java后端解决跨域的几种问题解决

public class SimpleCORSFilter implements Filter{ 
 
  @Override 
  public void destroy() { 
     
  } 
 
  @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", "POST, GET, OPTIONS, DELETE"); 
      response.setHeader("Access-Control-Max-Age", "3600"); 
      response.setHeader("Access-Control-Allow-Headers", "x-requested-with"); 
      chain.doFilter(req, res); 
     
  } 
 
  @Override 
  public void init(FilterConfig arg0) throws ServletException { 
     
  }  
}

<filter> 
   <filter-name>cors</filter-name> 
   <filter-class>com.ssm.web.filter.SimpleCORSFilter</filter-class> 
  </filter> 
  <filter-mapping> 
   <filter-name>cors</filter-name> 
   <url-pattern>/*</url-pattern> 
  </filter-mapping>
</filter>

    response.setHeader("Access-Control-Allow-Origin", "*"); 
      response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE"); 
      response.setHeader("Access-Control-Max-Age", "3600"); 
      response.setHeader("Access-Control-Allow-Headers", "x-requested-with");

try {
  HttpClient client = HttpClients.createDefault();      //client对象
  HttpGet get = new HttpGet("http://localhost:8080/test");  //创建get请求
  CloseableHttpResponse response = httpClient.execute(get);  //执行get请求
  String mes = EntityUtils.toString(response.getEntity());  //将返回体的信息转换为字符串
  System.out.println(mes);
} catch (ClientProtocolException e) {
  e.printStackTrace();
} catch (IOException e) {
  e.printStackTrace();
}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;
/**
 * 实现基本的跨域请求
 * @author linhongcun
 *
 */
@Configuration
public class CorsConfig {
  @Bean
  public CorsFilter corsFilter() {
    final UrlBasedCorsConfigurationSource urlBasedCorsConfigurationSource = new UrlBasedCorsConfigurationSource();
    final CorsConfiguration corsConfiguration = new CorsConfiguration();
    /*是否允许请求带有验证信息*/
    corsConfiguration.setAllowCredentials(true);
    /*允许访问的客户端域名*/
    corsConfiguration.addAllowedOrigin("*");
    /*允许服务端访问的客户端请求头*/
    corsConfiguration.addAllowedHeader("*");
    /*允许访问的方法名,GET POST等*/
    corsConfiguration.addAllowedMethod("*");
    urlBasedCorsConfigurationSource.registerCorsConfiguration("/**", corsConfiguration);
    return new CorsFilter(urlBasedCorsConfigurationSource);
  }
}

server {
    listen    80;
    server_name www.my.com;
    location /A {
      proxy_pass http://a.a.com:81/A;
      index index.html index.htm;
    }
    location /B {
      proxy_pass http://b.b.com:81/B;
      index index.html index.htm;
    }
  }

server {
    listen    80;
    server_name b.b.com;
    location /Api {
      proxy_pass http://b.b.com:81/Api;
      index index.html index.htm;
    }
  }