MyBatis3教程 - MyBatis插件（Plugins）开
2017-04-02 本文已影响428人
FX_SKY
MyBatis 允许你在已映射语句执行过程中的某一点进行拦截调用。默认情况下，MyBatis 允许使用插件来拦截的方法调用包括：
- Executor (update, query, flushStatements, commit, rollback,
getTransaction, close, isClosed) - ParameterHandler (getParameterObject, setParameters)
- ResultSetHandler (handleResultSets, handleOutputParameters)
- StatementHandler (prepare, parameterize, batch, update, query)
这些类中方法的细节可以通过查看每个方法的签名来发现，或者直接查看 MyBatis 的发行包中的源代码。 假设你想做的不仅仅是监控方法的调用，那么你应该很好的了解正在重写的方法的行为。 因为如果在试图修改或重写已有方法的行为的时候，你很可能在破坏 MyBatis 的核心模块。 这些都是更低层的类和方法，所以使用插件的时候要特别当心。
通过 MyBatis 提供的强大机制，使用插件是非常简单的，只需实现 Interceptor 接口，并指定了想要拦截的方法签名即可。
自定义插件
需求：
把Mybatis所有执行的sql都记录下来。
代码实现
通过对 MyBatis org.apache.ibatis.executor.statement.StatementHandler 中的prepare 方法进行拦截即可。
prepare 方法签名如下：
Statement prepare(Connection connection, Integer transactionTimeout)
throws SQLException;
自定义一个类，实现 org.apache.ibatis.pluginInterceptor 接口，代码如下：
package com.bytebeats.mybatis3.interceptor;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.plugin.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.sql.Connection;
import java.util.Properties;
/**
* ${DESCRIPTION}
*
* @author Ricky Fung
* @date 2017-02-17 11:52
*/
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class, Integer.class}) })
public class SQLStatsInterceptor implements Interceptor {
private final Logger logger = LoggerFactory.getLogger(this.getClass());
@Override
public Object intercept(Invocation invocation) throws Throwable {
StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
BoundSql boundSql = statementHandler.getBoundSql();
String sql = boundSql.getSql();
logger.info("mybatis intercept sql:{}", sql);
return invocation.proceed();
}
@Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
@Override
public void setProperties(Properties properties) {
String dialect = properties.getProperty("dialect");
logger.info("mybatis intercept dialect:{}", dialect);
}
}
这样一个插件就开发完成了，接下来需要在 mybatis-config.xml 文件中增加 plugins节点，完整配置如下：
<?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.bytebeats.mybatis3.interceptor.SQLStatsInterceptor">
<property name="dialect" value="mysql" />
</plugin>
</plugins>
</configuration>
spring-mybatis.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
<util:properties id="db" location="classpath:db.properties"/>
<!-- 配置数据源 -->
<bean name="parentDatasource" abstract="true" class="com.alibaba.druid.pool.DruidDataSource">
<!-- 初始化连接大小 -->
<property name="initialSize" value="1" />
<!-- 连接池最大使用连接数量 -->
<property name="maxActive" value="100" />
<!-- 连接池最小空闲 -->
<property name="minIdle" value="20" />
<!-- 获取连接最大等待时间 -->
<property name="maxWait" value="30000" />
<property name="validationQuery" value="SELECT 1" />
<property name="testOnBorrow" value="true" />
<property name="testOnReturn" value="true" />
<property name="testWhileIdle" value="true" />
<!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->
<property name="timeBetweenEvictionRunsMillis" value="60000" />
<!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->
<property name="minEvictableIdleTimeMillis" value="25200000" />
<!-- 打开removeAbandoned功能 -->
<property name="removeAbandoned" value="true" />
<!-- 1800秒，也就是30分钟 -->
<property name="removeAbandonedTimeout" value="1800" />
<!-- 关闭abanded连接时输出错误日志 -->
<property name="logAbandoned" value="true" />
<!-- 监控数据库 -->
<property name="filters" value="mergeStat" />
</bean>
<!-- trade数据源 -->
<bean name="trade" init-method="init" destroy-method="close" parent="parentDatasource">
<property name="driverClassName" value="#{db['trade.jdbc.driverClassName']}" />
<property name="url" value="#{db['trade.jdbc.url']}" />
<property name="username" value="#{db['trade.jdbc.username']}" />
<property name="password" value="#{db['trade.jdbc.password']}" />
</bean>
<!-- admin数据源 -->
<bean name="admin" init-method="init" destroy-method="close" parent="parentDatasource">
<property name="driverClassName" value="#{db['admin.jdbc.driverClassName']}" />
<property name="url" value="#{db['admin.jdbc.url']}" />
<property name="username" value="#{db['admin.jdbc.username']}" />
<property name="password" value="#{db['admin.jdbc.password']}" />
</bean>
<!--trade mybatis config-->
<bean id="tradeSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="trade" />
<property name="mapperLocations" value="classpath*:mapper/trade/*Mapper.xml" />
<property name="configLocation" value="classpath:mybatis-config.xml" />
<property name="typeAliasesPackage" value="com.bytebeats.mybatis3.domain.trade" />
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.bytebeats.mybatis3.mapper.trade" />
<property name="sqlSessionFactoryBeanName" value="tradeSqlSessionFactory" />
</bean>
<!--admin mybatis config-->
<bean id="adminSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="admin" />
<property name="mapperLocations" value="classpath*:mapper/admin/*Mapper.xml" />
<property name="typeAliasesPackage" value="com.bytebeats.mybatis3.domain.admin" />
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.bytebeats.mybatis3.mapper.admin" />
<property name="sqlSessionFactoryBeanName" value="adminSqlSessionFactory" />
</bean>
<!-- 配置事务 -->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="trade" />
</bean>
<tx:annotation-driven transaction-manager="transactionManager" />
</beans>
maven依赖
<properties>
<java.version>1.7</java.version>
<spring.version>4.2.7.RELEASE</spring.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!-- spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
<exclusions>
<exclusion>
<artifactId>commons-logging</artifactId>
<groupId>commons-logging</groupId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
</dependency>
<!-- db-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.26</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.25</version>
</dependency>
<!--mybatis-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.1</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.3.0</version>
</dependency>
<!--log-->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.21</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
<version>1.7.21</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>1.7.21</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>1.1.7</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.1.7</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
参考资料
MyBatis 插件（plugins）教程：http://www.mybatis.org/mybatis-3/zh/configuration.html#plugins
