log4j 数据库断连接解决办法

1、用自定义的JDBCAppender，获取连接后校验下合法性，非法的话重新取得连接。

package org.pentaho.di.dxt.common.Util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

import org.apache.log4j.jdbc.JDBCAppender;

public class DxtJdbcAppender extends JDBCAppender {
    @Override
    protected Connection getConnection() throws SQLException {
        if (!DriverManager.getDrivers().hasMoreElements())
            setDriver("sun.jdbc.odbc.JdbcOdbcDriver");

        if ((null != connection) && !connection.isValid(2)) {
            connection = null;
        }

        if (connection == null) {
            connection = DriverManager.getConnection(databaseURL, databaseUser, databasePassword);
        }

        return connection;
    }
}

2、log4j.properties中指定database为自定义的这个appender

########################
# JDBC Appender
#######################
log4j.appender.DATABASE = org.pentaho.di.dxt.common.Util.DxtJdbcAppender