自定义MVC--增删改查

使用自定义mvc框架完成CRUD操作

1、通用分页的jar、自定义mvc框架、自定义标签
 导入jar、导入之前写好的pageTag、自定义mvc.xml

1.1导入需要用到的jar包

1.2导入之前已写好的所有辅助类（可在前面写的mvc博客参考）

1.3优化BaseDao

 package com.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.sun.corba.se.spi.legacy.connection.GetEndPointInfoAgainException;
 import com.entity.Book;

 /**
  * 代表你要对哪个实体类对应的表进行分页查询
  * @author **
  *
  * @param <T>
  */
 public class BaseDao<T> {

     /**
      *
      * @param sql  查询不同的实体类，对应的sql语句不同所以需要传递
      * @param clz  生产出不同的实体类对应的实列，然后装进list容器中返回
      * @param pageBean  决定是否分页
      * @return
      * @throws SQLException
      * @throws IllegalAccessException
      * @throws InstantiationException
      */
     public List<T> executeQuery(String sql,Class clz,PageBean pageBean)throws SQLException, InstantiationException, IllegalAccessException {
         Connection con = DBAccess.getConnection();
         PreparedStatement ps =null;
         ResultSet rs = null;

         if(pageBean!=null && pageBean.isPagination()) {
             //需要分页
             //计算总记录数
             String consql= getCountsql(sql);
             ps = con.prepareStatement(consql);
             rs=ps.executeQuery();
             if(rs.next()) {
                 pageBean.setTotal(rs.getLong(1)+"");
             }
             //查询出符合条件的结果集
             String pagesql = getPageSql(sql,pageBean);
             ps = con.prepareStatement(pagesql);
             rs = ps.executeQuery();

         }else {
             ps = con.prepareStatement(sql);
             rs = ps.executeQuery();
         }
         List<T> list= new ArrayList<>();
         T t;
         while(rs.next()) {
             /**
              *1、实例化一个book对象(该对象为空)
              *2、取book的所有属性，然后给器赋值
              *  2.1获取所有属性对象
              *  2.2给属性赋值
              *3、赋值之后的book对象装进list容器中
              */
 //            list.add(new Book(rs.getInt("bid"), rs.getString("bname"), rs.getFloat("price")));

             t =(T) clz.newInstance();
             Field[] fields = clz.getDeclaredFields();
             for (Field field : fields) {
                 field.setAccessible(true);
                 field.set(t, rs.getObject(field.getName()));
             }
             list.add(t);
         }
         DBAccess.close(con, ps, rs);
         return list;

     }

     /**
      * 利用原生sql拼接出符合条件的结果集的查询sql
      * @param sql
      * @param pageBean
      * @return
      */
     private String getPageSql(String sql, PageBean pageBean) {
         // TODO Auto-generated method stub
         return sql+" LIMIT "+pageBean.getStartIndex()+","+pageBean.getRows()+"";
     }

     /**
      *
      * @param sql
      * @return
      */
     private String getCountsql(String sql) {

         return "SELECT COUNT(1) FROM ("+sql+")t";
     }

     /**
      * 通用的增删改方法
      * @param sql  决定增删改的一种
      * @param attrs   决定？的位置  new String[]{"bid","bname","price"}
      * @param t   要操作的实体类
      * @return
      * @throws SQLException
      * @throws IllegalAccessException
      * @throws IllegalArgumentException
      * @throws SecurityException
      * @throws NoSuchFieldException
      */
     public int executeUpdate(String sql,String[] attrs,T t) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException{
         Connection con = DBAccess.getConnection();
         PreparedStatement ps = con.prepareStatement(sql);
 //        ps.setString(2, book.getBname());
 //        ps.setFloat(3, book.getPrice());
 //        ps.setInt(1, book.getBid());

         for (int i = 1; i <= attrs.length; i++) {
             Field f = t.getClass().getDeclaredField(attrs[i-1]);
             f.setAccessible(true);
             ps.setObject(i, f.get(t));
         }
         int num = ps.executeUpdate();

         return num;
     }

 }

1.4配置mvc.xml文件

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

<config>

    <!-- <action path="/addCal" type="com.yuan.web.AddCalAction">
        <forward name="res" path="/res.jsp" redirect="false" />
    </action>

    <action path="/delCal" type="com.yuan.web.DelCalAction">
        <forward name="res" path="/res.jsp" redirect="true"/>
    </action>  -->

     <action path="/cal" type="com.yuan.web.CalAction">
        <forward name="res" path="/res.jsp" redirect="false"/>
    </action> 

    <action path="/book" type="com.yuan.web.BookAction">
        <forward name="list" path="/bookList.jsp" redirect="false"/>
        <forward name="edit" path="/bookEdit.jsp" redirect="false"/>
        <!-- 增删改一定要用重定向，查询用转发， -->
        <forward name="toList" path="/book.action?methodName=list"/>
    </action> 

</config>

注：在这里需要注意forward标签里面的redirect，当值为false时为重定向，为true或者不填则是转发，

配置的时候增删改一定要用重定向，查询用转发，否则会出现小bug！！！！

2、dao层 通用的增删改方法

2.1新建一个BookDao

 package com.dao;

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

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

 public class BookDao extends BaseDao<Book> {

     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+"%'";//注意拼接的时候一定要记得在前面打一个空格
         }
         if(bid != 0) {
             sql+= " AND bid ="+bid;
         }
         System.out.println(sql);
         return super.executeQuery(sql, Book.class, pageBean);
     }

     /**
      * 修改方法
      */
     public int edit (Book book) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException {
         String sql="UPDATE t_mvc_book SET bname=?,price=? WHERE bid=?";
         return super.executeUpdate(sql, new String[] {"bname","price","bid"}, book);
     }
     /**
      * 新增方法
      */
     public int add(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException {
         String sql = "INSERT INTO t_mvc_book VALUES(?,?,?)";
         System.out.println(sql);
         return super.executeUpdate(sql, new String[] {"bid","bname","price"}, book);
     }

