JSTL标签库

JSTL

• apache对EL表达式的扩展
• jstl.jar包
  • core 核心库
  • fmt 格式化标签库

---

Core (c标签)

• out && set

  • // ${xxx}
  • // 默认true

  ---

  • // scope默认pageContext

• remove

  • //所有域的变量

• url (路径前面自动加上项目名)

  • //必须以斜杠开头
  • 子标签 url后面添加参数
    • // value会有url编码

• if

  • 
    
    

• choose

  • 
    
    
    
    

• forEach

  • 
    
  • 
    ${item}
    

• 循环状态

• 
  ${vs.index} ${vs.count} ${vs.first} ${vs.last}
  

---

fmt (格式化标签)

---

SimpleTag || SimpleTagSurport

• void doTag() //每次执行
• void setJspBody(JspFragment jspBody)
• void setJspContext(JspContext context)
• JspTag getParent() //设置标签体
• void setParent(JspTag parent)

eg:

package com.suse.yuxin.tags;
import java.io.IOException;
import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.JspTag;
import javax.servlet.jsp.tagext.SimpleTag;
   
public class TestSimpleTag implements SimpleTag {
    @Override
    public void doTag() throws JspException, IOException {
      context.getOut().write("Hello tags");
    }

    @Override
    public JspTag getParent() {
        return parent;
    }

    @Override
    public void setJspBody(JspFragment jspBody) {
        this.fragment = jspBody;
    }
    
    
    private JspTag parent;
    private JspContext context;
    
    private JspFragment fragment;
    
    
    @Override
    public void setJspContext(JspContext pc) {
        this.context = pc;
    }

    @Override
    public void setParent(JspTag parent) {
        this.parent = parent;
    }
}

 1.0
 hellotag
 http://www.suse.yuxin/tags/1.0
 
 
    hellotag
    com.suse.yuxin.tags.TestSimpleTag
    empty
 
 

<%@ taglib prefix="mm" uri="/WEB-INF/tlds/hellotag.tld" %>

标签体内容

• empty
• scriptless 只能是EL表达式 或者其他标签 // ${el}

标签的属性

• 标签处理类至少要有一个set方法
• 在tld里面配置属性

   
    hellotag
    com.suse.yuxin.tags.TestSimpleTag
    empty
    
        test
        false
        true 
    
  

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# :)