Cross domain and CORS

1、 Cross domain

Cross domain , In essence, it is a kind of protection processing of browser . If cross domain , When the server returns the result, it will be intercepted by the browser ( Be careful ： At this time, the request can be initiated normally , It's just that the browser intercepted it ), The content that caused the response is not available . Generate cross domain

There are several cases :

2、 To solve the cross domain

2.1、JSONP

The browser allows some with src The label of the property is cross domain , That is, on some labels src Write on attribute url The address will not cause cross domain problems

2.2、CORS To solve the cross domain

CORS It's a W3C standard , The full name is " Cross-domain resource sharing "（Cross-origin resource sharing）.CORS Requires both browser and server support . at present , All browsers support this feature ,IE The browser cannot be lower than IE10. Before the browser makes a real request , Will launch a OPTIONS Type of pre inspection request , Used to request whether the server allows cross domain , Only with permission will the request be initiated

3、 be based on Spring Security Of CORS Support

3.1、 Declare cross domain configuration source

/**
     *  Cross domain information configuration source 
     */
    public CorsConfigurationSource corsConfigurationSource() {
        CorsConfiguration corsConfiguration = new CorsConfiguration();
        //  Allow cross domain sites 
        corsConfiguration.addAllowedOrigin("*");
        //  Allow cross domain http Method 
        corsConfiguration.addAllowedMethod("*");
        //  Allow cross domain request headers 
        corsConfiguration.addAllowedHeader("*");
        //  It is allowed to carry vouchers 
        corsConfiguration.setAllowCredentials(true);

        UrlBasedCorsConfigurationSource urlBasedCorsConfigurationSource = new UrlBasedCorsConfigurationSource();
        //  For all url All in force 
        urlBasedCorsConfigurationSource.registerCorsConfiguration("/**", corsConfiguration);
        return urlBasedCorsConfigurationSource;
    }

3.2、 Turn on cross domain support

// Allow cross-domain 
http.cors().configurationSource(corsConfigurationSource());

3.3、 Front end cross domain test code

function toCors() {
        $.ajax({
            //   By default , Standard cross domain requests are not sent cookie Of 
            xhrFields: {
                withCredentials: true
            },
            url: "http://localhost:8090/user/1",   //  according to ID Query the user 
            success: function (data) {
                alert(" The request is successful ." + data)
            }
        });