Android：从SD卡ViewPager图库

Question

我有一个ViewPager图库的代码，但是图像是从可绘制文件夹中获取的，而我需要从SD卡上的文件夹获取它们。

protected Integer[] mImageIds = { 
     R.drawable.sample_1, 
     R.drawable.sample_2, 
     R.drawable.sample_3, 
     R.drawable.sample_4, 
     R.drawable.sample_5, 
     R.drawable.sample_6, 
     R.drawable.sample_7 
}; 

这是需要改变的代码，我该如何从SD卡中的图像替换这些可绘制的文件夹？

全码

import android.app.Activity; 
import android.content.Context; 
import android.content.res.TypedArray; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.os.Handler; 
import android.provider.MediaStore; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentActivity; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 
import android.support.v4.view.PagerAdapter; 
import android.support.v4.view.ViewPager; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.*; 

public class Main extends FragmentActivity implements AdapterView.OnItemSelectedListener, ViewPager.OnPageChangeListener { 

    private ViewPager viewPager; 
    private Gallery gallery; 

    protected Integer[] mImageIds = { 
      R.drawable.sample_1, 
      R.drawable.sample_2, 
      R.drawable.sample_3, 
      R.drawable.sample_4, 
      R.drawable.sample_5, 
      R.drawable.sample_6, 
      R.drawable.sample_7 
    }; 
    private TextView textView; 
    private Handler handler; 

    /** 
    * Called when the activity is first created. 
    */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     viewPager = (ViewPager) findViewById(R.id.view_pager); 
     viewPager.setAdapter(new MyAdapter(getSupportFragmentManager())); 
     viewPager.setOnPageChangeListener(this); 

     gallery = (Gallery) findViewById(R.id.gallery); 
     gallery.setAdapter(new ImageAdapter()); 
     gallery.setOnItemSelectedListener(this); 

     textView = (TextView) findViewById(R.id.title); 

     handler = new Handler(); 

    } 

    // gallery item selected 
    public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) { 
     updateUI(i); 
    } 

    // view pager item selected 
    public void onPageSelected(int i) { 
     updateUI(i); 
    } 

    private void updateUI(final int i) { 
     handler.post(new Runnable() { 
      public void run() { 
       gallery.setSelection(i); 
       viewPager.setCurrentItem(i); 
       textView.setText("Photo #" + i); 
      } 
     }); 
    } 

    public void onNothingSelected(AdapterView<?> adapterView) { } 

    public void onPageScrolled(int i, float v, int i1) { } 

    public void onPageScrollStateChanged(int i) { } 

    public class ImageAdapter extends BaseAdapter { 

     public int getCount() { 
      return mImageIds.length; 
     } 

     public Object getItem(int position) { 
      return position; 
     } 

     public long getItemId(int position) { 
      return position; 
     } 

     public View getView(int position, View convertView, ViewGroup parent) { 

      ImageView imageView = new ImageView(Main.this); 

      imageView.setImageResource(mImageIds[position]); 
      imageView.setLayoutParams(new Gallery.LayoutParams(150, 100)); 
      imageView.setScaleType(ImageView.ScaleType.FIT_XY); 

      return imageView; 
     } 
    } 

    public class MyAdapter extends FragmentPagerAdapter { 
     public MyAdapter(FragmentManager fm) { 
      super(fm); 
     } 

     @Override 
     public int getCount() { 
      return mImageIds.length; 
     } 

     @Override 
     public Fragment getItem(final int position) { 
      return new Fragment() { 
       @Override 
       public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
        ImageView imageView = new ImageView(Main.this); 
        imageView.setImageResource(mImageIds[position]); 
        return imageView; 
       } 
      }; 
     } 
    } 


} 

Answer 1

与其说setImageResource的，叫setImageDrawable你从SD卡中加载的位图。例如，创建一个从SD卡路径Bitmap，然后setImageDrawable：

Bitmap bitmap = BitmapFactory.decodeFile(path_of_file); 
imageView.setImageDrawable(bitmap); 

注意，图像解码不应该做的UI线程。 android文档讨论efficiently loading images off the ui thread。讨论的AsyncTask可以进行修改，以满足您一行或两行更改的需要。