用安卓studio实现考试管理系统，并给出源码

很抱歉，考试管理系统是一个较为复杂的应用，无法在此简单地给出完整的源代码。不过，我可以提供一些基本的实现思路和代码示例，供您参考：

1. 登录页面布局文件（activity_login.xml）：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <EditText
        android:id="@+id/username_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="用户名"/>

    <EditText
        android:id="@+id/password_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="密码"
        android:inputType="textPassword"/>

    <Button
        android:id="@+id/login_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="登录"/>

</LinearLayout>

2. 登录页面Java代码（LoginActivity.java）：

public class LoginActivity extends AppCompatActivity {
    private EditText mUsernameEditText;
    private EditText mPasswordEditText;
    private Button mLoginButton;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        
        mUsernameEditText = findViewById(R.id.username_edittext);
        mPasswordEditText = findViewById(R.id.password_edittext);
        mLoginButton = findViewById(R.id.login_button);
        
        mLoginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = mUsernameEditText.getText().toString();
                String password = mPasswordEditText.getText().toString();
                
                if (isValidUser(username, password)) {
                    Intent intent = new Intent(LoginActivity.this, MainMenuActivity.class);
                    startActivity(intent);
                    finish();
                } else {
                    Toast.makeText(LoginActivity.this, "用户名或密码错误", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
    
    private boolean isValidUser(String username, String password) {
        // TODO: 根据数据库中的数据判断用户是否合法
        return true;
    }
}

3. SQLite数据库操作类（DBHelper.java）：

public class DBHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "exam.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_STUDENT = "student";
    private static final String TABLE_EXAM = "exam";
    
    public DBHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
    
    @Override
    public void onCreate(SQLiteDatabase db) {
        String createStudentTableSql = "CREATE TABLE " + TABLE_STUDENT + 
            " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
            "username TEXT NOT NULL, " +
            "password TEXT NOT NULL)";
        String createExamTableSql = "CREATE TABLE " + TABLE_EXAM + 
            " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
            "student_id INTEGER NOT NULL, " +
            "subject TEXT NOT NULL, " +
            "score INTEGER NOT NULL)";
        db.execSQL(createStudentTableSql);
        db.execSQL(createExamTableSql);
    }
    
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO: 数据库升级逻辑
    }
    
    public boolean insertStudent(String username, String password) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("username", username);
        values.put("password", password);
        long result = db.insert(TABLE_STUDENT, null, values);
        db.close();
        return result != -1;
    }
    
    public boolean updateStudent(String username, String password) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("password", password);
        String selection = "username = ?";
        String[] selectionArgs = { username };
        int result = db.update(TABLE_STUDENT, values, selection, selectionArgs);
        db.close();
        return result > 0;
    }
    
    public boolean deleteStudent(String username) {
        SQLiteDatabase db = getWritableDatabase();
        String selection = "username = ?";
        String[] selectionArgs = { username };
        int result = db.delete(TABLE_STUDENT, selection, selectionArgs);
        db.close();
        return result > 0;
    }
    
    public boolean insertExam(int studentId, String subject, int score) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("student_id", studentId);
        values.put("subject", subject);
        values.put("score", score);
        long result = db.insert(TABLE_EXAM, null, values);
        db.close();
        return result != -1;
    }
    
    public Cursor queryStudentByUsername(String username) {
        SQLiteDatabase db = getReadableDatabase();
        String[] columns = { "_id", "username", "password" };
        String selection = "username = ?";
        String[] selectionArgs = { username };
        Cursor cursor = db.query(TABLE_STUDENT, columns, selection, selectionArgs, null, null, null);
        return cursor;
    }
    
    public Cursor queryExamByStudentId(int studentId) {
        SQLiteDatabase db = getReadableDatabase();
        String[] columns = { "_id", "subject", "score" };
        String selection = "student_id = ?";
        String[] selectionArgs = { String.valueOf(studentId) };
        Cursor cursor = db.query(TABLE_EXAM, columns, selection, selectionArgs, null, null, null);
        return cursor;
    }
}

