Android应用中使用ContentProvider扫描本地图片并显示

package com.example.imagescan; 
 
/** 
 * gridview的每个item的数据对象 
 * 
 * @author len 
 * 
 */ 
public class imagebean{ 
  /** 
   * 文件夹的第一张图片路径 
   */ 
  private string topimagepath; 
  /** 
   * 文件夹名 
   */ 
  private string foldername;  
  /** 
   * 文件夹中的图片数 
   */ 
  private int imagecounts; 
   
  public string gettopimagepath() { 
    return topimagepath; 
  } 
  public void settopimagepath(string topimagepath) { 
    this.topimagepath = topimagepath; 
  } 
  public string getfoldername() { 
    return foldername; 
  } 
  public void setfoldername(string foldername) { 
    this.foldername = foldername; 
  } 
  public int getimagecounts() { 
    return imagecounts; 
  } 
  public void setimagecounts(int imagecounts) { 
    this.imagecounts = imagecounts; 
  } 
   
} 

<relativelayout 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" > 
 
  <gridview 
    android:id="@+id/main_grid" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:listselector="@android:color/transparent" 
    android:cachecolorhint="@android:color/transparent" 
    android:stretchmode="columnwidth" 
    android:horizontalspacing="20dip" 
    android:gravity="center" 
    android:verticalspacing="20dip" 
    android:columnwidth="90dip" 
    android:numcolumns="2" > 
  </gridview> 
 
</relativelayout> 

<?xml version="1.0" encoding="utf-8"?> 
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_width="fill_parent" 
  android:layout_height="wrap_content" > 
 
  <framelayout 
    android:id="@+id/framelayout" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" > 
 
    <com.example.imagescan.myimageview 
      android:id="@+id/group_image" 
      android:background="@drawable/albums_bg" 
      android:src="@drawable/friends_sends_pictures_no" 
      android:paddingleft="20dip" 
      android:paddingright="20dip" 
      android:paddingtop="18dip" 
      android:paddingbottom="30dip" 
      android:scaletype="fitxy" 
      android:layout_width="fill_parent" 
      android:layout_height="150dip" /> 
 
    <textview 
      android:id="@+id/group_count" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:background="@drawable/albums_icon_bg" 
      android:gravity="center" 
      android:layout_marginbottom="10dip" 
      android:text="5" 
      android:layout_gravity="bottom|center_horizontal" /> 
  </framelayout> 
 
  <textview 
    android:id="@+id/group_title" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:gravity="center" 
    android:layout_below="@id/framelayout" 
    android:layout_centerhorizontal="true" 
    android:ellipsize="end" 
    android:singleline="true" 
    android:text="camera" 
    android:textsize="16sp" /> 
 
</relativelayout> 

package com.example.imagescan; 
 
import java.io.file; 
import java.util.arraylist; 
import java.util.hashmap; 
import java.util.iterator; 
import java.util.list; 
import java.util.map; 
 
import android.app.activity; 
import android.app.progressdialog; 
import android.content.contentresolver; 
import android.content.intent; 
import android.database.cursor; 
import android.net.uri; 
import android.os.bundle; 
import android.os.handler; 
import android.os.message; 
import android.provider.mediastore; 
import android.view.view; 
import android.widget.adapterview; 
import android.widget.adapterview.onitemclicklistener; 
import android.widget.gridview; 


public class mainactivity extends activity { 
  private hashmap<string, list<string>> mgruopmap = new hashmap<string, list<string>>(); 
  private list<imagebean> list = new arraylist<imagebean>(); 
  private final static int scan_ok = 1; 
  private progressdialog mprogressdialog; 
  private groupadapter adapter; 
  private gridview mgroupgridview; 
   
  private handler mhandler = new handler(){ 
 
    @override 
    public void handlemessage(message msg) { 
      super.handlemessage(msg); 
      switch (msg.what) { 
      case scan_ok: 
        //关闭进度条 
        mprogressdialog.dismiss(); 
         
        adapter = new groupadapter(mainactivity.this, list = subgroupofimage(mgruopmap), mgroupgridview); 
        mgroupgridview.setadapter(adapter); 
        break; 
      } 
    } 
     
