android开发中关于视频、音频、图片的缩略图索引
Android 从1.5开始刚插入SD卡时系统会调用MediaScanner服务进行后台扫描,索引新的歌曲、图片和视频等信息,
1、 快速提取图片和视频缩略图可以直接访问
android.provider.MediaStore.Images.Thumbnails
android.provider.MediaStore.Video.Thumbnails
这两个数据库,即可查询出来缩略图
有关具体的缩略图可以通过一下方式
getThumbnail(ContentResolver cr, long origId, int kind, BitmapFactory.Options options)
getThumbnail(ContentResolver cr, long origId, long groupId, int kind, BitmapFactory.Options options)
方法获取,这两种方法返回Bitmap类型,而缩略图的分辨率可以从HEIGHT和WIDTH两个字段提取,在Android上缩略图分为两种,通过读取KIND字段来获得,分别为
MICRO_KIND和MINI_KIND 分别为微型和迷你两种缩略模式
另一种方法从Android2.2开始系统新增了一个缩略图ThumbnailUtils类
1. static Bitmap createVideoThumbnail(String filePath, int kind)
//获取视频文件的缩略图,第一个参数为视频文件的位置,比如/sdcard/android123.3gp,而第二个参数可以为 MINI_KIND或MICRO_KIND最终和分辨率有关
2. static Bitmap extractThumbnail(Bitmap source, int width, int height, int options)
//直接对Bitmap进行缩略操作,最后一个参数定义为OPTIONS_RECYCLE_INPUT,来回收资源
3. static Bitmap extractThumbnail(Bitmap source, int width, int height)
2、具体操作
android 获取视频和图片的缩略图、图片对应表images和thumbnails
images
_id 图片id
_data 图片路径
thumbnails
_id 缩略图id
_data 缩略图存储位置
image_id 对应原图id
视频对应表images和thumbnails
video
_id 视频id
_data 视频路径
videothumbnails
_id 视频缩略图id
_data 视频缩略图存储位置
image_id 对应视频id
//========================================================================
3 以获取视频的缩略图为例,具体步骤如下:
1 获取视频的uri
2 转换为String,得到视频id
3 去videothumbnails表中找到视频缩略图路径
4 根据路径得到图片(并绑定到listview上)
<配置文件> listview.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/iv"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/tv"
/>
</LinearLayout>
显示Activity::MainActivity.java
package com.lp;
import java.util.ArrayList;
import android.app.ListActivity;
import android.content.Context;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.provider.MediaStore.Images;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
/**
* 本实例,我们将通过检索SDCard上的Video信息
* 在MediaStore中,MediaStore.Video.Media中就有Video相关信息,
* 同时MediaStore.Video.Thumbnails中含有各个video对应的缩略图信息
*
* @author Administrator
*
*/
public class MainActivity extends ListActivity {
private Cursor cursor;
private ArrayList<VideoInfo> videoList = new ArrayList<MainActivity.VideoInfo>();
private ImageView img;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
init();
}
private void init(){
//MediaStore.Video.Thumbnails中含有各个video对应的缩略图信息
String[] thumbColumns = new String[]{
MediaStore.Video.Thumbnails.DATA,
MediaStore.Video.Thumbnails.VIDEO_ID
};
//MediaStore.Video.Media中就有Video相关信息
String[] mediaColumns = new String[]{
MediaStore.Video.Media.DATA,
MediaStore.Video.Media._ID,
MediaStore.Video.Media.TITLE,
MediaStore.Video.Media.MIME_TYPE
};
//首先检索SDcard上所有的video
cursor = this.managedQuery(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, mediaColumns, null, null, null);
while(cursor.moveToNext()){
VideoInfo info = new VideoInfo();
info.filePath = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA));
info.mimeType = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.MIME_TYPE));
info.title = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.TITLE));
//获取当前Video对应的Id,然后根据该ID获取其Thumb
int id = cursor.getInt(cursor.getColumnIndexOrThrow(MediaStore.Video.Media._ID));
String selection = MediaStore.Video.Thumbnails.VIDEO_ID +"=?";
String[] selectionArgs = new String[]{
id+""
};
Cursor thumbCursor = this.managedQuery(MediaStore.Video.Thumbnails.EXTERNAL_CONTENT_URI, thumbColumns, selection, selectionArgs, null);
BitmapFactory.Options options = new BitmapFactory.Options();
options.inDither = false;
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
info.b = MediaStore.Video.Thumbnails.getThumbnail(getContentResolver(), id, Images.Thumbnails.MICRO_KIND, options);
//然后将其加入到videoList
videoList.add(info);
}
System.out.println(videoList.size());
//然后需要设置ListView的Adapter了,使用我们自定义的Adatper
VideoAdapter adapter = new VideoAdapter(this);
this.getListView().setAdapter(adapter);
}
private static final String[] GENRES = new String[] {
"Action", "Adventure", "Animation", "Children", "Comedy", "Documentary", "Drama",
"Foreign", "History", "Independent", "Romance", "Sci-Fi", "Television", "Thriller"
};
class VideoInfo{
String filePath;
String mimeType;
// String thumbPath;
Bitmap b;
String title;
}
class ViewHolder{
ImageView thumbImage;
TextView titleText;
}
/**
* 定义一个Adapter来显示缩略图和视频title信息
* @author Administrator
*
*/
private class VideoAdapter extends BaseAdapter{
private Context mContext;
private LayoutInflater inflater;
public VideoAdapter(Context context){
this.mContext = context;
this.inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return videoList.size();
}
@Override
public Object getItem(int p) {
// TODO Auto-generated method stub
return videoList.get(p);
}
@Override
public long getItemId(int p) {
// TODO Auto-generated method stub
return p;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder ;
if(convertView == null){
holder = new ViewHolder();
convertView = inflater.inflate(R.layout.listview, null);
holder.thumbImage = (ImageView)convertView.findViewById(R.id.iv);
holder.titleText = (TextView)convertView.findViewById(R.id.tv);
convertView.setTag(holder);
}else{
holder = (ViewHolder)convertView.getTag();
}
//显示信息
holder.titleText.setText(videoList.get(position).title);
if(videoList.get(position).b != null){
holder.thumbImage.setImageBitmap(videoList.get(position).b);
}
return convertView;
}
}
}
还有的人采用解码视频第一帧作为缩略图,大家可以了解一下,至于音乐和图片则比较简单