     /**
      * 删除方法
      */
     public int del(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException {
         String sql = "DELETE FROM t_mvc_book WHERE bid=?";
         return super.executeUpdate(sql, new String[] {"bid"}, book);
     }

 }

2.2新建一个与数据库数据匹配的实体类Book

 package com.entity;

 public class Book {

     private int bid;
     private String bname;
     private float price;
     public int getBid() {
         return bid;
     }
     public void setBid(int bid) {
         this.bid = bid;
     }
     public String getBname() {
         return bname;
     }
     public void setBname(String bname) {
         this.bname = bname;
     }
     public float getPrice() {
         return price;
     }
     public void setPrice(float price) {
         this.price = price;
     }
     @Override
     public String toString() {
         return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
     }

 }

3、web层

3.1新建BookAction 继承上次写的优化后的子控制器并且实现（implement）ModelDrivern模型驱动接口

 package com.yuan.web;

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

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

 import com.dao.BookDao;
 import com.entity.Book;
 import com.util.PageBean;
 import com.yuan.framework.ActionSupport;
 import com.yuan.framework.ModelDrivern;

 /**
  * 分页查询
  * @author **
  *
  */
 public class BookAction extends ActionSupport implements ModelDrivern<Book> {

     private Book book = new Book();
     private BookDao bookDao = new BookDao();

     public String list(HttpServletRequest req, HttpServletResponse resp) {
         PageBean bean = new PageBean();
         bean.setRequest(req);
         try {
             List<Book> list = this.bookDao.list(book, bean);
             req.setAttribute("booklist", list);
             req.setAttribute("pageBean", bean);
         } catch (InstantiationException | IllegalAccessException | SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }

         return "list";
     }

     /**
      * 跳转到增加或者修改页面
      * @param req
      * @param resp
      * @return
      */
     public String preSave(HttpServletRequest req, HttpServletResponse resp) {
         //bid的类型是int类型 int类型的默认值是0，如果jsp未传递bid的参数值，那么bid=0；跳转新增，否则跳转修改。
         if(book.getBid() == 0) {
             System.out.println("增加....");
         }else {
             //修改数据后回显
             try {
                 Book b = this.bookDao.list(book, null).get(0);
                 req.setAttribute("book", b);
             } catch (InstantiationException | IllegalAccessException | SQLException e) {
                 e.printStackTrace();
             }
         }

         return "edit";
     }

     /**
      * 新增
      * @param req
      * @param resp
      * @return
      */
     public String add(HttpServletRequest req, HttpServletResponse resp) {
         try {
             this.bookDao.add(book);
         } catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException | SecurityException
                 | SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         //新增完之后需要刷新页面
         return "toList";
     }
     /**
      * 修改
      * @param req
      * @param resp
      * @return
      */
     public String edit(HttpServletRequest req, HttpServletResponse resp) {
         try {
             this.bookDao.edit(book);
         } catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException | SecurityException
                 | SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         //修改之后需要刷新页面
         return "toList";
     }

     /**
      * 删除
      * @param req
      * @param resp
      * @return
      */
     public String del(HttpServletRequest req, HttpServletResponse resp) {
         try {
             this.bookDao.del(book);
         } catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException | SecurityException
                 | SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         //删除之后需要刷新页面
         return "toList";
     }

     @Override
     public Book getModel() {
         // TODO Auto-generated method stub
         return book;
     }

 }

4、jsp页面

4.1数据展示首页booklist

 <%@ page language="java" contentType="text/html; charset=UTF-8"
     pageEncoding="UTF-8"%>
     <%@ page isELIgnored="false"%>
     <%@taglib prefix="z" uri="/yuan" %>
     <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
 <!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>
 <%-- <c:if test="${empty bookList }">
 <jsp:forward page="bookServlet.action"></jsp:forward>
 </c:if> --%>
 <h2>小说目录</h2>
     <br>
     <form action="${pageContext.request.contextPath}/book.action?methodName=list"
         method="post">
         书名：<input type="text" name="bname"> <input type="submit"
             value="确定">
             <input type="hidden" name="pagination" value="false">
             <input type="hidden" name="rows" value="20">
     </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="s">
             <tr>
                 <td>${s.bid }</td>
                 <td>${s.bname }</td>
                 <td>${s.price}</td>
                 <td>
                 <a href="${pageContext.request.contextPath}/book.action?methodName=preSave&&bid=${s.bid }">修改</a>&nbsp;&nbsp;&nbsp;
                 <a href="${pageContext.request.contextPath}/book.action?methodName=del&&bid=${s.bid }">删除</a>&nbsp;&nbsp;&nbsp;
                 </td>
             </tr>
             </c:forEach>
     </table>
     <z:Page pageBean="${pageBean }"></z:Page>

 </body>
 </html>

4.2新增和修改的页面

因为我们在web层做了判断，判别出是新增还是修改，所以不需要担心只有一个界面的问题

 <%@ 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>Insert title here</title>
 </head>
 <body>
 <form action="${pageContext.request.contextPath}/book.action" method="post">
 <input type="hidden" name="methodName" value="${book.bname==null ? 'add' : 'edit' }">
 书籍ID：<input type="text" name="bid" value="${book.bid }"><br>
 书籍名称：<input type="text" name="bname" value="${book.bname }"><br>
 书籍价格：<input type="text" name="price" value="${book.price }"><br>
 <input type="submit">
 </form>
 </body>
 </html>

5、结果展示

5.1新增（查询）

5.2修改

5.3删除

谢谢观看^-^！！！