Android中如何获取视频文件的缩略图

核心提示：推荐的方法是实现MediaMetadataRetriever类第一步:首先需要下载JNI库：libmedia_jni.so进入SDK的Tools目录下，运行DDMS，Android中如何获取视频文件的缩略图(2)，在DDMS中的菜单栏中，执行Device–FileExplore,在弹出的文件列表中选择: S

推荐的方法是实现MediaMetadataRetriever类

第一步:首先需要下载JNI库：libmedia_jni.so

进入SDK的Tools目录下，运行DDMS，
在DDMS中的菜单栏中，执行Device–FileExplore,
在弹出的文件列表中选择: System-Lib-libmedia_jni.so
选中这个文件后， 在弹出的文件列表的又上脚执行PULL file from device,提取出libmedia_jni.so文件
在Eclipse中新建文件夹libs-armeabi-,在里面放入libmedia_jni.so文件

第二部：实现MediaMetadataRetriever

public class MediaMetadataRetriever
{
static {
System.loadLibrary(“media_jni”);
native_init();
}
// The field below is accessed by native methods
@SuppressWarnings(“unused”)
private int mNativeContext;
public MediaMetadataRetriever() {
native_setup();
}
/**
* Call this method before setDataSource() so that the mode becomes
* effective for subsequent operations. This method can be called only once
* at the beginning if the intended mode of operation for a
* MediaMetadataRetriever object remains the same for its whole lifetime,
* and thus it is unnecessary to call this method each time setDataSource()
* is called. If this is not never called (which is allowed), by default the
* intended mode of operation is to both capture frame and retrieve meta
* data (i.e., MODE_GET_METADATA_ONLY | MODE_CAPTURE_FRAME_ONLY).
* Often, this may not be what one wants, since doing this has negative
* performance impact on execution time of a call to setDataSource(), since
* both types of operations may be time consuming.
*
* @param mode The intended mode of operation. Can be any combination of
* MODE_GET_METADATA_ONLY and MODE_CAPTURE_FRAME_ONLY:
* 1. MODE_GET_METADATA_ONLY & MODE_CAPTURE_FRAME_ONLY:
* For neither frame capture nor meta data retrieval
* 2. MODE_GET_METADATA_ONLY: For meta data retrieval only
* 3. MODE_CAPTURE_FRAME_ONLY: For frame capture only
* 4. MODE_GET_METADATA_ONLY | MODE_CAPTURE_FRAME_ONLY:
* For both frame capture and meta data retrieval
*/
public native void setMode(int mode);
/**
* @return the current mode of operation. A negative return value indicates
* some runtime error has occurred.
*/
public native int getMode();
/**
* Sets the data source (file pathname) to use. Call this
* method before the rest of the methods in this class. This method may be
* time-consuming.
*
* @param path The path of the input media file.
* @throws IllegalArgumentException If the path is invalid.
*/
public native void setDataSource(String path) throws IllegalArgumentException;
/**
* Sets the data source (FileDescriptor) to use. It is the caller’s
* responsibility to close the file descriptor. It is safe to do so as soon
* as this call returns. Call this method before the rest of the methods in
* this class. This method may be time-consuming.
*
* @param fd the FileDescriptor for the file you want to play