3.2 拷贝数据库到系统目录

加载外部文件的几种常见做法:

1. 放在assets目录下
InputStream is = am.open("address.db"); 不会对该文件生成id

2. 放在res目录下的raw目录下.
InputStream is =getResources().openRawResource(R.raw.address);
编译这个文件生成id


3. javase做法
InputStream is = getClassLoader().getResourceAsStream("address.db");
                        

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1.将数据库文件放到assets目录下

2.在splashActivity创建时判断系统目录下是否有该文件,如果没有则复制到系统目录下

 

 

 

 

 

 

/**

 * 子线程中弹出土司跟新 ui

 * @author Administrator

 *

 */

public class ToastUtils {

      public static void showToastInThread( final Activity context, final String msg){

             //在子线程里面更新 ui

            context.runOnUiThread( new Runnable() {

                   @Override

                   public void run() {

                        Toast. makeText(context, msg, 0).show();

                        

                  }

            }); //线程的join

      }

}

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2.在splashActivity创建时判断系统目录下是否有该文件,如果没有则复制到系统目录下

 /**

   * 拷贝号码地址数据库到手机目录下

   */

    private void copyAddressDb() {

            File file= new File(getFilesDir(), "address.db");

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

          return; 

      }

      

      

      new Thread(){

        public void run() {

             //得到assets目录下address.db对应输入流

             AssetManager am = getAssets();

             try {

                        InputStream is = am.open( "address.db");

                        File file= new File(getFilesDir(), "address.db");

                        FileOutputStream  fos= new FileOutputStream(file);

                        

                         byte[]  buffer= new byte[1024];

                         int len=0;

                         while((len=is.read(buffer))!=-1){

                              fos.write(buffer, 0,len);

                        }

                        

                        fos.close();

                        is.close();

                        

                         //在子线程中跟新 ui

                        ToastUtils. showToastInThread(SplashActivity.this,"拷贝数据库成功...");

                        

                  } catch (IOException e) {

                        e.printStackTrace();

                         //在子线程中跟新 ui

                        ToastUtils. showToastInThread(SplashActivity.this,"拷贝数据库失败...");

                        

                  }

             

             

        };

            

  }.start();

            

      

      }