MVC设计模式编写的一个login小项目 - JAVA

/ 5.释放资源
DBConnection.release(rs, ps);
}
return flag; // 这里的返回值一定要记得写，建议创建返回值对象user的时候就写上，以免编写完代码了忘了写，测试的时候出现空指针错误
}

public boolean update(User entity) {
// 1.声明返回值对象
boolean flag = false;
// 2.声明sql语句
String sql = "update user set password= where id= ";
// 3.获取连接对象
Connection con = DBConnection.getCon();
// 4.插入数据
try {
ps = con.prepareStatement(sql);
ps.setString(1, entity.getPassword());
ps.setInt(2, entity.getId());
int i = ps.executeUpdate();
if (i > 0) {
flag = true;
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
// 5.释放资源
DBConnection.release(rs, ps);
}
return flag;
}

public List queryAll() {
List list = new ArrayList();
String sql = "select id,username,password,logintime from user";
Connection con = DBConnection.getCon();
try {
ps = con.prepareStatement(sql);
rs = ps.executeQuery();
while (rs.next()) {
// 放到循环里面，否则就覆盖了
User user = new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setLogintime(rs.getDate("logintime"));
list.add(user);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
// 5.释放资源
DBConnection.release(rs, ps);
}
return list;
}

public boolean deleteById(Integer id) {
// 1.声明返回值对象
boolean flag = false;
// 2.声明sql语句
String sql = "delete from user where id= ";
// 3.获取连接对象
Connection con = DBConnection.getCon();
// 4.插入数据
try {
ps = con.prepareStatement(sql);
ps.setInt(1, id);
int i = ps.executeUpdate();
if (i > 0) {
flag = true;
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
// 5.释放资源
DBConnection.release(rs, ps);
}
return flag;
}

public User queryById(Integer id) {
User user = null;
String sql = "select id,username,password,logintime from user where id= ";
Connection con = DBConnection.getCon();
try {
ps = con.prepareStatement(sql);
// 这里要从方法参数中传过来的值
ps.setInt(1, id);
rs = ps.executeQuery();
if (rs.next()) {
user = new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setLogintime(rs.getDate("logintime"));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
// 5.释放资源
DBConnection.release(rs, ps);
}
return user;
}
}

package com.csdn.servlet;

import java.io.IOException;

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

import com.csdn.bean.User;
import com.csdn.service.UserService;
import com.csdn.service.UserServiceImp;

public class LoginServlet extends HttpServlet {
// userServlet相关操作
UserService userService = new UserServiceImp();

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 解决乱码:因为在index.html界面中提交表单用的是post方法，所以直接以下代码就ok
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
// 一定要与对应的html中的的name名称一致
String name = request.getParameter("username");
String pass = request.getParameter("password");
St

MVC设计模式编写的一个login小项目(二)