第15周作业

一、题目

编写一个应用程序，输入用户名和密码，访问test数据库中t_login表（字段包括id、username、password），验证登录是否成功。

二、源程序

 Test.java

package pac_7;

import java.sql.*;
import java.util.Scanner;

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        System.out.println("输入用户名密码");
        Scanner sc=new Scanner(System.in);
        System.out.println("输入用户名：");
        String username=sc.nextLine();
        System.out.println("输入密码：");
        String password=sc.nextLine();
        Connection con=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            con=DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root","");
            ps=con.prepareStatement("select * from t_login where username=? and password=?");
            ps.setString(1, username);
            ps.setString(2, password);
            rs=ps.executeQuery();
            if(rs.next()){
                System.out.println("登录成功");
            }
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try {
                if(rs!=null){
                    rs.close();
                }
                ps.close();
                con.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        
    }

}

三、运行结果

 一、题目

在上一题基础上，当登录成功后，将t_user表（id、name、sex、birthday）的信息进行显示（要求使用DB.java完成登录和获取t_user表中数据的操作），最后再对t_user表进行一条记录的添加操作。

二、源程序

DB.java

package pac_8;

import java.sql.*;

public class DB {
    private Connection con;
    private PreparedStatement pre;
    private ResultSet rs;
    private static DB db;
    static{
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    private DB(){
        try {
            con=DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public static DB getInstance(){
        if(db==null){
            db=new DB();
        }
        return db;
    }
    public ResultSet executeSelect(String sql,Object[] args){
        
        try {
            pre=con.prepareStatement(sql);
            if(args.length!=0){
                for(int i=0;i<args.length;i++){
                    pre.setObject(i+1, args[i]);
                }
            }
            rs=pre.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
    public int executeModify(String sql,Object[] args){
        int n=0;
        try {
            pre=con.prepareStatement(sql);
            if(args.length!=0){
                for(int i=0;i<args.length;i++){
                    pre.setObject(i+1, args[i]);
                }
            }
            n=pre.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return n;
        
    }
    public void close(){
        try {
            if(rs!=null){
                rs.close();
            }
            pre.close();
            con.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Test.java

package pac_8;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        ResultSet rs=null;
        DB d=DB.getInstance();
        Scanner sc=new Scanner(System.in);
        System.out.println("输入用户名：");
        String username=sc.nextLine();
        System.out.println("输入密码：");
        String password=sc.nextLine();
        rs=d.executeSelect("select * from t_login where username=? and password=?", new Object[]{username,password});
        try {
            if(rs.next()){
                System.out.println("登陆成功");
                rs=d.executeSelect("select * from t_user", new Object[]{});
                char sex = ' ';
                while(rs.next()){
                    if(rs.getInt(3)==0){
                        sex = '男';
                    }else if(rs.getInt(3)==1){
                        sex = '女';
                    }
                    System.out.println("name:"+rs.getString(2)+"   sex:"+sex+"   birthday:"+rs.getString(4));                
                }
                System.out.print("对t_user表进行添加一条记录:
");
                String name;
                String birthday;
                name=sc.nextLine();
                sex=sc.nextLine().charAt(0);
                birthday=sc.nextLine();
                int ssex = -1;
                if(sex=='男'){
                    ssex=0;
                }else if(sex=='女'){
                    ssex=1;
                }
                if(d.executeModify("insert into t_user (name,sex,birthday)values(?,?,?)", new Object[]{name,ssex,birthday})>0){
                    System.out.print("添加成功
");
                }
            }else{
                System.out.print("登录失败
");
            }
            
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            d.close();
        }
    }

}

三、运行结果