Mybatis配置之请求数据库时打印SQL语句

首先是在配置Mybatis_config.xml文件中：

<?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>
<settings>
<!-- 全局映射器启用缓存 -->
<setting name="cacheEnabled" value="true" />
<!-- 查询时，关闭关联对象即时加载以提高性能 -->
<setting name="lazyLoadingEnabled" value="true" />
<!-- 设置关联对象加载的形态，此处为按需加载字段(加载字段由SQL指 定)，不会加载关联表的所有字段，以提高性能 -->
<setting name="aggressiveLazyLoading" value="false" />
<!-- 对于未知的SQL查询，允许返回不同的结果集以达到通用的效果 -->
<setting name="multipleResultSetsEnabled" value="true" />
<!-- 允许使用列标签代替列名 -->
<setting name="useColumnLabel" value="true" />
<!-- 允许使用自定义的主键值(比如由程序生成的UUID 32位编码作为键值)，数据表的PK生成策略将被覆盖 -->
<setting name="useGeneratedKeys" value="true" />
<!-- 给予被嵌套的resultMap以字段-属性的映射支持 -->
<setting name="autoMappingBehavior" value="FULL" />
<!-- 数据库超过25000秒仍未响应则超时 -->
<setting name="defaultStatementTimeout" value="25000" />
</settings>

<plugins>
<!-- 上线时关闭，调试的时候打印SQL使用。插件顺序不要调换 -->
<plugin interceptor="com.guide.util.SQLInterceptor" />

</plugins>
</configuration>

SQLInterceptor.java
package com.guide.util;

import java.sql.Connection;
import java.util.Date;
import java.util.Properties;

import org.apache.ibatis.executor.statement.BaseStatementHandler;
import org.apache.ibatis.executor.statement.RoutingStatementHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
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;

/**
* 运行时SQL输出
*
*/
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })
public class SQLInterceptor implements Interceptor {

public Object intercept(Invocation invocation) throws Throwable {
RoutingStatementHandler statementHandler = (RoutingStatementHandler) invocation.getTarget();
BoundSql boundSql = statementHandler.getBoundSql();
BaseStatementHandler delegate = (BaseStatementHandler) ReflectHelper.getValueByFieldName(statementHandler,
"delegate");
MappedStatement mappedStatement = (MappedStatement) ReflectHelper.getValueByFieldName(delegate,
"mappedStatement");
System.err.println("-------------------------------------------------" + mappedStatement.getId());
System.out.println("sql:"+DateUtil.getDetailDate(new Date())+":"+boundSql.getSql());
return invocation.proceed();
}

public Object plugin(Object arg0) {
return Plugin.wrap(arg0, this);
}

public void setProperties(Properties properties) {
}
}


ReflectHelper.java
package com.guide.util;

import java.lang.reflect.Field;

/**
* 反射工具
*
*/
public class ReflectHelper {
/**
* 获取obj对象fieldName的Field
*
* @param obj
* @param fieldName
* @return
*/
public static Field getFieldByFieldName(Object obj, String fieldName) {
for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
try {
return superClass.getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
}
}
return null;
}

/**
* 获取obj对象fieldName的属性值
*
* @param obj
* @param fieldName
* @return
* @throws SecurityException
* @throws NoSuchFieldException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public static Object getValueByFieldName(Object obj, String fieldName) throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
Field field = getFieldByFieldName(obj, fieldName);
Object value = null;
if (field != null) {
if (field.isAccessible()) {
value = field.get(obj);
} else {
field.setAccessible(true);
value = field.get(obj);
field.setAccessible(false);
}
}
return value;
}

/**
* 设置obj对象fieldName的属性值
*
* @param obj
* @param fieldName
* @param value
* @throws SecurityException
* @throws NoSuchFieldException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public static void setValueByFieldName(Object obj, String fieldName, Object value) throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
Field field = obj.getClass().getDeclaredField(fieldName);
if (field.isAccessible()) {
field.set(obj, value);
} else {
field.setAccessible(true);
field.set(obj, value);
field.setAccessible(false);
}
}
}