MyBatis之设计模式学习总结
在学习MyBatis的过程中，不仅要掌握其设计理念，还需深入了解其中使用的设计模式。本文总结了在学习MyBatis时所接触到的7种设计模式，并将持续更新。
1、建造者模式（Builder模式）示例：
代码语言：javascript代码运行次数：0运行复制```javascript public class Book { private Integer id; private String name; public Book() { } public Book(Integer id, String name) { this.id = id; this.name = name; } @Override public String toString() { return "Book{" + "id=" + id + ", name='" + name + '}'; } // 使用内部类实现建造者模式 public static class Builder { private Integer id; private String name; public Builder id(Integer id) { this.id = id; return this; } public Builder name(String name) { this.name = name; return this; } public Book build() { return new Book(id, name); } } } /**
- 通过这种方式实现了链式创建，与Lombok的@Builder注解功能类似。 */ public class BuilderTest { public static void main(String[] args) { Book book = new Book.Builder().id(1).name("三国").build(); System.out.println(book.toString()); } }
MyBatis中对Builder模式的应用不仅仅限于内部类的方式。例如：
代码语言：javascript代码运行次数：0运行复制```javascript /**
- 根据不同的输入参数构建SqlSessionFactory工厂对象。
- 最终会调用这个build方法，创建SqlSessionFactory的实现类
*/
public class SqlSessionFactoryBuilder {
public SqlSessionFactory build(Reader reader) {
return build(reader, null, null);
}
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) {
XMLC
onfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
return build(parser.parse());
}
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) {
XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);
return build(parser.parse());
}
// 最终会调用这个build方法，创建SqlSessionFactory的实现类
public SqlSessionFactory build(Configuration config) {
return new DefaultSqlSessionFactory(config);
}
}
onfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
return build(parser.parse());
}
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) {
XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);
return build(parser.parse());
}
// 最终会调用这个build方法，创建SqlSessionFactory的实现类
public SqlSessionFactory build(Configuration config) {
return new DefaultSqlSessionFactory(config);
}
}