一：MyBatis工具类 中openSession到底做了什么？
Mybatis工具类
1 private static final String RESOURCE = "mybatis-config.xml";
2 private static SqlSessionFactory sqlSessionFactory = null;
3 private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
4
5
6
7
8 //关闭sqlsession
9 public static void closeSession(){
10 SqlSession session = (SqlSession) threadLocal.get(); // 2
11 threadLocal.set(null);
12 if (session !=null){
13 session.close();
14 }
15 }
16
17 public static SqlSession getSessionTwo() {
18 //读取配置文件
19 try {
20 InputStream stream = Resources.getResourceAsStream(RESOURCE);
21 sqlSessionFactory = new SqlSessionFactoryBuilder().build(stream);
22
23 return sqlSessionFactory.openSession(); //返回openSession 24 } catch (IOException e) {
25 e.printStackTrace();
26 }
27
28 return null;
29 }
首先点开openSession 发现踏实sqlsessionFactory的一个方法
1 package org.apache.ibatis.session;
2
3 import java.sql.Connection;
4
5 public interface SqlSessionFactory {
6 SqlSession openSession();
7
8 SqlSession openSession(boolean var1);
9
10 SqlSession openSession(Connection var1);
然后再看这 个方法的实现类DefaultSqlSessionFactory
这里主要返回他自己类的一个方法openSessionFroDataSource（） （数据源） 并赋值 autoCommit 为false
然后 进入这个方法
private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {
Transaction tx = null;
DefaultSqlSession var8;
try {
Environment environment = this.configuration.getEnvironment();
TransactionFactory transactionFactory = this.getTransactionFactoryFromEnvironment(environment);
tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);
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;
}
可以看到他这个方法主要是初始化一些configure.xml的配置信息和DefaultSqlSession
所以openSession的主要就是初始化了
configure.xml的配置信息和DefaultSqlSession
二：MyBatis工具类 中sqlSession.close()底层为什么回滚事务？
首先进入 close()找到他的实现类DefaultsqlSession
DefaultsqlSession里的close方法
session.close(); 底层为什么可以回滚事务？？？？？
DefaultsqlSession里的close方法
public void close() {
try {
this.executor.close(this.isCommitOrRollbackRequired(false));
this.dirty = false;
} finally {
ErrorContext.instance().reset();
}
}
进入Executor接口 查看他的实现类BaseExecutor 找到close()方法
public void close(boolean forceRollback) { //需要传入一个boolean参数
try {
try {
this.rollback(forceRollback); //为true则rollback
} finally {
if(this.transaction != null) {
this.transaction.close();
}
}
} catch (SQLException var11) {
log.warn("Unexpected exception on closing transaction. Cause: " + var11);
} finally {
this.transaction = null;
this.deferredLoads = null;
this.localCache = null;
this.localOutputParameterCache = null;
this.closed = true;
}
}
然后再看下executor.close()里的参数
this.executor.close(this.isCommitOrRollbackRequired(false));
------>isCommitOrRollbackRequired