Android Studio 无法进入管理页面

Question

所以我是 Android Studio 的新手，我正在尝试制作一个登录页面。在我的数据库中，我创建了 user_type 属性，如果用户类型是管理员，我希望登录屏幕重定向到管理员页面而不是普通主页。我尝试使用 if-else 语句来表示意图，但即使我的 user_type 已经是“Admin”，它仍然总是将我重定向到 MainActivity 类。谁能帮忙告诉我这个问题？提前致谢。

这是我的用户类：

package com.example.voluminous.model;

//Create User class
public class User {

    private int id;
    private String type;
    private String name;
    private String email;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

这是我的 DB Open Helper：

package com.example.voluminous.sql;

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

import com.example.voluminous.model.User;

import java.util.ArrayList;
import java.util.List;

public class UserDatabaseHelper extends SQLiteOpenHelper {
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "UserManager.db";

    // User table name
    private static final String TABLE_USER = "user";

    // User Table Columns names
    private static final String COLUMN_USER_ID = "user_id";
    private static final String COLUMN_USER_TYPE = "user_type";
    private static final String COLUMN_USER_NAME = "user_name";
    private static final String COLUMN_USER_EMAIL = "user_email";
    private static final String COLUMN_USER_PASSWORD = "user_password";

    // create table sql query
    private String CREATE_USER_TABLE = "CREATE TABLE " + TABLE_USER + "("
            + COLUMN_USER_ID + " INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," + COLUMN_USER_TYPE + " TEXT DEFAULT 'Customer' NOT NULL,"
            + COLUMN_USER_NAME + " TEXT NOT NULL," + COLUMN_USER_EMAIL + " TEXT NOT NULL," + COLUMN_USER_PASSWORD + " TEXT NOT NULL" + ")";

    // drop table sql query
    private String DROP_USER_TABLE = "DROP TABLE IF EXISTS " + TABLE_USER;

    /**
     * Constructor
     *
     * @param context
     */
    public UserDatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_USER_TABLE);
        db.execSQL("INSERT INTO user (user_type, user_name, user_email, user_password) VALUES (?,?,?,?)", new Object[]{"Admin","Administrator","admin@voluminous.com","123"});
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        //Drop User Table if exist
        db.execSQL(DROP_USER_TABLE);

        // Create tables again
        onCreate(db);

    }

    /**
     * This method is to create user record
     *
     * @param user
     */
    public void addUser(User user) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(COLUMN_USER_TYPE, user.getType());
        values.put(COLUMN_USER_NAME, user.getName());
        values.put(COLUMN_USER_EMAIL, user.getEmail());
        values.put(COLUMN_USER_PASSWORD, user.getPassword());

        // Inserting Row
        db.insert(TABLE_USER, null, values);
        db.close();
    }

    /**
     * This method is to fetch all user and return the list of user records
     *
     * @return list
     */
    public List<User> getAllUser() {
        // array of columns to fetch
        String[] columns = {
                COLUMN_USER_ID,
                COLUMN_USER_TYPE,
                COLUMN_USER_EMAIL,
                COLUMN_USER_NAME,
                COLUMN_USER_PASSWORD
        };
        // sorting orders
        String sortOrder =
                COLUMN_USER_NAME + " ASC";
        List<User> userList = new ArrayList<User>();

        SQLiteDatabase db = this.getReadableDatabase();

        // query the user table
        /**
         * Here query function is used to fetch records from user table this function works like we use sql query.
         * SQL query equivalent to this query function is
         * SELECT user_id,user_name,user_email,user_password FROM user ORDER BY user_name;
         */
        Cursor cursor = db.query(TABLE_USER, //Table to query
                columns,    //columns to return
                null,        //columns for the WHERE clause
                null,        //The values for the WHERE clause
                null,       //group the rows
                null,       //filter by row groups
                sortOrder); //The sort order


