0 SqlSessionFactoryBuilder类
SqlSessionFactoryBuilder sqlSessionFacotory=SqlSessionFactoryBuilder().build(reader)
public SqlSessionFactory build(Reader reader) {
return build(reader, null, null);
}
它使用了一个参照了XML文档或更特定的SqlMapConfig.xml文件的Reader实例。
//可选的参数是environment和properties。Environment决定加载哪种环境(开发环境/生产环境)，包括数据源和事务管理器。
//如果使用properties，那么就会加载那些properties（属性配置文件），那些属性可以用${propName}语法形式多次用在配置文件中。和Spring很像，一个思想？
public SqlSessionFactory build(Reader reader, String environment, Properties properties) {
try {
//委托XMLConfigBuilder来解析xml文件，并构建
XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
return build(parser.parse());
} catch (Exception e) {
//这里是捕获异常，包装成自己的异常并抛出的idiom？，最后还要reset ErrorContext
throw ExceptionFactory.wrapException("Error building SqlSession.", e);
} finally {
ErrorContext.instance().reset();
try {
reader.close();
} catch (IOException e) {
// Intentionally ignore. Prefer previous error.
}
}
}
public SqlSessionFactory build(Configuration config) {
return new DefaultSqlSessionFactory(config);
}
1 DefaultSqlSessionFactory类
public SqlSession openSession() {
return openSessionFromDataSource(configuration.getDefaultExecutorType(), null, false);
}
private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {
Transaction tx = null;
try {
final Environment environment = configuration.getEnvironment();
final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);
//通过事务工厂来产生一个事务
tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);
//生成一个执行器(事务包含在执行器里)
final Executor executor = configuration.newExecutor(tx, execType);
//然后产生一个DefaultSqlSession
return new DefaultSqlSession(configuration, executor, autoCommit);
} catch (Exception e) {
//如果打开事务出错，则关闭它
closeTransaction(tx); // may have fetched a connection so lets call close()
throw ExceptionFactory.wrapException("Error opening session. Cause: " + e, e);
} finally {
//最后清空错误上下文
ErrorContext.instance().reset();
}
}
2.DefaultSqlSession类
public DefaultSqlSession(Configuration configuration, Executor executor, boolean autoCommit) {
this.configuration = configuration;
this.executor = executor;
this.dirty = false;
this.autoCommit = autoCommit;
}
获得DefaultSqlSession类其中包含执行器（事务相关），配置信息
public interface SqlSession extends Closeable {.....}
SqlSession session = sqlMapper.openSession();