spring mvc 跨域请求处理——spring 4.2 以上

Controller method CORS configuration

You can add to your @RequestMapping annotated handler method a @CrossOrigin annotation in order to enable CORS on it (by default @CrossOrigin allows all origins and the HTTP methods specified in the @RequestMapping annotation):

@RestController
@RequestMapping("/account")
public class AccountController {

	@CrossOrigin
	@RequestMapping("/{id}")
	public Account retrieve(@PathVariable Long id) {
		// ...
	}

	@RequestMapping(method = RequestMethod.DELETE, value = "/{id}")
	public void remove(@PathVariable Long id) {
		// ...
	}
}

It is also possible to enable CORS for the whole controller:

@CrossOrigin(origins = "http://domain2.com", maxAge = 3600)
@RestController
@RequestMapping("/account")
public class AccountController {

	@RequestMapping("/{id}")
	public Account retrieve(@PathVariable Long id) {
		// ...
	}

	@RequestMapping(method = RequestMethod.DELETE, value = "/{id}")
	public void remove(@PathVariable Long id) {
		// ...
	}
}

In this example CORS support is enabled for both retrieve() and remove() handler methods, and you can also see how you can customize the CORS configuration using@CrossOrigin attributes.

You can even use both controller and method level CORS configurations, Spring will then combine both annotation attributes to create a merged CORS configuration.

@CrossOrigin(maxAge = 3600)
@RestController
@RequestMapping("/account")
public class AccountController {

	@CrossOrigin(origins = "http://domain2.com")
	@RequestMapping("/{id}")
	public Account retrieve(@PathVariable Long id) {
		// ...
	}

	@RequestMapping(method = RequestMethod.DELETE, value = "/{id}")
	public void remove(@PathVariable Long id) {
		// ...
	}
}

Global CORS configuration

In addition to fine-grained, annotation-based configuration you’ll probably want to define some global CORS configuration as well. This is similar to using filters but can be declared withing Spring MVC and combined with fine-grained @CrossOrigin configuration. By default all origins and GET, HEAD and POST methods are allowed.

JavaConfig

Enabling CORS for the whole application is as simple as:

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {

	@Override
	public void addCorsMappings(CorsRegistry registry) {
		registry.addMapping("/**");
	}
}

You can easily change any properties, as well as only apply this CORS configuration to a specific path pattern:

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {

	@Override
	public void addCorsMappings(CorsRegistry registry) {
		registry.addMapping("/api/**")
			.allowedOrigins("http://domain2.com")
			.allowedMethods("PUT", "DELETE")
			.allowedHeaders("header1", "header2", "header3")
			.exposedHeaders("header1", "header2")
			.allowCredentials(false).maxAge(3600);
	}
}

XML namespace

It is also possible to configure CORS with the mvc XML namespace.

This minimal XML configuration enable CORS on /** path pattern with the same default properties than the JavaConfig one:

<mvc:cors>
	<mvc:mapping path="/**" />
</mvc:cors>

It is also possible to declare several CORS mappings with customized properties:

<mvc:cors>

	<mvc:mapping path="/api/**"
		allowed-origins="http://domain1.com, http://domain2.com"
		allowed-methods="GET, PUT"
		allowed-headers="header1, header2, header3"
		exposed-headers="header1, header2" allow-credentials="false"
		max-age="123" />

	<mvc:mapping path="/resources/**"
		allowed-origins="http://domain1.com" />

</mvc:cors>

How does it work?

CORS requests (including preflight ones with an OPTIONS method) are automatically dispatched to the various HandlerMappings registered. They handle CORS preflight requests and intercept CORS simple and actual requests thanks to a CorsProcessor implementation (DefaultCorsProcessor by default) in order to add the relevant CORS response headers (likeAccess-Control-Allow-Origin). CorsConfiguration allows you to specify how the CORS requests should be processed: allowed origins, headers, methods, etc. It can be provided in various ways:

• AbstractHandlerMapping#setCorsConfiguration() allows to specify a Map with severalCorsConfiguration mapped on path patterns like /api/**
• Subclasses can provide their own CorsConfiguration by overridingAbstractHandlerMapping#getCorsConfiguration(Object, HttpServletRequest) method
• Handlers can implement CorsConfigurationSource interface (likeResourceHttpRequestHandler now does) in order to provide a CorsConfiguration for each request.