  }; 
 
  @override 
  protected void oncreate(bundle savedinstancestate) { 
    super.oncreate(savedinstancestate); 
    setcontentview(r.layout.activity_main); 
     
    mgroupgridview = (gridview) findviewbyid(r.id.main_grid); 
     
    getimages(); 
     
    mgroupgridview.setonitemclicklistener(new onitemclicklistener() { 
 
      @override 
      public void onitemclick(adapterview<?> parent, view view, 
          int position, long id) { 
        list<string> childlist = mgruopmap.get(list.get(position).getfoldername()); 
         
        intent mintent = new intent(mainactivity.this, showimageactivity.class); 
        mintent.putstringarraylistextra("data", (arraylist<string>)childlist); 
        startactivity(mintent); 
         
      } 
    }); 
     
  } 

  /** 
   * 利用contentprovider扫描手机中的图片，此方法在运行在子线程中 
   */ 
  private void getimages() { 
    //显示进度条 
    mprogressdialog = progressdialog.show(this, null, "正在加载..."); 
     
    new thread(new runnable() { 
       
      @override 
      public void run() { 
        uri mimageuri = mediastore.images.media.external_content_uri; 
        contentresolver mcontentresolver = mainactivity.this.getcontentresolver(); 
 
        //只查询jpeg和png的图片 
        cursor mcursor = mcontentresolver.query(mimageuri, null, 
            mediastore.images.media.mime_type + "=? or " 
                + mediastore.images.media.mime_type + "=?", 
            new string[] { "image/jpeg", "image/png" }, mediastore.images.media.date_modified); 
         
        if(mcursor == null){ 
          return; 
        } 
         
        while (mcursor.movetonext()) { 
          //获取图片的路径 
          string path = mcursor.getstring(mcursor 
              .getcolumnindex(mediastore.images.media.data)); 
           
          //获取该图片的父路径名 
          string parentname = new file(path).getparentfile().getname(); 
 
           
          //根据父路径名将图片放入到mgruopmap中 
          if (!mgruopmap.containskey(parentname)) { 
            list<string> chilelist = new arraylist<string>(); 
            chilelist.add(path); 
            mgruopmap.put(parentname, chilelist); 
          } else { 
            mgruopmap.get(parentname).add(path); 
          } 
        } 
         
        //通知handler扫描图片完成 
        mhandler.sendemptymessage(scan_ok); 
        mcursor.close(); 
      } 
    }).start(); 
     
  } 

  /** 
   * 组装分组界面gridview的数据源，因为我们扫描手机的时候将图片信息放在hashmap中 
   * 所以需要遍历hashmap将数据组装成list 
   * 
   * @param mgruopmap 
   * @return 
   */ 
  private list<imagebean> subgroupofimage(hashmap<string, list<string>> mgruopmap){ 
    if(mgruopmap.size() == 0){ 
      return null; 
    } 
    list<imagebean> list = new arraylist<imagebean>(); 
     
    iterator<map.entry<string, list<string>>> it = mgruopmap.entryset().iterator(); 
    while (it.hasnext()) { 
      map.entry<string, list<string>> entry = it.next(); 
      imagebean mimagebean = new imagebean(); 
      string key = entry.getkey(); 
      list<string> value = entry.getvalue(); 
       
      mimagebean.setfoldername(key); 
      mimagebean.setimagecounts(value.size()); 
      mimagebean.settopimagepath(value.get(0));//获取该组的第一张图片 
       
      list.add(mimagebean); 
    } 
     
    return list; 
     
  } 
 
 
} 

package com.example.imagescan; 
 
import java.util.concurrent.executorservice; 
import java.util.concurrent.executors; 
 
import android.graphics.bitmap; 
import android.graphics.bitmapfactory; 
import android.graphics.point; 
import android.os.handler; 
import android.os.message; 
import android.support.v4.util.lrucache; 
 
