不会框架不要紧，我带你自定义框架
不会框架不要紧，我带你自定义框架
前言：这标题说的有点大了，当一回标题党，之前在学JSP的时候提到了JSTL和EL表达式，由于一直钟情于Servlet,迟迟没有更新别的，这回算是跳出来了。这回放个大招，用Spring+SpringMVC+Spring Jdbc Template，实现一个增删改查加分页，但重点不在这，我的重心在于JSTL和EL表达式，标题虽然有点大，但话糙理不糙，我真的是要自定义框架，当然，这个框架可大可小，大的我不敢说，用JSTL自定义标签封装个分页还是可以的，也算补上JSTL和EL表达式的学习吧。对于那些一直跟着我跟新博客脚步的朋友，我提醒你们不要着急，你要是好奇就可以先试着跟着我的案例试试手，不要看到SSM框架就说还没学，不会啥的，哈哈，开玩笑，都没学怎么可能会呢，我说了，这篇的重点在于JSTL和EL表达式，重要的话说了不下三遍了，至于附加的SSM，我会持续跟新，会手把手带你理解的，别急，别急，就当先认识一下SSM吧。
环境准备
我用的开发工具是IDEA，如果有不会用IDEA的朋友可以看之前写过的博客《IDEA新手使用教程》，我建的这是一个Maven项目，如果有朋友不知道Maven，可以先看一下我之前写的介绍Maven的博客《Maven》,不知道如何配置Maven环境的可以看《Maven的安装与配置》https://www.cnblogs.com/zyx110/p/10801666.html不知道如何在IDEA中建Maven项目的朋友可以看《[IDEA为新手专业打造](https://www.cnblogs.com/zyx110/p/10802098.html)》，此案例还会用到Tomcat,同样，不会在IDEA中配置Tomcat的朋友可以看《[IDEA为新手专业打造](https://www.cnblogs.com/zyx110/p/10802098.html)》，好，完成这些，就可以开始敲代码了。
用JSTL封装框架
写之前先简单介绍一下JSTL和EL表达式：
JSTL简介及环境搭建
什么是JSTL
JSTL是Java中的一个定制标记库集
为什么要使用JSTL
实现了JSP页面中的代码复用，基于标签库原理，重复率较高的代码块支持复用，提高效率
书写JSP页面时可读性更强，长得很像XML，方便前端查看和参与开发
举例：
不同角色用户登录时显示不同提示信息
需要导入的JSTL模块
<!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>EL表达式配合使用JSTL
第一个JSTL小程序
在JSP页面中导入JSTL标签库
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>使用out标签输出
<c:out value="Hello JSTL"></c:out>JSTL标签的四大分类：核心标签、格式化标签、SQL标签、XML标签EL表达式
- EL表达式全名为Expression Language，经常与JSTL配合使用，使得JSP页面更直观，写法更简单。
普通表达式的写法： <%=session.getValue("name") %>
EL表达式写法： <c:out value="${sessionScope.name}" />
- EL表达式的格式
用美元符号“$”定界，内容包括在花括号“{ }”中；
- "."与" "运算符
² 通常情况是通用的${user.sex}或${user"sex"}
² " "还可以用来进行集合元素中的定位${booklist0.price}
² 当包含特殊字符时，必须使用" "，例如：${user"first-name"}
² 通过变量动态取值：${userparam}，例如：param可以是name/sex/others
EL变量
EL自动类型转换
EL隐式对象
EL运算符
JSP自定义标签
什么是自定义标签
在实际开发过程中不能出现大量的html+java代码相混合的jsp页面，但是有时候jsp标签和第三方标签满足不了正常的开发工作，这就需要开发人员将业务逻辑封装到符合jsp规范的类或接口中，来自己定义标签从而满足不同的开发需求。这样做的缺点是会加重开发的工作量，但在开发过程中简化了前后端的沟通，便于后期的维护，这点工作量也是微不足道的。我们可以自己定义一套标签机制，让完全不懂写代码的人开发一套网站出来。
开发第一个自定义标签
案例场景：
在页面中显示当前时间，格式：“当前时间为：2017年8月1日 10:30:50”
- 如果使用传统的jsp脚本开发，代码如下：
<%
SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
String date = sdf.format(new Date());
%>
当前时间为：<%=date %>显示结果：
- 下面使用自定义标签库来实现这个案例
第一步：编写自定义标签的业务逻辑处理类
DateTag
package utils;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class DateTag extends TagSupport {
private String format="yyyy-MM-dd HH:mm:ss";
private String color="blue";
private String fontSize="12px";
public void setFormat(String format) {
this.format = format;
}
public void setColor(String color) {
this.color = color;
}
public void setFontSize(String fontSize) {
this.fontSize = fontSize;
}
public int doStartTag() throws JspException {
//自定义业务
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(format);
String date = simpleDateFormat.format(new Date());
String htmlshow = "<p class='' style='font-size:"+fontSize+";color:"+color+"'>"+date+"</p>";
try {
pageContext.getOut().print(htmlshow);
} catch (IOException e) {
e.printStackTrace();
}
return super.doStartTag();
}
}第二步：在WEB-INF目录下编写*.tld文件注册标签
格式模板
datetag.tld
<?xml version="1.0" encoding="utf-8"?>
<taglib xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
version="2.1">
<tlib-version>1.0</tlib-version>
<short-name>myshortname</short-name>
<uri>http://mycompany.com</uri>
<tag>
<name>date</name>
<tag-class>utils.DateTag</tag-class>
<body-content>empty</body-content>
<attribute>
<name>format</name>
<required>false</required>
</attribute>
<attribute>
<name>color</name>
<required>false</required>
</attribute>
<attribute>
<name>fontSize</name>
<required>false</required>
</attribute>
</tag>
</taglib>JSP显示
