笔记之_Java的自定义标签
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自定义类： import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.jsp.JspException; import javax.servlet.jsp.tagext.TagSupport; public class CalcTag extends TagSupport { private int numA; private int numB; public int getNumA() { return numA; } public void setNumA(int numA) { this.numA = numA; } public int getNumB() { return numB; } public void setNumB(int numB) { this.numB = numB; } @Override public int doStartTag() throws JspException { ServletResponse sr= super.pageContext.getResponse(); try { PrintWriter out=sr.getWriter(); out.println("<h1>"); out.print(numA); out.print("+"); out.print(numB); out.print("="); out.println(numA+numB); out.println("</h1>"); out.flush(); out.close(); } catch (IOException e) { e.printStackTrace(); } return SKIP_BODY; } } 创建后缀为tld的文件： <?xml version="1.0" encoding="UTF-8"?> <taglib version="2.0" xmlns="http://Java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd"> <tlib-version>1.0</tlib-version> <jsp-version>2.0</jsp-version> <short-name>Example TLD with Body</short-name> <tag> <name>calc</name> <tag-class>com.wisezone.tag.CalcTag</tag-class> <body-content>empty</body-content> <attribute> <name>numA</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>numB</name>//变量名首字母不能大写 <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib> web.xml中配置注册： <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <display-name>tagweb</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> <!-- 注册 --> <jsp-config> <taglib> <taglib-uri>/wisezone</taglib-uri> <taglib-location>/WEB-INF/mytag.tld</taglib-location> </taglib> </jsp-config> </web-app> jsp页面使用： <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@taglib uri="/wisezone" prefix="c" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <c:calc numB="${5+3 }"numA="${8+2 }"/> </body> </html>
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