/** 
 * 本地图片加载器,采用的是异步解析本地图片，单例模式利用getinstance()获取nativeimageloader实例 
 * 调用loadnativeimage()方法加载本地图片，此类可作为一个加载本地图片的工具类 
 */ 
public class nativeimageloader { 
  private lrucache<string, bitmap> mmemorycache; 
  private static nativeimageloader minstance = new nativeimageloader(); 
  private executorservice mimagethreadpool = executors.newfixedthreadpool(1); 
   
   
  private nativeimageloader(){ 
    //获取应用程序的最大内存 
    final int maxmemory = (int) (runtime.getruntime().maxmemory() / 1024); 
 
    //用最大内存的1/4来存储图片 
    final int cachesize = maxmemory / 4; 
    mmemorycache = new lrucache<string, bitmap>(cachesize) { 
       
      //获取每张图片的大小 
      @override 
      protected int sizeof(string key, bitmap bitmap) { 
        return bitmap.getrowbytes() * bitmap.getheight() / 1024; 
      } 
    }; 
  } 
   
  /** 
   * 通过此方法来获取nativeimageloader的实例 
   * @return 
   */ 
  public static nativeimageloader getinstance(){ 
    return minstance; 
  } 

  /** 
   * 加载本地图片，对图片不进行裁剪 
   * @param path 
   * @param mcallback 
   * @return 
   */ 
  public bitmap loadnativeimage(final string path, final nativeimagecallback mcallback){ 
    return this.loadnativeimage(path, null, mcallback); 
  } 
   
  /** 
   * 此方法来加载本地图片，这里的mpoint是用来封装imageview的宽和高，我们会根据imageview控件的大小来裁剪bitmap 
   * 如果你不想裁剪图片，调用loadnativeimage(final string path, final nativeimagecallback mcallback)来加载 
   * @param path 
   * @param mpoint 
   * @param mcallback 
   * @return 
   */ 
  public bitmap loadnativeimage(final string path, final point mpoint, final nativeimagecallback mcallback){ 
    //先获取内存中的bitmap 
    bitmap bitmap = getbitmapfrommemcache(path); 
     
    final handler mhander = new handler(){ 
 
      @override 
      public void handlemessage(message msg) { 
        super.handlemessage(msg); 
        mcallback.onimageloader((bitmap)msg.obj, path); 
      } 
       
    }; 
     
    //若该bitmap不在内存缓存中，则启用线程去加载本地的图片，并将bitmap加入到mmemorycache中 
    if(bitmap == null){ 
      mimagethreadpool.execute(new runnable() { 
         
        @override 
        public void run() { 
          //先获取图片的缩略图 
          bitmap mbitmap = decodethumbbitmapforfile(path, mpoint == null ? 0: mpoint.x, mpoint == null ? 0: mpoint.y); 
          message msg = mhander.obtainmessage(); 
          msg.obj = mbitmap; 
          mhander.sendmessage(msg); 
           
          //将图片加入到内存缓存 
          addbitmaptomemorycache(path, mbitmap); 
        } 
      }); 
    } 
    return bitmap; 
     
  } 
 
   
   
  /** 
   * 往内存缓存中添加bitmap 
   * 
   * @param key 
   * @param bitmap 
   */ 
  private void addbitmaptomemorycache(string key, bitmap bitmap) { 
    if (getbitmapfrommemcache(key) == null && bitmap != null) { 
      mmemorycache.put(key, bitmap); 
    } 
  } 
 
  /** 
   * 根据key来获取内存中的图片 
   * @param key 
   * @return 
   */ 
  private bitmap getbitmapfrommemcache(string key) { 
    return mmemorycache.get(key); 
  } 
   
   
  /** 
   * 根据view(主要是imageview)的宽和高来获取图片的缩略图 
   * @param path 
   * @param viewwidth 
   * @param viewheight 
   * @return 
   */ 
  private bitmap decodethumbbitmapforfile(string path, int viewwidth, int viewheight){ 
    bitmapfactory.options options = new bitmapfactory.options(); 
    //设置为true,表示解析bitmap对象，该对象不占内存 
    options.injustdecodebounds = true; 
    bitmapfactory.decodefile(path, options); 
    //设置缩放比例 
    options.insamplesize = computescale(options, viewwidth, viewheight); 
     
