android - SQLite android 应用程序登录

Question

我目前正在开发一款游戏，我想要的只是我的登录屏幕能够检查我已经存储在我的数据库中的用户名和密码是否正确，当它正确时，登录按钮是单击以打开一个新 Activity 。我已经建立了我的数据库，还有一个登录名，我只需要弄清楚如何检查我的数据库，而不仅仅是字段中的文本。

我已经在数据库中存储了一个预先添加的登录名:

用户名:test

密码:1234

提前致谢 p.s 我是 Java 和 SQL lite 的新手，这仅适用于学校作业，绝不会在现实世界中使用我只希望它简单:)

登录屏幕 Activity :

package com.C05025.noughtsandcrosses;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.View;
import android.widget.EditText;

public class LogInScreen extends Activity {

    EditText txtUsername;
    EditText txtPassword;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.loginscreen);
        txtUsername = (EditText) findViewById(R.id.EditUsername);
        txtPassword = (EditText) findViewById(R.id.EditPassword);
    }

    public void newLogIn(View view) {
        if(txtUsername.getText().toString().equals("test") && 
                txtPassword.getText().toString().equals("1234")) {
            Intent intent = new Intent(LogInScreen.this, MainMenu.class);
            startActivity(intent);
    }   
}

数据库类:

package com.C05025.noughtsandcrosses;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHandler extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "userDB.db";
    private static final String TABLE_USERS   = "users";

    public static final String COLUMN_NAME     = "name";
    public static final String COLUMN_PASSWORD = "password";

    public DBHandler(Context context, String name, CursorFactory factory,
            int version) {
    super(context, DATABASE_NAME, factory, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_USER_TABLE = "CREATE TABLE " +    TABLE_USERS + "("
        + " INTEGER PRIMARY KEY," + COLUMN_NAME + " TEXT," 
        + COLUMN_PASSWORD + " INTEGER" + ")";
        db.execSQL(CREATE_USER_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {

    }

    public void addUser(LogIn user) {

        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, user.getName());
        values.put(COLUMN_PASSWORD, user.getPassword());

        SQLiteDatabase db = this.getWritableDatabase();

        db.insert(TABLE_USERS, null, values);
        db.close();
    }

    public LogIn findUser(String Username) {
        String query = "Select * FROM " + TABLE_USERS 
        + " WHERE " + COLUMN_NAME + " =  \""
        + Username + "\"";

        SQLiteDatabase db = this.getWritableDatabase();

        Cursor cursor = db.rawQuery(query, null);

        LogIn User = new LogIn();

        if (cursor.moveToFirst()) {
            cursor.moveToFirst();
            User.setName(cursor.getString(1));
            User.setPassword(Integer.parseInt(cursor.getString(2)));
            cursor.close();
        } 
        else {
            User = null;
        }

    db.close();
    return User;
    }
}

Answer 1

你可以试试下面的方法。

创建名为 DBAdapter.java 的类并添加以下代码。

public class DBAdapter {
    private static final String DATABASE_NAME         = "Your database name"; 
    private static final String DATABASE_CREATE_USERS = "create table TABLE_NAME (
    UserID integer primary key autoincrement, " + "Username text, Password text);" ; 

    private static final String DATABASE_SELECT_USERS = "users";
    public static final String USER_ID       = "UserID";
    public static final String USER_NAME     = "Username";
    public static final String USER_PASSWORD = "Password ";

    private final Context context;
    private DatabaseHelper DBHelper;
    private SQLiteDatabase db;  

    DBAdapter(Contex ctx) {
        this.context = ctx;
        DBHelper     = new DatabaseHelper(context);
    }

    private static class DatabaseHelper extends SQLiteOpenHelper {
        DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        public void onCreate(SQLiteDatabase db) {
            System.out.println("Creating table");
            db.execSQL(DATABASE_CREATE_USERS);
        }

        public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {

        }
    }   

    public DBAdapter open() throws SQLException {
        db = DBHelper.getWritableDatabase();
        return this;
    }

    public void close() {
        DBHelper.close();
    }

    public Cursor fetchUser(String username, String password) {  
        Cursor myCursor = db.query(DATABASE_SELECT_USERS,   
        new String[] { USER_ID, USER_NAME, USER_PASSWORD },   
                         USER_NAME + "='" + username + "' AND " +   
                         USER_PASSWORD + "='" + password + "'", null, null, null, null);  

        if (myCursor != null) {  
            myCursor.moveToFirst();  
        }  
        return myCursor;  
    }  

    public void InsertData(String username, String password) {
        String sql = "INSERT INTO users (Username,Password) VALUES('"+username+"','"+password+"')";
        db.execSQL(sql);
    }
}

然后创建你的Java文件

登录.java

public class Login extends Activity 
{

    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        final EditText txt_username = (EditText) findViewById(R.id.editText1);
        final EditText txt_psw      = (EditText) findViewById(R.id.editText2);

        Button btn_signin = (Button) findViewById(R.id.button1);

        // Inner class to implement Button Listener when button is clicked.
        btn_signin.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {                   
                DBAdapter db = new DBAdapter(getBaseContext());
                db.open();                              
                db.InsertData("Chao", "1234");              
                Log.v("LoginDetails", txt_username.getText().toString()+"../.."
                      +txt_psw.getText().toString());

                // Accessing user using the fetchUser method we created in DBAdapter
                Cursor cur = db.fetchUser( txt_username.getText().toString(), 
                                           txt_psw.getText().toString());

                // Use this line if you want to see the number of users with these login details
                System.out.println("cur.getCount()   "+cur.getCount());

                if(cur.getCount()!=0) {
                    String usn=cur.getString(1);
                    if(usn.equals("Chao")) {   

                    }
                    else { 

                    }

                    System.out.println("Query succedded");
                    Toast.makeText(getBaseContext(), "Success! Valid User name and password", Toast.LENGTH_LONG).show();

                    db.close();
                }
                else
                    Toast.makeText(getBaseContext(), "Please enter Valid User name and password", Toast.LENGTH_LONG).show();
            } //Closes the onClick method
        }); //Closes the onClickListener
    }
}