Android App中各種數據保存方式的使用實例總結

少量數據保存之SharedPreferences接口實例
SharedPreferences數據保存主要是通過鍵值的方式存儲在xml文件中
xml文件在data/此程序的包名/XX.xml。
格式：

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<int name="count" value="3" />
<string name="time">寫入日期:2013年10月07日,時間:11:28:09</string>
</map>

SharedPreferences讀寫的基本步驟：
讀：
 1.通過Context的getSharedPreferences獲取SharedPreferences接口的對象share：SharedPreferences share = this.getSharedPreferences("share",Context.MODE_PRIVATE);
"shre"保存的xml文件名 ,Context.MODE_PRIVATE 保存的類型為只被本程序訪問 (還有MODE_WORLD_READABLE表示其余的程序能夠讀不能寫,MODE
_WORLD_WRITEBLE能讀寫 這兩個都在api17的時候被廢了)
2.通過share的getXXX的方法獲取指定key的值 ：  share.getInt("count", 0);
寫：
1.通過SharedPreferences對象的edit()方法獲取Edit對象:Edit   editor = share.edit();
2.通過editor對象的putXXX方法來寫入值 ：editor.putInt("count", 1);
3.調用Editor的commit()方法提交修改值 ：editor.commit();

訪問其他程序的SharedPreferences
訪問其他程序的SharedPreferences 的讀寫唯一不同的是先的獲取該程序的Context接口對象：this.createPackageContext(packageName, flags)
packageName為要該目標程序的包名,flags訪問類型
其余的就和上面的步驟差不多 就不再概敘

實例

<LinearLayout 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:orientation="vertical" 
 tools:context=".MainActivity" > 
 
 <Button 
  android:id="@+id/write" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
   android:layout_gravity="center_horizontal" 
  android:text="寫入數據" /> 
 
 <Button 
  android:id="@+id/read" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
   android:layout_gravity="center_horizontal" 
  android:text="讀入數據" /> 
 <TextView 
  android:id="@+id/txtCount" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content"/> 
 
 <TextView 
  android:id="@+id/txt1" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" /> 
 
</LinearLayout> 

package com.android.xiong.sharepreferencestest; 
 
import java.text.SimpleDateFormat; 
import java.util.Date; 
 
import android.app.Activity; 
import android.content.Context; 
import android.content.SharedPreferences; 
import android.content.SharedPreferences.Editor; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.TextView; 
 
public class MainActivity extends Activity { 
 
 private Button write; 
 private Button read; 
 
 private TextView txt1; 
 private TextView countTxt; 
  
 SharedPreferences share ; 
  
 Editor editor; 
 
 int countO=0; 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  //獲取SharedPreferences對象 
  share = this.getSharedPreferences("share", 
    Context.MODE_PRIVATE); 
  //獲取Editor對象 
  editor = share.edit(); 
  write = (Button) findViewById(R.id.write); 
  read = (Button) findViewById(R.id.read); 
  txt1 = (TextView) findViewById(R.id.txt1); 
  countTxt=(TextView)findViewById(R.id.txtCount); 
  //獲取share中key為count的值 
  countO=share.getInt("count", 0); 
  countO++; 
  //修改share中key為count的值 
  editor.putInt("count", countO); 
  //提交修改 
  editor.commit(); 
  System.out.println("該應用程序使用了:"+countO+"次"); 
  countTxt.setText("該應用程序使用了:"+countO+"次"); 
   
  OnClickListener writeListener = new OnClickListener() { 
 
   @Override 
   public void onClick(View v) { 
    // TODO Auto-generated method stub 
 
    SimpleDateFormat data = new SimpleDateFormat( 
      "寫入日期:yyyy年MM月dd日,時間:hh:mm:ss"); 
    editor.putString("time", 
      data.format(new Date())); 
    editor.commit(); 
 
   } 
  }; 
  OnClickListener readListener=new OnClickListener() { 
    
   @Override 
   public void onClick(View v) { 
    // TODO Auto-generated method stub 
    if(!share.contains("share")){ 
     txt1.setText(share.getString("time", null)); 
    } 
     
   } 
  }; 
  write.setOnClickListener(writeListener); 
  read.setOnClickListener(readListener); 
 
