Have a look at the following links and see how the download mechanism works with Axios: and fakiolinhohandle-blobs-requests-with-axios-the-right-way-bb905bdb1c04.Tired of textplain Have a look at my online courses or YouTube channel for more Java, Spring Framework Jakarta EE content.Today I want to share a simple approach for up- and downloading files with JavaScript (ES6), React and a Spring Boot backend.
React File Download Mechanism WorksThis example can be used for any common content type like jpg, pdf, txt, HTML, png, etc. The backend will store the files in an H2 in-memory database and will randomly return a file. ![]() For sending the request Ill use the Fetch API and display a message in case of a successful upload. To read this byte array in full, I make use of the blob() function of the response. To extract the correct filename, I access the response header Content-Disposition and store the filename in a local variable. As the browsers currently dont support a standard way of downloading files from an AJAX request, I create an object URL for the incoming Blob and force the browser to download the image with a hidden HTML element. IDENTITY ) private Long id; private String fileName; private String contentType; Lob private byte data; constructors, getters setters. Moreover, we need to configure CORS to access the Content-Disposition header in the frontend application. As I store the content type of the file in the database, I can add the right Content-Type header of the response. ![]() React File Code Works ForI use this to show you that this code works for every common content type. Storing the files in a database might also not be the best solution for production. Usually, a web server (e.g. Nginx) hosts the static files which are created after you build the frontend application with npm run build. Nevertheless, for this example, I choose a self-contained system approach. To make this work, we have to instruct the application where to find the static content for the React application. Within the build section of the pom.xml we can configure this. This makes development much more convenient and as long your traffic is moderate, serving the frontend using the Spring Boot backend is feasible. This should be done by Spring with the following annotation: CrossOrigin(value, exposedHeaders Content-Disposition) as described in the post. Im using axios instead of fetch but I dont see why that would matter. I first got response.header.get is not a function so I hardcoded filename to continue to debug and got I get blob() is not a function.
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December 2020
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