android HorizontalScrollView替代Gallery

本文转自：http://www.apkbus.com/forum.php?mod=viewthread&tid=72694

以前我们展示图片，很多时候都用Gallery，但是Gallery每次切换图片时都要新建视图，造成太多的资源浪费
所以细心的同志们可能已发现，当新建项目的API最低为8，其实Gallery这个类已经过期。
曾经大家的最爱的android源生的Gallery类因为自身原因已被放弃了，你是否还在用？
The type Gallery is deprecated.This widget is no longer supported. 
ther horizontally scrolling widgets include HorizontalScrollView and ViewPager from the support library.
官方sdk文档提示用HSV和VP代替
但是我一直没有找到使用HorizontalScrollview来解决问题的实例
自已花了一个下午，整出实例来，希望对同志们有帮助，也欢迎讨论。

图片中使用了两个HorizontalScrollView，排成上下两行，每行均类似于之前gallery的效果
数据源一行在App的drawable包中，一行在sdcard中，sdk中的图片要自己找了拷进去，你懂的
附件是源码

布局文件如下：

 <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" >

     <HorizontalScrollView
         android:layout_width="match_parent"
         android:layout_height="wrap_content" >
         <LinearLayout
             android:orientation="horizontal"
             android:id="@+id/mygallery"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             />
     HorizontalScrollView>

     <HorizontalScrollView
         android:layout_width="match_parent"
         android:layout_height="wrap_content" >
         <LinearLayout
             android:orientation="horizontal"
             android:id="@+id/yourgallery"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             />
     HorizontalScrollView>
 LinearLayout>

activity代码如下

 package com.example.HSVdemo;

 import java.io.File;

 import com.example.galleydemo.R;

 import android.os.Bundle;
 import android.os.Environment;
 import android.app.Activity;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.BitmapFactory.Options;
 import android.util.Log;
 import android.view.Gravity;
 import android.view.Menu;
 import android.view.View;
 import android.view.ViewGroup.LayoutParams;
 import android.widget.ImageView;
 import android.widget.ImageView.ScaleType;
 import android.widget.LinearLayout;
 import android.widget.Toast;
 /**
  *  HorizontalScrollView in place of the Type Gallery
  * @author Administrator
  *
  */
 public class HSVDemoActivity extends Activity {

     private static final String tag="GH";
     private static final String path="/mnt/sdcard";
     private LinearLayout myGallery;
     private LinearLayout yourGallery;

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

         myGallery=(LinearLayout) findViewById(R.id.mygallery);
         yourGallery=(LinearLayout) findViewById(R.id.yourgallery);

         //pic in the drawable
         Integer[] images = { R.drawable.img0001, R.drawable.img0030,
                 R.drawable.img0100, R.drawable.img0130, R.drawable.img0200,
                 R.drawable.img0230, R.drawable.img0300, R.drawable.img0330,
                 R.drawable.img0354 };

         for(Integer id:images){
             myGallery.addView(insertImage(id));
         }


         //pic in the sdcard
         String targetPath=path+"/test/";
         Log.d(tag,targetPath);
         Toast.makeText(getApplicationContext(), targetPath,Toast.LENGTH_LONG).show();

         File targetDirector=new File(targetPath);
         File[] files=targetDirector.listFiles();
         Log.d(tag,files.length+"");
         for(File file:files){
             yourGallery.addView(insertPhoto(file.getAbsolutePath()));
         }

     }

     private View insertImage(Integer id) {
         LinearLayout layout=new LinearLayout(getApplicationContext());
         layout.setLayoutParams(new LayoutParams(320,320));
         layout.setGravity(Gravity.CENTER);

         ImageView imageView=new ImageView(getApplicationContext());
         imageView.setLayoutParams(new LayoutParams(300,300));
         imageView.setBackgroundResource(id);

         layout.addView(imageView);
         return layout;
     }


     private View insertPhoto(String absolutePath) {
         // TODO Auto-generated method stub
         Bitmap bm=decodeSampleBitmapFromUri(absolutePath,200,200);
         LinearLayout layout=new LinearLayout(getApplicationContext());
         layout.setLayoutParams(new LayoutParams(250,250));
         layout.setGravity(Gravity.CENTER);

         ImageView imageView=new ImageView(getApplicationContext());
         imageView.setLayoutParams(new LayoutParams(220,220));
         imageView.setScaleType(ScaleType.CENTER_CROP);
         imageView.setImageBitmap(bm);

         layout.addView(imageView);
         return layout;
     }


     private Bitmap decodeSampleBitmapFromUri(String absolutePath, int reqWidth, int reqHeight) {
         // TODO Auto-generated method stub
         Bitmap bm=null;

         // First decode with inJustDecodeBounds=true to check dimensions
         final Options options=new Options();
         options.inJustDecodeBounds=true;
         BitmapFactory.decodeFile(absolutePath,options);

         // Calculate inSampleSize
         options.inSampleSize=calculateInSampleSize(options,reqWidth,reqHeight);

         // Decode bitmap with inSampleSize set
         options.inJustDecodeBounds=false;
         bm=BitmapFactory.decodeFile(absolutePath,options);
         return bm;
     }


     private int calculateInSampleSize(Options options, int reqWidth,
             int reqHeight) {
         // TODO Auto-generated method stub
         // Raw height and width of image
         final int height=options.outHeight;
         final int width=options.outWidth;
         int inSampleSize=1;

         if(height>reqHeight||width>reqWidth){
             if(width>height){
                 inSampleSize=Math.round((float)height/(float)reqHeight);
             }else{
                 inSampleSize = Math.round((float)width / (float)reqWidth);
             }
         }
         return inSampleSize;
     }

 }

在使用HorizontalScrollView时需注意，它必须有一个子控件用于显示，在本文中是线性布局，在该线性布局中添加View即可。。。