Mybatis中怎么将sql语句打印到控制台

import java.util.Properties;

import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
//insert update delete都算作Executor的update方法  select算是query方法，详见Mybatis文档
@Intercepts( {
        @Signature(type = Executor.class, method = "update", args = {
                MappedStatement.class, Object.class }),
        @Signature(type = Executor.class, method = "query", args = {
                MappedStatement.class, Object.class, RowBounds.class,
                ResultHandler.class }) })
public class PrintSqlPlugin implements Interceptor {

    public Object intercept(Invocation invocation) throws Throwable {
/*
     

*/

        Object[] args = invocation.getArgs();
        //MyBatis将SQL配置信息加载成为不同的MappedStatement对象并存储在内存中。
        MappedStatement stmt = (MappedStatement) args[0];
       //为方法传递过来的参数
        Object arg = null;
       /*
       判断第二个参数是不是空，及是否传递过来了
        IStudentMapper studentDao = session.getMapper(IStudentMapper.class);
        studentDao.insert(student);
      */
        if (args.length > 1) {
            arg = args[1];
        }
       /*
           
      */
        BoundSql boundSql = stmt.getBoundSql(arg);

        String sql = boundSql.getSql();
        //以下代码为格式化输出将回车和制表符换成
        sql = sql.replaceAll("\n", "");
        sql = sql.replaceAll("\t", "");
        System.out.println(sql);

        return invocation.proceed();
    }

    public Object plugin(Object obj) {
        return Plugin.wrap(obj, this);
    }

    public void setProperties(Properties properties) {

    }

}

//主配置文件中配置config.xml

<pre name="code" class="html"><?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
    <properties resource="jdbc.properties"></properties>

    <typeAliases>
        <!--以下为实体类及其别名-->
        <typeAlias alias="student" type="com.oracle.wfc.model.Student" />
    </typeAliases>

    <plugins>
        <plugin interceptor="com.oracle.wfc.dao.PrintSqlPlugin"></plugin>
    </plugins>
        <!--以下数据库连接环境集，一个环境集中可以包含多个环境声明，每个环境都有自己的id，id可以任意指定，可以在环境集上用default声明哪个环境是默认的环境。
        -->
    <environments default="development">
        <environment id="development">
            <!--以下为使用JDBC管理事务，->
            <transactionManager type="JDBC" />
            <!--以下为配置dataSource POOLED表示使用连接池机制 ->
            <dataSource type="POOLED">
                     <!--以下为连接数据库的属性文件-->
                <property name="driver" value="${driver}" />
                <property name="url" value="${url}" />
                <property name="username" value="${username}" />
                <property name="password" value="${password}" />
            </dataSource>
        </environment>
        <environment>
               ......
        </environment>
    </environments>
    <!--以下为声明实体映射文件的位置->
    <mappers>
        <mapper resource="com/oracle/wfc/dao/mapper/IStudentMapper.xml" />
    </mappers>
</configuration>