------------吾亦无他,唯手熟尔，谦卑若愚，好学若饥-------------
1.找SqlSesionFactory实现类
Ctrl+H：DefaultSqlSessionFactory:
Ctrl+F :openSession()方法
原型如下：
public SqlSession openSession() {
return this.openSessionFromDataSource(this.configuration.getDefaultExecutorType(), (TransactionIsolationLevel)null, false);
}
2.查看openSessionFromDataSource方法的实现
private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {
Transaction tx = null; 定义事务对象
很明显：SqlSession实现类
DefaultSqlSession var8;
try {
//读取 MyBatis-Config.xml 形成 Environment对象
Environment e = this.configuration.getEnvironment();
//通过环境e作为入参，获取到事务工厂
TransactionFactory transactionFactory = this.getTransactionFactoryFromEnvironment(e);
//创建事务对象
tx = transactionFactory.newTransaction(e.getDataSource(), level, autoCommit);
//MyBatis执行器 Executor 执行器
Executor executor = this.configuration.newExecutor(tx, execType);
var8 = new DefaultSqlSession(this.configuration, executor, autoCommit);
} catch (Exception var12) {
this.closeTransaction(tx);
throw ExceptionFactory.wrapException("Error opening session. Cause: " + var12, var12);
} finally {
ErrorContext.instance().reset();
}
return var8;
}
3.查看DefaultSqlSession方法的实现
private Configuration configuration; //配置
private Executor executor; //执行器
private boolean autoCommit; //事务自动提交的
private boolean dirty; //脏 Java 内存中泛型数据 和底层DB数据 不一样 干净的（Java内存===DB Data 一致的）
private List<Cursor<?>> cursorList; 游标 让记录前进的一个工具
public DefaultSqlSession(Configuration configuration, Executor executor, boolean autoCommit) {
this.configuration = configuration;
this.executor = executor;
this.dirty = false; //干净的
this.autoCommit = autoCommit;
}
结论：通过以上3个步骤，我们不难发现，openSession 就是对DefaultSqlSession类中的成员变量赋值
