自定义mvc的增删改查

简介: 自定义mvc的增删改查

1.将框架导出打包成jar包

1.


1.2 选中我们的助手包点击export

出现

1.3在输入框中输入jar点击选择jar file点击next

1.4 点击browse

输入文件名mvc点击finsih就得到我们的jar包了

2、导入配置文夹

2.1中央控制器

<?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>mymvc_crud</display-name>
  <servlet>
    <servlet-name>mvc</servlet-name>
    <servlet-class>com.zking.framework.DispatchServlet</servlet-class>
    <init-param>
      <param-name>configurationLocation</param-name>
      <param-value>/mvc.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>mvc</servlet-name>
    <url-pattern>*.action</url-pattern>
  </servlet-mapping>
</web-app>

2.2增删改配置文件

<?xml version="1.0" encoding="UTF-8"?>
<config>
  <action path="/book" type="com.zking.web.BookAction">
<!--   查询:BookList.jsp    返回值:list -->
<!--   * 增删改确定:book.action?methodName=list    返回值:toList -->
<!--   * 增加修改跳转对应界面:bookEdit.jsp      返回值:toEdit -->
    <forward name="list" path="/bookList.jsp" redirect="false" />
    <forward name="toList" path="/book.action?methodName=list" redirect="true" />
    <forward name="toEdit" path="/bookEdit.jsp" redirect="false" />
  </action>
</config>

3、编写后端代码

3.1 通用增删改查

package com.zking.util;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import com.zking.util.DBAccess;
import com.zking.util.PageBean;
/**
 * 所有Dao层的父类
 * 
 * @author 
 *
 * @2023年7月3日 下午10:52:21
 */
public class BaseDao<T> {
  /**
   * 通用的增删改方法
   * 
   * @param book
   * @throws Exception
   */
  public void executeUpdate(String sql, T t, String[] attrs) throws Exception {
    Connection con = DBAccess.getConnection();
    PreparedStatement pst = con.prepareStatement(sql);
    /*
     * 思路: 1.从传进来的t中读取属性值 2.往预定义对象中设置了值
     * 
     * t->book f->bid
     */
    for (int i = 0; i < attrs.length; i++) {
      Field f = t.getClass().getDeclaredField(attrs[i]);
      f.setAccessible(true);
      pst.setObject(i + 1, f.get(t));
    }
    pst.executeUpdate();
  }
  /**
   * 通用分页查询
   * 
   * @param sql
   * @param clz
   * @return
   * @throws Exception
   */
  public List<T> executeQuery(String sql, Class<T> clz, PageBean pageBean) throws Exception {
    List<T> list = new ArrayList<T>();
    Connection con = DBAccess.getConnection();
    PreparedStatement pst = null;
    ResultSet rs = null;
    /*
     * 是否需要分页? 无需分页(项目中的下拉框,查询条件教员下拉框,无须分页) 必须分页(项目中列表类需求、订单列表、商品列表、学生列表...)
     */
    if (pageBean != null && pageBean.isPagination()) {
      // 必须分页(列表需求)
      String countSQL = getCountSQL(sql);
      pst = con.prepareStatement(countSQL);
      rs = pst.executeQuery();
      if (rs.next()) {
        pageBean.setTotal(String.valueOf(rs.getObject(1)));
      }
      // 挪动到下面,是因为最后才处理返回的结果集
      String pageSQL = getPageSQL(sql, pageBean);// 符合条件的某一页数据
      pst = con.prepareStatement(pageSQL);
      rs = pst.executeQuery();
    } else {
      // 不分页(select需求)
      pst = con.prepareStatement(sql);// 符合条件的所有数据
      rs = pst.executeQuery();
    }
    while (rs.next()) {
      T t = clz.newInstance();
      Field[] fields = clz.getDeclaredFields();
      for (Field f : fields) {
        f.setAccessible(true);
        f.set(t, rs.getObject(f.getName()));
      }
      list.add(t);
    }
    return list;
  }
  /**
   * 将原生SQL转换成符合条件的总记录数countSQL
   * 
   * @param sql
   * @return
   */
  private String getCountSQL(String sql) {
    return "select count(1) from (" + sql + ") t";
  }
  /**
   * 将原生SQL转换成pageSQL
   * 
   * @param sql
   * @param pageBean
   * @return
   */
  private String getPageSQL(String sql, PageBean pageBean) {
    return sql + " limit " + pageBean.getStartIndex() + "," + pageBean.getRows();
  }
}