    //设置为false,解析bitmap对象加入到内存中 
    options.injustdecodebounds = false; 
     
    return bitmapfactory.decodefile(path, options); 
  } 
   
   
  /** 
   * 根据view(主要是imageview)的宽和高来计算bitmap缩放比例。默认不缩放 
   * @param options 
   * @param width 
   * @param height 
   */ 
  private int computescale(bitmapfactory.options options, int viewwidth, int viewheight){ 
    int insamplesize = 1; 
    if(viewwidth == 0 || viewwidth == 0){ 
      return insamplesize; 
    } 
    int bitmapwidth = options.outwidth; 
    int bitmapheight = options.outheight; 
     
    //假如bitmap的宽度或高度大于我们设定图片的view的宽高，则计算缩放比例 
    if(bitmapwidth > viewwidth || bitmapheight > viewwidth){ 
      int widthscale = math.round((float) bitmapwidth / (float) viewwidth); 
      int heightscale = math.round((float) bitmapheight / (float) viewwidth); 
       
      //为了保证图片不缩放变形，我们取宽高比例最小的那个 
      insamplesize = widthscale < heightscale ? widthscale : heightscale; 
    } 
    return insamplesize; 
  } 
   
   
  /** 
   * 加载本地图片的回调接口 
   * 
   * @author xiaanming 
   * 
   */ 
  public interface nativeimagecallback{ 
    /** 
     * 当子线程加载完了本地的图片，将bitmap和图片路径回调在此方法中 
     * @param bitmap 
     * @param path 
     */ 
    public void onimageloader(bitmap bitmap, string path); 
  } 
} 

package com.example.imagescan; 
 
import java.util.list; 
 
import android.content.context; 
import android.graphics.bitmap; 
import android.graphics.point; 
import android.view.layoutinflater; 
import android.view.view; 
import android.view.viewgroup; 
import android.widget.baseadapter; 
import android.widget.gridview; 
import android.widget.imageview; 
import android.widget.textview; 
 
import com.example.imagescan.myimageview.onmeasurelistener; 
import com.example.imagescan.nativeimageloader.nativeimagecallback; 
 
public class groupadapter extends baseadapter{ 
  private list<imagebean> list; 
  private point mpoint = new point(0, 0);//用来封装imageview的宽和高的对象 
  private gridview mgridview; 
  protected layoutinflater minflater; 
   
  @override 
  public int getcount() { 
    return list.size(); 
  } 
 
  @override 
  public object getitem(int position) { 
    return list.get(position); 
  } 
 
 
  @override 
  public long getitemid(int position) { 
    return position; 
  } 
   
  public groupadapter(context context, list<imagebean> list, gridview mgridview){ 
    this.list = list; 
    this.mgridview = mgridview; 
    minflater = layoutinflater.from(context); 
  } 
   
 
  @override 
  public view getview(int position, view convertview, viewgroup parent) { 
    final viewholder viewholder; 
    imagebean mimagebean = list.get(position); 
    string path = mimagebean.gettopimagepath(); 
    if(convertview == null){ 
      viewholder = new viewholder(); 
      convertview = minflater.inflate(r.layout.grid_group_item, null); 
      viewholder.mimageview = (myimageview) convertview.findviewbyid(r.id.group_image); 
      viewholder.mtextviewtitle = (textview) convertview.findviewbyid(r.id.group_title); 
      viewholder.mtextviewcounts = (textview) convertview.findviewbyid(r.id.group_count); 
       
      //用来监听imageview的宽和高 
      viewholder.mimageview.setonmeasurelistener(new onmeasurelistener() { 
         
        @override 
        public void onmeasuresize(int width, int height) { 
          mpoint.set(width, height); 
        } 
      }); 
       
      convertview.settag(viewholder); 
    }else{ 
      viewholder = (viewholder) convertview.gettag(); 
      viewholder.mimageview.setimageresource(r.drawable.friends_sends_pictures_no); 
    } 
     
    viewholder.mtextviewtitle.settext(mimagebean.getfoldername()); 
    viewholder.mtextviewcounts.settext(integer.tostring(mimagebean.getimagecounts())); 
    //给imageview设置路径tag,这是异步加载图片的小技巧 
    viewholder.mimageview.settag(path); 
     
