分页功能实现

QLBF11 · Nov 30, 2020 · 1c04c0f · 1c04c0f
1 parent 038c487
commit 1c04c0f
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Showing 11 changed files with 268 additions and 16 deletions.
diff --git a/UserqueryInfo/src/cn/itcast/dao/UserDao.java b/UserqueryInfo/src/cn/itcast/dao/UserDao.java
@@ -30,4 +30,20 @@ public interface UserDao {
     //修改一行时，提交时用
     void update(User user);
 
+    /**
+     * 查询总记录数，分页时用
+     * @return
+     * @param
+     */
+    int findTotalCount();
+
+
+    /**
+     * 分页查询每页记录的list数据
+     * @param start
+     * @param rows
+     * @param
+     * @return
+     */
+    List<User> findByPage(int start, int rows);
 }
diff --git a/UserqueryInfo/src/cn/itcast/dao/impl/UserDaoImpl.java b/UserqueryInfo/src/cn/itcast/dao/impl/UserDaoImpl.java
@@ -83,4 +83,18 @@ public void update(User user) {
         String sql="update user set name=?,gender=?,age=?,address=?,qq=?,email=? where id=?";
         template.update(sql,user.getName(),user.getGender(),user.getAge(),user.getAddress(),user.getQq(),user.getEmail(),user.getId());
     }
+
+    @Override
+    public int findTotalCount() {
+        //查询数据库总的记录条数，分页时要用
+        String sql="select count(*) from user";
+        return template.queryForObject(sql,Integer.class);
+    }
+
+    @Override
+    public List<User> findByPage(int start, int rows) {
+        //分页查询时，返回list集合到页面展示
+        String sql="select * from user limit ?,?";
+        return template.query(sql,new BeanPropertyRowMapper<User>(User.class),start,rows);
+    }
 }
diff --git a/UserqueryInfo/src/cn/itcast/domain/PageBean.java b/UserqueryInfo/src/cn/itcast/domain/PageBean.java
@@ -0,0 +1,71 @@
+package cn.itcast.domain;
+
+/**
+ * @author QLBF
+ * @version 1.0
+ * @date 2020/11/30 10:49
+ */
+
+import java.util.List;
+
+/**
+ * 分页对象，分页查询要用的,加了泛型T更加通用，其他表也可以用的
+ */
+public class PageBean<T> {
+    private int totalCount; //总记录数
+    private int totalPage; //总页码
+    private List<T> list; //每页展示的数据
+    private int currentPage; //当前页码
+    private int rows; //每页展示的记录数
+
+    @Override
+    public String toString() {
+        return "PageBean{" +
+                "totalCount=" + totalCount +
+                ", totalPage=" + totalPage +
+                ", list=" + list +
+                ", currentPage=" + currentPage +
+                ", rows=" + rows +
+                '}';
+    }
+
+    public int getTotalCount() {
+        return totalCount;
+    }
+
+    public void setTotalCount(int totalCount) {
+        this.totalCount = totalCount;
+    }
+
+    public int getTotalPage() {
+        return totalPage;
+    }
+
+    public void setTotalPage(int totalPage) {
+        this.totalPage = totalPage;
+    }
+
+    public List<T> getList() {
+        return list;
+    }
+
+    public void setList(List<T> list) {
+        this.list = list;
+    }
+
+    public int getCurrentPage() {
+        return currentPage;
+    }
+
+    public void setCurrentPage(int currentPage) {
+        this.currentPage = currentPage;
+    }
+
+    public int getRows() {
+        return rows;
+    }
+
+    public void setRows(int rows) {
+        this.rows = rows;
+    }
+}
diff --git a/UserqueryInfo/src/cn/itcast/service/UserService.java b/UserqueryInfo/src/cn/itcast/service/UserService.java
@@ -6,6 +6,7 @@
  * @date 2020/11/28 10:14
  */
 
+import cn.itcast.domain.PageBean;
 import cn.itcast.domain.User;
 
 import java.util.List;
@@ -48,4 +49,13 @@ public interface UserService {
 
     //删除选中
     void delSelectedUser(String[] ids);
+
+    /**
+     * 分页条件查询
+     * @param currentPage
+     * @param rows
+     * @param
+     * @return
+     */
+    PageBean<User> findUserByPage(String currentPage, String rows);
 }
diff --git a/UserqueryInfo/src/cn/itcast/service/impl/UserServiceImpl.java b/UserqueryInfo/src/cn/itcast/service/impl/UserServiceImpl.java
@@ -2,6 +2,7 @@
 
 import cn.itcast.dao.UserDao;
 import cn.itcast.dao.impl.UserDaoImpl;
+import cn.itcast.domain.PageBean;
 import cn.itcast.domain.User;
 import cn.itcast.service.UserService;
 