3. 2book实现增删改查类

package com.zking.web;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.zking.dao.BookDao;
import com.zking.entity.Book;
import com.zking.framework.ActionSupport;
import com.zking.framework.ModelDriver;
import com.zking.util.PageBean;
/**
 * book工作类
 * @author 
 *
 * @2023年7月3日 下午10:53:52
 */
public class BookAction extends ActionSupport implements ModelDriver<Book>{
  private Book book = new Book();
  private BookDao bookDao = new BookDao();
  @Override
  public Book getModel() {
    return book;
  }
  /*
   * 增删改最终都要跳回查询界面
   * 分析增删改查一共有多少结果集的配置
   * 查询:BookList.jsp    返回值:list
   * 增删改确定:book.action?methodName=list    返回值:toList
   * 增加修改跳转对应界面:bookEdit.jsp      返回值:toEdit
   */
  public String add(HttpServletRequest req, HttpServletResponse resp) {
    try {
      bookDao.add(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toList";
  }
  public String list(HttpServletRequest req, HttpServletResponse resp) {
    try {
      PageBean pageBean = new PageBean();
      pageBean.setRequest(req);
      List<Book> list = bookDao.list(book,pageBean);
      req.setAttribute("books", list);
      req.setAttribute("pageBean", pageBean);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "list";
  }
  public String delete(HttpServletRequest req, HttpServletResponse resp) {
    try {
      bookDao.delete(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toList";
  }
  public String edit(HttpServletRequest req, HttpServletResponse resp) {
    try {
      bookDao.edit(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toList";
  }
  /**
   * 跳转到新增修改页面
   * @param req
   * @param resp
   * @return
   */
  public String toEdit(HttpServletRequest req, HttpServletResponse resp) {
    try {
      /*
       * 如果是跳转修改页面,那么需要做bid条件的精准查询
       */
      if(book.getBid() != 0) {
        List<Book> list = bookDao.list(book, null);
        req.setAttribute("b", list.get(0));
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toEdit";
  }
}

3.4.分页助手类

package com.zking.tag;
import com.zking.util.PageBean;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;
import java.io.IOException;
import java.util.Map;
import java.util.Set;
/**
 * Page助手类
 * 
 * @author
 *
 */
public class PageTag extends BodyTagSupport {
  private static final long serialVersionUID = 1L;
  private PageBean pageBean;
  public PageBean getPageBean() {
    return pageBean;
  }
  public void setPageBean(PageBean pageBean) {
    this.pageBean = pageBean;
  }
  @Override
  public int doStartTag() throws JspException {
    // 获取流
    JspWriter out = pageContext.getOut();
    try {
      out.print(toHTML());
    } catch (IOException e) {
      e.printStackTrace();
    }
    return SKIP_BODY;
  }
  /**
   * JSP自定义页面内容展示
   * 
   * @return
   */
  private String toHTML() {
    StringBuilder sb = new StringBuilder();
    // 这里拼接的是一个上一次发送的请求以及携带的参数,唯一改变的就是页码
    sb.append("<form id='pageBeanForm' action='" + pageBean.getUrl() + "' method='post'>");
    sb.append("<input type='hidden' name='page'>");
    // 重要设置拼接操作,将上一次请求参数携带到下一次
    Map<String, String[]> paMap = pageBean.getParameterMap();
    if (paMap != null && paMap.size() > 0) {
      Set<Map.Entry<String, String[]>> entrySet = paMap.entrySet();
      for (Map.Entry<String, String[]> entry : entrySet) {
        for (String val : entry.getValue()) {
          if (!"page".equals(entry.getKey())) {
            sb.append("<input type='hidden' name='" + entry.getKey() + "' value='" + val + "'>");
          }
        }
      }
    }
    sb.append("</form>");
    /**
     * 页码数据配置
     */
    int page = pageBean.getPage(); //当前页码
    int max = pageBean.getMaxPage();//最大页码
    int before = page > 4 ? 4 : page - 1;//当前页码前面的页码
    int after = 10 - 1 - before;//当前页码后面的页码
    //如果最大页码没有10页,就显示当前页面后面的所有页码 max - page
    after = page + after > max ? max - page : after;
    // 初始页码和结束页码值判断 disabled
    boolean startFlag = page == 1;
    boolean endFlag = max == page;
    // 拼接分页条
    sb.append("<ul class='pagination'>");
    sb.append("<li class='page-item " + (startFlag ? "disabled" : "")
        + "'><a class='page-link' href='javascript:gotoPage(1)'>首页</a></li>");
    sb.append("<li class='page-item " + (startFlag ? "disabled" : "")
        + "'><a class='page-link' href='javascript:gotoPage(" + pageBean.getPrevPage() + ")'>&lt;</a></li>");
    // 代表了当前页的前4页
    for (int i = before; i > 0; i--) {
      sb.append("<li class='page-item'><a class='page-link' href='javascript:gotoPage(" + (page - i) + ")'>"
          + (page - i) + "</a></li>");
    }
    sb.append("<li class='page-item active'><a class='page-link' href='javascript:gotoPage(" + pageBean.getPage()
        + ")'>" + pageBean.getPage() + "</a></li>");
    // 代表了当前页的后5页
    for (int i = 1; i <= after; i++) {
      sb.append("<li class='page-item'><a class='page-link' href='javascript:gotoPage(" + (page + i) + ")'>"
          + (page + i) + "</a></li>");
    }
    sb.append("<li class='page-item " + (endFlag ? "disabled" : "")
        + "'><a class='page-link' href='javascript:gotoPage(" + pageBean.getNextPage() + ")'>&gt;</a></li>");
    sb.append("<li class='page-item " + (endFlag ? "disabled" : "")
        + "'><a class='page-link' href='javascript:gotoPage(" + pageBean.getMaxPage() + ")'>尾页</a></li>");
    sb.append(
        "<li class='page-item go-input'><b>到第</b><input class='page-link' type='text' id='skipPage' name='' /><b>页</b></li>");
    sb.append("<li class='page-item go'><a class='page-link' href='javascript:skipPage()'>确定</a></li>");
    sb.append("<li class='page-item'><b>共" + pageBean.getTotal() + "条</b></li>");
    sb.append("</ul>");
    // 拼接分页的js代码
    sb.append("<script type='text/javascript'>");
    sb.append("function gotoPage(page) {");
    sb.append("document.getElementById('pageBeanForm').page.value = page;");
    sb.append("document.getElementById('pageBeanForm').submit();");
    sb.append("}");
    sb.append("function skipPage() {");
    sb.append("var page = document.getElementById('skipPage').value;");
    sb.append("if (!page || isNaN(page) || parseInt(page) < 1 || parseInt(page) > " + max + ") {");
    sb.append("alert('请输入1~N的数字');");
    sb.append("return;");
    sb.append("}");
    sb.append("gotoPage(page);");
    sb.append("}");
    sb.append("</script>");
    return sb.toString();
  }
}

