How to handle cross-domain requests in Java backend function development?

How to handle cross-domain requests in Java backend function development?

In the development mode where the front-end and back-end are separated, it is a very common scenario for the front-end to send requests to the back-end API interface to obtain data through JavaScript. However, due to the browser's same-origin policy, there are restrictions on cross-domain requests. Cross-domain request means that the front-end page requests servers with different domain names, different ports or different protocols through AJAX and other methods. This article will introduce a common method for handling cross-domain requests in the development of Java back-end functions, with code examples.

The common way to solve cross-domain problems is to make corresponding configurations on the backend. The following uses the Spring Boot framework as an example to introduce how to handle cross-domain requests.

1. Add CrossOrigin annotation

Add CrossOrigin annotation on the backend Controller method. This annotation is used to configure the domain name, request method and other related parameters that allow cross-domain. The following is an example:

@RestController
@RequestMapping("/api")
@CrossOrigin(origins = "http://frontend.com", methods = {RequestMethod.GET, RequestMethod.POST})
public class MyController {
    // Controller方法...
}

In the above code, the @CrossOrigin annotation specifies that the domain name of http://frontend.com is allowed to initiate GET and POST requests. You can modify these parameters according to your needs.

2. Configuring Spring Boot global cross-domain configuration

Through the configuration file, global cross-domain request processing can be achieved. Add the following configuration to the Spring Boot project configuration file (such as application.properties):

spring.webmvc.cors.allowed-origins=*

The above code indicates that all domain names are allowed to initiate cross-domain requests. You can also specify a specific domain name, such as:

spring.webmvc.cors.allowed-origins=http://frontend1.com,http://frontend2.com

3. Use Filter to handle cross-domain requests

In addition to the above two methods, you can also use Filter to handle cross-domain requests. . Create a class that implements the Filter interface, and then add cross-domain processing logic in the doFilter method. The following is an example:

@Component
public class CorsFilter implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "Content-Type, Authorization, X-Requested-With");

        chain.doFilter(req, res);
    }
}

In the above code, the configuration to allow cross-domain requests is implemented by setting the response header.

To sum up, there are many ways to handle cross-domain requests in Java back-end function development. Just choose the appropriate method according to actual needs. The above provides sample code for using CrossOrigin annotations, configuring Spring Boot global cross-domain configuration, and using Filter to handle cross-domain requests. I hope it will help you with cross-domain issues during development.

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