I am trying to create an app that displays a list of pdf files, and then load the pdf file in a new browser tab / android activity.
The idea is the user will click a button "Lectures" and then will be shown the list of lectures, clicking on any list item will load the specific pdf file.
I currently have a node js mysql back end, for user login and routes to other pages, which is followed up with both a handlebars and android front end.
I am struggling to understand how I can store pdf files so they can be called based on what the user clicks, I want to store the pdf files on a server rather than within my application and then call them when required.
I have seen a method using ejs view engine to render list of files in public folder, which then allows you to do this, but this entails storing pdfs within the application, alternatively I can host the files with my web hosting, still need to figure out how to load them based on user action.
Would appreciate any direction or solution!
Thanks in advance
Mohamed V
Without knowing how you have the DB set I will talk more along the lines of how you would do this and then modify as needed. In most cases you would probably want to use an object store to store the PDF files. This will allow for access on any application.
Your DB should contain a file name of the PDF file, as an example, lets say you table for 'files' is as such
id, filename, name, extension, courceID
Here you would have the filename maybe the extension type and a refrenceID
Next, in your response callback, you simply return the query for the files, for example let say you run a query like SELECT filename, name WHERE courceID = '12345'
You then return this to the view, if its ejs then you would just pass the object and do something like
<% for ( in in files ) {%>
<div><a href="url-to-object-store/<%-files[i].filename%>"><%-files[i].filename%>
<%}%>
I am getting data from an api which cannot be converted into pojo so am not able to get the data in a normal manner
Data that i am getting
{"TABLE_DATA":"
{\"data\":[
[\"Tiger Nixon\",\"System
Architect\",\"Edinburgh\",\"5421\",\"2011/04/25\",\"$320,800\"],
[\"Garrett
Winters\",\"Accountant\",\"Tokyo\",\"8422\",\"2011/07/25\",\"$170,750\"],
[\"Ashton Cox\",\"Junior Technical
Author\",\"SanFrancisco\",\"1562\",\"2009/01/12\",\"$86,000\"],
[\"Cedric Kelly\",\"Senior Javascript
Developer\",\"Edinburgh\",\"6224\",\"2012/03/29\",\"$433,060\"],
[\"Airi
Satou\",\"Accountant\",\"Tokyo\",\"5407\",\"2008/11/28\",\"$162,700\"],
[\"Brielle Williamson\",\"Integration Specialist\",\"New
York\",\"4804\",\"2012/12/02\",\"$372,000\"],
[\"Herrod Chandler\",\"Sales Assistant\",\"San
Francisco\",\"9608\",\"2012/08/06\",\"$137,500\"],
[\"Rhona Davidson\",\"Integration
Specialist\",\"Tokyo\",\"6200\",\"2010/10/14\",\"$327,900\"],
[\"Colleen Hurst\",\"Javascript Developer\",\"San
Francisco\",\"2360\",\"2009/09/15\",\"$205,500\"],
[\"Sonya Frost\",\"Software
Engineer\",\"Edinburgh\",\"1667\",\"2008/12/13\",\"$103,600\"],
[\"Jena Gaines\",\"Office
Manager\",\"London\",\"3814\",\"2008/12/19\",\"$90,560\"]`
there is no pojo available This is my first time working in an API any guide will be helpful. I am receiving the following data using retofit and rxjava2.
Data format is post method .
This is a jquery format. You may try to use this https://javacodegeeks.com/2013/02/jquery-datatables-and-java-integration.html
Look also this topic stackoverflow.com/questions/48942253/how-to-implement-jquery-datatable-in-android-any-library
The service you get data from may have an opportunity to set data format, you must specify it in your GET query, look in the API documentation.
That looks a lot like a .csv file. CSV files were the old format of Comma Separated Values, built from Tabular data.
Each row is one object and each column is its attribute/field. You can read about CSV files here.
Approach 1
Filter out using string manipulation the extra symbols of slashes and quotes. Delimit at the square braces (more info here) and then reading each delimited comma separated value text by any CSV reading library. Here's a tutorial using Apache Commons CSV library to read CSV files in Java.
Approach 2
Instead of using any library, if your response set is small and you don't need as much parsing optimization, write your object class's constructor to take in each row, filter out the useless symbols (using string manipulation) and initialize your object's fields.
All steps involved:
Clean response and remove unnecessary symbols using string manipulation.
