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在Spring框架中,MyBatis插件是一种用于扩展MyBatis功能的工具。通过编写自定义插件,可以实现对MyBatis的拦截、日志记录、性能分析等功能。下面是一个简单的MyBatis插件开发示例:
首先,需要在项目中引入MyBatis和Spring相关的依赖。以Maven为例,添加以下依赖:
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.7</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.3.10</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.3.10</version>
</dependency>
创建一个实现org.apache.ibatis.plugin.Interceptor
接口的类,用于定义插件的行为。例如,我们可以定义一个简单的日志记录插件:
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.plugin.*;
import java.sql.Connection;
import java.util.Properties;
@Intercepts({
@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class})
})
public class LoggingInterceptor implements Interceptor {
@Override
public Object intercept(Invocation invocation) throws Throwable {
long startTime = System.currentTimeMillis();
Object result = invocation.proceed();
long elapsedTime = System.currentTimeMillis() - startTime;
System.out.println("SQL执行时间: " + elapsedTime + "ms");
return result;
}
@Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
@Override
public void setProperties(Properties properties) {
}
}
接下来,需要在Spring配置文件中配置插件。以XML配置为例,添加以下内容:
<bean id="loggingInterceptor" class="com.example.LoggingInterceptor" />
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="mapperLocations" value="classpath:mapper/*.xml" />
<property name="plugins">
<array>
<bean class="com.example.LoggingInterceptor" />
</array>
</property>
</bean>
这里,我们创建了一个名为loggingInterceptor
的bean,并将其作为插件添加到sqlSessionFactory
中。
现在,可以编写一个简单的测试用例来验证插件是否生效。例如,创建一个简单的Mapper接口和对应的XML文件:
public interface UserMapper {
User getUserById(int id);
}
<mapper namespace="com.example.UserMapper">
<select id="getUserById" resultType="com.example.User">
SELECT * FROM user WHERE id = #{id}
</select>
</mapper>
然后,在Spring配置文件中添加一个UserMapper
的bean:
<bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
<property name="sqlSessionFactory" ref="sqlSessionFactory" />
<property name="mapperInterface" value="com.example.UserMapper" />
</bean>
最后,编写一个测试类来验证插件是否生效:
import com.example.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.support.AnnotationConfigContextLoader;
import org.junit.Test;
import static org.junit.Assert.assertNotNull;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = AppConfig.class, loader = AnnotationConfigContextLoader.class)
public class UserMapperTest {
@Autowired
private UserMapper userMapper;
@Test
public void testGetUserById() {
User user = userMapper.getUserById(1);
assertNotNull(user);
}
}
运行测试用例,如果插件生效,将会看到SQL执行时间的输出。
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