检查文件夹是否存在,如果不存在则创建它

Question

我注意到在SO上没有确定的答案,所以我正在寻找一个规范的答案,问题是" 如何检查文件夹是否存在,如果不存在则创建它,使用Google Drive Android API？ " .理想情况下显示使用异步方法ResultCallback和使用同步方法的示例.await().

PS我用相同的标题知道这个问题,但是接受的答案集中在已知的滞后错误上isTrashed(),并且不清楚你实际知道文件夹存在的代码中的哪一点.其他答案似乎已过时.

Answer 1

这个问题 - 虽然侧重于滞后删除状态问题 - 确实提供了测试文件夹是否存在的模式.

使用异步回调:

Query query = new Query.Builder()
    .addFilter(Filters.and(Filters.eq(
            SearchableField.TITLE, "MyFolder"),
            Filters.eq(SearchableField.TRASHED, false)))
    .build();
    Drive.DriveApi.query(getGoogleApiClient(), query)
        .setResultCallback(new ResultCallback<DriveApi.MetadataBufferResult>() {
    @Override
    public void onResult(DriveApi.MetadataBufferResult result) {
        if (!result.getStatus().isSuccess()) {
            showMessage("Cannot create folder in the root.");
        } else {
            boolean isFound = false;
            for(Metadata m : result.getMetadataBuffer()) {
                if (m.getTitle().equals("MyFolder")) {
                    showMessage("Folder exists");
                    isFound = true;
                    break;
                }
            }
            if(!isFound) {
                showMessage("Folder not found; creating it.");
                MetadataChangeSet changeSet = new MetadataChangeSet.Builder()
                    .setTitle("MyFolder")
                    .build();
                Drive.DriveApi.getRootFolder(getGoogleApiClient())
                        .createFolder(getGoogleApiClient(), changeSet)
                        .setResultCallback(new ResultCallback<DriveFolder.DriveFolderResult>() {
                    @Override
                    public void onResult(DriveFolder.DriveFolderResult result) {
                        if (!result.getStatus().isSuccess()) {
                            showMessage("Error while trying to create the folder");
                        } else {
                            showMessage("Created a folder");
                        }
                    }
                });
            }
        }
    }
});

使用同步 .await()

Query query = new Query.Builder()
    .addFilter(Filters.and(Filters.eq(
            SearchableField.TITLE, "MyFolder"),
            Filters.eq(SearchableField.TRASHED, false)))
    .build();

    DriveApi.MetadataBufferResult result = Drive.DriveApi.query(getGoogleApiClient(), query)
        .await();

    if (!result.getStatus().isSuccess()) {
        showMessage("Cannot create folder in the root.");
    } else {
        boolean isFound = false;
        for(Metadata m : result.getMetadataBuffer()) {
            if (m.getTitle().equals("MyFolder")) {
                showMessage("Folder exists");
                isFound = true;
                break;
            }
        }
        if(!isFound) {
            showMessage("Folder not found; creating it.");
            MetadataChangeSet changeSet = new MetadataChangeSet.Builder()
                    .setTitle("MyFolder")
                    .build();

            Drive.DriveApi.getRootFolder(getGoogleApiClient())
                        .createFolder(googleApiClient, changeSet).await();

            if (!result.getStatus().isSuccess()) {
                showMessage("Error while trying to create the folder");
            } else {
                showMessage("Created a folder");
            }
        }