io.mybatis.provider.keysql

Class GenIdKeyGenerator

java.lang.Object

io.mybatis.provider.keysql.GenIdKeyGenerator

All Implemented Interfaces:

org.apache.ibatis.executor.keygen.KeyGenerator

public class GenIdKeyGenerator
extends Object
implements org.apache.ibatis.executor.keygen.KeyGenerator

生成主键

Constructor Summary

Constructors

Constructor and Description
GenIdKeyGenerator(GenId<?> genId, EntityTable table, EntityColumn column, org.apache.ibatis.session.Configuration configuration, boolean executeBefore)

Method Summary

Modifier and Type	Method and Description
void	genId(Object parameter)
void	prepare(Object parameter) 准备参数，当executeBefore=true时，需要在执行前生成主键，如果是在ms初始化前进来该方法，就没有生成id，这里需要补充执行一次
void	processAfter(org.apache.ibatis.executor.Executor executor, org.apache.ibatis.mapping.MappedStatement ms, Statement stmt, Object parameter)
void	processBefore(org.apache.ibatis.executor.Executor executor, org.apache.ibatis.mapping.MappedStatement ms, Statement stmt, Object parameter)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GenIdKeyGenerator

public GenIdKeyGenerator(GenId<?> genId,
                         EntityTable table,
                         EntityColumn column,
                         org.apache.ibatis.session.Configuration configuration,
                         boolean executeBefore)

Method Detail

processBefore

public void processBefore(org.apache.ibatis.executor.Executor executor,
                          org.apache.ibatis.mapping.MappedStatement ms,
                          Statement stmt,
                          Object parameter)

Specified by:

processBefore in interface org.apache.ibatis.executor.keygen.KeyGenerator

processAfter

public void processAfter(org.apache.ibatis.executor.Executor executor,
                         org.apache.ibatis.mapping.MappedStatement ms,
                         Statement stmt,
                         Object parameter)

Specified by:

processAfter in interface org.apache.ibatis.executor.keygen.KeyGenerator

genId

public void genId(Object parameter)

prepare

public void prepare(Object parameter)

准备参数，当executeBefore=true时，需要在执行前生成主键，如果是在ms初始化前进来该方法，就没有生成id，这里需要补充执行一次

ms初始化之后再进来时，会按照selectKey的方式自动调用该方法，不需要再这里补充调用。

这里设置 CONCURRENCY 是为了避免后续ms正常后，这里判断为空会多此一举，所以设置一个阈值，超过阈值后就不再判断了。

只有当第一次出现并发插入超过 CONCURRENCY 值时，才可能会出现漏掉id的情况。