如何在android中保存和检索sqlite数据库中的图像

Question

我按照本教程http://vimaltuts.com/android-tutorial-for-beginners/android-sqlite-database-example告诉我如何在此代码中添加一个字段以将图像作为输入和显示？

请帮帮我

       import android.app.Activity;
import android.app.AlertDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

 public class AddEditCountry extends Activity {

 private long rowID; 
 private EditText nameEt;
 private EditText capEt;
 private EditText codeEt;

   @Override
   public void onCreate(Bundle savedInstanceState) 
   {
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.add_country);

      nameEt = (EditText) findViewById(R.id.nameEdit);
      capEt = (EditText) findViewById(R.id.capEdit);
      codeEt = (EditText) findViewById(R.id.codeEdit);

      Bundle extras = getIntent().getExtras(); 

      if (extras != null)
      {
         rowID = extras.getLong("row_id");
         nameEt.setText(extras.getString("name"));  
         capEt.setText(extras.getString("cap"));  
         codeEt.setText(extras.getString("code"));  
      }

      Button saveButton =(Button) findViewById(R.id.saveBtn);
      saveButton.setOnClickListener(new OnClickListener() {

          public void onClick(View v) 
          {
             if (nameEt.getText().length() != 0)
             {
                AsyncTask saveContactTask = 
                   new AsyncTask() 
                   {
                      @Override
                      protected Object doInBackground(Object... params) 
                      {
                         saveContact();
                         return null;
                      }

                      @Override
                      protected void onPostExecute(Object result) 
                      {
                         finish();
                      }
                   }; 

                saveContactTask.execute((Object[]) null); 
             }

             else
             {
                AlertDialog.Builder alert = new  
  AlertDialog.Builder(AddEditCountry.this);
                alert.setTitle(R.string.errorTitle); 
                alert.setMessage(R.string.errorMessage);
                alert.setPositiveButton(R.string.errorButton, null); 
                alert.show();
             }
          } 
     });
   }

   private void saveContact() 
   {
      DatabaseConnector dbConnector = new DatabaseConnector(this);

      if (getIntent().getExtras() == null)
      {
          dbConnector.insertContact(nameEt.getText().toString(),
                  capEt.getText().toString(),
                  codeEt.getText().toString());
      }
      else
      {
         dbConnector.updateContact(rowID,
            nameEt.getText().toString(),
            capEt.getText().toString(), 
            codeEt.getText().toString());
      }
   }
}




                import android.os.AsyncTask;
 import android.os.Bundle;
import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.CursorAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.AdapterView.OnItemClickListener;

 public class CountryList extends ListActivity {

 public static final String ROW_ID = "row_id";
 private ListView conListView;
 private CursorAdapter conAdapter;

 @Override
 public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    conListView=getListView();
    conListView.setOnItemClickListener(viewConListener);

    // map each name to a TextView
    String[] from = new String[] { "name" };
    int[] to = new int[] { R.id.countryTextView };
    conAdapter = new SimpleCursorAdapter(CountryList.this, R.layout.country_list,  
   null, from, to);
    setListAdapter(conAdapter); // set adapter
 }


 @Override
 protected void onResume() 
 {
   super.onResume();  
   new GetContacts().execute((Object[]) null);
 } 


  @Override
 protected void onStop() 
  {
   Cursor cursor = conAdapter.getCursor();

   if (cursor != null) 
      cursor.deactivate();

   conAdapter.changeCursor(null);
    super.onStop();
 }    


 private class GetContacts extends AsyncTask 
 {
   DatabaseConnector dbConnector = new DatabaseConnector(CountryList.this);

   @Override
   protected Cursor doInBackground(Object... params)
   {
      dbConnector.open();
      return dbConnector.getAllContacts(); 
   } 

   @Override
   protected void onPostExecute(Cursor result)
   {
      conAdapter.changeCursor(result); // set the adapter's Cursor
      dbConnector.close();
   } 
} 

 @Override
 public boolean onCreateOptionsMenu(Menu menu) 
{
   super.onCreateOptionsMenu(menu);
   MenuInflater inflater = getMenuInflater();
   inflater.inflate(R.menu.country_menu, menu);
   return true;
 }   

 @Override
 public boolean onOptionsItemSelected(MenuItem item) 
 {
    Intent addContact = new Intent(CountryList.this, AddEditCountry.class);
   startActivity(addContact);
   return super.onOptionsItemSelected(item);
}

OnItemClickListener viewConListener = new OnItemClickListener() 
{
   public void onItemClick(AdapterView arg0, View arg1, int arg2,long arg3) 
   {         
      Intent viewCon = new Intent(CountryList.this, ViewCountry.class);
      viewCon.putExtra(ROW_ID, arg3);
      startActivity(viewCon);
   }
};    

 }

















         import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
  import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.TextView;

 public class ViewCountry extends Activity {

   private long rowID;
   private TextView nameTv;
   private TextView capTv;
   private TextView codeTv; 

   @Override
   public void onCreate(Bundle savedInstanceState) 
   {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.view_country);

      setUpViews();
      Bundle extras = getIntent().getExtras();
      rowID = extras.getLong(CountryList.ROW_ID); 
   }

   private void setUpViews() {
       nameTv = (TextView) findViewById(R.id.nameText);
       capTv = (TextView) findViewById(R.id.capText);
       codeTv = (TextView) findViewById(R.id.codeText);
   }

