14 solutions to cross-domain problems in Java and front-end interaction

//  or = {
  devServer: {
    proxy: {
      '/api': {
        target: 'http://localhost:8080',
        changeOrigin: true,
        pathRewrite: {
          '^/api': ''
        }
      }
    }
  }
}

// 
export default defineConfig({
  server: {
    proxy: {
      '/api': {
        target: 'http://localhost:8080',
        changeOrigin: true,
        rewrite: (path) => (/^\/api/, '')
      }
    }
  }
})

function jsonp(url, callback) {
  const script = ('script');
   = `${url}?callback=${callback}`;
  (script);
}
 
// The backend needs to return a response similar to callbackName(data)

const socket = new WebSocket('ws://your-backend-url');

@RestController
@RequestMapping("/api")
@CrossOrigin(origins = "*") // All sources are allowedpublic class MyController {
    // Controller method}

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        ("/**")
            .allowedOrigins("http://localhost:3000", "")
            .allowedMethods("GET", "POST", "PUT", "DELETE", "OPTIONS")
            .allowedHeaders("*")
            .allowCredentials(true)
            .maxAge(3600);
    }
}

@Bean
public FilterRegistrationBean<CorsFilter> corsFilter() {
    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    CorsConfiguration config = new CorsConfiguration();
    (true);
    ("http://localhost:3000");
    ("*");
    ("*");
    ("/**", config);
    return new FilterRegistrationBean<>(new CorsFilter(source));
}

# Allowed Source-origins=http://localhost:3000,
# Allowed methods-methods=GET,POST,PUT,DELETE,OPTIONS
# Allowed head-headers=*
# Whether to allow credentials-credentials=true
# Preflight request cache time-age=3600

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        ().and()
            // Other security configurations            .csrf().disable(); // CSRF is usually required to simplify API development    }
    
    @Bean
    CorsConfigurationSource corsConfigurationSource() {
        CorsConfiguration configuration = new CorsConfiguration();
        (("http://localhost:3000"));
        (("GET","POST","PUT","DELETE","OPTIONS"));
        (("*"));
        (true);
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        ("/**", configuration);
        return source;
    }
}

server {
    listen 80;
    server_name ;
    
    location /api {
        proxy_pass http://backend-server:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
    
    location / {
        root /path/to/frontend/dist;
        try_files $uri $uri/ /;
    }
}

// Add response header to the backend("Access-Control-Expose-Headers", "Authorization");
("Authorization", "Bearer " + token);

@RestController
public class OptionsController {
    @RequestMapping(value = "/**", method = )
    public ResponseEntity<?> handleOptions() {
        return ().build();
    }
}

@Bean
public CorsFilter corsFilter() {
    return new CorsFilter(new UrlBasedCorsConfigurationSource() {
        @Override
        public CorsConfiguration getCorsConfiguration(HttpServletRequest request) {
            CorsConfiguration config = new CorsConfiguration();
            String origin = ("Origin");
            if ((origin)) { // Check if it is in the allowed list                (origin);
                (("GET","POST","PUT","DELETE","OPTIONS"));
                (("*"));
                (true);
            }
            return config;
        }
    });
}