Mybatis 拦截器

1.添加依赖

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.1</version>
</dependency>

2.添加mapper

1	`UserMapper.class`

@Mapper
public interface UserMapper {
    User selectById(Long userId);
}

1	`UserMapper.xml`

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.example.mapper.UserMapper">

    <select id="selectById" resultType="com.example.domain.User">
        select id, email, password, username
        from users
        where id = #{userId}
    </select>
</mapper>

3.application.properties添加mapper.xml文件配置

mybatis.mapper-locations=classpath:mapper/*.xml

4.启动类添加@MapperScan

@MapperScan("com.example.mapper")
@SpringBootApplication
public class MybatisDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(MybatisDemoApplication.class, args);
    }

}

5.添加拦截器

@Slf4j
@Component
@Intercepts(value = {
        @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}),
        @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})
})
public class SqlInterceptor implements Interceptor {
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        log.info("拦截器对象={}", invocation.toString());
        Object returnValue = null;
        try {
            MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];
            String sqlId = mappedStatement.getId();
            if(sqlId.contains("History") || sqlId.contains("Tmp")){
                return invocation.proceed();
            }
            Object parameter = null;
            if (invocation.getArgs().length > 1) {
                parameter = invocation.getArgs()[1];
            }
            BoundSql boundSql = mappedStatement.getBoundSql(parameter);
            Configuration configuration = mappedStatement.getConfiguration();

            long start = System.currentTimeMillis();

            returnValue = invocation.proceed();

            long end = System.currentTimeMillis();
            long time = (end - start);
            String sql = getSql(configuration, boundSql, sqlId, time);
            log.info("拦截器={}", sql);
        } catch (Exception e) {
            log.error("拦截器异常");
        }

        return returnValue;
    }

    @Override
    public Object plugin(Object target) {
        log.info("Interceptor::plugin#target={}", target);
        if(target instanceof Executor){
            return Plugin.wrap(target, this);
        }
        return target;
    }

    @Override
    public void setProperties(Properties properties) {

    }

    public static String getSql(Configuration configuration, BoundSql boundSql, String sqlId, long time) {
        String sql = showSql(configuration, boundSql);
        StringBuilder str = new StringBuilder(100);
        str.append("【sqlId】").append(sqlId);
        str.append("【SQL耗时-").append(time).append("-毫秒】");
        str.append("【SQL】").append(sql);
        log.debug(str.toString());
        return str.toString();
    }

    public static String showSql(Configuration configuration, BoundSql boundSql) {
        Object parameterObject = boundSql.getParameterObject();
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
        String sql = boundSql.getSql().replaceAll("[\\s]+", " ");
        if (parameterMappings.size() > 0 && parameterObject != null) {
            TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
            if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
                sql = sql.replaceFirst("\\?", getParameterValue(parameterObject));

            } else {
                MetaObject metaObject = configuration.newMetaObject(parameterObject);
                for (ParameterMapping parameterMapping : parameterMappings) {
                    String propertyName = parameterMapping.getProperty();
                    if (metaObject.hasGetter(propertyName)) {
                        Object obj = metaObject.getValue(propertyName);
                        sql = sql.replaceFirst("\\?", getParameterValue(obj));
                    } else if (boundSql.hasAdditionalParameter(propertyName)) {
                        Object obj = boundSql.getAdditionalParameter(propertyName);
                        sql = sql.replaceFirst("\\?", getParameterValue(obj));
                    }
                }
            }
        }
        return sql;
    }

    private static String getParameterValue(Object obj) {
        String value = null;
        if (obj instanceof String) {
            value = "'" + obj.toString() + "'";
            value = value.replaceAll("\\\\", "\\\\\\\\");
            value = value.replaceAll("\\$", "\\\\\\$");
        } else if (obj instanceof Date) {
            DateFormat formatter = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.CHINA);
            value = "'" + formatter.format(obj) + "'";
        } else {
            if (obj != null) {
                value = obj.toString();
            } else {
                value = "";
            }

        }
        return value;
    }

}

6.拦截器介绍

plugin方法，每种代理类型都会调用该方法

plugin#target=org.apache.ibatis.executor.CachingExecutor@aadddeb
plugin#target=org.apache.ibatis.scripting.defaults.DefaultParameterHandler@1bb554b0
plugin#target=org.apache.ibatis.executor.resultset.DefaultResultSetHandler@6824a9b0
plugin#target=org.apache.ibatis.executor.statement.RoutingStatementHandler@560f1f4b

2.@Intercepts注解指定需要创建代理的类型，会为该类型创建代理，而后会执行interceptor方法

@Intercepts(value = {
        @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}),
        @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})
})

type：拦截类型

method：拦截类型接口中定义的方法

args：拦截类型接口中定义的方法参数，method + args才能定位一个方法，可能会有多个重载的同名方法

拦截类型	拦截方法
org.apache.ibatis.executor.Executor
org.apache.ibatis.executor.parameter.ParameterHandler
org.apache.ibatis.executor.statement.StatementHandler
org.apache.ibatis.executor.resultset.ResultSetHandler