java 自定义标签-白红宇的个人博客

java 自定义标签

发布日期：2021-10-03 03:16:54 浏览次数：6 分类：技术文章

本文共 5776 字，大约阅读时间需要 19 分钟。

一种输入select内容

第一步

action实现

package *;

import java.io.IOException;

import java.io.Writer;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.servlet.jsp.JspException;

import javax.servlet.jsp.tagext.SimpleTagSupport;

import org.jboss.logging.Logger;

import cn.*.util.service.*;

public class SelectTag extends SimpleTagSupport {

private static final Logger log = Logger.getLogger(SelectTag.class);

//缓存map

private static Map<String, List<Map<String, String>>> cacheSelectMap = new HashMap<String, List<Map<String, String>>>();

// 标签的属性

private String id;

private String code;

private String name;

private String sql;

private boolean cache=false;

// 执行数据访问属性

private Connection conn = null;

private Statement st = null;

private ResultSet rs = null;

private static String url = null;

private static String username = null;

private static String password = null;

static

{

url = (*.getJDBC_URL());

username = (*.getJDBC_USERNAME());

password = (*.getJDBC_PASSWORD());

// 注册驱动类

try

{

Class.forName(*.getJDBC_CLASS_NAME());

}

catch (ClassNotFoundException e)

{

e.printStackTrace();

}

public void doTag() throws JspException, IOException {

try {

//获取页面输出流

Writer out = getJspContext().getOut();

if(cache&&cacheSelectMap.get(id)!=null&&cacheSelectMap.get(id).size()>0){//从缓存中写出数据

List<Map<String, String>> cacheData = cacheSelectMap.get(id);

for (Map<String, String> map : cacheData) {

String codeVo = map.get(code);

String nameVo = map.get(name);

out.write("<option value="+codeVo+">");

out.write(nameVo);

out.write("</option>");

}

}else{

//获取数据库连接

conn = DriverManager.getConnection(url, username, password);

// 创建Statement对象

st = conn.createStatement();

// 执行查询

rs = st.executeQuery(sql);

List<Map<String, String>> list = new ArrayList<Map<String,String>>();

// 在页面输出select

while (rs.next()) {

String codeVo = rs.getString(code);

String nameVo = rs.getString(name);

if(cache){//记录缓存

Map<String, String> map = new HashMap<String, String>();

map.put(code, codeVo);

map.put(name, nameVo);

list.add(map);

}

out.write("<option value="+codeVo+">");

out.write(nameVo);

out.write("</option>");

}

if(cache){

cacheSelectMap.put(id, list);

}

} catch (Exception e) {

e.printStackTrace();

log.error(e);

// throw new JspException("自定义标签错误" + cnfe.getMessage());

} finally {

// 关闭结果集

try {

if (rs != null)

rs.close();

if (st != null)

st.close();

if (conn != null)

conn.close();

} catch (SQLException sqle) {

sqle.printStackTrace();

}

public String getCode() {

return code;

}

public void setCode(String code) {

this.code = code;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getSql() {

return sql;

}

public void setSql(String sql) {

this.sql = sql;

}

public boolean isCache() {

return cache;

}

public void setCache(boolean cache) {

this.cache = cache;

}

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

第二步

WEB-INF/tlds 下文件 selectTag.tld

<?xml version="1.0" encoding="utf-8"?>

<taglib 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 http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"

version="2.0">

<tlib-version>2.0</tlib-version>

<short-name>下拉框</short-name>

<tag>

<name>option</name>

<tag-class>cn.*.ncp.tag.SelectTag</tag-class>

<body-content>empty</body-content>

</attribute>

<name>cache</name>

</attribute>

</attribute>

</attribute>

</attribute>

</tag>

</taglib>

第三步

web.xml 引入自定义标签

<jsp-config>

<taglib-uri>/WEB-INF/selectTag</taglib-uri>

<taglib-location>/WEB-INF/selectTag.tld</taglib-location>

</taglib>

<taglib-uri>/WEB-INF/authTag</taglib-uri>

<taglib-location>/WEB-INF/authTag.tld</taglib-location>

</taglib>

</jsp-config>

第四步 jsp页面引入

<%@taglib prefix="select" uri="/WEB-INF/tlds/selectTag.tld"%>

应用

<select:option id="org_add_city" cache="true" name="" code="" sql=""/>

第二种权限自定义标签

action

package *;

import javax.servlet.jsp.JspException;

import javax.servlet.jsp.tagext.TagSupport;

/**

* 权限标签

* @author Administrator

public class AuthorTag extends TagSupport{

//菜单编号

private String code;

@Override

public int doStartTag() throws JspException {

//默认无权限

boolean result = false;

if("0".equals(code)){//有权限

result = true;

}

return result ? EVAL_BODY_INCLUDE : SKIP_BODY;

}

public String getCode() {

return code;

}

public void setCode(String code) {

this.code = code;

}

第二步

在 WEB-INF/tlds 下创建文件 authTag.tld

<?xml version="1.0" encoding="utf-8"?>

<taglib 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 http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"

version="2.0">

<tlib-version>1.0</tlib-version>

<short-name>author</short-name>

<tag>

<tag-class>cn.*.ncp.tag.AuthorTag</tag-class>

<body-content>tagdependent</body-content>

</attribute>

</tag>

</taglib>

第三步

web.xml 引入自定义标签

第四步 jsp页面引入

<%@taglib prefix="auth" uri="/WEB-INF/tlds/authTag.tld"%>

应用

<auth:a code="0">

</auth:a>

转载地址：https://blog.csdn.net/KANGBROTHER/article/details/50828613 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！

上一篇：学习连接

下一篇：ajax上传文件

发表评论

关于作者

喝酒易醉，品茶养心，人生如梦，品茶悟道，何以解忧？唯有杜康！

-- 愿君每日到此一游！

发表评论

最新留言

关于作者

推荐文章