Mybatis配置之请求数据库时打印SQL语句，一份字节跳动面试官给你的Java技术面试指南

SQLInterceptor.java

package com.guide.util;

i

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mport java.sql.Connection;

import java.util.Date;

import java.util.Properties;

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

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

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

import org.apache.ibatis.mapping.BoundSql;

import org.apache.ibatis.mapping.MappedStatement;

import org.apache.ibatis.plugin.Interceptor;

import org.apache.ibatis.plugin.Intercepts;

import org.apache.ibatis.plugin.Invocation;

import org.apache.ibatis.plugin.Plugin;

import org.apache.ibatis.plugin.Signature;

/**

• 运行时SQL输出

*/

@Intercepts({ @Signature(type = StatementHandler.class, method = “prepare”, args = { Connection.class }) })

public class SQLInterceptor implements Interceptor {

public Object intercept(Invocation invocation) throws Throwable {

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

BoundSql boundSql = statementHandler.getBoundSql();

BaseStatementHandler delegate = (BaseStatementHandler) ReflectHelper.getValueByFieldName(statementHandler,

“delegate”);

MappedStatement mappedStatement = (MappedStatement) ReflectHelper.getValueByFieldName(delegate,

“mappedStatement”);

System.err.println("-------------------------------------------------" + mappedStatement.getId());

System.out.println(“sql:”+DateUtil.getDetailDate(new Date())+":"+boundSql.getSql());

return invocation.proceed();

}

public Object plugin(Object arg0) {

return Plugin.wrap(arg0, this);

}

public void setProperties(Properties properties) {

}

}

ReflectHelper.java

package com.guide.util;

import java.lang.reflect.Field;

/**

• 反射工具

*/

public class ReflectHelper {

/**

• 获取obj对象fieldName的Field

• @param obj

• @param fieldName

• @return

*/

public static Field getFieldByFieldName(Object obj, String fieldName) {

for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {

try {

return superClass.getDeclaredField(fieldName);

} catch (NoSuchFieldException e) {

}

}

return null;

}

/**

• 获取obj对象fieldName的属性值

• @param obj