分享一下实现jsp模板继承

2019独角兽企业重金招聘Python工程师标准>>>

初期学javaweb的时候动态输出网页就靠servlet和jsp完成了&＃xff0c;后来简单了解了php和python可以通过渲染网页模板完成网页的继承&＃xff0c;也在官网上了解了一下jsp模板的继承&＃xff0c;在这里分享一下。

jsp继承网页模板只需要两个类就可以简单完成&＃xff0c;依赖于rapid-framework-3.9.3.20100923.jar

第一次发表博文&＃xff0c;还希望大家多多鼓励~

这个是BlockTag类&＃xff0c;主要功能是定义jsp中的模板标签即

package com.cheney.jspInheritance;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

/**
*
* Project: jspInheritance
* Class: BlockTag
* &＃64;author : Cheney
* &＃64;Date 2015年9月8日下午9:06:36
* &＃64;version 1.0
*
*/
public class BlockTag extends TagSupport{

   private static final long serialVersionUID &＃61; -8246166191638588615L;

   private String name;

   public void setName(String name) {
       this.name &＃61; name;
   }

   /**
   * &＃64;return EVAL_BODY_INCLUDE or EVAL_BODY_BUFFERED or SKIP_BODY
   */
   &＃64;Override
   public int doStartTag() throws JspException {
       return getOverriedContent() &＃61;&＃61; null ? EVAL_BODY_INCLUDE : SKIP_BODY;
   }

   /**
   * &＃64;return EVAL_PAGE or SKIP_PAGE
   */
   &＃64;Override
   public int doEndTag() throws JspException {
       String overriedContent &＃61; getOverriedContent();
       if(overriedContent &＃61;&＃61; null) {
           return EVAL_PAGE;
       }

       try {
           pageContext.getOut().write(overriedContent);
       } catch (IOException e) {
           throw new JspException("write overridedContent occer IOException,block name:"&＃43;name,e);
       }
       return EVAL_PAGE;
   }

   private String getOverriedContent() {
       String varName &＃61; Utils.getOverrideVariableName(name);
       return (String)pageContext.getRequest().getAttribute(varName);
   }
}

下面这个是OverwriteTag 类,主要功能是定义jsp中子页面的继承标签即

package com.cheney.jspInheritance;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;
import org.apache.commons.lang3.StringUtils;

/**
*
* Project: jspInheritance
* Class: OverwriteTag
* &＃64;author: Cheney
* &＃64;Date 2015年9月8日下午9:12:04
* &＃64;version 1.0
*
*/
public class OverwriteTag extends BodyTagSupport {
private static final long serialVersionUID &＃61; -8379959647039117369L;

   private String name;

   public void setName(String name) {
       this.name &＃61; name;
   }

   &＃64;Override
   public int doStartTag() throws JspException {
       return isOverrided() ? SKIP_BODY : EVAL_BODY_BUFFERED;
   }

   &＃64;Override
   public int doEndTag() throws JspException {
       if(isOverrided()) {
           return EVAL_PAGE;
       }
       BodyContent b &＃61; getBodyContent();
//       System.out.println("Override.content:"&＃43;b.getString());
       String varName &＃61; Utils.getOverrideVariableName(name);

       pageContext.getRequest().setAttribute(varName, b.getString());
       return EVAL_PAGE;
   }

   private boolean isOverrided() {
       String varName &＃61; Utils.getOverrideVariableName(name);
       return pageContext.getRequest().getAttribute(varName) !&＃61; null;
   }
}

下面这个是一个工具类&＃xff0c;作用是定义标签的格式

package com.cheney.jspInheritance;
/**
*
* Project: jspInheritance
* Class: Utils
* &＃64;author: Cheney
* &＃64;Date 2015年9月10日下午8:46:53
* &＃64;version 1.0
*
*/
class Utils {

   public static String BLOCK &＃61; "__jsp_override__";

   static String getOverrideVariableName(String name) {
       return BLOCK &＃43; name;
    }
}