 } 
 
 @Override 
 public boolean onCreateOptionsMenu(Menu menu) { 
  // Inflate the menu; this adds items to the action bar if it is present. 
  getMenuInflater().inflate(R.menu.main, menu); 
  return true; 
 } 
 
} 

機身內存數據讀寫(Internal Storage)
1.機身內存讀取主要用個兩個類文件輸入流(FileInputStream)和文件輸出流(FileOutputStream): FileInputStream fileInput = this.openFileInput("test.txt") 第一個參數為 data/此程序包名/data/test.txt 文件下 的文件名 ;
FileOutputStream fileOut = this.openFileOutput("test.txt",this.MODE_APPEND)第一個參數表示文件名 第二個參數表示打開的方式 
2.獲取了文件輸入輸出流之後 其後的文件的讀寫和基本的IO操作一樣
機身內存數據讀寫實例

<LinearLayout 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:layout_gravity="center_horizontal" 
 android:orientation="vertical" 
 tools:context=".MainActivity" > 
 <EditText 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:id="@+id/ed1" 
  android:inputType="textMultiLine"/> 
 <Button 
  android:id="@+id/write" 
  android:text="寫入" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content"/> 
 <Button 
  android:id="@+id/read" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:text="讀入"/> 
 <EditText 
  android:id="@+id/ed2" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:inputType="textMultiLine"/> 
 <Button 
  android:id="@+id/delete" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:text="刪除指定的文件" 
  /> 
 <EditText 
  android:id="@+id/ed3" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  /> 
 
</LinearLayout> 

package com.android.xiong.fileiotest; 
 
import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.InputStreamReader; 
import java.lang.reflect.Array; 
import java.util.ArrayList; 
import java.util.Arrays; 
import java.util.List; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
 
public class MainActivity extends Activity { 
 
 private Button read; 
 private Button write; 
 private EditText ed1; 
 private EditText ed2; 
 private EditText ed3; 
 private Button delete; 
 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  read = (Button) findViewById(R.id.read); 
  write = (Button) findViewById(R.id.write); 
  delete = (Button) findViewById(R.id.delete); 
  ed3 = (EditText) findViewById(R.id.ed3); 
  ed2 = (EditText) findViewById(R.id.ed2); 
  ed1 = (EditText) findViewById(R.id.ed1); 
  write.setOnClickListener(new OnClickListener() { 
   @Override 
   public void onClick(View v) { 
    String str = ed1.getText().toString(); 
    if (!str.equals("")) { 
     write(str); 
    } 
 
   } 
  }); 
  read.setOnClickListener(new OnClickListener() { 
 
   @Override 
   public void onClick(View v) { 
    read(); 
 
   } 
  }); 
  delete.setOnClickListener(new OnClickListener() { 
   @Override 
   public void onClick(View v) { 
    String str = ed3.getText().toString(); 
    if (!str.equals("")) { 
     deleteFiles(str); 
    } else { 
     ed3.setText(str + ":該文件輸入錯誤或不存在!"); 
    } 
 
   } 
  }); 
 
 } 
 
 private void write(String content) { 
  try { 
   // 以追加的方式打開文件輸出流 
   FileOutputStream fileOut = this.openFileOutput("test.txt", 
     this.MODE_APPEND); 
   // 寫入數據 
   fileOut.write(content.getBytes()); 
   // 關閉文件輸出流 
   fileOut.close(); 
 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 } 
 
 private void read() { 
  try { 
   ed2.setText(""); 
   // 打開文件輸入流 
   FileInputStream fileInput = this.openFileInput("test.txt"); 
   BufferedReader br = new BufferedReader(new InputStreamReader( 
     fileInput)); 
   String str = null; 
   StringBuilder stb = new StringBuilder(); 
   while ((str = br.readLine()) !=null ) { 
    stb.append(str); 
   } 
   ed2.setText(stb); 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 
 } 
  
 //刪除指定的文件 
 private void deleteFiles(String fileName) { 
  try { 
   // 獲取data文件中的所有文件列表 
   List<String> name = Arrays.asList(this.fileList()); 
   if (name.contains(fileName)) { 
    this.deleteFile(fileName); 
    ed3.setText(fileName + ":該文件成功刪除！"); 
   } else 
    ed3.setText(fileName + ":該文件輸入錯誤或不存在!"); 
 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 } 
 
