public class SqlSessionFactoryBuilder {

//Reader读取mybatis配置文件，传入构造方法
//除了Reader外，其实还有对应的inputStream作为参数的构造方法，
//这也体现了mybatis配置的灵活性
public SqlSessionFactory build(Reader reader) {
return build(reader, null, null);
}

public SqlSessionFactory build(Reader reader, String environment) {
return build(reader, environment, null);
}

//mybatis配置文件 + properties, 此时mybatis配置文件中可以不配置properties，也能使用${}形式
public SqlSessionFactory build(Reader reader, Properties properties) {
return build(reader, null, properties);
}

//通过XMLConfigBuilder解析mybatis配置，然后创建SqlSessionFactory对象
public SqlSessionFactory build(Reader reader, String environment, Properties properties) {
try {
XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
//下面看看这个方法的源码
return build(parser.parse());
} catch (Exception e) {
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);
}

}

public class SqlSessionFactoryBuilder {  //Reader读取mybatis配置文件，传入构造方法  //除了Reader外，其实还有对应的inputStream作为参数的构造方法，  //这也体现了mybatis配置的灵活性  public SqlSessionFactory build(Reader reader) {    return build(reader, null, null);  }  public SqlSessionFactory build(Reader reader, String environment) {    return build(reader, environment, null);  }    //mybatis配置文件 + properties, 此时mybatis配置文件中可以不配置properties，也能使用${}形式  public SqlSessionFactory build(Reader reader, Properties properties) {    return build(reader, null, properties);  }    //通过XMLConfigBuilder解析mybatis配置，然后创建SqlSessionFactory对象  public SqlSessionFactory build(Reader reader, String environment, Properties properties) {    try {      XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);      //下面看看这个方法的源码      return build(parser.parse());    } catch (Exception e) {      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);  }}

测试2