Gallery学习前应用-本地开发

　　Gallery本地开发是一个相对简单的例子，下面将讲棕此例子开发的过程与代码！

　　首先main.xml文件的代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">
  <Gallery
  android:id="@+id/gallery"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
  </Gallery>
</LinearLayout>

　　MainActivity.java:

package com.chiefcto.TimePicker;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Gallery;
import android.widget.Toast;

public class MainActivity extends Activity {
    
    
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        Gallery g = (Gallery)findViewById(R.id.gallery);
        g.setAdapter(new ImageAdapter(this));
        
        g.setBackgroundResource(R.drawable.bg);
        g.setOnItemClickListener(new OnItemClickListener() {

            public void onItemClick(AdapterView<?> parent, View v, int position,
                    long id) {
                // TODO Auto-generated method stub
                /*Intent intent = new Intent();
                intent.setClass(MainActivity.this, PictureShow.class);
                intent.putExtra("pic", position);*/
                Log.i("CTO", String.valueOf(id));
                Toast.makeText(MainActivity.this, "你选 择了"+(id)+"号图片", Toast.LENGTH_LONG).show();
            }
            
        });
    }
}

　　ImageAdapter.java

package com.chiefcto.TimePicker;

import android.content.ContentResolver;
import android.content.Context;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.provider.MediaStore;
import android.provider.MediaStore.Images;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CursorAdapter;
import android.widget.Gallery;
import android.widget.ImageView;

public class ImageAdapter extends BaseAdapter {
    //Properties

    static long[] mImageid;
    private Context mContext;
    private Cursor cs,cursor;
    private ContentResolver cc;
    
    public ImageAdapter(Context c) {
        mContext=c;
        this.setMImageIds();
    }
    public void setMImageIds() {
        cc=mContext.getContentResolver();
        cs=cc.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, 
                null, null, MediaStore.Images.Media.DEFAULT_SORT_ORDER);
        String[] projection = {MediaStore.Images.Media._ID};   
        // Create the cursor pointing to the SDCard   
        cursor = cc.query( MediaStore.Images.Media.EXTERNAL_CONTENT_URI,   
                projection, // Which columns to return   
                null,       // Return all rows   
                null,   
                MediaStore.Images.Media.DEFAULT_SORT_ORDER);
        //cursor.moveToFirst();
        int i=1;
        mImageid = new long[getCount()+1];
        while(cursor.moveToNext()) {
            int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media._ID);  
            String imageid = cursor.getString(columnIndex);
            
            mImageid[i] = Long.parseLong(imageid);
            i++;
        }
    }
    
    public int getCount() {
        //return mImageids.length;
        return cs.getCount();
    }
    
    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(mContext);
        BitmapFactory.Options options = new BitmapFactory.Options();  
        options.inDither = false;  
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        //System.out.println(cs.getString(cs.getColumnIndex(MediaStore.Images.Media.BUCKET_DISPLAY_NAME)));
           
        // Get the column index of the Thumbnails Image ID   
        /*int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Thumbnails._ID); 
        int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media._ID);  
        String imageid = cursor.getString(columnIndex);
        long imagelong = Long.parseLong(imageid);*/
        //cursor.moveToPosition(position);  
        // Get image filename  
        //String imagePath = cursor.getString(columnIndex);
        //Bitmap pic = BitmapFactory.decodeFile(imagePath);
        Bitmap pic = MediaStore.Images.Thumbnails.getThumbnail(cc, mImageid[position], 
                Images.Thumbnails.MICRO_KIND, options);
        //Bitmap pib = Bitmap.createScaledBitmap(pic, 200, 200, false);
        
        imageView.setImageBitmap(pic);
        imageView.setLayoutParams(new Gallery.LayoutParams(230, 200));
        
        imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
        //cs.moveToFirst();
        return imageView;
    }
}

　　在ImageAdapter中，本地图片的获取是有点复杂的，由于Android系统架构，可以直接调用Android系统里的资源，本文用到的是ContentResolver，通过ContentResolver来获得Cursor，但如何通过Cursor取出图片，从官方文档中找到Cursor中取出_ID并转成图片的方法。