MyBatis openSession(),close(),和commit()用法解释

 1     private static final String RESOURCE = "mybatis-config.xml"; 2     private static SqlSessionFactory sqlSessionFactory = null; 3     private static ThreadLocal threadLocal = new ThreadLocal(); 4  5  6  7  8     //关闭sqlsession 9     public static void closeSession(){10         SqlSession session = (SqlSession) threadLocal.get(); // 211         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openSession24         } catch (IOException e) {25             e.printStackTrace();26         }27 28         return null;29     }

 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);

 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;
    }

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

.executor.close(.isCommitOrRollbackRequired(------>  isCommitOrRollbackRequired(  ||

forceRollback为true 然后进入rollback(forceRollBack)参数为true
看下最终的rollback方法　　

public void rollback(boolean required) throws SQLException {
    if(!this.closed) {
        try {
            this.clearLocalCache();
            this.flushStatements(true);
        } finally {
            if(required) {
                this.transaction.rollback();   //如果传入的参数为 true     则进行事务 回滚
            }

        }
    }