一、使用TagSupport类案例解析
1.自定义Tag使用jdbc连接mysql数据库
1.1定义标签处理器类
package com.able.tag;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class DBconnectionTag extends TagSupport {
private String driver;// 连接驱动
private String url;// 连接db地址
private String password;// 连接db密码
private String sql;// 查询sql
private String username;// 连接db用户名
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
@Override
public int doEndTag() throws JspException {
try {
Class.forName(this.driver);
conn = DriverManager.getConnection(this.url,this.username,this.password);
stmt = conn.createStatement();
rs = stmt.executeQuery(this.sql);
if (rs != null) {
while (rs.next()) {
pageContext.getOut().print(rs.getString("cname")+"<br/>");
}
}
return EVAL_PAGE;
} catch (Exception e) {
e.printStackTrace();
return SKIP_PAGE;
} finally {
try {
if (rs != null) {
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public String getDriver() {
return driver;
}
public void setDriver(String driver) {
this.driver = driver;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getSql() {
return sql;
}
public void setSql(String sql) {
this.sql = sql;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
}
1.2 在tag.tld文件中添加tag标签
<tag> <name>DBconnectionTag</name><!-- 定义标签名 --> <tag-class>com.able.tag.DBconnectionTag</tag-class> <body-content>empty</body-content> <!-- 定义标签体为空 --> <attribute> <name>driver</name> <required>true</required> <rtexprvalue>true</rtexprvalue><!-- 可以使用el表达式接收参数 --> </attribute> <attribute> <name>url</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>username</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>password</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>sql</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag>
1.3 定义jsp,页面引入标签库，并定义标签
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<tm:DBconnectionTag url="jdbc:mysql://192.168.9.223:3306/test_2016" driver="com.mysql.jdbc.Driver" username="root" password="ablejava" sql="select * from course"/>
<br/>
<br>
</body>
</html>
2.forEach循环遍历输出集合
2.1 定义自定义标签处理器类
package com.able.tag;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class ForEachTag extends TagSupport {
private String var;
private Iterator<?> iterator;
public void setItem(Object item) {
if (item instanceof Map) {
Map items = (Map) item;
this.iterator = items.entrySet().iterator();
} else {
Collection<?> c = (Collection) item;
this.iterator = c.iterator();
}
}
@Override
public int doStartTag() throws JspException {
if (this.process())
return EVAL_BODY_INCLUDE;
else
return EVAL_PAGE;
}
@Override
public int doAfterBody() throws JspException {
if (this.process()) {
return EVAL_BODY_AGAIN;
} else {
return EVAL_PAGE;
}
}
private boolean process() {
if (null != iterator && iterator.hasNext()) {
Object item = iterator.next();
pageContext.setAttribute(var, item);
return true;
} else {
return false;
}
}
public String getVar() {
return var;
}
public void setVar(String var) {
this.var = var;
}
}
2.3 在tld文件中定义标签
<tag> <name>foreach</name> <tag-class>com.able.tag.ForEachTag</tag-class> <body-content>JSP</body-content> <attribute> <name>var</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>item</name> <required>true</required> <rtexprvalue>true</rtexprvalue> <!-- <type>java.lang.Object</type> --> <type>java.util.Collection</type> </attribute> </tag>
2.4 在jsp页面定义循环标签
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%
List<String> list = new ArrayList<String>();
list.add("aa");
list.add("bb");
list.add("cc");
Map map = new HashMap();
map.put("1","a");
map.put("2","b");
map.put("3","c");
map.put("4","b");
%>
<tm:foreach var="hi" item="<%=map %>">
<h1>${hi }</h1>
</tm:foreach>
<br/>
<br>
</body>
</html>
3.定义Iterator循环输出数组
3.1定义标签处理器类
