SharedPreferences 使用

package com.mytest.android.romsave;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;

public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //readAccount();
        readAccount2();
    }
    public void readAccount(){
        try {
            File file = new File("data/data/com.mytest.android.romsave/info.txt");
            FileInputStream fis = new FileInputStream(file);
            BufferedReader bf = new BufferedReader(new InputStreamReader(fis));
            String text = bf.readLine();
            String[] s = text.split("##");
            EditText et_user = (EditText) findViewById(R.id.user);
            EditText et_password = (EditText) findViewById(R.id.password);
            et_user.setText(s[0]);
            et_password.setText(s[1]);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public void readAccount2(){
        SharedPreferences sp = getSharedPreferences("share",MODE_PRIVATE);
        String user = sp.getString("user", "");
        String password = sp.getString("password","");
        EditText et_user = (EditText) findViewById(R.id.user);
        EditText et_password = (EditText) findViewById(R.id.password);
        et_user.setText(user);
        et_password.setText(password);
    }
    public void login(View v){
        EditText et_user = (EditText) findViewById(R.id.user);
        EditText et_password = (EditText) findViewById(R.id.password);
        CheckBox checkbox = (CheckBox) findViewById(R.id.checkbox);
        String user = et_user.getText().toString();
        String password = et_password.getText().toString();
        if (checkbox.isChecked()) {
            File file = new File("data/data/com.mytest.android.romsave/info.txt");
            try{
                FileOutputStream fos = new FileOutputStream(file);
                fos.write((user + "##" + password).getBytes());
                fos.close();
            } catch (Exception e){
                e.printStackTrace();
            }

        }
        Toast.makeText(this,"登陆成功",0).show();
        System.out.println("登陆。。。");
    }
    public void login2(View v){
        EditText et_user = (EditText) findViewById(R.id.user);
        EditText et_password = (EditText) findViewById(R.id.password);
        CheckBox cb = (CheckBox) findViewById(R.id.checkbox);
        String user = et_user.getText().toString();
        String password = et_password.getText().toString();
        if (cb.isChecked()){
            SharedPreferences sp = getSharedPreferences("share",MODE_PRIVATE);
            SharedPreferences.Editor ed =  sp.edit();
            ed.putString("user",user);
            ed.putString("password",password);
            ed.commit();
            Toast.makeText(this,"ok",0).show();
        }

    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}