 @Override 
 public boolean onCreateOptionsMenu(Menu menu) { 
  getMenuInflater().inflate(R.menu.main, menu); 
  return true; 
 } 
 
} 

SDcard(External Storage)讀寫數據實例
1.SDcard數據讀寫需要注定的先要在Androidmainfest.xml文件中注冊新建刪除和讀寫的權限 : 

<!-- 在SD卡上創建與刪除權限 -->
<uses-permission Android:name="android.permission.MOUNT_FORMAT_FILESYSTEMS" />
<!-- 向SD卡上寫入權限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2.讀寫的基本流程就是:
2.1 通過Environment類的getExternalStorageState()方法來判斷手機是否有SDcard: 

Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)

2.2 最通過getExternalStorageDirectory()方法來獲取文件目錄:

復制代碼 代碼如下:

File file = new File(Environment.getExternalStorageDirectory().getCanonicalPath() + "/test.txt");

讀寫的文件都在sdcrad文件夾中 通過File Explorer可以導出來
2.3 其後就和基本IO操作相同了
2.4還有要注意一點的是 在運行的模擬器的時候要附帶虛擬的SDcard時  要在Run as->Run Configurations 中要關聯一下 如下圖
SDcard數據讀寫實例

<LinearLayout 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:gravity="center_horizontal" 
 android:orientation="vertical" 
 tools:context=".MainActivity" > 
 <EditText 
  android:id="@+id/ed1" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:inputType="textMultiLine"/> 
 <Button 
  android:id="@+id/write" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:text="寫入SD卡中"/> 
 <Button 
  android:id="@+id/read" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:text="讀取SD文件"/> 
 <TextView 
  android:id="@+id/txt1" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content"/> 
</LinearLayout> 

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
 package="com.android.xiong.sdcardtest" 
 android:versionCode="1" 
 android:versionName="1.0" > 
 
 <uses-sdk 
  android:minSdkVersion="14" 
  android:targetSdkVersion="17" /> 
 <!-- 在SD卡上創建與刪除權限 --> 
 <uses-permission android:name="android.permission.MOUNT_FORMAT_FILESYSTEMS" /> 
 <!-- 向SD卡上寫入權限 --> 
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 
 
 <application 
  android:allowBackup="true" 
  android:icon="@drawable/ic_launcher" 
  android:label="@string/app_name" 
  android:theme="@style/AppTheme" > 
  <activity 
   android:name="com.android.xiong.sdcardtest.MainActivity" 
   android:label="@string/app_name" > 
   <intent-filter> 
    <action android:name="android.intent.action.MAIN" /> 
 
    <category android:name="android.intent.category.LAUNCHER" /> 
   </intent-filter> 
  </activity> 
 </application> 
 
</manifest> 

package com.android.xiong.sdcardtest; 
 
import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.InputStreamReader; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.os.Environment; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.TextView; 
 
public class MainActivity extends Activity { 
 
 private Button write; 
 private Button read; 
 
 private EditText ed1; 
 private TextView txt1; 
 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  write = (Button) findViewById(R.id.write); 
  read = (Button) findViewById(R.id.read); 
  ed1 = (EditText) findViewById(R.id.ed1); 
  txt1 = (TextView) findViewById(R.id.txt1); 
  write.setOnClickListener(new OnClickListener() { 
 
   @Override 
   public void onClick(View v) { 
    // TODO Auto-generated method stub 
    writeSDcard(ed1.getText().toString()); 
 
   } 
  }); 
  read.setOnClickListener(new OnClickListener() { 
 
   @Override 
   public void onClick(View v) { 
    // TODO Auto-generated method stub 
 
    txt1.setText(readSDcard()); 
   } 
  }); 
 } 
 
 // 把數據寫入SD卡 
 
 private void writeSDcard(String str) { 
 
  try { 
   // 判斷是否存在SD卡 
   if (Environment.getExternalStorageState().equals( 
     Environment.MEDIA_MOUNTED)) { 
    // 獲取SD卡的目錄 
    File file = Environment.getExternalStorageDirectory(); 
    FileOutputStream fileW = new FileOutputStream(file.getCanonicalPath() + "/test.txt"); 
    fileW.write(str.getBytes()); 
    fileW.close(); 
   } 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 
 } 
 
