引言： 在项目中使用了MyBatis，一个比较苦恼的问题是无法看到执行的SQL的具体情况，所以，就找到了Log4jdbc-log4j2。这个是一个基于jdbc层面的监听工具，可以监听对于数据库的主要操作，从而完美的查看到其中执行的操作。
1. Log4jdbc-log4j2版本选择
- log4jdbc-log4j2-jdbc3.jar for JDBC 3 support in JDK 1.5
- log4jdbc-log4j2-jdbc4.jar for JDBC 4 support in JDK 1.6
- log4jdbc-log4j2-jdbc4.1.jar for JDBC 4.1 support in JDK 1.7
2. 如何引入到项目？
如果项目是基于Maven工具，则可以直接使用如下依赖，即可完美解决问题：
<dependency> <groupId>org.bgee.log4jdbc-log4j2</groupId> <artifactId>log4jdbc-log4j2-jdbcXX</artifactId> <version>1.16</version> </dependency>3. 依赖包的安装
a. 如有使用log4j, 则需要log4j.-core.jar和log4j-api.jar
b. 如使用slf4j，则需要 slf4j-api.jar
4. 修改数据库连接中的jdbc.url和driver.Class
xxx.driverClass=<strong>net.sf.log4jdbc.sql.jdbcapi.DriverSpy</strong> ------ 数据库驱动程序 ............................ xxxx.jdbcUrl = <strong>jdbc:log4</strong>\:oracle\:thin\:@192.168.1.20\:1521\:orcl -------------- 数据库连接URL说明：其中加粗的内容，表示其是被修改后的新内容。
原有的URL：
jdbc:derby://localhost:1527//db-derby-10.2.2.0-bin/databases/MyDatabase
替换的URL：
jdbc:log4jdbc:derby://localhost:1527//db-derby-10.2.2.0-bin/databases/MyDatabase
5. 配置好log4j和log4j.properties
6. 新增log4jdbc.log4j2.properties
这里使用Slf4j API， 声明如下：
log4jdbc.spylogdelegator.name=net.sf.log4jdbc.log.slf4j.Slf4jSpyLogDelegator7. 可用的Logger
| logger | description |
| jdbc.sqlonly | Logs only SQL. SQL executed within a prepared statement is automatically shown with it‘s bind arguments replaced with the data bound at that position, for greatly increased readability. |
| jdbc.sqltiming | Logs the SQL, post-execution, including timing statistics on how long the SQL took to execute. |
| jdbc.audit | Logs ALL JDBC calls except for ResultSets. This is a very voluminous output, and is not normally needed unless tracking down a specific JDBC problem. |
| jdbc.resultset | Even more voluminous, because all calls to ResultSet objects are logged. |
| jdbc.resultsettable | Log the jdbc results as a table. Level debug will fill in unread values in the result set. |
| jdbc.connection | Logs connection open and close events as well as dumping all open connection numbers. This is very useful for hunting down connection leak problems. |
这些都是需要配置到log4j.properties或者log4j.xml中去的。
示例如下：
! Log all JDBC calls except for ResultSet calls
log4j.logger.jdbc.audit=DEBUG,jdbc
log4j.additivity.jdbc.audit=false
! Log only JDBC calls to ResultSet objects
log4j.logger.jdbc.resultset=DEBUG,jdbc
log4j.additivity.jdbc.resultset=false
! Log only the SQL that is executed.
log4j.logger.jdbc.sqlonly=DEBUG,sql
log4j.additivity.jdbc.sqlonly=false
! Log timing information about the SQL that is executed.
log4j.logger.jdbc.sqltiming=DEBUG,sqltiming
log4j.additivity.jdbc.sqltiming=false
! Log connection open/close events and connection number dump
log4j.logger.jdbc.connection=FATAL,connection
log4j.additivity.jdbc.connection=false
! the appender used for the JDBC API layer call logging above, sql only
log4j.appender.sql=org.apache.log4j.FileAppender
log4j.appender.sql.File=./logs/sql.log
log4j.appender.sql.Append=false
log4j.appender.sql.layout=org.apache.log4j.PatternLayout
log4j.appender.sql.layout.ConversionPattern=-----> %d{yyyy-MM-dd HH:mm:ss.SSS} %m%n%n
! the appender used for the JDBC API layer call logging above, sql timing
log4j.appender.sqltiming=org.apache.log4j.FileAppender
log4j.appender.sqltiming.File=./logs/sqltiming.log
log4j.appender.sqltiming.Append=false
log4j.appender.sqltiming.layout=org.apache.log4j.PatternLayout
log4j.appender.sqltiming.layout.ConversionPattern=-----> %d{yyyy-MM-dd HH:mm:ss.SSS} %m%n%n
! the appender used for the JDBC API layer call logging above
log4j.appender.jdbc=org.apache.log4j.FileAppender
log4j.appender.jdbc.File=./logs/jdbc.log
log4j.appender.jdbc.Append=false
log4j.appender.jdbc.layout=org.apache.log4j.PatternLayout
log4j.appender.jdbc.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss.SSS} %m%n
! the appender used for the JDBC Connection open and close events
log4j.appender.connection=org.apache.log4j.FileAppender
log4j.appender.connection.File=./logs/connection.log
log4j.appender.connection.Append=false
log4j.appender.connection.layout=org.apache.log4j.PatternLayout
log4j.appender.connection.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss.SSS} %m%n
总结：
经过一番折腾之后呢，终于可以在系统看到数据库中各类的操作了，数据库的各种行为尽在眼底........