package com.example.login; 
import java.util.Map; 
import android.app.Activity; 
import android.os.Bundle; 
import android.text.TextUtils; 
import android.view.Menu; 
import android.view.View; 
import android.widget.Button; 
import android.widget.CheckBox; 
import android.widget.EditText; 
import android.widget.Toast; 
import com.example.login.service.FileService; 
public class LoginActivity extends Activity { 
  public EditText edit_name,edit_pass; 
  public Button btn_login; 
  public CheckBox box_remeber; 
  public FileService fileService; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_login); 
    fileService=new FileService(this); 
    edit_name=(EditText) findViewById(R.id.edit_name); 
    edit_pass=(EditText) findViewById(R.id.edit_pass); 
    btn_login=(Button) findViewById(R.id.btn_login); 
    box_remeber=(CheckBox) findViewById(R.id.cbx_remember); 
    btn_login.setOnClickListener(new MyOnClickListener()); 
    Map<String, String> map=fileService.readFile("private.txt"); 
    if(map!=null){ 
      edit_name.setText(map.get("name")); 
      edit_pass.setText(map.get("pass")); 
    } 
  } 
  @Override 
  public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.login, menu); 
    return true; 
  } 
  class MyOnClickListener implements View.OnClickListener{ 
    @Override 
    public void onClick(View v) { 
      int id=v.getId(); 
      switch (id) { 
      case R.id.btn_login: 
        String name=edit_name.getText().toString(); 
        String pass=edit_pass.getText().toString(); 
        if(TextUtils.isEmpty(name)){ 
          Toast.makeText(LoginActivity.this, "用戶名不能為空", Toast.LENGTH_SHORT).show(); 
          return; 
        }else if(TextUtils.isEmpty(pass)){ 
          Toast.makeText(LoginActivity.this, "密碼不能為空", Toast.LENGTH_SHORT).show(); 
          return; 
        }else{ 
          if(box_remeber.isChecked()){ 
            LoginActivity.this.fileService.saveToRom(name, pass, "private.txt"); 
            Toast.makeText(LoginActivity.this, "用戶名和密碼已保存", Toast.LENGTH_SHORT).show(); 
          }else{ 
            Toast.makeText(LoginActivity.this, "用戶名和密碼不需要保存", Toast.LENGTH_SHORT).show(); 
          } 
        } 
        break; 
      default: 
        break; 
      } 
      /*if(id==btn_login.getId()){ 
        String name=edit_name.getText().toString(); 
        String pass=edit_pass.getText().toString(); 
        if(TextUtils.isEmpty(name)){ 
          Toast.makeText(LoginActivity.this, "用戶名不能為空", Toast.LENGTH_SHORT).show(); 
          return; 
        }else if(TextUtils.isEmpty(pass)){ 
          Toast.makeText(LoginActivity.this, "密碼不能為空", Toast.LENGTH_SHORT).show(); 
          return; 
        }else{ 
          if(box_remeber.isChecked()){ 
            LoginActivity.this.fileService.saveToRom(name, pass, "private.txt"); 
            Toast.makeText(LoginActivity.this, "用戶名和密碼已保存", Toast.LENGTH_SHORT).show(); 
          }else{ 
            Toast.makeText(LoginActivity.this, "用戶名和密碼不需要保存", Toast.LENGTH_SHORT).show(); 
          } 
        } 
      }*/ 
    } 
  } 
}

package com.example.login.service; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.util.HashMap; 
import java.util.Map; 
import com.example.login.utils.StreamTools; 
import android.content.Context; 
public class FileService { 
  public Context context; 
  public FileService(Context context) { 
    this.context = context; 
  } 
  public boolean saveToRom(String name,String pass,String fileName){ 
    try{ 
      FileOutputStream fos=context.openFileOutput(fileName, Context.MODE_PRIVATE); 
      String result=name+":"+pass; 
      fos.write(result.getBytes()); 
      fos.flush(); 
      fos.close(); 
    }catch(Exception e){ 
      e.printStackTrace(); 
      return false; 
    } 
    return true; 
  } 
  public Map<String,String> readFile(String fileName){ 
    Map<String,String> map=null; 
    try{ 
      FileInputStream fis=context.openFileInput(fileName); 
      String value=StreamTools.getValue(fis); 
      String values[]=value.split(":"); 
      if(values.length>0){ 
        map=new HashMap<String, String>(); 
        map.put("name", values[0]); 
        map.put("pass", values[1]); 
      } 
    }catch(Exception e){ 
      e.printStackTrace(); 
    } 
    return map; 
  } 
}

package com.example.login.utils; 
import java.io.ByteArrayOutputStream; 
import java.io.FileInputStream; 
public class StreamTools { 
  public static String getValue(FileInputStream fis) throws Exception{ 
    ByteArrayOutputStream stream=new ByteArrayOutputStream(); 
    byte[] buffer=new byte[1024]; 
    int length=-1; 
    while((length=fis.read(buffer))!=-1){ 
      stream.write(buffer,0,length); 
    } 
    stream.flush(); 
    stream.close(); 
    String value=stream.toString(); 
    return value; 
  } 
}

<RelativeLayout xmlns: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=".LoginActivity" > 
  <LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentTop="true" 
    android:orientation="vertical" > 
    <LinearLayout 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" > 
      <TextView 
        android:id="@+id/view_name" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="@string/text_name" /> 
      <EditText 
        android:id="@+id/edit_name" 
        android:layout_width="0dp" 
        android:layout_height="wrap_content" 
        android:layout_weight="1" 
        android:ems="10"  
        android:inputType="textPersonName"> 
        <requestFocus /> 
      </EditText> 
    </LinearLayout> 
    <LinearLayout 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" > 
      <TextView 
        android:id="@+id/view_pass" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="@string/text_pass" /> 
      <EditText 
        android:id="@+id/edit_pass" 
        android:layout_width="0dp" 
        android:layout_height="wrap_content" 
        android:layout_weight="1" 
        android:ems="10" 
        android:inputType="textPassword" /> 
    </LinearLayout> 
    <LinearLayout 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" > 
      <Button 
        android:id="@+id/btn_login" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:layout_weight="0.17" 
        android:text="@string/text_login" /> 
      <CheckBox 
        android:id="@+id/cbx_remember" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:layout_marginLeft="80dp" 
        android:text="@string/text_rember" /> 
    </LinearLayout> 
  </LinearLayout> 
</RelativeLayout>

<?xmlversion="1.0"encoding="utf-8"?>
<resources>
<stringname="app_name">login</string>
<stringname="action_settings">Settings</string>
<stringname="hello_world">Login</string>
<stringname="text_name">用戶名:</string>
<stringname="text_pass">密　碼:</string>
<stringname="text_login">登陸</string>
<stringname="text_rember">記住密碼</string>
</resources>