 = sql.substring(0, msg_wildcard_pos-1) + "'";
//between the message...
new_sql_part2 = "'" + sql.substring(msg_wildcard_pos+msg_wildcard.length());
}
isconfigured = true;
}
/**
Sets a connection. Throws an exception, if the connection is not open !
*/
public void setConnection(Connection _con) throws Exception
{
con = _con;
if(!isConnected()) throw new Exception("JDBCLogger::setConnection(), Given connection isnt connected to database !");
}
/**
Sets a columns logtype (LogTypes) and value, which depends on that logtype.
Throws an exception, if the given arguments arent correct !
*/
public void setLogType(String _name, int _logtype, Object _value) throws Exception
{
if(!isconfigured) throw new Exception("JDBCLogger::setLogType(), Not configured !");
//setLogType() makes only sense for further configuration of configureTable()
if(sql != null) return;
_name = _name.toUpperCase();
if(_name == null || !(_name.trim().length() > 0)) throw new Exception("JDBCLogger::setLogType(), Missing argument name !");
if(!LogType.isLogType(_logtype)) throw new Exception("JDBCLogger::setLogType(), Invalid logtype '" + _logtype + "' !");
if((_logtype != LogType.MSG && _logtype != LogType.EMPTY) && _value == null) throw new Exception("JDBCLogger::setLogType(), Missing argument value !");
LogColumn logcol;
for(int i=0; i<num; i++)
{
logcol = (LogColumn)logcols.get(i);
if(logcol.name.equals(_name))
{
if(!logcol.isWritable) throw new Exception("JDBCLogger::setLogType(), Column " + _name + " is not writeable !");
//Column gets the message
if(_logtype == LogType.MSG)
{
logcol.logtype = _logtype;
return;
}
//Column will be provided by JDBCIDHandler::getID()
else if(_logtype == LogType.ID)
{
logcol.logtype = _logtype;
try
{
//Try to cast directly Object to JDBCIDHandler
logcol.idhandler = (JDBCIDHandler)_value;
}
catch(Exception e)
{
try
{
//Assuming _value is of class string which contains the classname of a JDBCIDHandler
logcol.idhandler = (JDBCIDHandler)(Class.forName((String)_value).newInstance());
}
catch(Exception e2)
{
throw new Exception("JDBCLogger::setLogType(), Cannot cast value of class " + _value.getClass() + " to class JDBCIDHandler !");
}
}
return;
}
//Column will be statically defined with Object _value
else if(_logtype == LogType.STATIC)
{
logcol.logtype = _logtype;
logcol.value = _value;
return;
}
//Column will be provided with a actually timestamp
else if(_logtype == LogType.TIMESTAMP)
{
logcol.logtype = _logtype;
return;
}
//Column will be fully ignored during process.
//If this column is not nullable, the column has to be filled by a database trigger,
//else a database error occurs !
//Columns which are not nullable, but should be not filled, must be explicit assigned with LogType.EMPTY,
//else a value is required !
else if(_logtype == LogType.EMPTY)
{
logcol.logtype = _logtype;
logcol.ignore = true;
return;
}
}
}
}
/**
Return true, if this class is ready to append(), else false.
When not ready, a reason-String is stored in the instance-variable msg.
*/
public boolean ready()
{
if(ready) return true;
if(!isconfigured){ errormsg = "Not ready to append ! Call configure() first !"; return false;}
//No need to doing the whole rest...
if(sql != null)
{
ready = true;
return true;
}
boolean msgcol_defined = false;
LogColumn logcol;
for(int i=0; i<num; i++)
{
logcol = (LogColumn)logcols.get(i);
if(logcol.ignore || !logcol.isWritable) continue;
if(!logcol.nullable && logcol.logtype == LogType.EMPTY)
{
errormsg = "Not ready to append ! Column " + logcol.name + " is not nullable, and must be specified by setLogType() !";
return false;
}
if(logcol.logtype == LogType.ID && logcol.idhandler == null)
{
errormsg = "Not ready to append ! Column " + logcol.name + " is specified as an ID-column, and a JDBCIDHandler has to be set !";
return false;
}
else if(logcol.logtype == LogType.STATIC && logcol.value == null)
{
errormsg = "Not ready to append ! Column " + logcol.name + " is specified as a static field, and a value has to be set !";
return false;
}
else if(logcol.logtype == LogType.MSG) msgcol_defined = true;
}
if(!msgcol_defined) return false;
//create the column_list
for(int i=0; i<num; i++)
{
logcol = (LogColumn)logcols.get(i);
if(logcol.ignore || !logcol.isWritable) continue;
if(logcol.logtype != LogType.EMPTY)
{
if(column_list == null)
{
column_list = logcol.name;
}
else column_list += ", " + logcol.name;
}
}
try
{
rs = stmt.executeQuery("SELECT " + column_list + " FROM " + table + " WHERE 1 = 2");
}
catch(Exception e)
{
errormsg = "Not ready to append ! Cannot select columns '" + column_list + "' of table " + table + " !";
return false;
}
ready = true;
return true;
}
/**
Return true, if this class is configured, else false.
*/
public boolean isConfigured(){ return isconfigured;}
/**
Return true, if this connection is open, else false.
*/
public boolean isConnected()
{
try
{
return (con != null && !con.isClosed());
}
catch(Exception e){return false;}
}
/**
Return the internal error message stored in instance variable msg.
*/
public String getErrorMsg(){String r = new String(errormsg); errormsg = null; return r;}
}
/**
This class encapsulate all by class JDBCLogger needed data around a column
*/
class LogColumn
{
//column name
String name = null;
//column type
String type = null;
//not nullability means that this column is mandatory
boolean nullable = false;
//isWritable means that the column can be updated, else column is only readable
boolean isWritable = false;
//if ignore is true, this column will be ignored by building sql-statements.
boolean ignore = false;
//Must be filled for not nullable columns ! In other case it is optional.
int logtype = LogType.EMPTY;
Object value = null; //Generic storage for typewrapper-classes Long, String, etc...
JDBCIDHandler idhandler = null;
}
/**
This class contains all constants which are necessary to define a columns log-type.
*/
class LogType
{
//A column of this type will receive the message.
public static final int MSG = 1;
//A column of this type will be a unique identifier of the logged row.
public static final int ID = 2;
//A column of this type will contain a static, one-time-defined value.
public static final int STATIC = 3;
//A column of this type will be filled with an actual timestamp depending by the time the logging will be done.
public static final int TIMESTAMP = 4;
//A column of this type will contain no value and will not be included in logging insert-statement.
//This could be a column which will be filled not by creation but otherwhere...
public static final int EMPTY = 5;
public static boolean isLogType(int _lt)
{
if(_lt == MSG || _lt == STATIC || _lt == ID || _lt == TIMESTAMP || _lt == EMPTY) return true;
return false;
}
public static int parseLogType(String _lt)
{
if(_lt.equals("MSG")) return MSG;
if(_lt.equals("ID")) return ID;
if(_lt.equals("STATIC")) return STATIC;
if(_lt.equals("TIMESTAMP")) return TIMESTAMP;
if(_lt.equals("EMPTY")) return EMPTY;
return -1;
}
}
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