4、编写前端代码

4.1 数据显示主界面

<%@ 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="http://jsp.xzs.cn" prefix="w" %> 
<!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">
<link
  href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.css"
  rel="stylesheet">
<script
  src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.js"></script>
<title>书籍列表</title>
<style type="text/css">
.page-item input {
  padding: 0;
  width: 40px;
  height: 100%;
  text-align: center;
  margin: 0 6px;
}
.page-item input, .page-item b {
  line-height: 38px;
  float: left;
  font-weight: 400;
}
.page-item.go-input {
  margin: 0 10px;
}
</style>
</head>
<body>
<c:if test="${empty books }">
<jsp:forward page="/BookServlet"></jsp:forward>
</c:if>
  <form class="form-inline"
    action="${pageContext.request.contextPath }/book.action?methodName=list" method="post">
    <div class="form-group mb-2">
      <input type="text" class="form-control-plaintext" name="bname" placeholder="请输入书籍名称">
        <input name="pagination" value="false" type="hidden">
    </div>
    <button type="submit" class="btn btn-primary mb-2">查询</button>
    <a class="btn btn-primary mb-2" href="${pageContext.request.contextPath }/book.action?methodName=toEdit">新增</a>
  </form>
  <table class="table table-striped">
    <thead>
      <tr>
        <th scope="col">书籍ID</th>
        <th scope="col">书籍名</th>
        <th scope="col">价格</th>
        <th scope="col">操作</th>
      </tr>
    </thead>
    <tbody>
      <c:forEach  var="b" items="${books }">
      <tr>
        <td>${b.bid }</td>
        <td>${b.bname }</td>
        <td>${b.price }</td>
        <td>
          <a href="${pageContext.request.contextPath }/book.action?methodName=toEdit&bid=${b.bid}">修改</a>
          <a href="${pageContext.request.contextPath }/book.action?methodName=delete&bid=${b.bid}">删除</a>
        </td>
      </tr>
      </c:forEach>
    </tbody>
  </table>
  <!-- 这一行代码就相当于前面分页需求前端的几十行了 -->
  <w:page pageBean="${pageBean }"></w:page>
</body>
</html>

4.2 默认运行显示所有数据servlet

package com.zking.web;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/BookServlet")
public class BookServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doPost(request, response);
  }
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.sendRedirect(request.getContextPath()+"/book.action?methodName=list");
  }
}

4.3 新增、修改共用页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<%@ taglib uri="http://jsp.xzs.cn" prefix="z"%> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> 
<!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">
<link
  href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.css"
  rel="stylesheet">
<script
  src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.js"></script>
<title>书籍新增/修改</title>
</head>
<body>
  <form class="form-inline"
    action="${pageContext.request.contextPath }/book.action?methodName=${empty b ? 'add' : 'edit'}" method="post">
    书籍ID:<input type="text" name="bid" value="${b.bid }"><br>
    书籍名称:<input type="text" name="bname" value="${b.bname }"><br>
    书籍价格:<input type="text" name="price" value="${b.price }"><br>
    <input type="submit">
  </form>
</body>
</html>


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