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">

</plugin>

</plugins>

</configuration>

<bean id="sqlSessionFactory"

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

<property name="configLocation"

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

</property>

</bean>