将数据直接从浏览器发送到Java Desktop应用程序

Question

I'm making a web application using TypeScript as the client-side scripting language. Further technologies I use are Spring Boot , PostgreSQL and Angular . When the user clicks a button on the website, my already running Java desktop application ("independent" from the web application, not the web application's server) should receive data sent from the web application and then prompt the user to import it into the Desktop application.

How can this be done? Any example codes available?

Can I start a simple listener server on my Desktop application waiting for the client (the browser) to send the payload of import data to the listening server (in a platform-independent way)?

Note that this is different from the Desktop application to download data from an Internet resource since the resource should be determined by a click in the browser itself , not through the Desktop application's interface.

Registering my Java Desktop application to an URI scheme only allows me to launch the Desktop application with a custom URI as parameter and it's Windows only as well which is therefore not a satisfying solution.

Answer 1

I understand your setup as follows:

Browser <--HTTP/HTTPS via Internet-->SpringBoot

A webpage rendered in the browser should communicate with a local desktop application.

The solution is to establish a HTTP connection between your webpage and the desktop application as follows:

• your desktop application must include an embedded servlet container as for example undertow that binds a server socket to 127.0.0.1:yourPort
• the embedded servlet container requires a CORS Filter as the webpage's origin is certainly different from 127.0.0.1.
• The webpage simply opens a connection with the help of XMLHttpRequest, eg

   var req = new XMLHTTPRequest(); req.open("POST", " http://127.0.0.1:yourPort "); req.setRequestHeader("content-type", "application/x-www-form-urlencoded"); req.send("payload="+ myPayload); 

When the browser has established a HTTPS connection with the SpringBoot server, you have the problem that the browser may display a "Mixed Content Warning" as a secured web context (your web page) accesses a resource via HTTP.

Fortunately, lately modern browsers like Chrome, Firefox, Edge and Safari implement the W3C Secure Contexts working draft and thus consider access to 127.0.0.1 as potentially trustworthy: no Mixed Content warning.

Still if you bring this into production you must be aware that your desktop application is now vulnerable against XSS attacks.