Login Example

1.activity_main.xml

<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:paddingBottom="@dimen/activity_vertical_margin"

android:paddingLeft="@dimen/activity_horizontal_margin"

android:paddingRight="@dimen/activity_horizontal_margin"

android:paddingTop="@dimen/activity_vertical_margin"

tools:context=".MainActivity">

<TextView

android:id="@+id/user_text"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignBottom="@+id/user_name"

android:layout_alignParentTop="true"

android:text="@string/user_text"

android:textSize="20sp"/>

<EditText

android:id="@+id/user_name"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_toRightOf="@+id/user_text"

android:inputType="text"

android:hint="@string/user_alert"

android:textSize="20sp"/>

<TextView

android:id="@+id/pass_text"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_below="@+id/user_text"

android:layout_alignBottom="@+id/pwd"

android:text="@string/pass_text"

android:textSize="20sp"/>

<EditText

android:id="@+id/pwd"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_below="@+id/user_name"

android:layout_toRightOf="@+id/pass_text"

android:inputType="textPassword"

android:hint="@string/pass_alert"

android:textSize="20sp"/>

<CheckBoxandroid:id="@+id/check_save"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_below="@+id/pass_text"

android:text="@string/check_save"

android:textSize="20sp"/>

<Button

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_below="@+id/check_save"

android:text="@string/login_text"

android:onClick="onLoginCeck"

android:textSize="20sp"

/>

</RelativeLayout>

2.MainActivity.java

packagecom.example.loginfile;

importjava.io.File;

importjava.io.FileInputStream;

importjava.io.FileOutputStream;

importjava.io.FileReader;

importjava.io.FileWriter;

importjava.io.IOException;

importandroid.annotation.SuppressLint;

importandroid.app.Activity;

importandroid.os.Bundle;

importandroid.view.Menu;

importandroid.view.View;

importandroid.widget.CheckBox;

importandroid.widget.EditText;

importandroid.widget.Toast;

publicclassMainActivityextendsActivity{

@Override

protectedvoidonCreate(BundlesavedInstanceState){

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//從文件中取出用戶名及密碼,并寫入到畫面中。

try{

Filefile=newFile(getFilesDir(),"login.txt");

//文件存在且不為空,才取用戶名與密碼.

if(file.exists()&&file.length()>0){

charbuffer[]=newchar[1024];

FileReaderrd=newFileReader(file);

intlen=rd.read(buffer);

rd.close();

Stringdata=newString(buffer,0,len);

Stringbuff[]=data.split(";");

if(buff.length>0){

Stringaccount=buff[0];

Stringpass=buff[1];

//System.out.println("account="+account+"--pass="+pass);

//將用戶名與密碼set到輸入框中.

((EditText)findViewById(R.id.user_name)).setText(account);

((EditText)findViewById(R.id.pwd)).setText(pass);

}

}}

catch(IOExceptione){

e.printStackTrace();

}

}

@Override

publicbooleanonCreateOptionsMenu(Menumenu){

//Inflatethemenu;thisaddsitemstotheactionbarifitispresent.

getMenuInflater().inflate(R.menu.main,menu);

returntrue;

}

publicvoidonLoginCeck(Viewv)throwsIOException{

//此方法主要是把用戶名與密碼保存到txt文件中.

EditTextet_userno=(EditText)findViewById(R.id.user_name);

Stringuser_no=et_userno.getText().toString();

EditTextet_pass=(EditText)findViewById(R.id.pwd);

Stringpwd=et_pass.getText().toString();

//System.out.println("user_no="+user_no);

//System.out.println("pwd="+pwd);

//用戶與密碼不能為空.

if(user_no==null||"".equalsIgnoreCase(user_no)){

Toast.makeText(getApplicationContext(),"usernamecan'tempty.",Toast.LENGTH_LONG).show();

return;

}

if(pwd==null||"".equalsIgnoreCase(pwd)){

Toast.makeText(getApplicationContext(),"passworldcannotempty.",Toast.LENGTH_LONG).show();

return;

}

System.out.println("afteruser_noempty.");

//保存復選框選中,則將用戶及密碼保存到txt文件.

Filefile=newFile(getFilesDir(),"login.txt");

CheckBoxcb=(CheckBox)findViewById(R.id.check_save);

if(cb.isChecked()){

FileWriterwt=newFileWriter(file);

wt.write(user_no+";"+pwd);

wt.close();

}

}

}

3.strings.xml

<?xmlversion="1.0"encoding="utf-8"?>

<resources>

<stringname="app_name">loginFile</string>

<stringname="action_settings">Settings</string>

<stringname="user_text">用户名称：</string>

<stringname="user_alert">pleaseinputaccount</string>

<stringname="pass_text">用户密码：</string>

<stringname="pass_alert">inputpassworld</string>

<stringname="check_save">是否保存用户及密码</string>

<stringname="login_text">登錄</string>

</resources>