package com.able.tag;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class IteratorTagDemo extends TagSupport {
private String var;
private String[] items;
private int i =1;
@Override
public int doStartTag() throws JspException {
if (items != null && items.length>0) {
pageContext.setAttribute("name", items[0]);
return EVAL_BODY_INCLUDE;
} else {
return SKIP_BODY;
}
}
@Override
public int doAfterBody() throws JspException {
if (i<items.length) {
pageContext.setAttribute("name", items[i]);
i++;
return EVAL_BODY_AGAIN;
} else {
return SKIP_BODY;
}
}
@Override
public int doEndTag() throws JspException {
// TODO Auto-generated method stub
return super.doEndTag();
}
public String getVar() {
return var;
}
public void setVar(String var) {
this.var = var;
}
public String[] getItems() {
return items;
}
public void setItems(String[] items) {
this.items = items;
}
}
3.2 在.tld文件中定义标签
<tag> <name>IteratorTagDemo</name><!-- 定义标签名 --> <tag-class>com.able.tag.IteratorTagDemo</tag-class> <body-content>scriptless</body-content> <!-- 定义标签体为空 --> <attribute> <name>var</name> <required>true</required> </attribute> <attribute> <name>items</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag>
3.3在jsp页面定义Tag
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%
String[] nbastar = {"jordan","kobar"};
pageContext.setAttribute("nbastar", nbastar);
%>
<tm:IteratorTagDemo items="${nbastar }" var="name">
${name }
</tm:IteratorTagDemo>
<br/>
<br>
</body>
</html>
4.自定义Tag实现防盗链
4.1自定义标签处理器类
package com.able.tag;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class SkipPageOrEvalPageTag extends TagSupport {
@Override
public int doEndTag() throws JspException {
HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
String referer = request.getHeader("referer");
String url = "http://"+request.getServerName();
if (referer != null && referer.startsWith(url)) {
return EVAL_PAGE;
} else {
try {
pageContext.getOut().print("盗链");
} catch (IOException e) {
e.printStackTrace();
}
}
return SKIP_PAGE;
}
}
4.2在.tld文件中定义tag标记
<tag> <name>SkipPageOrEvalPageTag</name><!-- 定义标签名 --> <tag-class>com.able.tag.SkipPageOrEvalPageTag</tag-class> <body-content>empty</body-content> <!-- 定义标签体为空 --> </tag>
4.3定义访问连接的SkipPageOrEvalPageAccess.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<!-- 防盗链 -->
<a href="http://localhost/JSP_Tag_Demo/SkipPageOrEvalPage.jsp">防盗链</a>
<br/>
<br>
</body>
</html>
4.4定义访问成功后的SkipPageOrEvalPage.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<!-- 防盗链 -->
<tm:SkipPageOrEvalPageTag/>
<h1>SkipPageOrEvalPage标签处理学习</h1>
<br/>
<br>
</body>
</html>
二、使用SimpleTagSupport实现自定义Tag
1.继承SimpleTagSupport类实现循环输出集合或数组
1.1定义标签处理器类
package com.able.simpleTag;
import java.io.IOException;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class foreachAll extends SimpleTagSupport {
private Object items;
private String var;
private Collection collection;
public void setItems(Object items) {
this.items = items;
if (items instanceof Collection) {//list set
collection=(Collection) items;
}
if (items instanceof Map) {
Map map=(Map) items;
collection =map.entrySet();//set
}
if (items instanceof Object[]) {
Object obj[]=(Object[]) items;
collection=Arrays.asList(obj);
}
if (items.getClass().isArray()) {
this.collection=new ArrayList();
int length=Array.getLength(items);
for (int i=0; i<length ; i++) {
Object value=Array.get(items, i);
this.collection.add(value);
}
}
}
public void setVar(String var) {
this.var = var;
}
@Override
public void doTag() throws JspException, IOException {
Iterator it=this.collection.iterator();
while (it.hasNext()) {
Object value=it.next();
this.getJspContext().setAttribute(var, value);
this.getJspBody().invoke(null);
}
}
}
1.2定义.tld文件中添加标签
