安卓：如何创建登录页面是从数据库

Question

验证我有3 Java文件 我）DBAdapter.java II）signup.java III）login.java 四一个是菜单，但没有必要在此提及。

现在我想这样做，当用户来登录页面，并在编辑视图中输入用户名和密码，检查数据库中的数据和重定向到菜单，如果发现匹配。 我不知道如何做到这一点，这里是DBAdapter.java我的代码文件和login.java

DBAdapter.java

public class DBAdapter 
{ 
    public static final String KEY_ROWID = "_id"; 
    public static final String KEY_FIRSTNAME = "FirstName"; 
    public static final String KEY_LASTNAME = "LastName"; 
    public static final String KEY_USERNAME = "UserName"; 
    public static final String KEY_PASSWORD = "Password";  
    private static final String TAG = "DBAdapter"; 

    private static final String DATABASE_NAME = "master"; 
    private static final String DATABASE_TABLE = "register"; 
    private static final int DATABASE_VERSION = 1; 

    private static final String DATABASE_CREATE = 
     "create table titles (_id integer primary key autoincrement, " 
     + "FirstName text not null, LastName text not null, " 
     + "UserName text not null, Password text not null);"; 

    private final Context context; 

    private DatabaseHelper DBHelper; 
    private SQLiteDatabase db; 

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

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

     @Override 
     public void onCreate(SQLiteDatabase db) 
     { 
      db.execSQL(DATABASE_CREATE); 
     } 

     @Override 
     public void onUpgrade(SQLiteDatabase db, int oldVersion, 
     int newVersion) 
     { 
      Log.w(TAG, "Upgrading database from version " + oldVersion 
        + " to " 
        + newVersion + ", which will destroy all old data"); 
      db.execSQL("DROP TABLE IF EXISTS titles"); 
      onCreate(db); 
     } 
    } 

login.java

public class login extends Activity { 

    private EditText username; 
    private EditText password; 

    public String user_name; 
    public String pass_word; 


    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.login); 

     username = (EditText) findViewById(R.id.ev_unameLogin); 
     password = (EditText) findViewById(R.id.ev_passwordLogin); 

     final Button button = (Button) findViewById(R.id.btn_login); 
     button.setOnClickListener(new View.OnClickListener() {   
      public void onClick(View v) {    

       user_name = username.getText().toString(); 
       pass_word = password.getText().toString(); 

       Intent goToNextActivity = new Intent(getApplicationContext(), menu.class); 
       startActivity(goToNextActivity); 


      } 
     });     


    } 
} 

那么什么我应该更新这两个文件..

非常感谢提前

Answer 1

在您需要创建一个方法来访问数据库，例如数据库类。

public boolean validateUser(String username, String password){ 
    Cursor c = getReadableDatabase().rawQuery(
      "SELECT * FROM " + TABLE_NAME + " WHERE " 
        + USER_NAME + "='" + username +"'AND "+PASSWORD+"='"+password+"'" , null); 
    if (c.getCount>0) 
     return true; 
     return false; 
} 

你当然需要创建一些数据库表像

public void createTable(SQLiteDatabase database) { 
    String creationString = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME 
      + " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " 
      + USER_NAME + " TEXT NOT NULL, " 
      + PASSWORD + " TEXT NOT NULL, " 
      ");"; 
    database.execSQL(creationString); 
} 

而且有变量，如TABLE_NAME这显然是要为表的名称，USER_NAME它代表用户名列的名称，以及PASSWORD的名称。

您需要在数据库的onCreate中调用createTable（）方法。

要使用数据库的登录按钮，你可以这样做：

if (myDatabase.vaidateUser(user_name,pass_word)) { 
    Intent goToNextActivity = new Intent(getApplicationContext(), menu.class); 
    startActivity(goToNextActivity); 

} 
else 
    Toast.makeText(mContext, "Wrong username/password", Toast.LENGTH_LONG).show(); 

希望这有助于。我给了你一个很好的起点。还有其他一些你需要自己去解决的东西，但是这应该会给你一个关于它是如何工作的以及接下来要去哪里的好主意（比如把记录添加到数据库等）。你将需要创建一些变量等，但这并不困难！

Answer 2

public void onClick（View v）方法应该调用一个方法来验证用户。

公共无效的onClick（视图v）{

  user_name = username.getText().toString(); 
      pass_word = password.getText().toString(); 
      if(validate(user_name, pasass_word)); 
      {    
       Intent goToNextActivity = new Intent(getApplicationContext(), menu.class); 
      startActivity(goToNextActivity); 
      } 
     } 




public boolean validate(String name,String password) { 
    String url = "http://n.n.n.n:nnnn/WebServicePro/services/Authentication";/*give Ip addres:portnumber*/ 
    String nameSpace="http://com.xxx.yy"; /**give proper namespace*/ 
    String methoName= "authenticate"; /*This method is an operation in the webservice*/ 
    SoapObject request = new SoapObject(nameSpace,methoName); 

    request.addProperty("in0",name); 
    request.addProperty("in1",password); 

    try { 
    resultsRequestSOAP = makeSoapCall(request, "", url); 
     if(resultsRequestSOAP.toString().equalsIgnoreCase("true")){  
     return true; 
      } 
    else{  /*handle error*/} 
    }catch (Exception exp) {    
     /*handle exception*/} 
    return false; 
}