How to implement common frameworks

MyBatis

mybatis It's a persistence layer framework , It's solved JDBC To operate the database, you need to write complex connections 、 Data manual mapping . Use xml Configuration omits establishment sqlSession The process of , Use object relational mapping to solve the troublesome manual mapping .

What you need to do is to execute the corresponding... When calling an interface SQL, I'm gonna use it here A dynamic proxy

Generate proxy objects , The proxy object can be based on the incoming SQL, Complete connection establishment and use JDBC The method of execution SQL; Get the type of the return value of this method through reflection , Map the data set returned by the database in turn

Spring IOC Containers

1. Define something Bean Annotations , We want to scan these annotations and add them to Bean Containers
2. Read the scan path in the configuration and scan , Then put the .class Files are stored in one Set in
3. Let's go through this set , According to the annotation on the class, give it to IOC Containers , It's a Map aggregate
4. If there is Bean Depend on others Bean Complete dependency injection
5. Generate circular dependencies , Create two more Map Make L2 cache and L3 cache

MQ

1. Specify the message protocol （JMS、AMQP）
2. Select the storage method （ Memory 、 journal 、 database ） Balance efficiency and reliability

Naocs

Reference resources Nacos Realization principle

Eureka&Ribbon&Nacos

Distributed lock

Reference resources Redis Do distributed locking process setnx -> red lock

Distributed lock Redis

Distributed transactions

Reference resources XA、AT、TCC

Distributed transactions Seata

Local message table ？？？ I don't understand

MQ： I guarantee the reliability of the information （ Release confirmation + Persistence + Manual response ）, Retry to prevent inconsistencies caused by downtime . however ！ If it is my downstream service business problem , For example, the user's balance is insufficient , Then I How the downstream service notifies the upstream service to rollback ？？？？（ use Seata？？？）