第 10
编写步骤：
- 标签处理类
- 编写 tld 文件
- taglib 导入 tld 文件
依赖
<dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>javax.servlet.jsp-api</artifactId> <version>2.3.3</version> <scope>provided</scope> </dependency>
定义无内容标签
package com.pengshiyu.taglibs; import javax.servlet.jsp.JspException; import javax.servlet.jsp.tagext.SimpleTagSupport; import java.io.IOException; public class HelloTag extends SimpleTagSupport { @Override public void doTag() throws JspException, IOException { this.getJspContext().getOut().println("hello"); } }
声明
package com.pengshiyu.taglibs; import javax.servlet.jsp.JspException; import javax.servlet.jsp.tagext.SimpleTagSupport; import java.io.IOException; public class HelloTag extends SimpleTagSupport { @Override public void doTag() throws JspException, IOException { this.getJspContext().getOut().println("hello"); } }
引入声明文件并使用标签
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %> <%@ taglib prefix="ext" uri="WEB-INF/custom.tld" %> <ext:Hello />
定义有内容标签
package com.pengshiyu.taglibs; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspWriter; import javax.servlet.jsp.tagext.SimpleTagSupport; import java.io.IOException; public class HelloTag extends SimpleTagSupport { @Override public void doTag() throws JspException, IOException { JspWriter out = this.getJspContext().getOut(); out.write("******"); this.getJspBody().invoke(out); out.write("******"); } }
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %> <%@ taglib prefix="ext" uri="WEB-INF/custom.tld" %> <ext:Hello> 你好 </ext:Hello>
输出
****** 你好 ******不再执行标签下面的内容
package com.pengshiyu.taglibs; import javax.servlet.jsp.JspException; import javax.servlet.jsp.SkipPageException; import javax.servlet.jsp.tagext.SimpleTagSupport; import java.io.IOException; public class HelloTag extends SimpleTagSupport { @Override public void doTag() throws JspException, IOException { this.getJspContext().getOut().write("以下内容不显示"); throw new SkipPageException(); } }
带有属性的标签
标签类
package com.pengshiyu.taglibs; import javax.servlet.jsp.JspException; import javax.servlet.jsp.tagext.SimpleTagSupport; import java.io.IOException; public class HelloTag extends SimpleTagSupport { private String name = ""; public void setName(String name) { this.name = name; } @Override public void doTag() throws JspException, IOException { this.getJspContext().getOut().write(this.name); } }
tld 配置
<tag> <name>Hello</name> <tag-class>com.pengshiyu.taglibs.HelloTag</tag-class> <body-content>scriptless</body-content> <attribute> <!-- 属性名称--> <name>name</name> <!-- 是否可选--> <required>true</required> <!-- 支持表达式--> <rtexprvalue>true</rtexprvalue> </attribute> </tag>
使用
<ext:Hello name="Tom"></ext:Hello>