控制层：com.emp.controller.PageSelectServlet package com.emp.controller;
import com.emp.model.Employee;
import com.emp.service.EmployeeService;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
/**
* 员工的分页查询（可以带条件）
*/
@WebServlet("/pageSelect")
public class PageSelectServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
int current = Integer.parseInt(req.getParameter("current"));
int limit = Integer.parseInt(req.getParameter("limit"));
Employee employee = dealReqParams(req);
EmployeeService service = new EmployeeService();
String data = service.pageSelect(current, limit, employee);
resp.setContentType("text/html;charset=UTF-8");
PrintWriter out = resp.getWriter();
out.write(data);
}
/**
* 将请求参数封装为Employee对象
* @return 将条件封装为Employee对象
*/
public Employee dealReqParams(HttpServletRequest req) {
Employee employee = new Employee();
// 获取请求参数（条件查询表单的条件）
String username = req.getParameter("username");
String name = req.getParameter("name");
String age = req.getParameter("age");
String hometown = req.getParameter("hometown");
String createTime = req.getParameter("createTime");
String sex = req.getParameter("sex");
String level = req.getParameter("level");
String workTime = req.getParameter("workTime");
// 对条件查询表单的条件进行判断
if (username != null && !username.equals("")) {
employee.setUsername(username);
}
if (name != null && !name.equals("")) {
employee.setName(name);
}
if (age != null && !age.equals("")) {
employee.setAge(Integer.parseInt(age));
}
if (workTime != null && !workTime.equals("")) {
employee.setWorkTime(Integer.parseInt(workTime));
}
if (hometown != null && !hometown.equals("")) {
employee.setHometown(hometown);
}
if (createTime != null && !createTime.equals("")) {
employee.setCreateTime(createTime);
}
if (sex != null && !sex.equals("")) {
employee.setSex(Integer.parseInt(sex));
}
if (level != null && !level.equals("")) {
employee.setLevel(Integer.parseInt(level));
}
return employee;
}
} |
服务层：com.emp.service.EmployeeService /**
* 条件分页查询
*
* @param current：当前页
* @param limit：从结果集中获取数据的长度
* @param employee：查询条件
* @return 当前页显示的记录数
*/
public String pageSelect(int current, int limit, Employee employee) {
int total = dao.selectCount(employee); // 获取总记录数
HashMap<String, Object> map = new HashMap<>();
if (total > 0) {
int pages = (total + limit - 1) / limit; // 计算分页总数
// 计算从结果集中获取数据的起始索引
int startIndex = (current - 1) * limit;
List<Employee> list = dao.pageSelect(startIndex, limit, employee);
map.put("code", 200);
map.put("total", total); // 总记录数
map.put("pages", pages); // 分页总数
map.put("rows", list); // 表格中显示的数据
map.put("current", current); // 当前页
map.put("limit", limit); // 每页显示记录数
} else {
map.put("code", 500);
map.put("data", null);
}
return JSON.toJSONString(map);
} |
数据访问层：com.emp.dao.EmployeeDao /**
* 将查询条件处理为SQL语句
*
* @param employee：查询条件
* @return select语句
*/
private String dealSQL(Employee employee) {
String sql = "select * from employee where deleted=0 ";
if (employee.getUsername() != null && !employee.getUsername().equals("")) {
sql += " and username like '%" + employee.getUsername() + "%'";
}
if (employee.getName() != null && !employee.getName().equals("")) {
sql += " and name like '%" + employee.getName() + "%'";
}
if (employee.getCreateTime() != null && !employee.getCreateTime().equals("")) {
sql += " and createTime >= '" + employee.getCreateTime() + "'";
}
if (employee.getHometown() != null && !employee.getHometown().equals("")) {
sql += " and hometown like '%" + employee.getHometown() + "%'";
}
if (employee.getAge() > 0) {
sql += " and age>= " + employee.getAge();
}
if (employee.getSex() > 0) {
sql += " and sex= " + employee.getSex();
}
if (employee.getWorkTime() > 0) {
sql += " and workTime>= " + employee.getWorkTime();
}
if (employee.getLevel() > 0) {
sql += " and level= " + employee.getLevel();
}
return sql;
} /**
* 查询符合条件的总记录数
*
* @param employee：查询条件
* @return 查询符合条件的总记录数
*/
public int selectCount(Employee employee) {
String sql = dealSQL(employee);
try {
PreparedStatement ps = connection.prepareStatement(sql);
ResultSet resultSet = ps.executeQuery();
resultSet.last(); // 指针移到最后一行
return resultSet.getRow(); // 获得当前的行号
} catch (SQLException e) {
e.printStackTrace();
}
return 0;
} /**
* 条件分页查询
*
* @param startIndex：从结果集中获取数据的起始索引
* @param limit：从结果集中获取数据的长度
* @param condition：查询条件
* @return 当前页显示的记录数
*/
public List<Employee> pageSelect(int startIndex, int limit, Employee condition) {
List<Employee> list = new ArrayList<>();
String sql = dealSQL(condition);
sql += " order by role asc, createTime desc limit " + startIndex + ", " + limit;
try {
PreparedStatement ps = connection.prepareStatement(sql);
ResultSet resultSet = ps.executeQuery();
while (resultSet.next()) {
int id = resultSet.getInt("id");
int age = resultSet.getInt("age");
int workTime = resultSet.getInt("workTime");
String username = resultSet.getString("username");
String password = resultSet.getString("password");
String name = resultSet.getString("name");
String introduction = resultSet.getString("introduction");
String hometown = resultSet.getString("hometown");
String phone = resultSet.getString("phone");
String createTime = resultSet.getString("createTime");
int role = resultSet.getInt("role");
int sex = resultSet.getInt("sex");
int level = resultSet.getInt("level");
// 创建Employee对象
Employee employee = new Employee();
employee.setId(id);
employee.setUsername(username);
employee.setPassword(password);
employee.setRole(role);
employee.setName(name);
employee.setSex(sex);
employee.setAge(age);
employee.setLevel(level);
employee.setIntroduction(introduction);
employee.setHometown(hometown);
employee.setWorkTime(workTime);
employee.setPhone(phone);
employee.setCreateTime(createTime);
list.add(employee);
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
} |