     
    //利用nativeimageloader类加载本地图片 
    bitmap bitmap = nativeimageloader.getinstance().loadnativeimage(path, mpoint, new nativeimagecallback() { 
       
      @override 
      public void onimageloader(bitmap bitmap, string path) { 
        imageview mimageview = (imageview) mgridview.findviewwithtag(path); 
        if(bitmap != null && mimageview != null){ 
          mimageview.setimagebitmap(bitmap); 
        } 
      } 
    }); 
     
    if(bitmap != null){ 
      viewholder.mimageview.setimagebitmap(bitmap); 
    }else{ 
      viewholder.mimageview.setimageresource(r.drawable.friends_sends_pictures_no); 
    } 
     
     
    return convertview; 
  } 
   
   
   
  public static class viewholder{ 
    public myimageview mimageview; 
    public textview mtextviewtitle; 
    public textview mtextviewcounts; 
  } 
 
   
} 

package com.example.imagescan; 
 
import android.content.context; 
import android.util.attributeset; 
import android.widget.imageview; 
 
public class myimageview extends imageview { 
  private onmeasurelistener onmeasurelistener; 
   
  public void setonmeasurelistener(onmeasurelistener onmeasurelistener) { 
    this.onmeasurelistener = onmeasurelistener; 
  } 
 
  public myimageview(context context, attributeset attrs) { 
    super(context, attrs); 
  } 
 
  public myimageview(context context, attributeset attrs, int defstyle) { 
    super(context, attrs, defstyle); 
  } 
 
  @override 
  protected void onmeasure(int widthmeasurespec, int heightmeasurespec) { 
    super.onmeasure(widthmeasurespec, heightmeasurespec); 
     
    //将图片测量的大小回调到onmeasuresize()方法中 
    if(onmeasurelistener != null){ 
      onmeasurelistener.onmeasuresize(getmeasuredwidth(), getmeasuredheight()); 
    } 
  } 
 
  public interface onmeasurelistener{ 
    public void onmeasuresize(int width, int height); 
  } 
   
} 

package com.example.imagescan; 
 
import java.util.list; 
 
import android.app.activity; 
import android.os.bundle; 
import android.widget.gridview; 
import android.widget.toast; 
 
public class showimageactivity extends activity { 
  private gridview mgridview; 
  private list<string> list; 
  private childadapter adapter; 
 
  @override 
  protected void oncreate(bundle savedinstancestate) { 
    super.oncreate(savedinstancestate); 
    setcontentview(r.layout.show_image_activity); 
     
    mgridview = (gridview) findviewbyid(r.id.child_grid); 
    list = getintent().getstringarraylistextra("data"); 
     
    adapter = new childadapter(this, list, mgridview); 
    mgridview.setadapter(adapter); 
     
  } 
 
  @override 
  public void onbackpressed() { 
    toast.maketext(this, "选中 " + adapter.getselectitems().size() + " item", toast.length_long).show(); 
    super.onbackpressed(); 
  } 
   
   
} 

package com.example.imagescan; 
 
import java.util.arraylist; 
import java.util.hashmap; 
import java.util.iterator; 
import java.util.list; 
import java.util.map; 
 
import android.content.context; 
import android.graphics.bitmap; 
import android.graphics.point; 
import android.view.layoutinflater; 
import android.view.view; 
import android.view.viewgroup; 
import android.widget.baseadapter; 
import android.widget.checkbox; 
import android.widget.compoundbutton; 
import android.widget.imageview; 
import android.widget.compoundbutton.oncheckedchangelistener; 
import android.widget.gridview; 
 
import com.example.imagescan.myimageview.onmeasurelistener; 
import com.example.imagescan.nativeimageloader.nativeimagecallback; 
import com.nineoldandroids.animation.animatorset; 
import com.nineoldandroids.animation.objectanimator; 
 
public class childadapter extends baseadapter { 
  private point mpoint = new point(0, 0);//用来封装imageview的宽和高的对象 
  /** 
   * 用来存储图片的选中情况 
   */ 
  private hashmap<integer, boolean> mselectmap = new hashmap<integer, boolean>(); 
  private gridview mgridview; 
  private list<string> list; 
  protected layoutinflater minflater; 
 
  public childadapter(context context, list<string> list, gridview mgridview) { 
    this.list = list; 
    this.mgridview = mgridview; 
    minflater = layoutinflater.from(context); 
  } 
   
