Android App中各种数据保存方式的使用实例总结

吴唯

2023-03-14

本文向大家介绍Android App中各种数据保存方式的使用实例总结，包括了Android App中各种数据保存方式的使用实例总结的使用技巧和注意事项，需要的朋友参考一下

少量数据保存之SharedPreferences接口实例
SharedPreferences数据保存主要是通过键值的方式存储在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">写入日期:2013年10月07日,时间:11:28:09</string>
</map>

SharedPreferences读写的基本步骤：
读：
1.通过Context的getSharedPreferences获取SharedPreferences接口的对象share：SharedPreferences share = this.getSharedPreferences("share",Context.MODE_PRIVATE);
"shre"保存的xml文件名 ,Context.MODE_PRIVATE 保存的类型为只被本程序访问 (还有MODE_WORLD_READABLE表示其余的程序能够读不能写,MODE
_WORLD_WRITEBLE能读写这两个都在api17的时候被废了)
2.通过share的getXXX的方法获取指定key的值： share.getInt("count", 0);
写：
1.通过SharedPreferences对象的edit()方法获取Edit对象:Edit editor = share.edit();
2.通过editor对象的putXXX方法来写入值：editor.putInt("count", 1);
3.调用Editor的commit()方法提交修改值：editor.commit();

访问其他程序的SharedPreferences
访问其他程序的SharedPreferences 的读写唯一不同的是先的获取该程序的Context接口对象：this.createPackageContext(packageName, flags)
packageName为要该目标程序的包名,flags访问类型
其余的就和上面的步骤差不多就不再概叙

实例

<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="写入数据" /> 
 
 <Button 
  android:id="@+id/read" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
   android:layout_gravity="center_horizontal" 
  android:text="读入数据" /> 
 <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); 
  //获取SharedPreferences对象 
  share = this.getSharedPreferences("share", 
    Context.MODE_PRIVATE); 
  //获取Editor对象 
  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); 
  //获取share中key为count的值 
  countO=share.getInt("count", 0); 
  countO++; 
  //修改share中key为count的值 
  editor.putInt("count", countO); 
  //提交修改 
  editor.commit(); 
  System.out.println("该应用程序使用了:"+countO+"次"); 
  countTxt.setText("该应用程序使用了:"+countO+"次"); 
   
  OnClickListener writeListener = new OnClickListener() { 
 
   @Override 
   public void onClick(View v) { 
    // TODO Auto-generated method stub 
 
    SimpleDateFormat data = new SimpleDateFormat( 
      "写入日期:yyyy年MM月dd日,时间: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; 
 } 
 
}

机身内存数据读写(Internal Storage)
1.机身内存读取主要用个两个类文件输入流(FileInputStream)和文件输出流(FileOutputStream): FileInputStream fileInput = this.openFileInput("test.txt") 第一个参数为 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)第一个参数表示文件名第二个参数表示打开的方式
2.获取了文件输入输出流之后其后的文件的读写和基本的IO操作一样
机身内存数据读写实例

<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="写入" 
  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="读入"/> 
 <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="删除指定的文件" 
  /> 
 <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 + ":该文件输入错误或不存在!"); 
    } 
 
   } 
  }); 
 
 } 
 
 private void write(String content) { 
  try { 
   // 以追加的方式打开文件输出流 
   FileOutputStream fileOut = this.openFileOutput("test.txt", 
     this.MODE_APPEND); 
   // 写入数据 
   fileOut.write(content.getBytes()); 
   // 关闭文件输出流 
   fileOut.close(); 
 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 } 
 
 private void read() { 
  try { 
   ed2.setText(""); 
   // 打开文件输入流 
   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(); 
  } 
 
 } 
  
 //删除指定的文件 
 private void deleteFiles(String fileName) { 
  try { 
   // 获取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 + ":该文件成功删除！"); 
   } else 
    ed3.setText(fileName + ":该文件输入错误或不存在!"); 
 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 } 
 
 @Override 
 public boolean onCreateOptionsMenu(Menu menu) { 
  getMenuInflater().inflate(R.menu.main, menu); 
  return true; 
 } 
 
}

SDcard(External Storage)读写数据实例
1.SDcard数据读写需要注定的先要在Androidmainfest.xml文件中注册新建删除和读写的权限 :

<!-- 在SD卡上创建与删除权限 -->
<uses-permission Android:name="android.permission.MOUNT_FORMAT_FILESYSTEMS" />
<!-- 向SD卡上写入权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2.读写的基本流程就是:
2.1 通过Environment类的getExternalStorageState()方法来判断手机是否有SDcard:

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

2.2 最通过getExternalStorageDirectory()方法来获取文件目录:


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

读写的文件都在sdcrad文件夹中通过File Explorer可以导出来
2.3 其后就和基本IO操作相同了
2.4还有要注意一点的是在运行的模拟器的时候要附带虚拟的SDcard时要在Run as->Run Configurations 中要关联一下如下图

SDcard数据读写实例

<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="写入SD卡中"/> 
 <Button 
  android:id="@+id/read" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:text="读取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卡上创建与删除权限 --> 
 <uses-permission android:name="android.permission.MOUNT_FORMAT_FILESYSTEMS" /> 
 <!-- 向SD卡上写入权限 --> 
 <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()); 
   } 
  }); 
 } 
 
