JSP技术中的开发自定义标签
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2022-04-15 13:29:18
因为在jsp中不要使用一行java代码，所以说必须使用标签来移除显示的java代码，下面罗列一下标签的开发过程。
1.首先编写一个实现tag接口的java类
packag...
因为在jsp中不要使用一行java代码，所以说必须使用标签来移除显示的java代码，下面罗列一下标签的开发过程。
1.首先编写一个实现tag接口的java类
package com.bird.web.tag;
import java.io.ioexception;
import javax.servlet.http.httpservletrequest;
import javax.servlet..jspexception;
import javax.servlet.jsp.jspwriter;
import javax.servlet.jsp.tagext.tagsupport;
/**
* 显示来访者ip的自定义标签
* @author bird
*
*/
public class viewiptag extends tagsupport{
private static final long serialversionuid = 1l;
@override
public int dostarttag() throws jspexception {
httpservletrequest request = (httpservletrequest) this.pagecontext.getrequest();
jspwriter out = this.pagecontext.getout();
string ip = request.getremoteaddr();
try {
out.print(ip);
} catch (ioexception e) {
throw new runtimeexception(e);
}
return super.dostarttag();
}
}
package com.bird.web.tag;
import java.io.ioexception;
import javax.servlet.http.httpservletrequest;
import javax.servlet.jsp.jspexception;
import javax.servlet.jsp.jspwriter;
import javax.servlet.jsp.tagext.tagsupport;
/**
* 显示来访者ip的自定义标签
* @author bird
*
*/
public class viewiptag extends tagsupport{
private static final long serialversionuid = 1l;
@override
public int dostarttag() throws jspexception {
httpservletrequest request = (httpservletrequest) this.pagecontext.getrequest();
jspwriter out = this.pagecontext.getout();
string ip = request.getremoteaddr();
try {
out.print(ip);
} catch (ioexception e) {
throw new runtimeexception(e);
}
return super.dostarttag();
}
}
2.在tld文件里面对标签处理器类进行描述，tld文件的位置在web-inf下面可以在tomcat的webapps下面抄一下
<?xml version="1.0" encoding="utf-8" ?>
<taglib xmlns="https://java.sun.com/xml/ns/j2ee"
xmlns:xsi="https://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="https://java.sun.com/xml/ns/j2ee https://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>a tag library exercising simpletag handlers.</description>
<tlib-version>1.0</tlib-version>
<short-name>bird</short-name>
<uri>https://www.bird.net</uri>
<tag>
<name>viewip</name>
<tag-class>com.bird.web.tag.viewiptag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
<?xml version="1.0" encoding="utf-8" ?>
<taglib xmlns="https://java.sun.com/xml/ns/j2ee"
xmlns:xsi="https://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="https://java.sun.com/xml/ns/j2ee https://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>a tag library exercising simpletag handlers.</description>
<tlib-version>1.0</tlib-version>
<short-name>bird</short-name>
<uri>https://www.bird.net</uri>
<tag>
<name>viewip</name>
<tag-class>com.bird.web.tag.viewiptag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
4.在界面里面使用tablib命令到导入和使用标签就可以了，
<%@ page language="java" import="java.util.*" pageencoding="utf-8" contenttype="text/html; charset=utf-8"%>
<%@taglib uri="https://www.bird.net" prefix="bird" %>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>一个简单的自定义标签</title>
</head>
<body>
您访问的ip为: <bird:viewip/>
</body>
</html>
<%@ page language="java" import="java.util.*" pageencoding="utf-8" contenttype="text/html; charset=utf-8"%>
<%@taglib uri="" prefix="bird" %>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>一个简单的自定义标签</title>
</head>
<body>
您访问的ip为: <bird:viewip/>
</body>
</html>
作者 小愤青
1.首先编写一个实现tag接口的java类
package com.bird.web.tag;
import java.io.ioexception;
import javax.servlet.http.httpservletrequest;
import javax.servlet..jspexception;
import javax.servlet.jsp.jspwriter;
import javax.servlet.jsp.tagext.tagsupport;
/**
* 显示来访者ip的自定义标签
* @author bird
*
*/
public class viewiptag extends tagsupport{
private static final long serialversionuid = 1l;
@override
public int dostarttag() throws jspexception {
httpservletrequest request = (httpservletrequest) this.pagecontext.getrequest();
jspwriter out = this.pagecontext.getout();
string ip = request.getremoteaddr();
try {
out.print(ip);
} catch (ioexception e) {
throw new runtimeexception(e);
}
return super.dostarttag();
}
}
package com.bird.web.tag;
import java.io.ioexception;
import javax.servlet.http.httpservletrequest;
import javax.servlet.jsp.jspexception;
import javax.servlet.jsp.jspwriter;
import javax.servlet.jsp.tagext.tagsupport;
/**
* 显示来访者ip的自定义标签
* @author bird
*
*/
public class viewiptag extends tagsupport{
private static final long serialversionuid = 1l;
@override
public int dostarttag() throws jspexception {
httpservletrequest request = (httpservletrequest) this.pagecontext.getrequest();
jspwriter out = this.pagecontext.getout();
string ip = request.getremoteaddr();
try {
out.print(ip);
} catch (ioexception e) {
throw new runtimeexception(e);
}
return super.dostarttag();
}
}
2.在tld文件里面对标签处理器类进行描述，tld文件的位置在web-inf下面可以在tomcat的webapps下面抄一下
<?xml version="1.0" encoding="utf-8" ?>
<taglib xmlns="https://java.sun.com/xml/ns/j2ee"
xmlns:xsi="https://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="https://java.sun.com/xml/ns/j2ee https://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>a tag library exercising simpletag handlers.</description>
<tlib-version>1.0</tlib-version>
<short-name>bird</short-name>
<uri>https://www.bird.net</uri>
<tag>
<name>viewip</name>
<tag-class>com.bird.web.tag.viewiptag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
<?xml version="1.0" encoding="utf-8" ?>
<taglib xmlns="https://java.sun.com/xml/ns/j2ee"
xmlns:xsi="https://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="https://java.sun.com/xml/ns/j2ee https://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>a tag library exercising simpletag handlers.</description>
<tlib-version>1.0</tlib-version>
<short-name>bird</short-name>
<uri>https://www.bird.net</uri>
<tag>
<name>viewip</name>
<tag-class>com.bird.web.tag.viewiptag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
4.在界面里面使用tablib命令到导入和使用标签就可以了，
<%@ page language="java" import="java.util.*" pageencoding="utf-8" contenttype="text/html; charset=utf-8"%>
<%@taglib uri="https://www.bird.net" prefix="bird" %>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>一个简单的自定义标签</title>
</head>
<body>
您访问的ip为: <bird:viewip/>
</body>
</html>
<%@ page language="java" import="java.util.*" pageencoding="utf-8" contenttype="text/html; charset=utf-8"%>
<%@taglib uri="" prefix="bird" %>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>一个简单的自定义标签</title>
</head>
<body>
您访问的ip为: <bird:viewip/>
</body>
</html>
作者 小愤青
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