 // 從SD卡中讀取數據 
 private String readSDcard() { 
  StringBuffer str = new StringBuffer(); 
  try { 
   // 判斷是否存在SD 
   if (Environment.getExternalStorageState().equals( 
     Environment.MEDIA_MOUNTED)) { 
    File file = new File(Environment.getExternalStorageDirectory() 
      .getCanonicalPath() + "/test.txt");                 
    // 判斷是否存在該文件 
    if (file.exists()) { 
     // 打開文件輸入流 
     FileInputStream fileR = new FileInputStream(file); 
     BufferedReader reads = new BufferedReader( 
       new InputStreamReader(fileR)); 
     String st = null; 
     while ((st =reads.readLine())!=null ) { 
      str.append(st); 
     } 
     fileR.close(); 
    } else { 
     txt1.setText("該目錄下文件不存在"); 
    } 
   } 
 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
  return str.toString(); 
 } 
 
 @Override 
 public boolean onCreateOptionsMenu(Menu menu) { 
  // Inflate the menu; this adds items to the action bar if it is present. 
  getMenuInflater().inflate(R.menu.main, menu); 
  return true; 
 } 
 
} 

SQLite簡介和簡單的登錄與注冊源代碼
1.獲取SQLiteDatabase對象db創建數據庫或連接數據庫：SQLiteDatabasedb = SQLiteDatabase.openOrCreateDatabase(MainActivity.this.getFilesDir().toString()+ "/test.dbs", null);如果目錄下有test.dbs數據庫則是連接沒有就是創建
2.用對象db的方法來執行sql語句：db.execSQL(String sql) 此方法木有返回值 所以查詢不好弄。查詢一般用db.rawQuery返回一個Cursor對象(相當與jdbc中的ResultSet),Cursor有如下幾個方法來查詢數據:
  2.1 move ToFirst 將記錄指針跳到第一行
  2.2 moveToLast將記錄指針跳到最後一行
  2.3 moveNext將記錄指針移到下一行
  2.4moveToPosition( int ss)將記錄指針跳到指定的ss行
  2.5moveToPrevious將記錄指針跳到上一行
將記錄指針跳到指定的行之後就可以通過對象的getXXX方法來獲取數據 :如 Cursor cursor = db.rawQuery("select  na,pw from user where na=? and pw=?", new String []{name,pwd});
3.回收資源close
當然以SQLiteDatabase對象還可以調用許多方法來操作數據庫，不過俺是覺得這幾個方法基本夠了

簡單的登錄與注冊源代碼：
（僅此來練習SQLite的操作  一般注冊的信息都樣上傳到服務器而不會是存儲在手機數據庫）

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
  package="com.android.xiong.sqlitelogin" 
  android:versionCode="1" 
  android:versionName="1.0" > 
 
  <uses-sdk 
    android:minSdkVersion="8" 
    android:targetSdkVersion="14" /> 
 
  <application 
    android:allowBackup="true" 
    android:icon="@drawable/ic_launcher" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" > 
    <activity 
      android:name="com.android.xiong.sqlitelogin.MainActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
        <action android:name="android.intent.action.MAIN" /> 
 
        <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
    </activity> 
    <activity 
      android:name="com.android.xiong.sqlitelogin.RegistersActivity" 
      android:label="@string/app_name" > 
    </activity> 
  </application> 
 
</manifest> 

<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" 
  tools:context=".MainActivity" > 
 
