Android-将对象保存在内部存储器中

Question

this code is supposed to create a new user with the username and password he entered and then save that new object to phone memory with the file name matching his email so that in the login method I can look for the file matching the email entered deserialize it, and all his user info would be there... But I keep getting a FileNotFooundException... I really don't understand... please someone help me! :)

Here's the code:

  package com.example.eventmanager;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

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

public class CreateAccount extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_create_account);
    }

    public void createUserAccount(View v) {

        EditText username = (EditText) findViewById(R.id.editText1);
        EditText password = (EditText) findViewById(R.id.editText2);
        EditText secondPassword = (EditText) findViewById(R.id.editText3);

        if (!(password.getText().toString().equals((secondPassword.getText()
                .toString())))) {
            Toast.makeText(this, "Passwords Don't Match", Toast.LENGTH_LONG).show();
        } else {

            User newUser = new User(username.getText().toString(), password.getText().toString());

            String fileName = newUser.getEmail();

            try {
                ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream(fileName));
                os.writeObject(newUser);
                os.close();

            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                Toast.makeText(this, "FileNotFoundException", Toast.LENGTH_LONG)
                        .show();
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                Toast.makeText(this, "IOException", Toast.LENGTH_LONG).show();
                e.printStackTrace();
            }

            Intent intent = new Intent(this, LoginScreen.class);
            startActivity(intent);

            Toast.makeText(this, "Account Created Successfully",
                    Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_create_account, menu);
        return true;
    }
}

Answer 1

Per FileOutputStream documentation: it throws FileNotFoundException in below scenario:

FileNotFoundException - if the file exists but is a directory rather than a regular file OR does not exist but cannot be created, or cannot be opened for any other reason

Please make sure, String fileName = newUser.getEmail().toString(); results in valid file name, which I suspect is the case.

Answer 2

FileOutputStream uses an absolute path which (I think) will default to the root of the internal storage if you only provide a filename - on a normal device, the root of the internal storage will not be accessible.

You should use openFileOutput(String name, int mode) instead. This guarantees creating a file in the internal storage in the area allocated to your own app. To read the file back, use the corresponding openFileInput(String name) method.