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<%@ taglib prefix="z" uri="http://mycompany.com" %>
<%@ taglib prefix="c" uri="http://mycompany.com" %>
<html>
<head>
<title>显示时间</title>
</head>
<body>
<h1>index.jsp</h1>
<c:date/>
</body>
</html>
Spring+SpringMVC+Spring Jdbc Template
数据库结构
项目结构
Pom.xml
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.38</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!--Spring核心基础依赖-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<!--日志相关-->
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.2</version>
</dependency>
</dependencies>Web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!--处理中文乱码-->
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>forceEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!--设置访问静态资源-->
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.css</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.js</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.jpg</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.png</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.gif</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.mp3</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.mp4</url-pattern>
</servlet-mapping>
</web-app>applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
">
<!--配置注解要扫描的包-->
<context:component-scan base-package="controller"></context:component-scan>
<context:component-scan base-package="dao"></context:component-scan>
<context:component-scan base-package="Service"></context:component-scan>
<context:component-scan base-package="pojo"></context:component-scan>
<context:component-scan base-package="utils"></context:component-scan>
<context:component-scan base-package="test"></context:component-scan>
<mvc:annotation-driven></mvc:annotation-driven>
<!--配置spring-jdbcTemplate-->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://localhost:3306/bbb?useUnicode=true&characterEncoding=UTF-8"></property>
<property name="username" value="root"></property>
<property name="password" value="root"></property>
</bean>
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
<property name="dataSource" ref="dataSource"></property>
</bean>
<!--配置事务-->
<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"></property>
</bean>
<!--注册事务注解驱动-->
<tx:annotation-driven transaction-manager="txManager"></tx:annotation-driven>
<!--配置访问静态资源-->
<mvc:resources mapping="/js/**" location="/js/"></mvc:resources>
<mvc:resources mapping="/css/**" location="/css/"></mvc:resources>
<mvc:resources mapping="/img/**" location="/img/"></mvc:resources>
<!--配置视图解析器-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!--配置前缀-->
<property name="prefix" value="/"></property>
<!--配置后缀-->
<property name="suffix" value=".jsp"></property>
</bean>
<!--创建文件上传组件对象-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"></bean>
</beans>Book
package pojo;
public class Book {
@Override
public String toString() {
return "Book{" +
"id=" + id +
", bookname='" + bookname + '\'' +
", price=" + price +
'}';
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getBookname() {
return bookname;
}
public void setBookname(String bookname) {
this.bookname = bookname;
}
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
private int id;
private String bookname;
private int price;
}PageBean
package pojo;
import java.util.List;
public class PageBean<T> {
private int pageCode;//当前页码
private int totalPage;//总页数
private int count;//总记录数
private int pageSize;//每页记录数
private List<T> pageList;//每页的数据