  <TextView 
    android:id="@+id/login" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_margin="30dp" 
    android:gravity="center_horizontal" 
    android:textColor="#8a2be2" 
    android:textSize="35dp" 
    android:text="登錄界面" /> 
  <TextView  
    android:id="@+id/txtname" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_below="@id/login" 
    android:layout_marginRight="5dp" 
    android:layout_marginBottom="30dp" 
    android:textSize="28dp" 
    android:text="用戶帳號:"/> 
  <EditText  
    android:id="@+id/edname" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_marginBottom="30dp" 
    android:layout_below="@id/login" 
    android:layout_toRightOf="@id/txtname" 
    android:layout_alignParentRight="true" 
     android:hint="請輸入用戶帳號"/> 
    <TextView  
    android:id="@+id/txtpassword" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_below="@id/txtname" 
    android:layout_marginRight="5dp" 
    android:textSize="28dp" 
    android:text="用戶密碼:"/> 
  <EditText  
    android:id="@+id/edpassword" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_below="@id/edname" 
    android:layout_toRightOf="@id/txtpassword" 
    android:layout_alignParentRight="true" 
    android:inputType="textPassword" 
    android:hint="請輸入用戶密碼"/> 
  <LinearLayout  
    android:layout_below="@id/edpassword" 
    android:orientation="horizontal" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_marginTop="30dp" 
    android:gravity="center_horizontal" > 
  <Button  
    android:id="@+id/btregister" 
    android:layout_height="wrap_content" 
    android:layout_width="wrap_content" 
    android:layout_marginRight="20dp" 
    android:text="用戶注冊"/> 
   <Button  
    android:id="@+id/btlogin" 
    android:layout_height="wrap_content" 
    android:layout_width="wrap_content" 
    android:text="用戶登錄"/> 
   </LinearLayout> 
 
</RelativeLayout> 

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" > 
   
 
  <TextView 
    android:id="@+id/txt1" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_margin="30dp" 
    android:gravity="center_horizontal" 
    android:text="注冊界面" 
    android:textColor="#8a2be2" 
    android:textSize="35dp" /> 
 
  <TextView 
    android:id="@+id/txtname1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_below="@id/txt1" 
    android:layout_marginBottom="30dp" 
    android:layout_marginRight="5dp" 
    android:text="帳號:" 
    android:textSize="28dp" /> 
 
  <EditText 
    android:id="@+id/edname1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentRight="true" 
    android:layout_below="@id/txt1" 
     android:layout_toRightOf="@id/txtname1" 
    android:layout_marginBottom="30dp" /> 
 
  <TextView 
    android:id="@+id/txtpassword1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_below="@id/txtname1" 
    android:layout_marginRight="5dp" 
    android:text="密碼:" 
    android:textSize="28dp" /> 
 
  <EditText 
    android:id="@+id/edpassword1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentRight="true" 
    android:layout_below="@id/edname1" 
    android:layout_toRightOf="@id/txtpassword1" /> 
 
  <LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_below="@id/edpassword1" 
    android:layout_marginTop="30dp" 
    android:gravity="center_horizontal" 
    android:orientation="horizontal" > 
 
    <Button 
      android:id="@+id/btregister1" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_marginRight="20dp" 
      android:text="提交數據" /> 
  </LinearLayout> 
</RelativeLayout> 

package com.android.xiong.sqlitelogin; 
 
import android.app.Activity; 
import android.app.AlertDialog; 
import android.content.Intent; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteException; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
 
public class MainActivity extends Activity { 
 
  // 帳號和密碼 
  private EditText edname; 
  private EditText edpassword; 
 
  private Button btregister; 
  private Button btlogin; 
  // 創建SQLite數據庫 
  public static SQLiteDatabase db; 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    edname = (EditText) findViewById(R.id.edname); 
    edpassword = (EditText) findViewById(R.id.edpassword); 
    btregister = (Button) findViewById(R.id.btregister); 
    btlogin = (Button) findViewById(R.id.btlogin); 
    db = SQLiteDatabase.openOrCreateDatabase(MainActivity.this.getFilesDir().toString() 
        + "/test.dbs", null); 
    // 跳轉到注冊界面 
    btregister.setOnClickListener(new OnClickListener() { 
 
      @Override 
      public void onClick(View v) { 
        // TODO Auto-generated method stub 
        Intent intent = new Intent(); 
        intent.setClass(MainActivity.this, RegistersActivity.class); 
        startActivity(intent); 
      } 
    }); 
    btlogin.setOnClickListener(new LoginListener()); 
  } 
 
