android 保存用户登录账号

android应用程序中有些使用到用户账号登录，例如QQ登录，登录界面需要用户输入账号，为了提高用户体验，应该尽量减少用户的输入操作，因此需要将用户登录过的账号保存下来，以供下次使用。保存登录账号是一个小量数据，使用Sharedpreferences或普通文件均可实现。以下程序代码保存用户使用过的5个账号。

程序运行界面：





布局文件（/res/layout/main.xml)

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout

android:id="@+id/RelativeLayout1"

xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent">

<TextView

android:textAppearance="?android:attr/textAppearanceLarge"

android:layout_height="wrap_content"

android:layout_width="wrap_content"

android:id="@+id/textView1"

android:text="name:"

android:gravity="center"

android:layout_alignParentTop="true"

android:layout_alignParentLeft="true"

android:layout_alignBottom="@+id/name"></TextView>

<EditText

android:layout_height="wrap_content"

android:layout_width="wrap_content"

android:id="@+id/name"

android:layout_alignParentTop="true"

android:layout_alignParentRight="true"

android:layout_toRightOf="@+id/textView2">

<requestFocus></requestFocus>

</EditText>

<TextView

android:textAppearance="?android:attr/textAppearanceLarge"

android:layout_height="wrap_content"

android:layout_width="wrap_content"

android:id="@+id/textView2"

android:text="password:"

android:layout_below="@+id/name"

android:layout_alignParentLeft="true"></TextView>

<EditText

android:layout_height="wrap_content"

android:layout_width="wrap_content"

android:id="@+id/password"

android:layout_alignTop="@+id/textView2"

android:layout_alignParentRight="true"

android:layout_alignLeft="@+id/name"></EditText>

<Button

android:layout_height="wrap_content"

android:layout_width="wrap_content"

android:id="@+id/button2"

android:text="Button"

android:layout_below="@+id/password"

android:layout_toLeftOf="@+id/button1"></Button>

<Button

android:layout_height="wrap_content"

android:layout_width="wrap_content"

android:id="@+id/button1"

android:text="Button"

android:layout_alignBaseline="@+id/button2"

android:layout_alignBottom="@+id/button2"

android:layout_alignParentRight="true"

android:layout_marginRight="20dp"></Button>

<ImageView

android:layout_width="wrap_content"

android:src="@drawable/array_down"

android:layout_height="wrap_content"

android:id="@+id/show"

android:layout_alignParentTop="true"

android:layout_alignParentRight="true"

android:layout_alignBottom="@+id/name"></ImageView>

</RelativeLayout>

java源文件(MainActivity.java)

package com.ex09;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.util.ArrayList;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.ViewGroup;

import android.view.View.OnClickListener;

import android.widget.AdapterView;

import android.widget.ArrayAdapter;

import android.widget.EditText;

import android.widget.ImageView;

import android.widget.ListView;

import android.widget.PopupWindow;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.PopupWindow.OnDismissListener;

public class MainActivity extends Activity implements

OnClickListener, OnItemClickListener, OnDismissListener {

private ArrayList<String> mList = new ArrayList<String>();

private EditText mEditText;

private ImageView mImageView;

private PopupWindow mPopup;

private boolean mShowing;

private ArrayAdapter<String> mAdapter;

private ListView mListView;

private boolean mInitPopup;

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

mEditText = (EditText) findViewById(R.id.name);

mImageView = (ImageView) findViewById(R.id.show);

mImageView.setOnClickListener(this);

init();

}

private void init() {

ObjectInputStream in = null;

try {

InputStream is = openFileInput("account.obj");

in = new ObjectInputStream(is);

mList = (ArrayList<String>) in.readObject();

if (mList.size() > 0) {

mEditText.setText(mList.get(mList.size() - 1));

}

} catch (Exception e) {

e.printStackTrace();

} finally {

if (in != null) {

try {

in.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

}

@Override

protected void onDestroy() {

super.onDestroy();

String input = mEditText.getText().toString();

mList.remove(input);

mList.add(input);

if (mList.size() > 5) {

mList.remove(0);

}

ObjectOutputStream out = null;

try {

FileOutputStream os = openFileOutput("account.obj",

MODE_PRIVATE);

out = new ObjectOutputStream(os);

out.writeObject(mList);

} catch (Exception e) {

} finally {

if (out != null) {

try {

out.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

}

@Override

public void onClick(View v) {

if (v.getId() == R.id.show) {

if(mList!=null && mList.size()>0 && !mInitPopup){

mInitPopup = true;

initPopup();

}

if (mPopup != null) {

if (!mShowing) {

mPopup.showAsDropDown(mEditText,0,-5);

mShowing = true;

} else {

mPopup.dismiss();

}

}

}

}

private void initPopup() {

mAdapter = new ArrayAdapter<String>(this,

android.R.layout.simple_dropdown_item_1line, mList);

mListView = new ListView(this);

mListView.setAdapter(mAdapter);

mListView.setOnItemClickListener(this);

int height = ViewGroup.LayoutParams.WRAP_CONTENT;

int width = mEditText.getWidth();

System.out.println(width);

mPopup = new PopupWindow(mListView, width, height, true);

mPopup.setOutsideTouchable(true);

mPopup.setBackgroundDrawable(getResources().getDrawable(

R.drawable.popup_bg));

mPopup.setOnDismissListener(this);

}

@Override

public void onItemClick(AdapterView<?> parent, View view,

int position, long id) {

mEditText.setText(mList.get(position));

mPopup.dismiss();

}

@Override

public void onDismiss() {

mShowing = false;

}

}