JSP + Servlet + JDBC + Mysql简单实现增删改查.rar

package com.dao; import com.domain.User; import com.util.DBUtil; import org.junit.Test; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; /** * 数据库交互 dao层 */ public class UserDao { public List<User> getAllUser(){ List<User> list = new ArrayList<>(); Connection conn = DBUtil.getConn(); String sql = "select * from user"; try { PreparedStatement pst = conn.prepareStatement(sql); ResultSet rs = pst.executeQuery(); while(rs.next()){ User user = new User(); user.setId(rs.getInt("id")); user.setUsername(rs.getString("username")); user.setPassword(rs.getString("password")); list.add(user); } rs.close(); pst.close(); } catch (SQLException e) { e.printStackTrace(); } return list; } public boolean addUser(User user){ String sql = "insert into user(username, password) values(?,?)"; Connection conn = DBUtil.getConn(); try { PreparedStatement pst = conn.prepareStatement(sql); pst.setString(1, user.getUsername()); pst.setString(2, user.getPassword()); int count = pst.executeUpdate(); pst.close(); return count>0 ? true:false; } catch (SQLException e) { e.printStackTrace(); } return false; } public boolean deleteUser(int id){ String sql = "delete from user where id = ?"; Connection conn = DBUtil.getConn(); try { PreparedStatement pst = conn.prepareStatement(sql); pst.setInt(1, id); int count = 0; count = pst.executeUpdate(); pst.close(); return count>0 ? true:false; } catch (SQLException e) { e.printStackTrace(); } return false; } public boolean updateUser(User user){ String sql = "update user set username=?,password=? where id=?"; Connection conn = DBUtil.getConn(); try { PreparedStatement pst = conn.prepareStatement(sql); pst.setString(1,user.getUsername()); pst.setString(2, user.getPassword()); pst.setInt(3, user.getId()); int count = pst.executeUpdate(); pst.close(); return count>0 ? true:false; } catch (SQLException e) { e.printStackTrace(); } return false; } public User findUserById(int id){ String sql = "select * from user where id = " + id; Connection conn = DBUtil.getConn(); User user = null; try { PreparedStatement pst = conn.prepareStatement(sql); ResultSet rs = pst.executeQuery(); while (rs.next()){ user = new User(); user.setId(rs.getInt("id")); user.setUsername(rs.getString("username")); user.setPassword(rs.getString("password")); } rs.close(); pst.close(); } catch (SQLException e) { e.printStackTrace(); } return user; } @Test public void test(){ User user = new User(); user.setUsername("admin1"); user.setPassword("123456"); UserDao ud = new UserDao(); boolean b = ud.addUser(user); if(b){ System.out.println("添加数据成功"); } } }