myBatis源码学习之SqlSessionFactoryBuilder

SqlSessionFactoryBuilder通过类名就可以看出这个类的主要作用就是创建一个SqlSessionFactory，通过输入mybatis配置文件的字节流或者字符流，生成XMLConfigBuilder，XMLConfigBuilder创建一个Configuration，Configuration这个类中包含了mybatis的配置的一切信息，mybatis进行的所有操作都需要根据Configuration中的信息来进行。

SqlSessionFactoryBuilder源码及注释：

/*
* Builds {@link SqlSession} instances.
*
*/
/**
* @author Clinton Begin
*/
//通过读入配置文件，最终获得一个sqlSessionFactory
public class SqlSessionFactoryBuilder {
//已字符输入流引入配置文件
public SqlSessionFactory build(Reader reader) {
return build(reader, null, null);
}
//environment是数据源环境
public SqlSessionFactory build(Reader reader, String environment) {
return build(reader, environment, null);
}

public SqlSessionFactory build(Reader reader, Properties properties) {
return build(reader, null, properties);
}

public SqlSessionFactory build(Reader reader, String environment, Properties properties) {
try {
//解析myBatis配置文件，以字符流的方式
XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
return build(parser.parse());//获得SqlSessionFactory
} 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.
}
}
}
//以字节输入流传入配置信息
public SqlSessionFactory build(InputStream inputStream) {
return build(inputStream, null, null);
}

public SqlSessionFactory build(InputStream inputStream, String environment) {
return build(inputStream, environment, null);
}

public SqlSessionFactory build(InputStream inputStream, Properties properties) {
return build(inputStream, null, properties);
}

public SqlSessionFactory build(InputStream inputStream, String environment, Properties properties) {
try {
//解析myBatis配置文件，以字节流的方式
XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);
return build(parser.parse());//获得SqlSessionFactory
} catch (Exception e) {
throw ExceptionFactory.wrapException("Error building SqlSession.", e);
} finally {
ErrorContext.instance().reset();
try {
inputStream.close();
} catch (IOException e) {
// Intentionally ignore. Prefer previous error.
}
}
}

public SqlSessionFactory build(Configuration config) {
//获得sqlsessionFactory工厂，再从工厂中获得sqlsession
return new DefaultSqlSessionFactory(config);
}

}

mybatis执行流程图：