        // Traversing through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                User user = new User();
                user.setId(Integer.parseInt(cursor.getString(cursor.getColumnIndex(COLUMN_USER_ID))));
                user.setType(cursor.getString(cursor.getColumnIndex(COLUMN_USER_TYPE)));
                user.setName(cursor.getString(cursor.getColumnIndex(COLUMN_USER_NAME)));
                user.setEmail(cursor.getString(cursor.getColumnIndex(COLUMN_USER_EMAIL)));
                user.setPassword(cursor.getString(cursor.getColumnIndex(COLUMN_USER_PASSWORD)));
                // Adding user record to list
                userList.add(user);
            } while (cursor.moveToNext());
        }
        cursor.close();
        db.close();

        // return user list
        return userList;
    }

    /**
     * This method to update user record
     *
     * @param user
     */
    public void updateUser(User user) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(COLUMN_USER_TYPE, user.getType());
        values.put(COLUMN_USER_NAME, user.getName());
        values.put(COLUMN_USER_EMAIL, user.getEmail());
        values.put(COLUMN_USER_PASSWORD, user.getPassword());

        // updating row
        db.update(TABLE_USER, values, COLUMN_USER_ID + " = ?",
                new String[]{String.valueOf(user.getId())});
        db.close();
    }

    /**
     * This method is to delete user record
     *
     * @param user
     */
    public void deleteUser(User user) {
        SQLiteDatabase db = this.getWritableDatabase();
        // delete user record by id
        db.delete(TABLE_USER, COLUMN_USER_ID + " = ?",
                new String[]{String.valueOf(user.getId())});
        db.close();
    }

    /**
     * This method to check user exist or not
     *
     * @param email
     * @return true/false
     */
    public boolean checkUser(String email) {

        // array of columns to fetch
        String[] columns = {
                COLUMN_USER_ID
        };
        SQLiteDatabase db = this.getReadableDatabase();

        // selection criteria
        String selection = COLUMN_USER_EMAIL + " = ?";

        // selection argument
        String[] selectionArgs = {email};

        // query user table with condition
        /**
         * Here query function is used to fetch records from user table this function works like we use sql query.
         * SQL query equivalent to this query function is
         * SELECT user_id FROM user WHERE user_email = 'jack@androidtutorialshub.com';
         */
        Cursor cursor = db.query(TABLE_USER, //Table to query
                columns,                    //columns to return
                selection,                  //columns for the WHERE clause
                selectionArgs,              //The values for the WHERE clause
                null,                       //group the rows
                null,                      //filter by row groups
                null);                      //The sort order
        int cursorCount = cursor.getCount();
        cursor.close();
        db.close();

        if (cursorCount > 0) {
            return true;
        }

        return false;
    }

    /**
     * This method to check user exist or not
     *
     * @param email
     * @param password
     * @return true/false
     */
    public boolean checkUser(String email, String password) {

        // array of columns to fetch
        String[] columns = {
                COLUMN_USER_ID
        };
        SQLiteDatabase db = this.getReadableDatabase();
        // selection criteria
        String selection = COLUMN_USER_EMAIL + " = ?" + " AND " + COLUMN_USER_PASSWORD + " = ?";

        // selection arguments
        String[] selectionArgs = {email, password};

        // query user table with conditions
        /**
         * Here query function is used to fetch records from user table this function works like we use sql query.
         * SQL query equivalent to this query function is
         * SELECT user_id FROM user WHERE user_email = 'jack@androidtutorialshub.com' AND user_password = 'qwerty';
         */
        Cursor cursor = db.query(TABLE_USER, //Table to query
                columns,                    //columns to return
                selection,                  //columns for the WHERE clause
                selectionArgs,              //The values for the WHERE clause
                null,                       //group the rows
                null,                       //filter by row groups
                null);                      //The sort order

        int cursorCount = cursor.getCount();

        cursor.close();
        db.close();
        if (cursorCount > 0) {
            return true;
        }

        return false;
    }
}

这是我的 LoginActivity 类：

package com.example.voluminous;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.service.autofill.UserData;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import com.example.voluminous.model.User;
import com.example.voluminous.sql.UserDatabaseHelper;

import java.util.ArrayList;

public class LoginActivity extends AppCompatActivity implements View.OnClickListener {

    private UserDatabaseHelper UserDBHelper;
    private Button mBtLoginactivityRegister;
    private RelativeLayout mRlLoginactivityLayout;
    private EditText mEtLoginactivityEmail;
    private EditText mEtLoginactivityPassword;
    private LinearLayout mLlLoginactivityTwo;
    private Button mBtLoginactivityLogin;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        initView();

