mvc(三)

最新推荐文章于 2024-10-30 10:59:51 发布

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在做增删改之前要先导入之前所学过的一些工具类以及jar包

需要导入的jar包
在这里插入图片描述

导入之前所写过的工具类等
在这里插入图片描述

将处理中文乱码的配置加入安全目录下的web.xml中

<?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>web_mvc</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <!-- 处理中文乱码 -->
  <filter>
    <filter-name>encodingFiter</filter-name>
    <filter-class>com.xfz.util.EncodingFiter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>encodingFiter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>com.xfz.framework.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>mvcXmlLocation</param-name>
      <param-value>/mvc.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>*.action</url-pattern>
  </servlet-mapping>
  
</web-app>

准备工作到这里结束，开始编码

写一个BookDao继承BaseDao
先写分页的查询，再写增删改的一些通用方法

注意：用完数据库连接的一些方法时要记得关闭数据库，否则在后面的课程中会出现太多连接的错误

package com.xfz.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;

import com.xfz.entity.Book;
import com.xfz.util.BaseDao;
import com.xfz.util.DBAccess;
import com.xfz.util.PageBean;
import com.xfz.util.StringUtils;

public class BookDao extends BaseDao<Book>{
	//查询
	public List<Book> list(Book book,PageBean pageBean) throws InstantiationException, IllegalAccessException, SQLException{
		String sql="select * from t_mvc_book where true";
		String bname=book.getBname();
		int bid=book.getBid();
		if(StringUtils.isNotBlank(bname)) {
			sql+=" and bname like '%"+bname+"%'";
		}
		if(bid!=0) {
			sql+=" and bid= "+bid;
		}
		return super.executeQuery(sql, Book.class, pageBean);
	}
	
	//增加
	public int add(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException {
		String sql="insert into t_mvc_book values (?,?,?)";
		return super.executeUpdate(sql, new String[] {"bid","bname","price"},book);
	}
	
	//修改
	public int edit(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException {
		String sql="update t_mvc_book set bname=?,price=? where bid=?";
		return super.executeUpdate(sql, new String[] {"bname","price","bid"},book);
	}
	
	//删除
	public int del(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException {
		String sql="delete from t_mvc_book where bid=?";
		return super.executeUpdate(sql, new String[] {"bid"},book);
	}
	
	public static void main(String[] args) {
		BookDao bookDao=new BookDao();
		Book book=new Book(141313, "啦啦啦", 56);
		try {
			bookDao.del(book);
		} catch (IllegalArgumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}

将BookDao中的重复的代码封装起来

在这里插入代码片package com.xfz.util;

import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.xfz.entity.Book;

/**
 * @author ld
 * @param <T>
 * 用来处理所有表的通用的增删改查
 * 
 * 查询指的是通用分页的查询
 */
public class BaseDao<T> {
	/**
	 * @param sql   可能不同的表，那么意味着sql是变化的，那么它是从子类处理好再传到父类
	 * @param claz   需要返回不同的对象集合 Book.class/Order.class
	 * @param pagebean   可能要分页
	 * @return
	 * @throws SQLException
	 * @throws IllegalAccessException 
	 * @throws InstantiationException 
	 */
	public List<T> executeQuery(String sql,Class claz,PageBean pageBean) throws SQLException, InstantiationException, IllegalAccessException{
		List<T> list=new ArrayList<>();
		//建立连接
		Connection con=DBAccess.getConnection();
		//拿到处理对象
		PreparedStatement ps=null;
		ResultSet rs=null;
		if(pageBean !=null && pageBean.isPagination()) {//是否分页
			//分页
			/**
			 * 分析：
			 *  1.分页与pagebean中total  意味着需要查询数据库得到total赋值给pagebean
			 *  2.查询出符合条件的某一页的数据
			 */
			//通过原生sql拼接出查询符合条件的总记录数的sql语句
			//select count(*) from (select * from t_mvc_book where bname like '%圣墟%') t;
			String countSql=getCountSql(sql);
			ps=con.prepareStatement(countSql);
			rs=ps.executeQuery();
			if(rs.next()) {
				pageBean.setTotal(rs.getObject(1).toString());
			}
			
			//select * from t_mvc_book where bname like '%圣墟%' limit 0,10;
			String pageSql=getPageSql(sql,pageBean);
			ps=con.prepareStatement(pageSql);
			rs=ps.executeQuery();
		}else {
			//不分页
			ps=con.prepareStatement(sql);
			rs=ps.executeQuery();
		}
		
		T t=null;
		while(rs.next()) {//如果说游标有下一个就放到list集合中
			//list.add(new Book(rs.getInt("bid"), rs.getString("bname"), rs.getFloat("price")));
			t=(T) claz.newInstance();//t 相当于book对象
			//获取所有属性
			Field [] fields=claz.getDeclaredFields();
			//给每一个属性赋值
			for (Field f : fields) {
				//打开访问权限
				f.setAccessible(true);
				f.set(t, rs.getObject(f.getName()));
			}
			list.add(t);
		}
		DBAccess.close(con, ps, rs);
		return list;
	}

	private String getPageSql(String sql,PageBean pageBean) {
		// TODO Auto-generated method stub
		return sql+" limit "+pageBean.getStartIndex()+","+pageBean.getRows();
	}

	private String getCountSql(String sql) {
		// TODO Auto-generated method stub
		return "select count(1) from ("+sql+") t";
	}
	
	/**
	 * @param sql   代表增删改的sql语句
	 * @param attrs   代表sql语句中的问号
	 * @param t   实体类（里面包含了参数值）
	 * @return
	 * @throws SQLException 
	 * @throws IllegalAccessException 
	 * @throws IllegalArgumentException 
	 */
	public int executeUpdate(String sql,String [] attrs,T t) throws IllegalArgumentException, IllegalAccessException, SQLException {
		Connection con=DBAccess.getConnection();
		PreparedStatement ps=con.prepareStatement(sql);
//		ps.setInt(1, book.getBid());
//		ps.setString(2, book.getBname());
//		ps.setFloat(3, book.getPrice());
		//反射
		Field field=null;
		//拿到所有的属性对象并且遍历
		for (int i = 0; i < attrs.length; i++) {
			try {
				field=t.getClass().getDeclaredField(attrs[i]);
				field.setAccessible(true);
				ps.setObject(i+1,field.get(t));
			} catch (NoSuchFieldException | SecurityException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		int num=ps.executeUpdate();
		DBAccess.close(con, ps, null);
		return num;
	}
}

然后在BookDao中进行增删测试
打开数据库输入查询语句，然后运行代码之后再运行查询语句
在这里插入图片描述
增加结果：

删除结果：

接着写web层，写一个BookAction继承ActionSupport并且实现模拟驱动接口ModelDriven
写入五个方法增删改查注意还有新增修改的跳转页面的方法

package com.xfz.web;

import java.sql.SQLException;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.xfz.dao.BookDao;
import com.xfz.entity.Book;
import com.xfz.framework.ActionSupport;
import com.xfz.framework.ModelDriven;
import com.xfz.util.PageBean;

public class BookAction extends ActionSupport implements ModelDriven<Book>{
	private Book book=new Book();
	private BookDao bookDao=new BookDao();
	
	//增删改查的五个方法
	
	/**
	 * @param req
	 * @param resp
	 * @return
	 * 查询
	 */
	public String list(HttpServletRequest req,HttpServletResponse resp) {
		//分页
		PageBean pageBean=new PageBean();
		pageBean.setRequest(req);
		try {
			List<Book> list=this.bookDao.list(book, pageBean);
			req.setAttribute("bookList", list);
			req.setAttribute("pageBean", pageBean);
		} catch (InstantiationException | IllegalAccessException | SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return "list";
	}
	
	
	/**
	 * @param req
	 * @param resp
	 * @return
	 * 跳转新增修改页面（新增修改页面是同一个）
	 */
	public String preSave(HttpServletRequest req,HttpServletResponse resp) {
		if(book.getBid()!=0) {
			try {
				//数据回显的数据
				Book b=this.bookDao.list(book, null).get(0);
				req.setAttribute("book", b);
			} catch (InstantiationException | IllegalAccessException | SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return "edit";
	}
	
