Question

大家好我是Java和SQLite编程方面的新手，我从SQLite数据库中获取和检索特定数据时遇到了问题，我想创建一个登录程序，用户将输入用户名和密码（LoginScreen.java），它将检查数据库中的现有数据（database.java），如果存在，它将返回true给LoginScreen.java。

之后，LoginScreen.java将检查，如果为true，它将运行SQLViews Intent，如果为false，它将运行Registration Intent。

问题是，即使数据存在于数据库中，我的代码也总是返回false。你能帮我检查一下我的代码吗？

谢谢，

以下是代码： Database.java

package com.thesis.teamizer;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class Database {

public static final String DATABASE_NAME = "TeamizerDB.db";
public static final String TABLE_MEMBER = "Member";
public static final int DATABASE_VERSION = 1;
public static final String MEMBER_USERNAME = "Username";
public static final String MEMBER_PASSWORD = "Password";
public static final String MEMBER_EMAIL = "Email";
public DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;

public static class DbHelper extends SQLiteOpenHelper {

    public DbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        db.execSQL("CREATE TABLE " + TABLE_MEMBER + " (" + MEMBER_USERNAME
                + " TEXT PRIMARY KEY NOT NULL, " + MEMBER_PASSWORD
                + " TEXT NOT NULL, " + MEMBER_EMAIL + " TEXT NOT NULL);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_MEMBER);
        onCreate(db);
    }

}

public Database(Context c) {
    ourContext = c;
}

public Database open() throws SQLException {
    ourHelper = new DbHelper(ourContext);
    ourDatabase = ourHelper.getWritableDatabase();
    return this;
}

public void close() {

    ourHelper.close();
}

public boolean createEntry(String username, String password, String email) {
    // TODO Auto-generated method stub
    ContentValues cv = new ContentValues();
    cv.put(MEMBER_USERNAME, username);
    cv.put(MEMBER_PASSWORD, password);
    cv.put(MEMBER_EMAIL, email);
    ourDatabase.insert(TABLE_MEMBER, null, cv);
    return true;
}

public String getData() {
    // TODO Auto-generated method stub
    String[] columns = new String[] { MEMBER_USERNAME, MEMBER_PASSWORD,
            MEMBER_EMAIL };
    Cursor c = ourDatabase.query(TABLE_MEMBER, columns, null, null, null,
            null, null);

    String result = "";

    int iUsername = c.getColumnIndex(MEMBER_USERNAME);
    int iPassword = c.getColumnIndex(MEMBER_PASSWORD);
    int iEmail = c.getColumnIndex(MEMBER_EMAIL);

    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {

        result = result + c.getString(iUsername) + " "
                + c.getString(iPassword) + " " + c.getString(iEmail) + "\n";

    }

    return result;
}

public Boolean getName(String l) throws SQLException {
    // TODO Auto-generated method stub
    String Query = "SELECT USERNAME FROM " + TABLE_MEMBER + " WHERE "
            + MEMBER_USERNAME + " =?";
    Cursor mCursor = ourDatabase.rawQuery(Query, new String[] { l });

    boolean hasObject = false;
    if (mCursor.moveToFirst()) {
        hasObject = false;
        mCursor.close();
    }

    else
        hasObject = true;

    return hasObject;

}

public Boolean getMatched(String username, String password) {
    // TODO Auto-generated method stub


    String Query = "SELECT USERNAME FROM " + TABLE_MEMBER + " WHERE "
            + MEMBER_USERNAME + " =? AND " + MEMBER_PASSWORD + " =?";

    Cursor c = ourDatabase.rawQuery(Query, new String[] { username,
            password });
    if (c.moveToFirst()) {
        return true;
    } else {
        return false;
    }
}

}

LoginScreen.java

package com.thesis.teamizer;

import android.app.Activity;
import android.app.Dialog;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class LoginScreen extends Activity {

private EditText etUsername;
private EditText etPassword;
private Button bLogin;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    setContentView(R.layout.login_screen);

    validationUsernameAndPassword();
    ifRegisterButtonClicked();

}

private void validationUsernameAndPassword() {
    // TODO Auto-generated method stub
    etUsername = (EditText) findViewById(R.id.etLoginUsername);
    etPassword = (EditText) findViewById(R.id.etLoginPassword);
    bLogin = (Button) findViewById(R.id.bLogin);

    final String username = etUsername.getText().toString();
    final String password = etPassword.getText().toString();

    bLogin.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub

            int flag = 0;

            /*
             * if (!isValid(username)) {
             * etUsername.setError("Username must be filled"); flag++; }
             * 
             * if (!isValid(password)) {
             * etPassword.setError("Password must be filled"); flag++; }
             */
            if (flag == 0) {

                Database checkLogin = new Database(LoginScreen.this);
                checkLogin.open();
                Boolean temp = checkLogin.getMatched(username, password);

                // Kalo username n passwordnya benar2 ada di database

                if (temp == true) {
                    Intent intent = new Intent(
                            "com.thesis.teamizer.SQLVIEWS");
                    startActivity(intent);

                } // Kalo username n passwordnya salah atau gak ada di
                    // database
                if (temp == false) {
                    Intent i = new Intent("com.thesis.teamizer.REGISSCREEN");
                    startActivity(i);
                }

                checkLogin.close();
            }

        }

        private boolean isValid(String temp) {

            if (temp != null && temp.length() > 6 && !temp.contains(" ")) {
                return true;
            }

            return false;
        }

    });
}

private void ifRegisterButtonClicked() {
    // TODO Auto-generated method stub
    Button bRegis = (Button) findViewById(R.id.bRegister);
    bRegis.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Intent intent = new Intent("com.thesis.teamizer.REGISSCREEN");
            startActivity(intent);
        }
    });
}

}

Answer 1

private void validationUsernameAndPassword() {
    ...
    final String username = etUsername.getText().toString();
    final String password = etPassword.getText().toString();

    bLogin.setOnClickListener(new OnClickListener() {
        ...

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无法从SQLite数据库（Android）中检索特定数据

1 个答案: