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以一个登陆的例子来将，将登陆时的信息保存在指定目录的文件中。在第一次登陆后，对用户名等在内存文件中保存。
android界面：
界面：
1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" 6 android:paddingBottom="@dimen/activity_vertical_margin" 7 android:paddingLeft="@dimen/activity_horizontal_margin" 8 android:paddingRight="@dimen/activity_horizontal_margin" 9 android:paddingTop="@dimen/activity_vertical_margin" 10 tools:context=".MainActivity" > 11 12 <TextView 13 android:layout_width="fill_parent" 14 android:layout_height="wrap_content" 15 android:text="@string/PlaseInputName" 16 android:textSize="20dp" 17 /> 18 19 <EditText 20 android:id="@+id/et_username" 21 android:layout_width="fill_parent" 22 android:layout_height="wrap_content" 23 android:layout_marginBottom="20dp" 24 android:textColor="#FFFF00" 25 /> 26 27 <TextView 28 android:layout_width="fill_parent" 29 android:layout_height="wrap_content" 30 android:text="@string/PlaseInputPwd" 31 android:textSize="20dp" /> 32 33 <EditText 34 android:inputType="textPassword" 35 android:id="@+id/et_userpwd" 36 android:layout_width="fill_parent" 37 android:layout_height="wrap_content" /> 38 39 <RelativeLayout 40 android:layout_width="fill_parent" 41 android:layout_height="wrap_content" > 42 43 <CheckBox 44 android:id="@+id/cb_remeber_pwd" 45 android:layout_width="wrap_content" 46 android:layout_height="wrap_content" 47 android:checked="true" 48 android:text="@string/checkpwd" /> 49 50 <Button 51 android:layout_width="wrap_content" 52 android:layout_height="wrap_content" 53 android:layout_alignParentRight="true" 54 android:onClick="login" 55 android:text="@string/login" 56 /> 57 </RelativeLayout> 58 59 </LinearLayout>
界面原型：
在第一次登陆时，看是否选择记住密码，如果是将登陆信息保存后读取
public class LoginService {
public static boolean saveUerInfo(Context context, String UerName,
String password) {
try {
File file = new File(context.getFilesDir(), "info.txt");
// File file = new File("/data/data/com.example.login/info.txt");
FileOutputStream fos = new FileOutputStream(file);
fos.write((UerName + "###" + password).getBytes());
return true;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
return false;
}
}
主函数：
1 package com.example.login; 2 3 import java.util.Map; 4 5 import com.example.login.service.LoginService; 6 7 import android.os.Bundle; 8 import android.app.Activity; 9 import android.text.TextUtils; 10 import android.view.Menu; 11 import android.view.View; 12 import android.widget.CheckBox; 13 import android.widget.EditText; 14 import android.widget.Toast; 15 16 public class MainActivity extends Activity { 17 private EditText et_username; 18 private EditText et_userpwd; 19 private CheckBox cb; 20 21 @Override 22 protected void onCreate(Bundle savedInstanceState) { 23 super.onCreate(savedInstanceState); 24 setContentView(R.layout.activity_main); 25 et_username = (EditText) this.findViewById(R.id.et_username); 26 et_userpwd = (EditText) this.findViewById(R.id.et_userpwd); 27 cb = (CheckBox) this.findViewById(R.id.cb_remeber_pwd); 28 Map<String, String> map = LoginService.getSaveUserInfo(this); 29 if(map!=null){ 30 et_username.setText(map.get("name")); 31 et_userpwd.setText(map.get("password")); 32 } 33 } 34 35 // 登陆 36 public void login(View view) { 37 String name = et_username.getText().toString().trim(); 38 String password = et_userpwd.getText().toString().trim(); 39 if (TextUtils.isEmpty(name) || (TextUtils.isEmpty(password))) { 40 Toast.makeText(this, "用户名或密码不能为空", Toast.LENGTH_SHORT).show(); 41 } else { 42 // 登陆 43 if (cb.isChecked()) { 44 // 保存密码 45 boolean result = LoginService.saveUerInfo(this, name, password); 46 if (result) { 47 Toast.makeText(this, "保存信息成功", 0).show(); 48 } 49 } 50 // 登陆 51 if ("zhangsan".equals(name) && ("12345").equals(password)) { 52 Toast.makeText(this, "登陆成功", 0).show(); 53 } else { 54 Toast.makeText(this, "登陆失败", 0).show(); 55 } 56 } 57 } 58 59 public EditText getEt_username() { 60 return et_username; 61 } 62 63 public void setEt_username(EditText et_username) { 64 this.et_username = et_username; 65 } 66 67 public EditText getEt_userpwd() { 68 return et_userpwd; 69 } 70 71 public void setEt_userpwd(EditText et_userpwd) { 72 this.et_userpwd = et_userpwd; 73 } 74 75 public CheckBox getCb() { 76 return cb; 77 } 78 79 public void setCb(CheckBox cb) { 80 this.cb = cb; 81 } 82 83 }
方法：
1 package com.example.login.service; 2 3 import java.io.BufferedReader; 4 import java.io.File; 5 import java.io.FileInputStream; 6 import java.io.FileNotFoundException; 7 import java.io.FileOutputStream; 8 import java.io.IOException; 9 import java.io.InputStreamReader; 10 import java.util.HashMap; 11 import java.util.Map; 12 13 import org.apache.http.entity.InputStreamEntity; 14 15 import android.content.Context; 16 17 public class LoginService { 18 public static boolean saveUerInfo(Context context, String UerName, 19 String password) { 20 21 try { 22 File file = new File(context.getFilesDir(), "info.txt"); 23 // File file = new File("/data/data/com.example.login/info.txt"); 24 FileOutputStream fos = new FileOutputStream(file); 25 fos.write((UerName + "###" + password).getBytes()); 26 return true; 27 } catch (Exception e) { 28 // TODO Auto-generated catch block 29 e.printStackTrace(); 30 return false; 31 } 32 33 } 34 35 public static Map<String, String> getSaveUserInfo(Context context) { 36 try { 37 File file = new File(context.getFilesDir(), "info.txt"); 38 FileInputStream fis = new FileInputStream(file); 39 BufferedReader br = new BufferedReader(new InputStreamReader(fis)); 40 String str = br.readLine(); 41 String[] infos = str.split("###"); 42 Map<String, String> map = new HashMap<String, String>(); 43 map.put("name", infos[0]); 44 map.put("password", infos[1]); 45 return map; 46 } catch (Exception e) { 47 // TODO Auto-generated catch block 48 e.printStackTrace(); 49 } 50 return null; 51 52 53 } 54 }
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原文地址：http://www.cnblogs.com/danwuxinbolg/p/4836723.html
