第 10 章 ： 自定义标签
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
<?xml version="1.0" encoding="utf-8"?>
<taglib>
<tlib-version>1.0</tlib-version>
<jsp-version>2.0</jsp-version>
<short-name>Example TLD with Body</short-name>
<tag>
<name>Hello</name>
<tag-class>com.pengshiyu.taglibs.HelloTag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
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) {
= name;
}
@Override
public void doTag() throws JspException, IOException {
this.getJspContext().getOut().write();
}
}
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>
