jsp第六次作业

SQL

USE test;
CREATE TABLE lg(
id INT(10),
sname VARCHAR(10),
spassword VARCHAR(10)
);

login

public class login {
    private int id;
    private String sname;
    private String spassword;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public String getSpassword() {
        return spassword;
    }
    public void setSpassword(String spassword) {
        this.spassword = spassword;
    }
}

JDBCUtils

import java.sql.Statement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;


public class JDBCUtils {
//获取连接对象的方法
    public static Connection getCon() throws Exception{
        //1.加载数据库驱动
                Class.forName("com.mysql.jdbc.Driver");
                //2.通过DriverManager获取数据库连接
                Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "ROOT");
                return con;
                //3.通过Connection対象获取Statement対象                
    }
    
//关闭连接，释放资源
    public static void realse(ResultSet rs,Statement stmt,Connection con){
        if(rs!=null){
            try{
                rs.close();
            }catch (SQLException e){
                //TODO Auto-generated catch block
                e.printStackTrace();
                }
            rs=null;
            }
        if(stmt!=null){
            try{
                stmt.close();
            }catch (SQLException e){
                //TODO Auto-generated catch block
                e.printStackTrace();
                }
            stmt=null;
            }
        if(con!=null){
            try{
                con.close();
            }catch (SQLException e){
                e.printStackTrace();
                }
            con=null;
            }
    }
}

Dao

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

/*
 完成对数据库的增删改查（crud操作）
 */
public class Dao { 
    // 1.提供添加方法
    public boolean insert(login lg) {
        Connection con = null;
        Statement stmt = null;
        try {
//1.获取连接对象
            con=JDBCUtils.getCon();
//2.获取执行sql语句的对象
            stmt=con.createStatement();
//3.执行sql语句(添加信息语句)
            String sql="insert into lg(id,sname,spassword)"+"values('"
                    +lg.getId()+"','"
                    +lg.getSname()+"','"
                    +lg.getSpassword()+"'"//user.getBirthDay()替换成sqlBirthDay
                    +")";
            int row = stmt.executeUpdate(sql);
            if(row>0){
                //插入成功
                return true;
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JDBCUtils.realse(null, stmt, con);
        }

        return false;

    }
    
    
    //2.提供查询所有的方法
    public List<login>findAllUser(){
        Connection con= null;
        Statement stmt = null;
        ResultSet rs = null;
        try{
            //1.获取连接对象
            con = JDBCUtils.getCon();
            //2.获取执行sql语句的对象
            stmt = con.createStatement();
            //3.执行sql语句(查询语句)
            String sql ="select * from lg";
            rs = stmt.executeQuery(sql);
            //4.遍历rs
            List<login> list = new ArrayList<login>();
            while(rs.next()){
                //一行数据对应一个对象，获取每一行的对象，就设置给一个user对象
                login lg=new login();
                lg.setId(rs.getInt("id"));
                lg.setSname(rs.getString("sname"));
                lg.setSpassword(rs.getString("spassword"));               
                list.add(lg);                
            }
            return list;
                
        }catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JDBCUtils.realse(rs, stmt, con);
        }        
    //    return null;
    }
    
    
    
    //3.根据id，来查询记录
    public login findUserById(int id){
        Connection con= null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        try{
            //1.获取连接对象
            con = JDBCUtils.getCon();
            //2.获取执行sql语句的对象
            String sql ="select * from lg where id=?";
            stmt = con.prepareStatement(sql);
            //3.执行sql语句,给id赋值
            stmt.setInt(1, id);       
            rs = stmt.executeQuery();
            //4.遍历rs
            
            if(rs.next()){
                //一行数据对应一个对象，获取每一行的对象，就设置给一个user对象
                 login lg=new login();
                 lg.setId(rs.getInt("id"));
                 lg.setSname(rs.getString("sname"));
                 lg.setSpassword(rs.getString("spassword"));  
                
                return lg;            
            }
            
        }catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JDBCUtils.realse(rs, stmt, con);
        }        
        return null;            
    }
    

    
    //4.提供一个修改方法，根据id值修改记录
    public boolean update(login lg){
    Connection con = null;
    PreparedStatement stmt = null;
    try {
//1.获取连接对象
        con=JDBCUtils.getCon();
//2.获取执行sql语句的对象
        String sql="update lg set sname =?,spassword=? where id=?";
        stmt = con.prepareStatement(sql);//2.的sql语句*
//3.执行sql语句(给占位符赋值)
        
        stmt.setString(1, lg.getSname());
        stmt.setString(2, lg.getSpassword());
        stmt.setInt(3, lg.getId());
                
        int row = stmt.executeUpdate();//应该（）里无sql,因为在2.里已经传了sql语句*
        if(row>0){
            //插入成功
            return true;
        }
    } catch (Exception e) {
        throw new RuntimeException(e);
    } finally {
        JDBCUtils.realse(null, stmt, con);
    }
    return false;
    }
    
    
    //5.删除方法
    public boolean delete (int id){
        Connection con = null;
        PreparedStatement stmt = null;
        try {
    //1.获取连接对象
            con=JDBCUtils.getCon();
    //2.获取执行sql语句的对象
            String sql="delete from lg where id=?";
            stmt = con.prepareStatement(sql);//2.的sql语句*
    //3.执行sql语句(给占位符赋值)
            
            stmt.setInt(1,id);
                    
            int row = stmt.executeUpdate();//应该（）里无sql,因为在2.里已经传了sql语句*
            if(row>0){
                //插入成功
                return true;
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JDBCUtils.realse(null, stmt, con);
        }
        return false;
        
    }
}

 

test(添加)

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class test {
    public static void main(String[] args) {
        // 测试1插入信息代码
        Dao dao = new Dao();
        login lg = new login();
        lg.setId(2);
        lg.setSname("zqb");
        lg.setSpassword("1111");
        boolean flag = dao.insert(lg);
        System.out.print(flag);
        // jdbc操作步骤
        // 注册学生信息
    }

}

test2(查看)

import java.util.List;


public class test2 {

     public static void main(String[] args){
            //测试2查询所有信息条数代码
            Dao dao= new Dao();
            List<login> list =dao.findAllUser();    
            System.out.println(list.size());
    }

}

test3(按id查)

public class test3 {
     public static void main(String[] args){
            //测试3查询id=？的名字代码
        Dao dao= new Dao();
        login lg = dao.findUserById(2);
        System.out.println(lg.getSname());
        }
}

test4(修改)

public class test4 {
    public static void main(String[] args){
        //测试4修改信息代码
        Dao dao= new Dao();
        login lg=new login();
        lg.setId(2);
        lg.setSname("zqbb");
        lg.setSpassword("2222");      
        boolean flag = dao.update(lg);
        System.out.println(flag);
        //true则成功，否则不成功
}
}

test5(删)

public class test5 {
    public static void main(String[] args){
        //测试5删除信息代码
        Dao dao= new Dao();
        boolean flag = dao.delete(2);
        System.out.println(flag);
    }
}