Mybatis 拦截器（一）

1、编写自定义拦截器类
@Intercepts({

@Signature(method = "prepare", type = StatementHandler.class, args = { Connection.class }) 

})

public class MyInterceptor implements Interceptor {

 

public Object intercept(Invocation invocation) throws Throwable {

RoutingStatementHandler handler =
(RoutingStatementHandler) invocation.getTarget(); /**通过反射获取到当前RoutingStatementHandler对象的delegate属性  */      

    StatementHandler delegate =
(StatementHandler)ReflectUtil.getFieldValue(handler, "delegate");  

      /*获取到当前StatementHandler的 boundSql,因为之前已经说过了,RoutingStatementHandler实现的StatementHandler接口方法里面调用的delegate对应的方法*/ 

    BoundSql boundSql = delegate.getBoundSql();  /**拿到当前绑定Sql的参数对象，就是我们在调用对应的Mapper映射语句时所传入的参数对象  */

          Object param = bs.getParameterObject();

String sql = bs.getSql();

if (param instanceof HashMap) {//param 已是hashMap,验证dao中接口方法的传入参数 是否含有分页标示

HashMap map = (HashMap) param;

PageList p = (PageList) map.get(PAGE_KEY);

if (p != null) {

/*p.setCount(queryTotal(ivk, ms, bs, param, sql));--分页sql 拼写逻辑

set(p);

ReflectHelper.setValueByFieldName(bs, "sql", pageSql(sql, p));*/

}

}

      return invocation.proceed();  

}

 

public Object plugin(Object target) {

return Plugin.wrap(target,this);

}

/**

* 设置初始化变量

*/

public void setProperties(Properties arg0) {

System.out.println("set begin....");

}

 

}

2、在mybatis-confg.xml 中初始化参数并 在sqlsessionfactory 中注册拦截器

<?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>

<plugins>

<!-- <plugin interceptor="com.common.page.ResultSetInterceptor" /> -->

<plugin interceptor="com.tool.MyInterceptor">

<!-- <property name="dialect" value="oracle" /> -->

</plugin>

</plugins>

</configuration>

<bean id="sqlSessionFactory"

class="org.mybatis.spring.SqlSessionFactoryBean">

<property name="configLocation"

value="classpath:config/mybatis-config.xml">

</property>

<property name="dataSource" ref="dataSource" />

</bean>