add<产品分页>

src/main/java/example/controller/ComputerServlet.java

@@ -13,6 +13,7 @@ import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.sql.SQLException;
 import java.util.List;
+import java.util.Map;
 
 @WebServlet(urlPatterns = {"/computer"})
 public class ComputerServlet extends HttpServlet {
@@ -64,11 +65,26 @@ public class ComputerServlet extends HttpServlet {
     }
 
     private void listServlet(HttpServletRequest req, HttpServletResponse resp) throws SQLException, ServletException, IOException {
-        List<Computer> computers= computerService.listComputer();
-        req.setAttribute("computers", computers);
+        int page = 1;
+        int pageSize = 5; // 每页显示的条数
+
+        // 获取页码参数
+        String pageParam = req.getParameter("page");
+        if (pageParam != null) {
+            page = Integer.parseInt(pageParam);
+        }
+
+        // 获取分页数据
+        Map<String, Object> data = computerService.listComputersWithPagination(page, pageSize);
+
+        req.setAttribute("computers", data.get("computers"));
+        req.setAttribute("totalPages", data.get("totalPages"));
+        req.setAttribute("currentPage", data.get("currentPage"));
+
         req.getRequestDispatcher("computerList.jsp").forward(req, resp);
     }
 
+
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         String action = req.getParameter("action");

src/main/java/example/dao/ComputerDao.java

@@ -41,11 +41,21 @@ public class ComputerDao {
         }
     }
 
-    public List<Computer> getAllComputer() throws SQLException {
-        String sql = "select * from computer";
-        return queryRunner.query(sql,new BeanListHandler<>(Computer.class));
+    public List<Computer> getComputersByPage(int page, int pageSize) throws SQLException {
+        int offset = (page - 1) * pageSize;
+        String sql = "SELECT * FROM computer LIMIT ? OFFSET ?";
+        return queryRunner.query(sql, new BeanListHandler<>(Computer.class), pageSize, offset);
     }
 
+    public int getComputerCount() throws SQLException {
+        String sql = "SELECT COUNT(*) FROM computer";
+        return queryRunner.query(sql, rs -> {
+            rs.next();
+            return rs.getInt(1);
+        });
+    }
+
+
 
     public Computer getComputerById(int i) {
         String sql = "select * from computer where id=?";

src/main/java/example/service/IComputerService.java

@@ -4,6 +4,7 @@ import example.model.Computer;
 
 import java.sql.SQLException;
 import java.util.List;
+import java.util.Map;
 
 public interface IComputerService {
     
@@ -16,4 +17,6 @@ public interface IComputerService {
     Computer getComputer(String id);
 
     void updateComputer(String id, String name, double v, int i);
+
+    Map<String, Object> listComputersWithPagination(int page, int pageSize) throws SQLException;
 }

src/main/java/example/service/impl/ComputerServiceImpl.java

@@ -5,7 +5,10 @@ import example.model.Computer;
 import example.service.IComputerService;
 
 import java.sql.SQLException;
+import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 public class ComputerServiceImpl implements IComputerService {
 
@@ -19,9 +22,10 @@ public class ComputerServiceImpl implements IComputerService {
 
     @Override
     public List<Computer> listComputer() throws SQLException {
-        return computerDao.getAllComputer();
+        return Collections.emptyList();
     }
 
+
     @Override
     public void deleteComputer(String id) {
         computerDao.deleteComputer(Integer.parseInt(id));
@@ -36,4 +40,20 @@ public class ComputerServiceImpl implements IComputerService {
     public void updateComputer(String id, String name, double v, int i) {
         computerDao.updateComputer(name, v, i, Integer.parseInt(id));
     }
+
+    @Override
+    public Map<String, Object> listComputersWithPagination(int page, int pageSize) throws SQLException {
+        List<Computer> computers = computerDao.getComputersByPage(page, pageSize);
+        int totalCount = computerDao.getComputerCount();
+        int totalPages = (int) Math.ceil((double) totalCount / pageSize);
+
+        Map<String, Object> result = new HashMap<>();
+        result.put("computers", computers);
+        result.put("totalPages", totalPages);
+        result.put("currentPage", page);
+
+        return result;
+    }
+
+
 }

src/main/webapp/computerList.jsp

@@ -44,6 +44,31 @@
                     </c:forEach>
                 </tbody>
             </table>
+            <div>
+                <!-- 首页链接 -->
+                <a href="/computer?action=list&page=1">首页</a>
+
+                <!-- 上一页链接 -->
+                <c:if test="${currentPage > 1}">
+                    <a href="/computer?action=list&page=${currentPage - 1}">上一页</a>
+                </c:if>
+
+                <!-- 分页页码 -->
+                <c:forEach var="i" begin="1" end="${totalPages}">
+                    <a href="/computer?action=list&page=${i}"
+                        style="margin: 0 5px; ${i == currentPage ? 'font-weight:bold;' : ''}">
+                        ${i}
+                    </a>
+                </c:forEach>
+
+                <!-- 下一页链接 -->
+                <c:if test="${currentPage < totalPages}">
+                    <a href="/computer?action=list&page=${currentPage + 1}">下一页</a>
+                </c:if>
+
+                <!-- 尾页链接 -->
+                <a href="/computer?action=list&page=${totalPages}">尾页</a>
+            </div>
             <hr>
             <p style="color: red;">${requestScope.msg}</p>