 // 把数据写入SD卡 
 
 private void writeSDcard(String str) { 
 
  try { 
   // 判断是否存在SD卡 
   if (Environment.getExternalStorageState().equals( 
     Environment.MEDIA_MOUNTED)) { 
    // 获取SD卡的目录 
    File file = Environment.getExternalStorageDirectory(); 
    FileOutputStream fileW = new FileOutputStream(file.getCanonicalPath() + "/test.txt"); 
    fileW.write(str.getBytes()); 
    fileW.close(); 
   } 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 
 } 
 
 // 从SD卡中读取数据 
 private String readSDcard() { 
  StringBuffer str = new StringBuffer(); 
  try { 
   // 判断是否存在SD 
   if (Environment.getExternalStorageState().equals( 
     Environment.MEDIA_MOUNTED)) { 
    File file = new File(Environment.getExternalStorageDirectory() 
      .getCanonicalPath() + "/test.txt");                 
    // 判断是否存在该文件 
    if (file.exists()) { 
     // 打开文件输入流 
     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("该目录下文件不存在"); 
    } 
   } 
 
  } 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简介和简单的登录与注册源代码
1.获取SQLiteDatabase对象db创建数据库或连接数据库：SQLiteDatabasedb = SQLiteDatabase.openOrCreateDatabase(MainActivity.this.getFilesDir().toString()+ "/test.dbs", null);如果目录下有test.dbs数据库则是连接没有就是创建
2.用对象db的方法来执行sql语句：db.execSQL(String sql) 此方法木有返回值所以查询不好弄。查询一般用db.rawQuery返回一个Cursor对象(相当与jdbc中的ResultSet),Cursor有如下几个方法来查询数据:
2.1 move ToFirst 将记录指针跳到第一行
2.2 moveToLast将记录指针跳到最后一行
2.3 moveNext将记录指针移到下一行
2.4moveToPosition( int ss)将记录指针跳到指定的ss行
2.5moveToPrevious将记录指针跳到上一行
将记录指针跳到指定的行之后就可以通过对象的getXXX方法来获取数据 :如 Cursor cursor = db.rawQuery("select na,pw from user where na=? and pw=?", new String []{name,pwd});
3.回收资源close
当然以SQLiteDatabase对象还可以调用许多方法来操作数据库，不过俺是觉得这几个方法基本够了

简单的登录与注册源代码：
（仅此来练习SQLite的操作一般注册的信息都样上传到服务器而不会是存储在手机数据库）

<?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="登录界面" /> 
  <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="用户帐号:"/> 
  <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="请输入用户帐号"/> 
    <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="用户密码:"/> 
  <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="请输入用户密码"/> 
  <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="用户注册"/> 
   <Button  
    android:id="@+id/btlogin" 
    android:layout_height="wrap_content" 
    android:layout_width="wrap_content" 
    android:text="用户登录"/> 
   </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="注册界面" 
    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="帐号:" 
    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="密码:" 
    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="提交数据" /> 
  </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 { 
 
  // 帐号和密码 
  private EditText edname; 
  private EditText edpassword; 
 
  private Button btregister; 
  private Button btlogin; 
  // 创建SQLite数据库 
  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); 
    // 跳转到注册界面 
    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("")) { 
        // 弹出消息框 
        new AlertDialog.Builder(MainActivity.this).setTitle("错误") 
            .setMessage("帐号或密码不能空").setPositiveButton("确定", null) 
            .show(); 
      } else { 
        isUserinfo(name, password); 
      } 
    } 
 
    // 判断输入的用户是否正确 
    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("错误") 
          .setMessage("帐号或密码错误！").setPositiveButton("确定", null) 
          .show(); 
          return false; 
        }else{ 
          new AlertDialog.Builder(MainActivity.this).setTitle("正确") 
          .setMessage("成功登录").setPositiveButton("确定", null) 
          .show(); 
          return true; 
        } 
         
      }catch(SQLiteException e){ 
        createDb(); 
      } 
      return false; 
    } 
   
  } 
  // 创建数据库和用户表 
  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 
                // 跳转到登录界面 
                Intent in = new Intent(); 
                in.setClass(RegistersActivity.this, 
                    MainActivity.class); 
                startActivity(in); 
                // 销毁当前activity 
                RegistersActivity.this.onDestroy(); 
              } 
            }; 
            new AlertDialog.Builder(RegistersActivity.this) 
                .setTitle("注册成功").setMessage("注册成功") 
                .setPositiveButton("确定", ss).show(); 
 
          } else { 
            new AlertDialog.Builder(RegistersActivity.this) 
                .setTitle("注册失败").setMessage("注册失败") 
                .setPositiveButton("确定", null); 
          } 
        } else { 
          new AlertDialog.Builder(RegistersActivity.this) 
              .setTitle("帐号密码不能为空").setMessage("帐号密码不能为空") 
              .setPositiveButton("确定", null); 
        } 
 
      } 
    }); 
 
  } 
 
  // 添加用户 
  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; 
  } 
 
}

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