	/**
	 * @param req
	 * @param resp
	 * @return
	 * 增加
	 */
	public String add(HttpServletRequest req,HttpServletResponse resp){
		try {
			this.bookDao.add(book);
		} catch (IllegalArgumentException | IllegalAccessException | SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return "toList";
	}
	
	/**
	 * @param req
	 * @param resp
	 * @return
	 * 修改
	 */
	public String edit(HttpServletRequest req,HttpServletResponse resp) {
		try {
			this.bookDao.edit(book);
		} catch (IllegalArgumentException | IllegalAccessException | SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return "toList";
	}
	
	/**
	 * @param req
	 * @param resp
	 * @return
	 * 删除
	 */
	public String del(HttpServletRequest req,HttpServletResponse resp) {
		try {
			this.bookDao.del(book);
		} catch (IllegalArgumentException | IllegalAccessException | SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return "toList";
	}

	@Override
	public Book getModel() {
		return book;
	}
	

}

配置conf里面的mvc.xml文件

注意：增删改的时候一定要用重定向不能用转发，查询则用转发，因为查询要携带参数到页面上去

<?xml version="1.0" encoding="UTF-8"?>
	<!--
		config标签:可以包含0~N个action标签
	-->
<config>

	<action path="/cal" type="com.xfz.web.CalAction">
		<forward name="rs" path="/rs.jsp" redirect="false" />
	</action>
	
	<!-- 增删改的时候一定要用重定向不能用转发 -->
	<action path="/book" type="com.xfz.web.BookAction">
		<forward name="list" path="/bookList.jsp" redirect="false" />
		<forward name="edit" path="/bookEdit.jsp" redirect="false" />
		<forward name="toList" path="/book.action?methodName=list"/>
	</action>
	
</config>

后台代码到这里结束，开始写前台代码
写一个书籍主页的jsp页面和一个书籍编辑的jsp页面

书籍主页：

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
    <%@ taglib uri="/xiefuzhen" prefix="fz"%>
<!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>
<h2>小说目录</h2>
	<br>

	<form action="${pageContext.request.contextPath}/book.action?methodName=list"
		method="post">
		<!-- <input type="hidden" name="rows" value="20"> -->
		<!-- <input type="hidden" name="pagination" value="false"> -->
		书名：<input type="text" name="bname">
		<input type="submit" value="确定">
	</form>
	<a href="${pageContext.request.contextPath}/book.action?methodName=preSave">新增</a>
	<table border="1" width="100%">
		<tr>
			<td>编号</td>
			<td>名称</td>
			<td>价格</td>
			<td>操作</td>
		</tr>
		<c:forEach items="${bookList }" var="b">
			<tr>
				<td>${b.bid }</td>
				<td>${b.bname }</td>
				<td>${b.price }</td>
				<td>
				  <a href="${pageContext.request.contextPath}/book.action?methodName=preSave&&bid=${b.bid}">修改</a>&nbsp;&nbsp;
				  <a href="${pageContext.request.contextPath}/book.action?methodName=del&&bid=${b.bid}">删除</a>
				</td>
			</tr>
		</c:forEach>
	</table>
	
	<fz:page pageBean="${pageBean}"></fz:page>

</body>
</html>

书籍编辑：

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!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></title>
</head>
<body>
<form action="${pageContext.request.contextPath}/book.action?methodName=${book.bname==null ? 'add' :'edit'}" method="post">
  bid:<input type="text" value="${book.bid}" name="bid"><br>
  bname:<input type="text" value="${book.bname}" name="bname"><br>
  price:<input type="text" value="${book.price}" name="price"><br>
  <input type="submit" value="ok">
</form>
</body>
</html>

如果要访问数据的话浏览地址必须要写成：自己的项目名/book.action?methodName=list不然会没有数据
增加界面显示：
在这里插入图片描述

数据库中：

修改界面显示：

删除界面显示（数据库）：