Android从相册获取图片

应用中经常会有去相册获取图片的需求，每次总是会忘，现在这做个记录，以便以后查阅。

从应用去相册获取图片主要有以下几个步骤：

1、设置intent调用系统相册

2、进入相册选取图片，如果相册没有满意的图片，可以使用相机照相获取，最后返回数据到应用

3、应用获取图片后，调用裁剪程序对图片进行裁剪

4、返回裁剪的图片并显示出来

一、设置intent调用系统相册，并进入相册选取图片

/**
 * 调用相册
 */
private void goAlbums() {
        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.setType("image/*");
        startActivityForResult(intent, SELECT_PIC);
 }

通过以上设置进入相册，返回的图片数据交由Activity的onActivityResult方法处理，请求码是SELECT_PIC，请求码为int型，可以随意设置

获取到返回的图片之后，下面便进入裁剪的步骤了

二、调用裁剪程序对图片进行裁剪

/**
     * 裁剪大图
     * @param context
     * @param uri
     */
    private void clipperBigPic(Context context, Uri uri) {
        if (null == uri) {
            return;
        }
        Intent intent = new Intent("com.android.camera.action.CROP");
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            String url = PhotoClipperUtil.getPath(context, uri);
            intent.setDataAndType(Uri.fromFile(new File(url)), "image/*");
        }
        //发送裁剪命令
        intent.putExtra("crop", true);
        //X方向上的比例
        intent.putExtra("aspectX", 1);
        //Y方向上的比例
        intent.putExtra("aspectY", 1);
        //裁剪区的宽
        intent.putExtra("outputX", 124);
        //裁剪区的高
        intent.putExtra("outputY", 124);
        //是否保留比例
        intent.putExtra("scale", true);
        //返回数据
        intent.putExtra("return-data", true);
        //输出图片格式
        intent.putExtra("outputFormat", Bitmap.CompressFormat.PNG.toString());
        //裁剪图片保存位置
        intent.putExtra(MediaStore.EXTRA_OUTPUT, getTempUri());
        startActivityForResult(intent, SELECT_CLIPPER_PIC);
    }

上面代码中的Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT，是因为KITKAT以上版本中返回的data数据和KITKAT以下版本的data数据可能不同，需要单独处理。

下面的代码便是正常处理，设置裁剪的参数，请求的数据同样交由onActivityResult处理

getTempUri为设置临时图片存储目录，代码如下：

private Uri getTempUri() {
        return Uri.fromFile(getTempFile());
    }

    /**
     * 临时图片保存路径
     * @return
     */
    private File getTempFile() {
        File file = new File(Environment.getExternalStorageDirectory(), IMAGE_FILE_NAME);
        try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return file;
    }

上面代码中中的IMAGE_FILE_NAME需要自己指定

上面代码中的PhotoClipperUtil类代码如下：

package tmg.gotoalarm;

import android.annotation.SuppressLint;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.provider.DocumentsContract;
import android.provider.MediaStore;

public class PhotoClipperUtil {

    @SuppressLint("NewApi")
    public static String getPath(final Context context, final Uri uri) {

        final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

        // DocumentProvider
        if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
            // ExternalStorageProvider
            if (isExternalStorageDocument(uri)) {
                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];
                }

            }
            // DownloadsProvider
            else if (isDownloadsDocument(uri)) {
                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);
            }
            // MediaProvider
            else if (isMediaDocument(uri)) {
                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);
            }
        }
        // MediaStore (and general)
        else if ("content".equalsIgnoreCase(uri.getScheme())) {
            // Return the remote address
            if (isGooglePhotosUri(uri))
                return uri.getLastPathSegment();

            return getDataColumn(context, uri, null, null);
        }
        // File
        else if ("file".equalsIgnoreCase(uri.getScheme())) {
            return uri.getPath();
        }

        return null;
    }

    /**
     * Get the value of the data column for this Uri. This is useful for
     * MediaStore Uris, and other file-based ContentProviders.
     *
     * @param context The context.
     * @param uri The Uri to query.
     * @param selection (Optional) Filter used in the query.
     * @param selectionArgs (Optional) Selection arguments used in the query.
     * @return The value of the _data column, which is typically a file path.
     */
    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 index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(index);
            }
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return null;
    }


    /**
     * @param uri The Uri to check.
     * @return Whether the Uri authority is ExternalStorageProvider.
     */
    public static boolean isExternalStorageDocument(Uri uri) {
        return "com.android.externalstorage.documents".equals(uri.getAuthority());
    }

    /**
     * @param uri The Uri to check.
     * @return Whether the Uri authority is DownloadsProvider.
     */
    public static boolean isDownloadsDocument(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri.getAuthority());
    }

    /**
     * @param uri The Uri to check.
     * @return Whether the Uri authority is MediaProvider.
     */
    public static boolean isMediaDocument(Uri uri) {
        return "com.android.providers.media.documents".equals(uri.getAuthority());
    }

    /**
     * @param uri The Uri to check.
     * @return Whether the Uri authority is Google Photos.
     */
    public static boolean isGooglePhotosUri(Uri uri) {
        return "com.google.android.apps.photos.content".equals(uri.getAuthority());
    }
}

总的获取相册图片的流程如下：

mGoAlarmIv.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //调用系统相册，进入相册获取图片
                goAlbums();
            }
        });    

进入相册后，应用的中转工作交由onActivityResult处理

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (data == null) {
            return;
        }
        switch (requestCode) {
            case SELECT_PIC:
               //获取图片后裁剪图片
                clipperBigPic(this, data.getData());
                break;
            case SELECT_CLIPPER_PIC:
               //获取图片后保存图片到本地，是否需要保存看情况而定
                saveBitmap(data);
                //显示图片
                showImage(mGoAlarmIv);
                break;
        }
    }

保存图片的代码如下：

/**
     * 保存图片
     * @param data
     */
    private void saveBitmap(Intent data) {
        Bundle bundle = data.getExtras();
        if (bundle != null) {
            Bitmap bitmap = bundle.getParcelable("data");
            File file = new File(Environment.getExternalStorageDirectory(), IMAGE_FILE_NAME);
            try {
                file.createNewFile();
                FileOutputStream fileOutputStream = new FileOutputStream(file);
                bitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream);
                fileOutputStream.flush();
                fileOutputStream.close();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }

OK，以上便是第三方应用调用相册获取图片的整个流程。