  @Override 
  protected void onDestroy() { 
    // TODO Auto-generated method stub 
    super.onDestroy(); 
    db.close(); 
  } 
 
 
  class LoginListener implements OnClickListener { 
 
    @Override 
    public void onClick(View v) { 
      // TODO Auto-generated method stub 
      String name = edname.getText().toString(); 
      String password = edpassword.getText().toString(); 
      if (name.equals("") || password.equals("")) { 
        // 彈出消息框 
        new AlertDialog.Builder(MainActivity.this).setTitle("錯誤") 
            .setMessage("帳號或密碼不能空").setPositiveButton("確定", null) 
            .show(); 
      } else { 
        isUserinfo(name, password); 
      } 
    } 
 
    // 判斷輸入的用戶是否正確 
    public Boolean isUserinfo(String name, String pwd) { 
      try{ 
        String str="select * from tb_user where name=? and password=?"; 
        Cursor cursor = db.rawQuery(str, new String []{name,pwd}); 
        if(cursor.getCount()<=0){ 
          new AlertDialog.Builder(MainActivity.this).setTitle("錯誤") 
          .setMessage("帳號或密碼錯誤！").setPositiveButton("確定", null) 
          .show(); 
          return false; 
        }else{ 
          new AlertDialog.Builder(MainActivity.this).setTitle("正確") 
          .setMessage("成功登錄").setPositiveButton("確定", null) 
          .show(); 
          return true; 
        } 
         
      }catch(SQLiteException e){ 
        createDb(); 
      } 
      return false; 
    } 
   
  } 
  // 創建數據庫和用戶表 
  public void createDb() { 
    db.execSQL("create table tb_user( name varchar(30) primary key,password varchar(30))"); 
  } 
  @Override 
  public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.main, menu); 
    return true; 
  } 
 
} 

package com.android.xiong.sqlitelogin; 
 
import android.app.Activity; 
import android.app.AlertDialog; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.database.sqlite.SQLiteDatabase; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
 
public class RegistersActivity extends Activity { 
 
  private EditText edname1; 
  private EditText edpassword1; 
  private Button btregister1; 
  SQLiteDatabase db; 
 
  @Override 
  protected void onDestroy() { 
    // TODO Auto-generated method stub 
    super.onDestroy(); 
    db.close(); 
  } 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    // TODO Auto-generated method stub 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.register); 
    edname1 = (EditText) findViewById(R.id.edname1); 
    edpassword1 = (EditText) findViewById(R.id.edpassword1); 
    btregister1 = (Button) findViewById(R.id.btregister1); 
    btregister1.setOnClickListener(new OnClickListener() { 
 
      @Override 
      public void onClick(View v) { 
        // TODO Auto-generated method stub 
        String name = edname1.getText().toString(); 
        String password = edpassword1.getText().toString(); 
        if (!(name.equals("") && password.equals(""))) { 
          if (addUser(name, password)) { 
            DialogInterface.OnClickListener ss = new DialogInterface.OnClickListener() { 
              @Override 
              public void onClick(DialogInterface dialog, 
                  int which) { 
                // TODO Auto-generated method stub 
                // 跳轉到登錄界面 
                Intent in = new Intent(); 
                in.setClass(RegistersActivity.this, 
                    MainActivity.class); 
                startActivity(in); 
                // 銷毀當前activity 
                RegistersActivity.this.onDestroy(); 
              } 
            }; 
            new AlertDialog.Builder(RegistersActivity.this) 
                .setTitle("注冊成功").setMessage("注冊成功") 
                .setPositiveButton("確定", ss).show(); 
 
          } else { 
            new AlertDialog.Builder(RegistersActivity.this) 
                .setTitle("注冊失敗").setMessage("注冊失敗") 
                .setPositiveButton("確定", null); 
          } 
        } else { 
          new AlertDialog.Builder(RegistersActivity.this) 
              .setTitle("帳號密碼不能為空").setMessage("帳號密碼不能為空") 
              .setPositiveButton("確定", null); 
        } 
 
      } 
    }); 
 
  } 
 
  // 添加用戶 
  public Boolean addUser(String name, String password) { 
    String str = "insert into tb_user values(?,?) "; 
    MainActivity main = new MainActivity(); 
    db = SQLiteDatabase.openOrCreateDatabase(this.getFilesDir().toString() 
        + "/test.dbs", null); 
    main.db = db; 
    try { 
      db.execSQL(str, new String[] { name, password }); 
      return true; 
    } catch (Exception e) { 
      main.createDb(); 
    } 
    return false; 
  } 
 
}