JAVA简单链接Oracle数据库 注册和登陆功能的实现代码

//user 用户的基本信息，也是userinfo表中的3个列
package 登陆判断;

public class user {

  private string name;
  private string loginname;
  private string loginpsw;
  public string getname() {
   return name;
  }
  public void setname(string name) {
   this.name = name;
  }
  public string getloginname() {
   return loginname;
  }
  public void setloginname(string loginname) {
   this.loginname = loginname;
  }
  public string getloginpsw() {
   return loginpsw;
  }
  public void setloginpsw(string loginpsw) {
   this.loginpsw = loginpsw;
  }
}
//用于注册和登陆的小小代码块
package 登陆判断;

import java.util.scanner;

public class in {

  public static user getuser(){
   user u = new user();
   scanner sc = new scanner(system.in);
   system.out.println("请输入登陆名");
   u.setloginname(sc.nextline());
   system.out.println("请输入密码");
   u.setloginpsw(sc.nextline());
   return  u;
  }
  public static user registeruser(){
   user u = new user();
   scanner sc = new scanner(system.in);
   system.out.println("请注册用户名名");
   u.setname(sc.nextline());
   system.out.println("请注册登陆名");
   u.setloginname(sc.nextline());
   system.out.println("请注册密码");
   u.setloginpsw(sc.nextline());
   return  u;
  }
}

//登陆时的检查，判断登陆名和密码是否正确，正确则返回 用户名
package 登陆判断;

import java.sql.connection;
import java.sql.drivermanager;
import java.sql.preparedstatement;
import java.sql.resultset;
import java.sql.sqlexception;

public class check {

  public static void checkuser(user u)
  {
   try {
    class.forname("oracle.jdbc.driver.oracledriver");
   } catch (classnotfoundexception e) {
    e.printstacktrace();
   }
   string url = "jdbc:oracle:thin:@localhost:1521:orcl";
   string user = "scott";
   string password = "tiger";
   connection conn = null;
   resultset rs = null;
   preparedstatement pst = null;

   string sql = "select name from userinfo where loginname = ? and loginpsw = ? ";
   try {
    conn = drivermanager.getconnection(url, user, password);
    pst = conn.preparestatement(sql);
    pst.setstring(1, u.getloginname());
    pst.setstring(2,u.getloginpsw());
    rs = pst.executequery();
    while(rs.next()){
     u.setname(rs.getstring(1));
    }    
   } catch (sqlexception e) {
    e.printstacktrace();
   }finally{
    try {
     rs.close();
     pst.close();
     conn.close();
    } catch (sqlexception e) {
     e.printstacktrace();
    }
   }
   if(u.getname() == null || u.getname().isempty()){
    system.out.println("登陆失败");
   }else{
    system.out.println("欢迎"+u.getname()+"登陆");
   }

  }
}

//注册界面，要判断 登陆名是否有重复，有重复则注册失败。有点小疑问，已用注释标出来
package 登陆判断;

import java.sql.connection;
import java.sql.drivermanager;
import java.sql.preparedstatement;
import java.sql.resultset;
import java.sql.sqlexception;
import java.sql.statement;

public class register {

  public static void registuser(user u){

   try {
    class.forname("oracle.jdbc.driver.oracledriver");
   } catch (classnotfoundexception e) {
    e.printstacktrace();
   }
   string url = "jdbc:oracle:thin:@localhost:1521:orcl";
   string user = "scott";
   string password = "tiger";
   connection conn = null;
   string sql = "insert into userinfo values(?,?,?)";
   preparedstatement pst = null;

   //判断登陆名是否已经存在
   statement s = null;
   resultset rs = null;
   string sql_ck = "select loginname from userinfo";
   try {
    conn = drivermanager.getconnection(url, user, password);
    pst = conn.preparestatement(sql);
    pst.setstring(1, u.getname());
    pst.setstring(2, u.getloginname());
    pst.setstring(3, u.getloginpsw());
    //判断登陆名是否已经存在
    s = conn.createstatement();
    rs = s.executequery(sql_ck);
    while(rs.next()){//为什么用 rs.getstring(2)会提示 无效的索引呢
     if( rs.getstring("loginname").equals(u.getloginname()) ){
      system.out.println("登陆名已经存在，注册失败");
      break;
     }else{
      pst.executeupdate();
      system.out.println("注册成功");
      break;
     }
    } 
   } catch (sqlexception e) {
    e.printstacktrace();
   }finally{
    try {
     rs.close();
     pst.close();
     s.close();
     conn.close();
    } catch (sqlexception e) {
     e.printstacktrace();
    }
   }

   
  }
}
//main界面//
//数据库中表的结构式这样
//name(用户名，用于显示),
//loginname(登录名,即登陆时输入的id)
//loginpsw(登陆时输入的密码)
package 登陆判断;

import java.util.scanner;

public class test {

 public static void main(string[] args) {

  int chos = 0;
  scanner sc = new scanner(system.in);
  system.out.println("\t\t登陆请按1\t\t注册请按2");
  chos = sc.nextint();
  switch(chos){
  case 1: check.checkuser(in.getuser());break;
  case 2: register.registuser(in.registeruser());break;
  default: system.out.println("请输入正确的选择");break;
  }
 }

}