@@ -85,6 +86,51 @@ public void delSelectedUser(String[] ids) {
         }
     }
 
+
+
+    @Override
+    public PageBean<User> findUserByPage(String _currentPage, String _rows) {
+        //分页查询，在这里封装PageBean对象
+        //把string转为int
+        int currentPage=Integer.parseInt(_currentPage);
+        int rows=Integer.parseInt(_rows);
+
+        //为第一页点上一页出现异常做准备
+        if (currentPage<=0){
+            currentPage=1;
+        }
+
+
+        //1.创建空的PageBean对象
+        PageBean<User> pb=new PageBean<User>();
+        //2.设置参数
+        pb.setCurrentPage(currentPage);
+        pb.setRows(rows);
+
+        //3.调用dao查询总记录数
+        int totalCount=dao.findTotalCount();
+        pb.setTotalCount(totalCount);
+
+        //4.调用dao查询的List集合
+        //计算开始的记录索引
+        int start=(currentPage-1)*rows;
+        List<User> list=dao.findByPage(start,rows);
+        pb.setList(list);
+
+
+        //5.计算总页码
+        int totalPage=(totalCount % rows)==0?totalCount/rows:(totalCount/rows)+1;
+        pb.setTotalPage(totalPage);
+
+        //为最后一页点下一页出现异常做准备
+//        if (currentPage>=pb.getTotalPage()+1){
+//            currentPage=pb.getTotalPage();
+//        }
+
+        return pb;
+
+    }
+
     /*public static void main(String[] args) {
         User u=new User();
         u.setUsername("zhangsan1");

diff --git a/UserqueryInfo/src/cn/itcast/servlet/AddUserServlet.java b/UserqueryInfo/src/cn/itcast/servlet/AddUserServlet.java
@@ -41,7 +41,9 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
         service.addUser(user);//保存成功就x，不用返回
 
         //5.跳转到userListServlet
-        response.sendRedirect(request.getContextPath()+"/userListServlet");
+//        response.sendRedirect(request.getContextPath()+"/userListServlet");
+        response.sendRedirect(request.getContextPath()+"/findUserByPageServlet");
+
 
     }
 

diff --git a/UserqueryInfo/src/cn/itcast/servlet/DelSelectedServlet.java b/UserqueryInfo/src/cn/itcast/servlet/DelSelectedServlet.java
@@ -25,7 +25,9 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
         service.delSelectedUser(ids);
 
         //3.跳转查询所有Servlet，重定向或者转发都行
-        response.sendRedirect(request.getContextPath()+"/userListServlet");
+        //response.sendRedirect(request.getContextPath()+"/userListServlet");
+        response.sendRedirect(request.getContextPath()+"/findUserByPageServlet");
+
     }
 
     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

diff --git a/UserqueryInfo/src/cn/itcast/servlet/DelUserServlet.java b/UserqueryInfo/src/cn/itcast/servlet/DelUserServlet.java
@@ -25,10 +25,12 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
         service.deleteUser(id);
 
         //3.跳转到查询所有Servlet，重定向
-        response.sendRedirect(request.getContextPath()+"/userListServlet");
+        //response.sendRedirect(request.getContextPath()+"/userListServlet");
+        response.sendRedirect(request.getContextPath()+"/findUserByPageServlet");
+
 
         //这里因为没设置上面键值，所以用转发也行的
-        //request.getRequestDispatcher(request.getContextPath()+"/userListServlet").forward(request,response);
+        //request.getRequestDispatcher(request.getContextPath()+"/findUserByPageServlet").forward(request,response);
     }
 