   @Override
   protected void onResume()
   {
      super.onResume();
      new LoadContacts().execute(rowID);
   } 

   private class LoadContacts extends AsyncTask 
   {
      DatabaseConnector dbConnector = new DatabaseConnector(ViewCountry.this);

      @Override
      protected Cursor doInBackground(Long... params)
      {
         dbConnector.open();
         return dbConnector.getOneContact(params[0]);
      } 

      @Override
      protected void onPostExecute(Cursor result)
      {
         super.onPostExecute(result);

         result.moveToFirst();
         // get the column index for each data item
         int nameIndex = result.getColumnIndex("name");
         int capIndex = result.getColumnIndex("cap");
         int codeIndex = result.getColumnIndex("code");

         nameTv.setText(result.getString(nameIndex));
         capTv.setText(result.getString(capIndex));
         codeTv.setText(result.getString(codeIndex));

         result.close();
         dbConnector.close();
      }
   } 


   @Override
   public boolean onCreateOptionsMenu(Menu menu) 
   {
      super.onCreateOptionsMenu(menu);
      MenuInflater inflater = getMenuInflater();
      inflater.inflate(R.menu.view_country_menu, menu);
      return true;
   }

   @Override
   public boolean onOptionsItemSelected(MenuItem item) 
   {
      switch (item.getItemId())
      {
         case R.id.editItem:
            Intent addEditContact =
               new Intent(this, AddEditCountry.class);

            addEditContact.putExtra(CountryList.ROW_ID, rowID);
            addEditContact.putExtra("name", nameTv.getText());
            addEditContact.putExtra("cap", capTv.getText());
            addEditContact.putExtra("code", codeTv.getText());
            startActivity(addEditContact); 
            return true;

         case R.id.deleteItem:
            deleteContact();
            return true;

         default:
            return super.onOptionsItemSelected(item);
      } 
   }

   private void deleteContact()
   {

      AlertDialog.Builder alert = new AlertDialog.Builder(ViewCountry.this);

      alert.setTitle(R.string.confirmTitle); 
      alert.setMessage(R.string.confirmMessage); 

      alert.setPositiveButton(R.string.delete_btn,
         new DialogInterface.OnClickListener()
         {
            public void onClick(DialogInterface dialog, int button)
            {
               final DatabaseConnector dbConnector = 
                  new DatabaseConnector(ViewCountry.this);

               AsyncTask deleteTask =
                  new AsyncTask()
                  {
                     @Override
                     protected Object doInBackground(Long... params)
                     {
                        dbConnector.deleteContact(params[0]); 
                        return null;
                     } 

                     @Override
                     protected void onPostExecute(Object result)
                     {
                        finish(); 
                     }
                  };

               deleteTask.execute(new Long[] { rowID });               
            }
         }
      );

      alert.setNegativeButton(R.string.cancel_btn, null).show();
   }
}








import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;


  public class DatabaseConnector {

private static final String DB_NAME = "WorldCountries";
private SQLiteDatabase database;
private DatabaseOpenHelper dbOpenHelper;

public DatabaseConnector(Context context) {
    dbOpenHelper = new DatabaseOpenHelper(context, DB_NAME, null, 1);
}

   public void open() throws SQLException 
   {
      //open database in reading/writing mode
      database = dbOpenHelper.getWritableDatabase();
   } 

   public void close() 
   {
      if (database != null)
         database.close();
   }       

   public void insertContact(String name, String cap, String code) 
           {
              ContentValues newCon = new ContentValues();
              newCon.put("name", name);
              newCon.put("cap", cap);
              newCon.put("code", code);

              open();
              database.insert("country", null, newCon);
              close();
           }


           public void updateContact(long id, String name, String 
       cap,String code) 
           {
              ContentValues editCon = new ContentValues();
              editCon.put("name", name);
              editCon.put("cap", cap);
              editCon.put("code", code);

              open();
              database.update("country", editCon, "_id=" + id, null);
              close();
           }


           public Cursor getAllContacts() 
           {
              return database.query("country", new String[] {"_id",  
         "name"}, 
                 null, null, null, null, "name");
           }

           public Cursor getOneContact(long id) 
           {
              return database.query("country", null, "_id=" + id, null,   
     null, null, null);
           }

           public void deleteContact(long id) 
           {
              open(); 
              database.delete("country", "_id=" + id, null);
              close();
           }
 }





              import android.content.Context;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteDatabase.CursorFactory;
   import android.database.sqlite.SQLiteOpenHelper;

 public class DatabaseOpenHelper extends SQLiteOpenHelper {

public DatabaseOpenHelper(Context context, String name,
        CursorFactory factory, int version) {
    super(context, name, factory, version);
}

@Override
public void onCreate(SQLiteDatabase db) {
    String createQuery = "CREATE TABLE country (_id integer primary key  
    autoincrement,name, cap, code);";                 
    db.execSQL(createQuery);        
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

}

Answer 1

您可以在sql中轻松添加BLOB类型的字段，并将图像设置为字节集：

//while writing to db:
ByteArrayOutputStream outStr = new ByteArrayOutputStream();
image.compress(CompressFormat.PNG, 100, outStr);
byte[] blob = outStr.toByteArray();

contentValues.put("image", blob);


//while reading from cursor:
byte[] blob = cursor.getBlob("image");
Bitmap image = BitmapFactory.decodeByteArray(blob, 0, blob.length);