  @override 
  public int getcount() { 
    return list.size(); 
  } 
 
  @override 
  public object getitem(int position) { 
    return list.get(position); 
  } 
 
 
  @override 
  public long getitemid(int position) { 
    return position; 
  } 
   
  @override 
  public view getview(final int position, view convertview, viewgroup parent) { 
    final viewholder viewholder; 
    string path = list.get(position); 
     
    if(convertview == null){ 
      convertview = minflater.inflate(r.layout.grid_child_item, null); 
      viewholder = new viewholder(); 
      viewholder.mimageview = (myimageview) convertview.findviewbyid(r.id.child_image); 
      viewholder.mcheckbox = (checkbox) convertview.findviewbyid(r.id.child_checkbox); 
       
      //用来监听imageview的宽和高 
      viewholder.mimageview.setonmeasurelistener(new onmeasurelistener() { 
         
        @override 
        public void onmeasuresize(int width, int height) { 
          mpoint.set(width, height); 
        } 
      }); 
       
      convertview.settag(viewholder); 
    }else{ 
      viewholder = (viewholder) convertview.gettag(); 
      viewholder.mimageview.setimageresource(r.drawable.friends_sends_pictures_no); 
    } 
    viewholder.mimageview.settag(path); 
    viewholder.mcheckbox.setoncheckedchangelistener(new oncheckedchangelistener() { 
       
      @override 
      public void oncheckedchanged(compoundbutton buttonview, boolean ischecked) { 
        //如果是未选中的checkbox,则添加动画 
        if(!mselectmap.containskey(position) || !mselectmap.get(position)){ 
          addanimation(viewholder.mcheckbox); 
        } 
        mselectmap.put(position, ischecked); 
      } 
    }); 
     
    viewholder.mcheckbox.setchecked(mselectmap.containskey(position) ? mselectmap.get(position) : false); 
     
    //利用nativeimageloader类加载本地图片 
    bitmap bitmap = nativeimageloader.getinstance().loadnativeimage(path, mpoint, new nativeimagecallback() { 
       
      @override 
      public void onimageloader(bitmap bitmap, string path) { 
        imageview mimageview = (imageview) mgridview.findviewwithtag(path); 
        if(bitmap != null && mimageview != null){ 
          mimageview.setimagebitmap(bitmap); 
        } 
      } 
    }); 
     
    if(bitmap != null){ 
      viewholder.mimageview.setimagebitmap(bitmap); 
    }else{ 
      viewholder.mimageview.setimageresource(r.drawable.friends_sends_pictures_no); 
    } 
     
    return convertview; 
  } 
   
  /** 
   * 给checkbox加点击动画，利用开源库nineoldandroids设置动画 
   * @param view 
   */ 
  private void addanimation(view view){ 
    float [] vaules = new float[]{0.5f, 0.6f, 0.7f, 0.8f, 0.9f, 1.0f, 1.1f, 1.2f, 1.3f, 1.25f, 1.2f, 1.15f, 1.1f, 1.0f}; 
    animatorset set = new animatorset(); 
    set.playtogether(objectanimator.offloat(view, "scalex", vaules),  
        objectanimator.offloat(view, "scaley", vaules)); 
        set.setduration(150); 
    set.start(); 
  } 
   
   
  /** 
   * 获取选中的item的position 
   * @return 
   */ 
  public list<integer> getselectitems(){ 
    list<integer> list = new arraylist<integer>(); 
    for(iterator<map.entry<integer, boolean>> it = mselectmap.entryset().iterator(); it.hasnext();){ 
      map.entry<integer, boolean> entry = it.next(); 
      if(entry.getvalue()){ 
        list.add(entry.getkey()); 
      } 
    } 
     
    return list; 
  } 
   
   
  public static class viewholder{ 
    public myimageview mimageview; 
    public checkbox mcheckbox; 
  } 
 
 
}