Build a POJO class to keep one row of the dataset. Have its constructor to take in the first row of your dataset to initialize its attributes.
Build a list format or ArrayList format of your previous class with additional methods to sort, search or call by indices as required.
Build a constructor for this list object class to read in your cleaned string response and iterate over it to build Employee objects and adding them to your list.
EDIT: This question is about using AssetBundle, while that question (List of files in flutter) was about using Directory. They are different because of different classes. ALSO: I removed one section, that can be similar to previous question.
I don't understand how to use AssetBundle for accessing files...
For example, my assets in pubspec.yaml
assets:
- assets/images/
- assets/texts/
AssetBundle has methods: loadString(key, ...) and loadStructuredData(key, ...) - what is a key and how to use this methods?
I need to load data from text files and others files. I know that there is a rootBundle (or DefaultAssetBundle.of(context))... But how to use it to load files?!
Thanks!
Let's assume that you have an image clock.png in assets/images and a UTF-8 encoded text file distances.json in assets/texts.
The key is really just the path to the asset, so you might load the whole file as a String and decode the json like this:
String distancesText = await rootBundle.loadString('assets/texts/distances.json');
Map distances = json.decode(distancesText);
loadString takes care of the UTF-8 decode for you, and also caches the String for faster access next time.
loadStructuredData takes loadString one step further - it loads the String then calls your provided callback to parse the String and returns the result. This time it caches the decoded result - now saving the reading and decoding step the next time.
Map distances2 = await rootBundle
.loadStructuredData('assets/texts/distances.json', (String s) async {
return json.decode(s);
});
So, this is great for text files; what about binary files? You can read the whole asset as a byte array.
ByteData clockData = await rootBundle.load('assets/images/clock.png');
Uint8List clockBytes = clockData.buffer.asUint8List());
Now you can do whatever you need to do with the binary contents of the file. Note that unlike Strings, binary data isn't cached.
Of course, for a PNG, you would most likely not read it as bytes, but instead load it as an Image Widget with AssetImage. (Also asset images should have multiple resolutions for different DPI devices.) See Assets and Images.
I think that earlier you wanted to obtain a complete list of all the assets available. In some ways this makes no sense. You know which assets you provided at build time, so you could keep the list of assets somewhere yourself - in code or in your own manifest. If you really want to enumerate them at runtime, I think you can load an asset called AssetManifest.json, but this seems to be an implementation detail, so possibly subject to change.
I created an android test app with camera interface in which I want to save a text message and image file as one object. I am able to enter message, call the camera,take a picture and also populate the image in the image view on the app. Now I want to save them as one single record/object so that I can transfer it over network using protocol such as ftp. How to save image file and text together as one single file/object? Could someone please tell me how to do that. Thanks in advance.
There are lots of possibilities, and it depends to some extent on what will be consuming the file after it is transferred. You could, for instance, simply serialize the string and the image data using a DataOutputStream wrapped around a FileOutputStream. As a fancy version of that, you could define a class to contain the text and the image, have that class implement Serializable, and serialize it to a file. Alternatively, you could serialize the image data as a base-64 string and then put the text and the base-64 image data into an XML document or JSON string. Other approaches are also possible.
If you provide more details about what kind of process will consume this file after it has been transferred, perhaps we can provide more focused suggestions.
In my project I have one requirement to show the number of pages in Word documents (.doc, .docx) files and number of sheets in Excel documents (.xls, .xlsx). I have tried to read the .docx file using Docx4j but the performance is very poor but I need just the word count and tried using Apache POI. I am getting an error, something like:
"trouble writing output: Too many methods: 94086; max is 65536. By package:"
I want to know whether there is any paid/open source library available for android.
There is just no way to show exact number of pages in MS Word file, because it will be different for different users. The exact number depends on printer settings, paper settings, fonts, available images, etc.
Still, you can do the following for binary files:
open file use POIFSFileSystem or NPOIFSFileSystem
extract only FileInformationBlock as it is done in the constructor HWPFDocumentCore
create DocumentProperties using information from FileInformationBlock as it is done in constuctor of HWPFDocument
get value of property cPg of DOP: DocumentProperties::getCPg()
The description of this field is: "A signed integer value that specifies the last calculated or estimated count of pages in the main document, depending on the values of fExactCWords and fIncludeSubdocsInStats."
For DOCX/XLSX documents you will need to access the same (I assume) property but using SAX or StAX methods.