The technical principle of the "Polymer" framework in the Java class library
The Polymer framework is a Java class library that supports web components development. It is based on the Web Components standard and provides a set of tools and APIs to simplify and accelerate the construction process of Web components.Polymer's technical principles mainly involve two key concepts: Web Components and Shadow DOM.
Web Components is a set of standards, including Custom Elements, Shadow Dom, and HTML Templates. They improve component development by encapsulating each part of the webpage into independent custom elements.Custom Elements allows developers to define their own HTML elements so that they can be reused and customized on web pages.Shadow Dom provides a mechanism that encapsulates the style, structure and behavior of the element in an independent scope to avoid conflicting with other elements.HTML Templates allows developers to create reused basic templates in order to instantiated in different places.
Polymer provides developers with a set of powerful and flexible tools and APIs by using these Web Components standards to simplify the creation and use of Web components.Developers can define their own components by writing the Polymer element class. The Polymer element class is the extension of the Custom Elements and provides some additional functions.For example, Polymer's binding syntax can be used to declare attributes and attribute bindings, and monitoring attribute changes.Developers can also use Polymer's event processing mechanism to handle user interaction.In addition, Polymer also provides some built -in functions, such as data binding, template rendering, and component style management.
The following is a simple Polymer element class code example:
import com.vaadin.flow.component.*;
import com.vaadin.flow.templatemodel.TemplateModel;
import com.vaadin.flow.component.Tag;
import com.vaadin.flow.component.dependency.HtmlImport;
@Tag("my-element")
@HtmlImport("frontend://src/my-element.html")
public class MyElement extends PolymerTemplate<MyElement.MyElementModel> {
public interface MyElementModel extends TemplateModel {
void setUsername(String username);
String getUsername();
}
public MyElement() {
getModel().setUsername("Polymer");
}
}
In this example, we define a Polymer element called "My-Element".We specify the label name of the element through the @TAG annotation, and the @Htmlimport annotation specifies the HTML template file path of the element.Polymertemplate is a base class provided by the Polymer framework to create a custom element bound to template.In the MyELEMENTMOL interface, we declare a attribute "username" and provide the corresponding getter and setter method.In myElement's constructor, we set the "username" property to "polymer".
Through the above code, we created a simple Polymer element.When adding this element to the page, Polymer will automatically render the template to the actual HTML and bind the "username" property to the corresponding position.In this way, we can use this custom element in the page and dynamically update the page content by changing the value of the "username" property.
In addition to the above code examples, some related configurations are required to use the Polymer framework, such as pom.xml, webpack.config.js and other files, as well as the installation and configuration of some construction tools.Due to space limitations, it is impossible to display them one by one. Please read the official documentation and related information of the Polymer framework for a deeper understanding and learning.
