android4.4.4 获取系统相册图片出错的问题（二）

呵呵，今天很高兴，因为自己正式步入准爸爸阶段了！特此记录下！
好吧，今天，我接着上次的问题讲解，如何从android4.4以上系统进行选图而避免报错，而

android4.4.4 获取系统相册图片出错的问题（一）
中介绍的那种方式，其实在性能方面的话，还是一般，因为每次读取一张图片，它都要在本地生成一张，造成存储空间的浪费。今天介绍的这种方法，是根据网上的不同的资料进行的整理。

第一步：也就是我们调转到我们的系统相册进行图片的选择

Intent intent = new Intent(Intent.ACTION_GET_CONTENT);// ACTION_OPEN_DOCUMENT
            intent.addCategory(Intent.CATEGORY_OPENABLE);
            intent.setType("image/jpeg");
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.KITKAT) {/**4.4系统以上**/
                startActivityForResult(intent, SELECT_PIC_KITKAT);
            } else {
                startActivityForResult(intent, SELECT_PIC);
            }

第二步自然就是在onActivityResult中进行处理

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
        case SELECT_PIC_KITKAT:
            if (resultCode != Activity.RESULT_OK) {
                return;
            }
            String path = "";
            if (DocumentsContract.isDocumentUri(MainActivity.this,
                    data.getData())) {
// path = selectImage(MainActivity.this, data);
                 path = getPath(data);
            } else {
                path = getPath(MainActivity.this, data);
            }
            Message msg = new Message();
            msg.obj = path;
            handler.sendMessage(msg);
            break;
        case SELECT_PIC:
            if (resultCode != Activity.RESULT_OK) {
                return;
            }
            Message msg1 = new Message();
            msg1.obj = getPath(data);
            handler.sendMessage(msg1);
            break;
        }
    }

好，关键代码来了，如下：

public static String getPath(final Context context, Intent data) {
        Uri uri = data.getData();
        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];
                }
                // TODO handle non-primary volumes
            }
            // 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());
    }

现在就是通过handler进行本地的显示：

private Handler handler = new Handler(Looper.getMainLooper()) {
        public void handleMessage(android.os.Message msg) {
            String path = (String) msg.obj;
            // Bitmap myBitmap = getLoacalBitmap(path);
            Bitmap bitmap = LocalImageCompression.comp(path);
            img.setImageBitmap(bitmap);
        };
    };

其中用到了一个通过本地路径进行图片的处理，主要是相册图片的size太大了，显示不了，

/** * @方法说明:图片按比例大小压缩方法（根据路径获取图片并压缩） * @方法名称:getimage * @param srcPath * @return * @返回值:Bitmap */
    public static Bitmap comp(String srcPath) {
        BitmapFactory.Options newOpts = new BitmapFactory.Options();
        /** 开始读入图片，此时把options.inJustDecodeBounds 设回true了**/
        newOpts.inJustDecodeBounds = true;
        Bitmap bitmap = BitmapFactory.decodeFile(srcPath, newOpts);/** 此时返回bm为空**/

        newOpts.inJustDecodeBounds = false;
        int w = newOpts.outWidth;
        int h = newOpts.outHeight;
        /** 现在主流手机比较多是800*480分辨率，所以高和宽我们设置为**/
        float hh = 800f;/** 这里设置高度为800f**/
        float ww = 480f;/** 这里设置宽度为480f**/
        /** 缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可**/
        int be = 1;/** be=1表示不缩放**/
        if (w > h && w > ww) {/** 如果宽度大的话根据宽度固定大小缩放**/
            be = (int) (newOpts.outWidth / ww);
        } else if (w < h && h > hh) {/** 如果高度高的话根据宽度固定大小缩放**/
            be = (int) (newOpts.outHeight / hh);
        }
        if (be <= 0)
            be = 1;
        newOpts.inSampleSize = be;/** 设置缩放比例**/
        /** 重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了**/
        bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
        return compressImage(bitmap);/** 压缩好比例大小后再进行质量压缩**/
    }

源码地址：http://yunpan.cn/cJ8WZm9NsnvuX （提取码：3719）