java后台调用接口及处理跨域问题的解决

public String httpPost(String urlStr,Map<String,String> params){

     URL connect;

     StringBuffer data = new StringBuffer(); 

     try { 

         connect = new URL(urlStr); 

         HttpURLConnection connection = (HttpURLConnection)connect.openConnection(); 

         connection.setRequestMethod( "POST" ); 

         connection.setDoOutput( true );

         connection.setDoInput( true );

         connection.setUseCaches( false ); //post不能使用缓存

         connection.setInstanceFollowRedirects( true );

         connection.setRequestProperty( "accept" , "*/*" );

         connection.setRequestProperty( "connection" , "Keep-Alive" );

         connection.setRequestProperty( "user-agent" , "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)" );

         OutputStreamWriter paramout = new OutputStreamWriter(  connection.getOutputStream(), "UTF-8" );

         String paramsStr = "" ;   //拼接Post 请求的参数

         for (String param : params.keySet()){

            paramsStr += "&" + param + "=" + params.get(param);

         } 

         if (!paramsStr.isEmpty()){

             paramsStr = paramsStr.substring( 1 );

         }

         paramout.write(paramsStr); 

         paramout.flush(); 

         BufferedReader reader = new BufferedReader( new InputStreamReader( 

                     connection.getInputStream(), "UTF-8" )); 

         String line;             

         while ((line = reader.readLine()) != null ) {         

             data.append(line);           

         }  

         paramout.close(); 

             reader.close(); 

         } catch (Exception e) { 

             // TODO Auto-generated catch block 

             e.printStackTrace(); 

         } 

        return data.toString();

}

@Override

    public void addCorsMappings(CorsRegistry registry) {

        registry.addMapping( "/**" )

                .allowedOrigins( "*" )  

                .allowedMethods( "GET" , "HEAD" , "POST" , "PUT" , "DELETE" , "OPTIONS" )

                .allowCredentials( true )

                .maxAge( 3600 )

                .allowedHeaders( "*" );  

    }

private CorsConfiguration corsConfig() {

    CorsConfiguration corsConfiguration = new CorsConfiguration();

    * 请求常用的三种配置，*代表允许所有，当时你也可以自定义属性（比如header只能带什么，只能是post方式等等）

    */

    corsConfiguration.addAllowedOrigin( "*" );

    corsConfiguration.addAllowedHeader( "*" );

    corsConfiguration.addAllowedMethod( "*" );

    corsConfiguration.setAllowCredentials( true );

    corsConfiguration.setMaxAge(3600L);

    return corsConfiguration;

}

@Bean

public CorsFilter corsFilter() {

    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();

    source.registerCorsConfiguration( "/**" , corsConfig());

    return new CorsFilter(source);

}