android 如何实现登陆界面的记住密码功能

今天 写了一个有关登录记住密码的列子 其实这个例子的关键使用到了AutoCompleteTextView 以及sharedPreference的两个关键知识点，大家知道 AutoCompleteTextView 他的默认字体颜色以及背景颜色都是白色 所以我们要对下拉菜单的textview进行颜色定义区分好 我们先来看怎么区分的

list_item.xml

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

<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:textSize="16sp"
android:textColor="#000">
</TextView>

接下来是重点哦

/*author: conowen
* date: 2012.4.2
*
*/
package com.hipikids.remeber;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.text.Editable;
import android.text.InputType;
import android.text.TextWatcher;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class RemeberPwdActivity extends Activity {

AutoCompleteTextView cardNumAuto;
EditText passwordET;
Button logBT;

CheckBox savePasswordCB;
SharedPreferences sp;
String cardNumStr;
String passwordStr;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_remeber_pwd);
cardNumAuto = (AutoCompleteTextView) findViewById(R.id.cardNumAuto);
passwordET = (EditText) findViewById(R.id.passwordET);
logBT = (Button) findViewById(R.id.logBT);

sp = this.getSharedPreferences("passwordFile", MODE_PRIVATE);
savePasswordCB = (CheckBox) findViewById(R.id.savePasswordCB);
savePasswordCB.setChecked(true);// 默认为记住密码
cardNumAuto.setThreshold(1);// 输入1个字母就开始自动提示
passwordET.setInputType(InputType.TYPE_CLASS_TEXT
| InputType.TYPE_TEXT_VARIATION_PASSWORD);
// 隐藏密码为InputType.TYPE_TEXT_VARIATION_PASSWORD，也就是0x81
// 显示密码为InputType.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD，也就是0x91

cardNumAuto.addTextChangedListener(new TextWatcher() {

@Override
public void onTextChanged(CharSequence s, int start, int before,
int count) {
// TODO Auto-generated method stub
String[] allUserName = new String[sp.getAll().size()];// sp.getAll().size()返回的是有多少个键值对
allUserName = sp.getAll().keySet().toArray(new String[0]);
// sp.getAll()返回一张hash map
// keySet()得到的是a set of the keys.
// hash map是由key-value组成的

ArrayAdapter<String> adapter = new ArrayAdapter<String>(
RemeberPwdActivity.this,
R.layout.list_item,
allUserName);

cardNumAuto.setAdapter(adapter);// 设置数据适配器

}

@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub

}

@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
passwordET.setText(sp.getString(cardNumAuto.getText()
.toString(), ""));// 自动输入密码

}
});

// 登陆
logBT.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub

cardNumStr = cardNumAuto.getText().toString();
passwordStr = passwordET.getText().toString();

if (!((cardNumStr.equals("test")) && (passwordStr
.equals("test")))) {
Toast.makeText(RemeberPwdActivity.this, "密码 误，请重新输入",
Toast.LENGTH_SHORT).show();
} else {
if (savePasswordCB.isChecked()) {// 登陆成功才保存密码
sp.edit().putString(cardNumStr, passwordStr).commit();
}
Toast.makeText(RemeberPwdActivity.this, "登陆成功，正在获取用户数据……",
Toast.LENGTH_SHORT).show();
// 跳转到另一个Activity
// do something

}

}
});

}

}

activity_remeber_pwd.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="@drawable/ic_launcher" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="简单登陆DEMO"
android:textSize="25px" />

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

<LinearLayout
android:layout_width="250dip"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="15dp"
android:orientation="vertical" >

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >

<TextView
android:id="@+id/tv_account"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:text="用  户  名:"
android:textSize="15px" />

<AutoCompleteTextView
android:id="@+id/cardNumAuto"
android:textColor="#000000"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</AutoCompleteTextView>
</LinearLayout>

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:text="用户密码:"
android:textSize="15px" />

<EditText
android:id="@+id/passwordET"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</EditText>
</LinearLayout>
</LinearLayout>
</LinearLayout>

<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal" >

<CheckBox
android:id="@+id/savePasswordCB"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:text="记住密码" >
</CheckBox>

<Button
android:id="@+id/logBT"
android:layout_width="100px"
android:layout_height="wrap_content"
android:layout_marginLeft="40dp"
android:layout_marginRight="10dp"
android:text="登录" >
</Button>
</LinearLayout>
</LinearLayout>
</LinearLayout>

</LinearLayout>