public PageBean(int pageCode, int pageSize, int count, List<T> pageList) {
this.pageCode = pageCode;
this.count = count;
this.pageSize = pageSize;
this.pageList = pageList;
}
public PageBean() {
}
public int getPageCode() {
return pageCode;
}
public void setPageCode(int pageCode) {
this.pageCode = pageCode;
}
public int getTotalPage() {
int tp = count/pageSize;
return count%pageSize==0 ? tp : tp+1;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public List<T> getPageList() {
return pageList;
}
public void setPageList(List<T> pageList) {
this.pageList = pageList;
}
}BookDao
package dao;
import pojo.Book;
import java.util.List;
public interface BookDao {
public List<Book> findByPage(int pageCode,int pageSize);
public int count();
}BookDaoImpl
package dao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;
import pojo.Book;
import java.util.List;
@Repository
public class BookDaoImpl implements BookDao {
@Autowired
private JdbcTemplate jdbcTemplate;
@Override
public List<Book> findByPage(int pageCode, int pageSize) {
String sql = "select * from book limit ?,?";
Object[] param = {(pageCode-1)*pageSize,pageSize};
return jdbcTemplate.query(sql,new BeanPropertyRowMapper<Book>(Book.class),param);
}
@Override
public int count() {
String sql = "select count(*) from book";
return jdbcTemplate.queryForObject(sql,Integer.class);
}
}BookService
package Service;
import pojo.Book;
import pojo.PageBean;
public interface BookService {
public PageBean<Book> findByPage(int pageCode,int pageSize);
}BookServiceImpl
package Service;
import dao.BookDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import pojo.Book;
import pojo.PageBean;
@Service
public class BookServiceImpl implements BookService {
@Autowired
private BookDao bookDao;
@Override
public PageBean<Book> findByPage(int pageCode, int pageSize) {
return new PageBean<Book>(pageCode,pageSize,bookDao.count(),bookDao.findByPage(pageCode,pageSize));
}
}BookController
package controller;
import Service.BookService;
import com.sun.org.apache.xml.internal.resolver.readers.XCatalogReader;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import pojo.Book;
import pojo.PageBean;
import utils.RequestPage;
@Controller
@RequestMapping("/book")
public class BookController {
@Autowired
private BookService bookService;
@RequestMapping("/query")
public String findByPage(Integer page, Model model){
page = RequestPage.getPage(page);//判断是否为空
PageBean<Book> pageBean = bookService.findByPage(page,RequestPage.PAGE_SIZE);
model.addAttribute("pageBean",pageBean);
return "book";
}
}DateTag
package utils;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class DateTag extends TagSupport {
private String format="yyyy-MM-dd HH:mm:ss";
private String color="blue";
private String fontSize="12px";
public void setFormat(String format) {
this.format = format;
}
public void setColor(String color) {
this.color = color;
}
public void setFontSize(String fontSize) {
this.fontSize = fontSize;
}
public int doStartTag() throws JspException {
//自定义业务
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(format);
String date = simpleDateFormat.format(new Date());
String htmlshow = "<p class='' style='font-size:"+fontSize+";color:"+color+"'>"+date+"</p>";
try {
pageContext.getOut().print(htmlshow);
} catch (IOException e) {
e.printStackTrace();
}
return super.doStartTag();
}
}PageTag
package utils;
import pojo.PageBean;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import java.io.IOException;
public class PageTag extends TagSupport {
private PageBean pageBean;
private String url;
