Android选择图片的两种方式

原文地址 http://www.jb51.net/article/78201.htm

Android选择图片的两种方式：

第一种：单张选取

通过隐式启动activity，跳转到相册选择一张返回结果

关键代码如下：

发送请求：

private static final int PICTURE = 10086 ; //requestcode

Intent intent = new Intent();
if (Build.VERSION.SDK_INT < 19 ) { //因为Android SDK在4.4版本后图片action变化了 所以在这里先判断一下
      intent.setAction(Intent.ACTION_GET_CONTENT);
    } else {
      intent.setAction(Intent.ACTION_OPEN_DOCUMENT);
    }
    intent.setType( "image/*" );
    intent.addCategory(Intent.CATEGORY_OPENABLE);
startActivityForResult(intent, PICTURE);

接收结果：

@Override
  protected void onActivityResult( int requestCode, int resultCode, Intent data) {
    if (data == null ) {
      this .finish();
      return ;
    }
    Uri uri = data.getData();
    switch (requestCode) {
      case PICTURE:
        image = FileUtils.getUriPath( this , uri); //（因为4.4以后图片uri发生了变化）通过文件工具类 对uri进行解析得到图片路径
        break ;
      default :
        break ;
    }
    this .finish();
  }

文件工具类：

public class FileUtils {
  private static final String TAG = "FileUtils" ;
  private static final boolean DEBUG = false ;
  /**
   * 获取可读的文件大小
   */
  public static String getReadableFileSize( int size) {
    final int BYTES_IN_KILOBYTES = 1024 ;
    final DecimalFormat dec = new DecimalFormat( "###.#" );
    final String KILOBYTES = " KB" ;
    final String MEGABYTES = " MB" ;
    final String GIGABYTES = " GB" ;
    float fileSize = 0 ;
    String suffix = KILOBYTES;
    if (size > BYTES_IN_KILOBYTES) {
      fileSize = size / BYTES_IN_KILOBYTES;
      if (fileSize > BYTES_IN_KILOBYTES) {
        fileSize = fileSize / BYTES_IN_KILOBYTES;
        if (fileSize > BYTES_IN_KILOBYTES) {
          fileSize = fileSize / BYTES_IN_KILOBYTES;
          suffix = GIGABYTES;
        } else {
          suffix = MEGABYTES;
        }
      }
    }
    return String.valueOf(dec.format(fileSize) + suffix);
  }
  /**
   * 获取文件的文件名(不包括扩展名)
   */
  public static String getFileNameWithoutExtension(String path) {
    if (path == null ) {
      return null ;
    }
    int separatorIndex = path.lastIndexOf(File.separator);
    if (separatorIndex < 0 ) {
      separatorIndex = 0 ;
    }
    int dotIndex = path.lastIndexOf( "." );
    if (dotIndex < 0 ) {
      dotIndex = path.length();
    } else if (dotIndex < separatorIndex) {
      dotIndex = path.length();
    }
    return path.substring(separatorIndex + 1 , dotIndex);
  }
  /**
   * 获取文件名
   */
  public static String getFileName(String path) {
    if (path == null ) {
      return null ;
    }
    int separatorIndex = path.lastIndexOf(File.separator);
    return (separatorIndex < 0 ) ? path : path.substring(separatorIndex + 1 , path.length());
  }
  /**
   * 获取扩展名
   */
  public static String getExtension(String path) {
    if (path == null ) {
      return null ;
    }
    int dot = path.lastIndexOf( "." );
    if (dot >= 0 ) {
      return path.substring(dot);
    } else {
      return "" ;
    }
  }
  public static File getUriFile(Context context, Uri uri) {
    String path = getUriPath(context, uri);
    if (path == null ) {
      return null ;
    }
    return new File(path);
  }
  public static String getUriPath(Context context, Uri uri) {
    if (uri == null ) {
      return null ;
    }
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT && DocumentsContract.isDocumentUri(context, uri)) {
      if ( "com.android.externalstorage.documents" .equals(uri.getAuthority())) {
        final String docId = DocumentsContract.getDocumentId(uri);
        final String[] split = docId.split( ":" );
        final String type = split[ 0 ];
        if ( "primary" .equalsIgnoreCase(type)) {
          return Environment.getExternalStorageDirectory() + "/" + split[ 1 ];
        }
      } else if ( "com.android.providers.downloads.documents" .equals(uri.getAuthority())) {
        final String id = DocumentsContract.getDocumentId(uri);
        final Uri contentUri = ContentUris.withAppendedId(Uri.parse( "content://downloads/public_downloads" ), Long.valueOf(id));
        return getDataColumn(context, contentUri, null , null );
      } else if ( "com.android.providers.media.documents" .equals(uri.getAuthority())) {
        final String docId = DocumentsContract.getDocumentId(uri);
        final String[] split = docId.split( ":" );
        final String type = split[ 0 ];
        Uri contentUri = null ;
        if ( "image" .equals(type)) {
          contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
        } else if ( "video" .equals(type)) {
          contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
        } else if ( "audio" .equals(type)) {
          contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        }
        final String selection = "_id=?" ;
        final String[] selectionArgs = new String[] {split[ 1 ]};
        return getDataColumn(context, contentUri, selection, selectionArgs);
      }
    } else if ( "content" .equalsIgnoreCase(uri.getScheme())) {
      if ( "com.google.android.apps.photos.content" .equals(uri.getAuthority())) {
        return uri.getLastPathSegment();
      }
      return getDataColumn(context, uri, null , null );
    } else if ( "file" .equalsIgnoreCase(uri.getScheme())) {
      return uri.getPath();
    }
    return null ;
  }
  public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {
    Cursor cursor = null ;
    final String column = "_data" ;
    final String[] projection = {column};
    try {
      cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null );
      if (cursor != null && cursor.moveToFirst()) {
        final int column_index = cursor.getColumnIndexOrThrow(column);
        return cursor.getString(column_index);
      }
    } finally {
      if (cursor != null ) cursor.close();
    }
    return null ;
  }
}

第二种方式 批量选择图片

如果我们需要类似于微信那样的一次选取多张图片，很明显第一种方式是不能满足需求，那么怎么才能批量选取呢？andorid并提供像单张选取似的批量选取的直接方法，所以我们只能自己从数据库中获得。

首先我们要认识一个类mediastore  android中所有的多媒体文件都存储在这个数据库中，例如图片 视频 音频 等等，他通过contentprovider 向其他进程提供数据的接口

想要从mediastore中获得数据，我们可以使用与ContentProvider 对应的ContentResolver

关键代码：

final String[] projectionPhotos = {
        MediaStore.Images.Media._ID, //每一列的ID 图片的ID
        MediaStore.Images.Media.BUCKET_ID, //图片所在文件夹ID
        MediaStore.Images.Media.BUCKET_DISPLAY_NAME, //图片所在文件夹名称
        MediaStore.Images.Media.DATA, //图片路径
        MediaStore.Images.Media.DATE_TAKEN, //图片创建时间
    };


cursor = MediaStore.Images.Media.query(context.getContentResolver(), MediaStore.Images.Media.EXTERNAL_CONTENT_URI
    , projectionPhotos, "" , null , MediaStore.Images.Media.DATE_TAKEN + " DESC" );

所有图片都在cursor里了 再从cursor中取出即可