mybatis 源码分析二

1.SqlSession下的四大对象

Executor、StatementHandler、ParameterHandler、ResultSetHandler

StatementHandler的作用是使用数据库的Statement(PreparedStatement)执行操作

ParameterHandler是用来处理SQL参数的

ResultSetHandler是进行数据集的封装返回处理的

2.mybatis中有3中执行器：

SIMPLE——简易执行器，默认

REUSE——是一种能够执行重用预处理语句的执行器

BATCH ——执行器重用语句和批量更新，批量专用的执行器

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, autoCommit);
            var8 = new DefaultSqlSession(this.configuration, executor);
        } catch (Exception var12) {
            this.closeTransaction(tx);
            throw ExceptionFactory.wrapException("Error opening session.  Cause: " + var12, var12);
        } finally {
            ErrorContext.instance().reset();
        }

        return var8;
    }

　　

public Executor newExecutor(Transaction transaction, ExecutorType executorType, boolean autoCommit) {
        executorType = executorType == null ? this.defaultExecutorType : executorType;
        executorType = executorType == null ? ExecutorType.SIMPLE : executorType;
        Object executor;
        if (ExecutorType.BATCH == executorType) {
            executor = new BatchExecutor(this, transaction);
        } else if (ExecutorType.REUSE == executorType) {
            executor = new ReuseExecutor(this, transaction);
        } else {
            executor = new SimpleExecutor(this, transaction);
        }

        if (this.cacheEnabled) {
            executor = new CachingExecutor((Executor)executor, autoCommit);
        }

        Executor executor = (Executor)this.interceptorChain.pluginAll(executor);
        return executor;
    }