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Cross-Origin Resource Sharing (CORS) is managed by setting specific HTTP response headers, primarily Access-Control-Allow-Origin, which dictates which external domains are permitted to access the resource. When a browser blocks a request due to CORS policy, the error typically resembles: Access to XMLHttpRequest has been blocked by CORS policy: ...

Introduction to CORS When discussing AJAX cross-domain requests, many developers first think of JSONP. JSONP has been widely used for years, but it has significant limitations. It works by injecting a <script> tag into the page to execute remote JavaScript, which can lead to XSS vulnerabilities if the source is compromised. Additionally, ...

Temporary Directory Setup Before implementing file upload, configure the temporary directory where uploaded files are stored during processing. Option 1: JVM parameter mkdir -p /app/tmp -Djava.io.tmpdir=/app/tmp Option 2: Spring Boot configuration spring: servlet: multipart: location: /app/tmp max-file-size: 500MB max-r ...

@Controller Applied at the class level, @Controller marks a class as a Spring MVC controller and registers it as a Spring bean. The DispatcherServlet automatically detects such classes and routes incoming HTTP requests to methods annotated with @RequestMapping. This annotation is specifically intended for web controllers—use @Component or other ...

Spring MVC's core components—HandlerMapping, HandlerAdapter, and Controller—each have distinct responsibilities. Responsibilities HandlerMapping (Mapper): Maps incoming HTTP requests to appropriate handlers based on the request URL. It associates request paths with controller beans. HandlerAdapter (Adapter): Invokes the actual handler metho ...

Recently, I decided to stop using sessions and explore tokens for a more secure and robust approach, while also creating a unified interface for both browsers and mobile apps. I refactored a practice project's frontend to use Ajax entirely, keeping Spring MVC for view controller forwarding. This deepened my understanding of JSON data transmissi ...