现象1：

mybatis版本：3.0.5
logback配置：

 <logger name="com.apache.ibatis" level="DEBUG" />
 <logger name="java.sql.Connection" level="DEBUG" />
 <logger name="java.sql.Statement" level="DEBUG" />
 <logger name="java.sql.PreparedStatement" level="DEBUG" />

正常打印日志。

现象2：

mybatis版本：3.2+
logback配置：

 <logger name="com.apache.ibatis" level="DEBUG" />
 <logger name="java.sql.Connection" level="DEBUG" />
 <logger name="java.sql.Statement" level="DEBUG" />
 <logger name="java.sql.PreparedStatement" level="DEBUG" />

不正常打印sql日志

源码分析：

mybatis版本：3.0.5

查看类PreparedStatementLogger:

 public Object invoke(Object proxy, Method method, Object[] params) throws Throwable {
  try {
    if (EXECUTE_METHODS.contains(method.getName())) {
      if (log.isDebugEnabled()) {
        log.debug("==>  Executing: " + removeBreakingWhitespace(sql));
        log.debug("==> Parameters: " + getParameterValueString());
      }
      clearColumnInfo();
      if ("executeQuery".equals(method.getName())) {
        ResultSet rs = (ResultSet) method.invoke(statement, params);
        if (rs != null) {
          return ResultSetLogger.newInstance(rs);
        } else {
          return null; 
...

这里log是 “PreparedStatement.class”：

  private static final Log log = LogFactory.getLog(PreparedStatement.class);

所以只要配置了PreparedStatement类的级别为DEBUG就可以打印PreparedStatement日志：

<logger name="java.sql.PreparedStatement" level="DEBUG" />

mybatis版本：3.2+

查看类ConnectionLogger:

  public Object invoke(Object proxy, Method method, Object[] params) throws Throwable {
  try {
    if (EXECUTE_METHODS.contains(method.getName())) {
      if (log.isDebugEnabled()) {
        log.debug("==>  Executing: " + removeBreakingWhitespace(sql));
        log.debug("==> Parameters: " + getParameterValueString());
      }
  ....

其中log为：

  protected boolean isDebugEnabled() {
    return statementLog.isDebugEnabled();
  }

注意这里的statementLog，看SimpleExecutor的prepareStatement(handler, ms.getStatementLog())

  public <E> List<E> doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds,ResultHandler resultHandler, BoundSql boundSql) throws SQLException {

    Statement stmt = null;
    try {
      Configuration configuration = ms.getConfiguration();
      StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter,     rowBounds,resultHandler, boundSql);
      stmt = prepareStatement(handler, ms.getStatementLog());
      return handler.<E>query(stmt, resultHandler);
    } finally {
      closeStatement(stmt);
    }
  }

这个statementLog是ms.getStatementLog()而来的。而MappedStatement的StatementLog

String logId = id; if (configuration.getLogPrefix() != null) 
    logId = configuration.getLogPrefix() + id; 
mappedStatement.statementLog = LogFactory.getLog(logId);

这里可以看到，logPrefix决定了所有log前缀，所以只需要配置logPrefix就行了。

总结：

mybatis版本：3.2+版本的需要配置：###

在mybatis的configuration中增加setting配置

<settings>
     <setting name="logPrefix" value="dao."/>
</settings>

然后增加配置

<logger name="dao" level="DEBUG"/>