转:struts2 标签

struts标签的继承

 

BodyTagSupport

        StrutsBodyTagSupport

                ComponentTagSupport

                         AbstractUITag

 

每个struts标签都继承AbstractUITag

 

重点是ComponentTagSupport:

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import javax.servlet.jsp.JspException;

import org.apache.struts2.components.Component;

import org.apache.struts2.dispatcher.Dispatcher;

import com.opensymphony.xwork2.inject.Container;

import com.opensymphony.xwork2.util.ValueStack;

public abstract class ComponentTagSupport extends StrutsBodyTagSupport {

    protected Component component;

    // 定义一个组件(虚方法)
    public abstract Component getBean(ValueStack stack, HttpServletRequest req, HttpServletResponse res);

    public int doEndTag() throws JspException {
        component.end(pageContext.getOut(), getBody());
        component = null;
        return EVAL_PAGE;
    }

    public int doStartTag() throws JspException {
        // 获取组件
        component = getBean(getStack(), (HttpServletRequest) pageContext.getRequest(), (HttpServletResponse) pageContext.getResponse());
        Container container = Dispatcher.getInstance().getContainer();
        container.inject(component);
        // 填充参数
        populateParams();
        // 组件开始
        boolean evalBody = component.start(pageContext.getOut());
        if (evalBody) {
            return component.usesBody() ? EVAL_BODY_BUFFERED : EVAL_BODY_INCLUDE;
        } else {
            return SKIP_BODY;
        }
    }

    protected void populateParams() {
    }

    public Component getComponent() {
        return component;
    }

}

 

如果自定义struts标签，那么一定要看这类的源码。这里记录下。。。