<tag> <name>simpleforeachAll</name> <tag-class>com.able.simpleTag.foreachAll</tag-class> <body-content>scriptless</body-content> <attribute> <name>items</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>var</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag>
1.3定义jsp页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%
List<String> list = new ArrayList<String>();
list.add("aa");
list.add("bb");
list.add("cc");
Map map = new HashMap();
map.put("1","a");
map.put("2","b");
map.put("3","c");
map.put("4","b");
int arr[]={1,2,3,4,5};
request.setAttribute("arr", arr);
%>
<br/>
<br>
<tm:simpleforeachAll var="i" items="${arr }">${i }</tm:simpleforeachAll>
</body>
</html>
2.使用SimpleTagSupport实现防盗链
2.1定义标签处理器类
package com.able.simpleTag;
import java.io.IOException;
import java.sql.Date;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.SkipPageException;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class RefererTag extends SimpleTagSupport {
private String site;
private String page;
public void setSite(String site) {
this.site = site;
}
public void setPage(String page) {
this.page = page;
}
@Override
public void doTag() throws JspException, IOException {
PageContext pageContext =(PageContext) this.getJspContext();
HttpServletRequest httpServletRequest=(HttpServletRequest) pageContext.getRequest();
HttpServletResponse httpServletResponse=(HttpServletResponse) pageContext.getResponse();
//1.referer
String referer=httpServletRequest.getHeader("referer");
if (referer==null || !referer.startsWith(site)) {
if (page.startsWith(httpServletRequest.getContextPath())) {
httpServletResponse.sendRedirect(page);
return;
}else if (page.startsWith("/")) {
httpServletResponse.sendRedirect(httpServletRequest.getContextPath()+page);
}else{
httpServletResponse.sendRedirect(httpServletRequest.getContextPath()+"/"+page);
}
throw new SkipPageException();
}
}
}
2.2 定义.tld文件
<tag> <name>referer</name> <tag-class>com.able.simpleTag.RefererTag</tag-class> <body-content>empty</body-content> <attribute> <name>site</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>page</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag>
2.3定义refererAccess.jsp文件
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<!-- 防盗链 -->
<a href="http://localhost/JSP_Tag_Demo/Referer.jsp">防盗链</a>
<br/>
<br>
</body>
</html>
2.4定义访问页面referer.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<!-- 防盗链 -->
<tm:referer site="" page=""/>
<br/>
<br>
</body>
</html>
三、使用BodyTagSupport实现自定义Tag
1.继承BodyTagSupport实现简单数据输出
1.1定义标签处理器类
package com.able.bodyTag;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;
public class BodyTagSupportTag extends BodyTagSupport {
private BodyContent bodyContent;
@Override
public int doEndTag() throws JspException {
String content = bodyContent.getString();
System.out.println(content);
String newStr = "www.cnblogs.com/izhongwei";
JspWriter jspWriter= bodyContent.getEnclosingWriter();
try {
jspWriter.write(newStr);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return EVAL_PAGE;
}
public BodyContent getBodyContent() {
return bodyContent;
}
public void setBodyContent(BodyContent bodyContent) {
this.bodyContent = bodyContent;
}
}
1.2在.tld文件中定义标签
<tag> <name>bodyTag</name><!-- 定义标签名 --> <tag-class>com.able.bodyTag.BodyTagSupportTag</tag-class> <body-content>scriptless</body-content> <!-- 定义标签体为空 --> </tag>
1.3定义jsp文件
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%-- <%@taglib uri="http://www.able.com" prefix="tm" %> --%>
<%-- <%@ taglib prefix="tm" uri="/WEB-INF/tlds/online.tld" %> --%>
<%@taglib prefix="tm" uri="/WEB-INF/tag.tld" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<tm:bodyTag>
hello
</tm:bodyTag>
<br/>
<br>
</body>
</html>
源码下载地址:https://github.com/ablejava/jsp-Tag
git克隆地址:https://github.com/ablejava/jsp-Tag.git