mybatis攔截處理

在工作中，我們常常需要在不改變源碼的條件下對sql進行壹些修改。

? 在這過程中用到的技術原理就是mybatis的攔截器（對於mybatis的內置對象筆者也還知之甚少，但這個不耽誤咱使用mybatis的攔截器）。

package com.interceptors.mybatis;

import lombok.extern.slf4j.Slf4j;

import org.apache.commons.lang3.StringUtils;

import org.apache.ibatis.executor.statement.StatementHandler;

import org.apache.ibatis.mapping.BoundSql;

import org.apache.ibatis.mapping.MappedStatement;

import org.apache.ibatis.mapping.SqlCommandType;

import org.apache.ibatis.mapping.SqlSource;

import org.apache.ibatis.plugin.*;

import org.apache.ibatis.reflection.DefaultReflectorFactory;

import org.apache.ibatis.reflection.MetaObject;

import org.apache.ibatis.reflection.SystemMetaObject;

import org.apache.ibatis.reflection.factory.DefaultObjectFactory;

import org.apache.ibatis.reflection.wrapper.DefaultObjectWrapperFactory;

import org.apache.ibatis.session.ResultHandler;

import org.apache.ibatis.session.RowBounds;

import org.springframework.stereotype.Component;

import java.lang.reflect.Field;

import java.lang.reflect.Method;

import java.sql.Connection;

import java.util.Properties;

@Component

@Intercepts({

@Signature(

type = StatementHandler.class, method ="prepare", args = {Connection.class, Integer.class})

})

@Slf4j

public class MybatisSqlInterceptorimplements Interceptor {

@Override

public Object intercept(Invocation invocation)throws Throwable {

StatementHandler statementHandler = (StatementHandler) invocation.getTarget();

MetaObject metaObject = MetaObject.forObject(statementHandler, SystemMetaObject.DEFAULT_OBJECT_FACTORY, SystemMetaObject.DEFAULT_OBJECT_WRAPPER_FACTORY,new DefaultReflectorFactory());

//先攔截到RoutingStatementHandler，裏面有個StatementHandler類型的delegate變量，其實現類是BaseStatementHandler，然後就到BaseStatementHandler的成員變量mappedStatement

MappedStatement mappedStatement = (MappedStatement) metaObject.getValue("delegate.mappedStatement");

//id為執行的mapper方法的全路徑名

String id = mappedStatement.getId();

//sql語句類型 select、delete、insert、update

String sqlCommandType = mappedStatement.getSqlCommandType().toString();

BoundSql boundSql = statementHandler.getBoundSql();

//獲取到原始sql語句

String sql = boundSql.getSql();

String mSql = sql;

//TODO 修改位置

//註解邏輯判斷? 添加註解了才攔截

Class classType = Class.forName(mappedStatement.getId().substring(0, mappedStatement.getId().lastIndexOf(".")));

String mName = mappedStatement.getId().substring(mappedStatement.getId().lastIndexOf(".") +1, mappedStatement.getId().length());

for (Method method : classType.getDeclaredMethods()) {

if (method.isAnnotationPresent(InterceptAnnotation.class) && mName.equals(method.getName())) {

InterceptAnnotation interceptorAnnotation = method.getAnnotation(InterceptAnnotation.class);

if (interceptorAnnotation.flag()) {

//重新設置mapper接口的參數或者對sql進行改造

boundSql.setAdditionalParameter("","");

}

}

}

//通過反射修改sql語句

Field field = boundSql.getClass().getDeclaredField("sql");

field.setAccessible(true);

field.set(boundSql, mSql);

return invocation.proceed();

}

@Override

public Object plugin(Object target) {

if (targetinstanceof StatementHandler) {

return Plugin.wrap(target,this);

}else {

return target;

}

}

@Override

public void setProperties(Properties properties) {

}

}

package com.interceptors.mybatis;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

@Target({ElementType.METHOD, ElementType.PARAMETER})

@Retention(RetentionPolicy.RUNTIME)

public @interface InterceptAnnotation {

boolean flag()default true;

}

（對於mybatis攔截器的使用還需要了解mybatis更多的內置方法，本篇文章也只是mybatis攔截器的壹點皮毛）

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