public void setUrl(String url) {
this.url = url;
}
public void setPageBean(PageBean pageBean) {
this.pageBean = pageBean;
}
@Override
public int doStartTag() throws JspException {
try {
StringBuffer sb = new StringBuffer();
//首页
sb.append("<a href=\"" + url + "?page=1\">首页</a> ");
//上一页
if (pageBean.getPageCode() <= 1) {
sb.append("<span style=\"color: #555;\">上一页</span> ");
} else {
sb.append("<a href=\"" + url + "?page=" + (pageBean.getPageCode() - 1) + "\">上一页</a> ");
}
//显示页码
int begin, end;
if (pageBean.getTotalPage() <= 10) {
begin = 1;
end = pageBean.getTotalPage();
} else {
begin = pageBean.getPageCode() - 5;
end = pageBean.getPageCode() + 4;
if (begin < 1) {
begin = 1;
end = 10;
} else if (end > pageBean.getTotalPage()) {
begin = pageBean.getTotalPage() - 9;
end = pageBean.getTotalPage();
}
}
for (int i = begin; i <= end; i++) {
if (i == pageBean.getPageCode()) {
sb.append("<span style=\"color:red;\">" + i + "</span> ");
} else {
sb.append("<a href=\"" + url + "?page=" + i + "\">[" + i + "]</a> ");
}
}
//下一页
if (pageBean.getPageCode() >= pageBean.getTotalPage()) {
sb.append("<span style=\"color: #555;\">下一页</span>");
} else {
sb.append("<a href=\"" + url + "?page=" + (pageBean.getPageCode() + 1) + "\">下一页</a> ");
}
//尾页
sb.append("<a href=\"" + url + "?page=" + pageBean.getTotalPage() + "\">尾页</a> \n" +
" 页码" + pageBean.getPageCode() + "/" + pageBean.getTotalPage());
pageContext.getOut().print(sb.toString());
} catch (IOException e) {
e.printStackTrace();
}
return super.doStartTag();
}
}
RequestPage
package utils;
public class RequestPage {
public static final int PAGE_SIZE =5;
public static Integer getPage(Integer page){
if (page==null||page<1){
page=1;
}
return page;
}
}datetag.tld
<?xml version="1.0" encoding="utf-8"?>
<taglib xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
version="2.1">
<tlib-version>1.0</tlib-version>
<short-name>myshortname</short-name>
<uri>http://mycompany.com</uri>
<tag>
<name>date</name>
<tag-class>utils.DateTag</tag-class>
<body-content>empty</body-content>
<attribute>
<name>format</name>
<required>false</required>
</attribute>
<attribute>
<name>color</name>
<required>false</required>
</attribute>
<attribute>
<name>fontSize</name>
<required>false</required>
</attribute>
</tag>
<tag>
<name>page</name>
<tag-class>utils.PageTag</tag-class>
<body-content>empty</body-content>
<attribute>
<name>pageBean</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>url</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>book.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="z" uri="http://mycompany.com" %>
<link rel="stylesheet" href="${pageContext.request.contextPath}/css/book.css">
<html>
<head>
<title>图书</title>
</head>
<body>
<h1 align="center">图书列表</h1>
<hr>
<table>
<tr>
<th>ID</th>
<th>书名</th>
<th>价格</th>
</tr>
<c:forEach var="book" items="${pageBean.pageList}">
<tr>
<td>${book.id}</td>
<td>${book.bookname}</td>
<td>${book.price}</td>
</tr>
</c:forEach>
</table>
<div id="page">
<z:page url="${pageContext.request.contextPath}/book/query" pageBean="${pageBean}"></z:page>
</div>
</body>
</html>运行显示
分享结束
后面我会持续分享SSM框架知识，欲知后文如何，请看下回分解
*****************************************************************************************************
我的博客园地址：https://www.cnblogs.com/zyx110/
转载请说明出处
我不能保证我所说的都是对的，但我能保证每一篇都是用心去写的，我始终认同“分享的越多，你的价值增值越大”，欢迎大家关注我的技术分享“Java匹马行天下”和学习心得分享“匹马行天下”，在分享中进步，越努力越幸运，人生赢在转折处，改变从现在开始！
支持我的朋友们记得点波推荐哦，您的肯定就是我前进的动力。
本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2019-08-03 ，如有侵权请联系 cloudcommunity@tencent.com 删除
评论
登录后参与评论
推荐阅读