android安卓Sqlite数据库实现用户登录注册

package zcd.sqlite;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

public class MySqliteHelper extends SQLiteOpenHelper {


    public MySqliteHelper(Context context) {
        super(context, "userdb.db", null, 3);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub

        db.execSQL("create table users(id integer primary key ,name text,pwd text)");

         String sql = "insert into users values (0,0,0)"; //id 自增加
         db.execSQL(sql);

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }

}

package zcd.sqlite;



import zcd.main.MainActivity;
import zcd.netanything.R;

import android.app.ActionBar;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


public class Userlogin extends Activity implements  OnClickListener{


       private MySqliteHelper helper;

       Button sign;  
       Button reg;

       String  name;
       String  mypwd;
       private EditText user;
       private EditText pwd;
       int userflag ;//定义一个标示判断 用户名是否存在
       int loginflag ;//登录时判断用户密码是否输入正确
   public void onCreate(Bundle savedInstanceState) {  
       super.onCreate(savedInstanceState);
       //设置状态栏颜色 
       getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
       getWindow().setStatusBarColor(getResources().getColor(R.color.StatusBar));   
       //设置actionbar颜色 
       ActionBar actionBar = getActionBar();
       actionBar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#0099CC")));
       setContentView(R.layout.login);

       findViewById(R.id.button1).setOnClickListener(this);
       findViewById(R.id.button2).setOnClickListener(this);
       user = (EditText)findViewById(R.id.editText1);
       pwd=(EditText)findViewById(R.id.editText2);

   }  


 public void  insert()
 {


      helper = new MySqliteHelper(getApplicationContext());
      SQLiteDatabase db=helper.getWritableDatabase();    //建立打开可读可写的数据库实例



      //查询一下，是否用户名重复
       String sql1 = "select * from users";
       Cursor cursor = db.rawQuery(sql1, null);
       while (cursor.moveToNext()) {
          //第一列为id
          name =  cursor.getString(1); //获取第2列的值,第一列的索引从0开始
          mypwd = cursor.getString(2);//获取第3列的值

          if((user.getText().toString().isEmpty())||(pwd.getText().toString().isEmpty())){

                 Toast.makeText(this, "不能为空，请重新输入", Toast.LENGTH_SHORT).show();  
                 break;
          }


          userflag = 1;  //不存在此用户


          if((user.getText().toString().equals(name)))
             {
                    Toast.makeText(this, "已存在此用户，请重新注册", Toast.LENGTH_SHORT).show();


                     userflag =0;
                     break;
             }

      }

      if(userflag==1)
      {
         String sql2 = "insert into users(name,pwd) values ('"+user.getText().toString()+"','"+pwd.getText().toString()+"')";
         db.execSQL(sql2);
         Toast.makeText(this, "注册成功！", Toast.LENGTH_SHORT).show(); 
      }  





        }


  public void select()
 {

      helper = new MySqliteHelper(getApplicationContext());
      SQLiteDatabase db=helper.getWritableDatabase();

      String sql = "select * from users";

      Cursor cursor = db.rawQuery(sql, null);
      while (cursor.moveToNext()) {
          //第一列为id
          name =  cursor.getString(1); //获取第2列的值,第一列的索引从0开始
          mypwd = cursor.getString(2);//获取第3列的值



           if((user.getText().toString().equals(name))&&(pwd.getText().toString().equals(mypwd)))
             {
                    Toast.makeText(this, "用户验证成功", Toast.LENGTH_SHORT).show(); 
                     loginflag=1;

                    //intent bundle传值
                    Intent MainActivity = new Intent();
                    MainActivity .setClass(this,MainActivity.class);
                    Bundle bundle = new Bundle(); //该类用作携带数据    
                    bundle.putString("user", user.getText().toString()); 
                    MainActivity.putExtras(bundle);   //向MainActivity传值
                    this.startActivity(MainActivity); 
                    finish();//退出

             }


      }

      if((user.getText().toString().isEmpty())||(pwd.getText().toString().isEmpty())){

         Toast.makeText(this, "不能为空，请重新输入", Toast.LENGTH_SHORT).show();  
     }


          if(loginflag!=1)
          {
             Toast.makeText(this, "账号或者密码错误,请重新输入", Toast.LENGTH_SHORT).show();  
          }

                cursor.close();
                db.close();
                //Toast.makeText(this, "已经关闭数据库", Toast.LENGTH_SHORT).show();  
      }



@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
       switch(v.getId()){  
        case R.id.button1:  
            select();

            break;  
        case R.id.button2:  
            insert();
            break;  
         }

}


}