4. 主菜单页面布局文件（activity_main_menu.xml）：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <Button
        android:id="@+id/exam_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="考试"/>

    <Button
        android:id="@+id/score_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="成绩"/>

    <Button
        android:id="@+id/logout_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="注销"/>

</LinearLayout>

5. 主菜单页面Java代码（MainMenuActivity.java）：

public class MainMenuActivity extends AppCompatActivity {
    private Button mExamButton;
    private Button mScoreButton;
    private Button mLogoutButton;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_menu);
        
        mExamButton = findViewById(R.id.exam_button);
        mScoreButton = findViewById(R.id.score_button);
        mLogoutButton = findViewById(R.id.logout_button);
        
        mExamButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainMenuActivity.this, ExamActivity.class);
                startActivity(intent);
            }
        });
        
        mScoreButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainMenuActivity.this, ScoreActivity.class);
                startActivity(intent);
            }
        });
        
        mLogoutButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainMenuActivity.this, LoginActivity.class);
                startActivity(intent);
                finish();
            }
        });
    }
}

6. 考试页面布局文件（activity_exam.xml）：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:id="@+id/subject_textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="科目"/>

    <EditText
        android:id="@+id/score_edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="分数"/>

    <Button
        android:id="@+id/submit_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="提交"/>

</LinearLayout>

7. 考试页面Java代码（ExamActivity.java）：

public class ExamActivity extends AppCompatActivity {
    private TextView mSubjectTextView;
    private EditText mScoreEditText;
    private Button mSubmitButton;
    private DBHelper mDBHelper;
    private int mStudentId;
    private String mSubject;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_exam);
        
        mSubjectTextView = findViewById(R.id.subject_textview);
        mScoreEditText = findViewById(R.id.score_edittext);
        mSubmitButton = findViewById(R.id.submit_button);
        mDBHelper = new DBHelper(this);
        mStudentId = 1;  // TODO: 获取当前登录的学生ID
        mSubject = "数学";  // TODO: 获取当前考试的科目
        
        mSubjectTextView.setText(mSubject);
        
        mSubmitButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int score = Integer.parseInt(mScoreEditText.getText().toString());
                mDBHelper.insertExam(mStudentId, mSubject, score);
                Toast.makeText(ExamActivity.this, "提交成功", Toast.LENGTH_SHORT).show();
                finish();
            }
        });
    }
}

8. 成绩页面布局文件（activity_score.xml）：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:id="@+id/subject_textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="科目"/>

    <TextView
        android:id="@+id/score_textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="分数"/>

</LinearLayout>

9. 成绩页面Java代码（ScoreActivity.java）：

public class ScoreActivity extends AppCompatActivity {
    private TextView mSubjectTextView;
    private TextView mScoreTextView;
    private DBHelper mDBHelper;
    private int mStudentId;
    private String mSubject;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_score);
        
        mSubjectTextView = findViewById(R.id.subject_textview);
        mScoreTextView = findViewById(R.id.score_textview);
        mDBHelper = new DBHelper(this);
        mStudentId = 1;  // TODO: 获取当前登录的学生ID
        mSubject = "数学";  // TODO: 获取当前查询的科目
        
        mSubjectTextView.setText(mSubject);
        
        Cursor cursor = mDBHelper.queryExamByStudentId(mStudentId);
        while (cursor.moveToNext()) {
            String subject = cursor.getString(cursor.getColumnIndex("subject"));
            int score = cursor.getInt(cursor.getColumnIndex("score"));
            if (subject.equals(mSubject)) {
                mScoreTextView.setText(String.valueOf(score));
                break;
            }
        }
        cursor.close();
    }
}

需要注意的是，以上代码仅供参考，实际应用中还需要根据具体需求进行修改和调整。另外，数据库操作和数据安全等方面也需要格外注意。