     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

diff --git a/UserqueryInfo/src/cn/itcast/servlet/FindUserByPageServlet.java b/UserqueryInfo/src/cn/itcast/servlet/FindUserByPageServlet.java
@@ -0,0 +1,58 @@
+package cn.itcast.servlet;
+
+import cn.itcast.domain.PageBean;
+import cn.itcast.domain.User;
+import cn.itcast.service.UserService;
+import cn.itcast.service.impl.UserServiceImpl;
+
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+/**
+ * @author QLBF
+ * @version 1.0
+ * @date 2020/11/30 12:08
+ */
+@WebServlet("/findUserByPageServlet")
+public class FindUserByPageServlet extends HttpServlet {
+    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        request.setCharacterEncoding("utf-8");
+        //1.获取参数,从list.jsp获取的
+        String currentPage=request.getParameter("currentPage");
+        String rows=request.getParameter("rows");
+
+        //防止刚进来首页时没值
+        if (currentPage==null ||"".equals(currentPage)){
+            currentPage="1";
+        }
+        if (rows==null || "".equals(rows)){
+            rows="5";
+        }
+        //2.调用service查询
+        UserService service=new UserServiceImpl();
+        PageBean<User> pb=service.findUserByPage(currentPage,rows);
+
+        //为最后一页点下一页出现异常做准备
+        if (Integer.parseInt(currentPage)>=pb.getTotalPage()+1){
+            currentPage= String.valueOf(pb.getTotalPage());
+        }
+
+        //System.out.println(pb);
+        //3.将PageBean存入request
+        request.setAttribute("pb",pb);
+
+        //4.转发到list.jsp
+        request.getRequestDispatcher("/list.jsp").forward(request,response);
+
+
+
+    }
+
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        this.doPost(request, response);
+    }
+}
diff --git a/UserqueryInfo/src/cn/itcast/servlet/UpdateUserServlet.java b/UserqueryInfo/src/cn/itcast/servlet/UpdateUserServlet.java
@@ -42,7 +42,9 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
         service.updateUser(user);
 
         //5.跳转到查询所有Servlet，重定向，userListServlet显示列表的
-        response.sendRedirect(request.getContextPath()+"/userListServlet");
+//        response.sendRedirect(request.getContextPath()+"/userListServlet");
+        response.sendRedirect(request.getContextPath()+"/findUserByPageServlet");
+
     }
 
     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

diff --git a/UserqueryInfo/web/list.jsp b/UserqueryInfo/web/list.jsp
@@ -127,7 +127,7 @@
             </tr>
 
             <%--通过el表达式来获取servlet传给它的集合--%>
-            <c:forEach items="${users}" var="user" varStatus="s">
+            <c:forEach items="${pb.list}" var="user" varStatus="s">
                 <tr>
                     <th><input type="checkbox" name="uid" value="${user.id}"></th>
                     <td>${s.count}</td>
@@ -151,23 +151,52 @@
     <div>
         <nav aria-label="Page navigation">
             <ul class="pagination">
-                <li>
-                    <a href="#" aria-label="Previous">
+                <%--在第一页再点击上一页设置禁用状态，但还是可以点击会报错（在后台UserServiceImpl代码写控制<0就返回1就行）--%>
+                <c:if test="${pb.currentPage ==1}">
+                    <li class="disabled">
+                </c:if>
+
+                <c:if test="${pb.currentPage !=1}">
+                    <li>
+                </c:if>
+
+                    <%--返回上一页（点击后，当前页码-1就行），这里</li>和上面c:if其中一个匹配--%>
+                    <a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${pb.currentPage-1}&rows=5" aria-label="Previous">
                         <span aria-hidden="true">&laquo;</span>
                     </a>
                 </li>
-                <li><a href="#">1</a></li>
-                <li><a href="#">2</a></li>
-                <li><a href="#">3</a></li>
-                <li><a href="#">4</a></li>
-                <li><a href="#">5</a></li>
-                <li>
-                    <a href="#" aria-label="Next">
+
+                <%--中间的数字,currentPage=${i}&rows=5(当前页码写死了)就这样发送给findUserByPageServlet获取的--%>
+                <c:forEach begin="1" end="${pb.totalPage}" var="i" step="1">
+                    <%--用c:if来搬bootstrap来弄个激活状态--%>
+                    <c:if test="${pb.currentPage==i}">
+                        <li class="active"><a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${i}&rows=5">${i}</a></li>
+                    </c:if>
+
+                    <c:if test="${pb.currentPage!=i}">
+                        <li><a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${i}&rows=5">${i}</a></li>
+                    </c:if>
+                </c:forEach>
+
+
+                <%--在最后页再点击下一页设置禁用状态，但还是可以点击会报错（在后台UserServiceImpl代码写控制）--%>
+                <c:if test="${pb.currentPage ==pb.totalPage}">
+                    <li class="disabled">
+                </c:if>
+
+                <c:if test="${pb.currentPage !=pb.totalPage}">
+                    <li>
+                </c:if>
+
+                    <%--下一页，和上一页差不多的配置--%>
+                    <a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${pb.currentPage+1}&rows=5" aria-label="Next">
                         <span aria-hidden="true">&raquo;</span>
                     </a>
                 </li>
+
+
                 <span style="font-size: 25px;margin-left: 5px">
-                    共16条记录，共4页
+                    共${pb.totalCount}条记录，共${pb.totalPage}页
                 </span>
             </ul>
         </nav>