        UserDBHelper = new UserDatabaseHelper(this);
    }

    private void initView() {

        mBtLoginactivityLogin = findViewById(R.id.bt_loginactivity_login);
        mBtLoginactivityRegister = findViewById(R.id.bt_loginactivity_register);
        mRlLoginactivityLayout = findViewById(R.id.rl_loginactivity_layout);
        mEtLoginactivityEmail = findViewById(R.id.et_loginactivity_email);
        mEtLoginactivityPassword = findViewById(R.id.et_loginactivity_password);
        mLlLoginactivityTwo = findViewById(R.id.loginactivity_loginbox);

        mBtLoginactivityLogin.setOnClickListener(this);
        mBtLoginactivityRegister.setOnClickListener(this);
    }

    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.tv_loginactivity_register:
                startActivity(new Intent(this, RegisterActivity.class));
                finish();
                break;

            case R.id.bt_loginactivity_login:
                String email = mEtLoginactivityEmail.getText().toString().trim();
                String password = mEtLoginactivityPassword.getText().toString().trim();
                if (!TextUtils.isEmpty(email) && !TextUtils.isEmpty(password)) {
                    ArrayList<User> data = (ArrayList<User>) UserDBHelper.getAllUser();
                    boolean match = false;
                    boolean isAdmin = false;
                    for (int i = 0; i < data.size(); i++) {
                        User user = data.get(i);
                        if (email.equals(user.getEmail()) && password.equals(user.getPassword())) {
                            if (user.getType().equals("Admin"))
                                isAdmin = true;
                            match = true;
                            break;
                        } else {
                            match = false;
                        }
                    }
                    if (match) {
                        SharedPreferences sp = getSharedPreferences("user",MODE_PRIVATE);
                        SharedPreferences.Editor editor = sp.edit();
                        editor.putString("e-mail", email);
                        editor.commit();
                        Toast.makeText(this, "Login successful", Toast.LENGTH_SHORT).show();
                        if (!isAdmin)
                        {
                            Intent intent = new Intent(this, MainActivity.class);
                            startActivity(intent);
                        }
                        else if (isAdmin)
                        {
                            Intent intent = new Intent(this, AdminActivity.class);
                            startActivity(intent);
                        }
                        finish();
                    } else {
                        Toast.makeText(this, "Incorrect user name or password, please re-enter.", Toast.LENGTH_SHORT).show();
                    }
                } else {
                    Toast.makeText(this, "Please enter your user name or password.", Toast.LENGTH_SHORT).show();
                }
                break;
        }
    }
}

Answer 1

在您的登录活动中

从 for 循环中删除以下行

 else { match = false;}

for (int i = 0; i < data.size(); i++) {
User user = data.get(i);
if (email.equals(user.getEmail()) && password.equals(user.getPassword())) {
                            if (user.getType().equals("Admin"))
                                isAdmin = true;
                            match = true;
                            break;
                        }
                    }

如果您的电子邮件和密码匹配，则设置 match =true。但随后循环将继续进行下一次检查，它将在哪里设置 match=false。如果您只是尝试使用 for 循环查找匹配项，则不需要 else 条件。当您获得匹配项时，您应该在这种情况下停止循环，删除您设置 match=false 的 else 条件

Answer 2

这需要调试。我建议添加几行，以便您在 LogCat 中查看信息。

                        if (user.getType().equals("Admin"))
                            isAdmin = true;
                        else
                            Log.i("Match", user.getName() + " has type " +  user.getType() + " is not Admin");

如果您仍有问题，请将您的 LogCat 粘贴到此处向我们展示。