jsp第6个作业—jdbc

UsersDao.java

package a;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

/*
 * 对数据库进行增删改查
 *
 */
public class UsersDao{
    //1.提供添加方法
    public boolean insert(User user){
        Connection con= null;
        Statement  st = null;
        try{
            //1.获取连接对象
            con=JDBCUtils.getCon();
            //2.获取执行sql语句的对象
            st=con.createStatement();
            //3.执行sql
            java.util.Date birthday = user.getBirthday();
            String sqlBirthday = String.format("%tF", birthday);
            String sql="insert into users(id,name,password,email,birthday)"+"values('"+user.getId()+"','"
                    +user.getUsername()+"','"
                    +user.getPassword()+"','"
                    +user.getEmail()+"','"
                    +sqlBirthday+"'"
                    +")";
            int row=st.executeUpdate(sql);
            if(row>0){
                //插入成功
                return true;
            }

        }catch(Exception e){
            throw new RuntimeException(e);
        }finally{
            JDBCUtils.realse(null, st, con);
        }

        return false;
    }

    //2.提供查询所有方法
    public List<User>findAllUser(){
        Connection con = null;
        Statement st = null;
        ResultSet rs = null;
        try{
            //1.获取连接对象
            con = JDBCUtils.getCon();
            //2.获取执行SQL语句对象
            st = con.createStatement();
            //3.执行SQL
            String sql = "select * from users";
            rs = st.executeQuery(sql);
            //4.遍历rs
            List<User>list = new ArrayList<User>();
            while(rs.next()){
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("name"));
                user.setPassword(rs.getString("password"));
                user.setEmail(rs.getString("email"));
                user.setBirthday(rs.getDate("birthday"));
                //把对象添加到集合中
                list.add(user);
            }
            return list;
        }catch(Exception e){
            throw new RuntimeException(e);
        }finally{
            JDBCUtils.realse(rs, st, con);
        }
    }
    //3.提供根据id查询方法
    public User findUserById(int id){
        Connection con = null;
        ResultSet rs= null;
        PreparedStatement st = null;
        try{
            //1.获取连接
            con = JDBCUtils.getCon();
            //2.获取执行sql语句对象
            String sql = "select * from users where id =?";
            st = con.prepareStatement(sql);
            //3.执行aql
            st.setInt(1, id);
            rs = st.executeQuery();
            //4.遍历rs
            if(rs.next()){
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("name"));
                user.setPassword(rs.getString("password"));
                user.setEmail(rs.getString("email"));
                user.setBirthday(rs.getDate("birthday"));
                return user;
            }
        }catch(Exception e){
            throw new RuntimeException(e);
        }finally{
            JDBCUtils.realse(rs, st, con);
        }
        return null;
    }
    //4.提供修改方法
    public boolean update(User user){
        Connection con = null;
        PreparedStatement st = null;
        ResultSet rs = null;
        try{
            //1.获取连接
            con = JDBCUtils.getCon();
            //2.执行SQL语句对象
            String sql = "update from users name=?,password=? where id=? " ;
            st = con.prepareStatement(sql);
            //3.执行SQL，给占位符赋值
            st.setString(1, user.getUsername());
            st.setString(2, user.getPassword());
            st.setInt(3, user.getId());
            int row = st.executeUpdate();
            if(row>0){
                //修改成功
                return true;
            }
        }catch(Exception e){
            throw new RuntimeException(e);
        }finally{
            JDBCUtils.realse(rs, st, con);
        }
        return false;
    }
    //5.提供删除方法
    public boolean delete(int id){
        Connection con = null;
        PreparedStatement st =null;
        ResultSet rs = null;
        try{
            //1.获取连接
            con = JDBCUtils.getCon();
            //2.执行SQL语句对象
            String sql = "delete  from users where id=?";
            st = con.prepareStatement(sql);
            //3.执行SQL，给占位符赋值
            st.setInt(1, id);
            int row = st.executeUpdate();
            if(row>0){
                //删除成功
                return true;
            }
        }catch(Exception e){
            throw new RuntimeException(e);
        }finally{
            JDBCUtils.realse(rs, st, con);
        }
        return false;
    }
}
    

JDBCUtils.java

package a;
/*
 * 工具类
 * */
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JDBCUtils {
    //获取连接对象的方法
    public static Connection getCon() throws Exception{
        //1.注册和加载驱动
        Class.forName("com.mysql.jdbc.Driver");
        //2.获取连接
        Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbc","root","root");
        return con;
    }
    //关闭连接，释放资源
    public static void realse(ResultSet rs,Statement st,Connection con){
        if (rs!=null) {
            try{
                rs.close();
            }catch (SQLException e){
                e.printStackTrace();
            }
            rs=null;
        }
        if (st!=null) {
            try{
                st.close();
            }catch (SQLException e){
                e.printStackTrace();
            }
            st=null;
        }
        if (con!=null) {
            try{
                con.close();
            }catch (SQLException e){
                e.printStackTrace();
            }
            con=null;
        }
    }
}

User.java

package a;

import java.util.Date;
public class User {

        private int id;
        private String username;
        private String password;
        private String email;
        private Date birthday;
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getUsername() {
            return username;
        }
        public void setUsername(String username) {
            this.username = username;
        }
        public String getPassword() {
            return password;
        }
        public void setPassword(String password) {
            this.password = password;
        }
        public String getEmail() {
            return email;
        }
        public void setEmail(String email) {
            this.email = email;
        }
        public Date getBirthday() {
            return birthday;
        }
        public void setBirthday(Date birthday) {
            this.birthday = birthday;
        }

}