HttpURLConnection 实现代理。

public class ForwardProxyController extends AbstractController {
    private String sourceContextPath;
    private String targetContextHostUrl;

    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws IOException {
        Logger.info(this, "request : " + request.getPathInfo());
        try {
            HttpURLConnection connection = parse(request);
            response.setContentType(connection.getHeaderField("Content-Type"));
            IOUtils.copy(connection.getInputStream(), response.getOutputStream());
        }catch (Exception e) {
            response.getOutputStream().write("".getBytes());
        }

        return null;
    }

    private HttpURLConnection parse(HttpServletRequest request) throws IOException {
        Logger.info(this, "request : " + request.getRequestURI());
        String requestString = request.getRequestURI().replace(sourceContextPath, "");
        String queryString = request.getQueryString();
        String uri = targetContextHostUrl + requestString;
        if(StringUtils.isNotBlank(queryString)){
            uri = uri + "?" + queryString;
        }

        Logger.info(this, "target uri : " + uri);
        HttpURLConnection connection =  (HttpURLConnection) new URL(uri).openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod(request.getMethod());
        connection.setRequestProperty("Content-type", request.getContentType());
        connection.setRequestProperty("contentType", "utf-8");

        IOUtils.copy(request.getInputStream(), connection.getOutputStream());

        return connection;
    }
}

<bean id="reverseProxyController" class="com.lufax.operation.gw.ForwardProxyController" >
        <property name="sourceContextPath" value="${OPERATION_GW_CONTENT_PATH}" />
        <property name="targetContextHostUrl" value="${OPERATION_APP_HOST_URL}${OPERATION_APP_CONTENT_PATH}" />
    </bean>

    <bean id="forwardProxyController" class="com.lufax.operation.gw.ForwardProxyController" >
        <property name="sourceContextPath" value="${OPERATION_GW_CONTENT_PATH}" />
        <property name="targetContextHostUrl" value="${B_SYSTEM_HOST_URL}" />
    </bean>

    <bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
        <property name="mappings">
            <value>
                /bsfront/**=forwardProxyController
                /service/**=reverseProxyController
            </value>
        </property>
        <property name="order" value="10000" />
    </bean>

web.xml

    <servlet>
        <servlet-name>dynamic-velocity</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/operation-gw-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>


    <servlet-mapping>
        <servlet-name>dynamic-velocity</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>