HttpClient获取重定向后的url并对跳转中的url特殊字符做空格处理

本文链接：https://blog.youkuaiyun.com/weixin_47952625/article/details/115133215

这段代码展示了如何在HTTP客户端中重新实现重定向策略。它集成`DefaultRedirectStrategy`或实现`RedirectStrategy`接口，处理`location`头并检查是否允许相对和循环重定向。在处理过程中，对重定向URL进行校验和调整，确保其绝对化，并存储重定向历史以防止循环重定向。

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http示例代码

httpclient = HttpClients.custom().setConnectionManager(connectionManager).setDefaultRequestConfig(requestConfig).setRedirectStrategy(new **UrlHandlerRedirectStrategy**())

重新实现重定向策略

集成DefaultRedirectStrategy或者实现RedirectStrategy

public URI getLocationURI(
            final HttpRequest request,
            final HttpResponse response,
            final HttpContext context) throws ProtocolException {
        Args.notNull(request, "HTTP request");
        Args.notNull(response, "HTTP response");
        Args.notNull(context, "HTTP context");

        final HttpClientContext clientContext = HttpClientContext.adapt(context);

        //get the location header to find out where to redirect to
        final Header locationHeader = response.getFirstHeader("location");
        if (locationHeader == null) {
            // got a redirect response, but no location header
            throw new ProtocolException(
                    "Received redirect response " + response.getStatusLine()
                            + " but no location header");
        }
        // TODO 对地址中存在的空格做替换处理
        final String location = locationHeader.getValue().replaceAll(" ", "");
        if (this.log.isDebugEnabled()) {
            this.log.debug("Redirect requested to location '" + location + "'");
        }

        final RequestConfig config = clientContext.getRequestConfig();

        URI uri = createLocationURI(location);
        try {
            if (!uri.isAbsolute()) {
                if (!config.isRelativeRedirectsAllowed()) {
                    throw new ProtocolException("Relative redirect location '"
                            + uri + "' not allowed");
                }
                // Adjust location URI
                final HttpHost target = clientContext.getTargetHost();
                Asserts.notNull(target, "Target host");
                final URI requestURI = new URI(request.getRequestLine().getUri());
                final URI absoluteRequestURI = URIUtils.rewriteURI(requestURI, target, false);
                uri = URIUtils.resolve(absoluteRequestURI, uri);
            }
        } catch (final URISyntaxException ex) {
            throw new ProtocolException(ex.getMessage(), ex);
        }

        RedirectLocations redirectLocations = (RedirectLocations) clientContext.getAttribute(
                HttpClientContext.REDIRECT_LOCATIONS);
        if (redirectLocations == null) {
            redirectLocations = new RedirectLocations();
            context.setAttribute(HttpClientContext.REDIRECT_LOCATIONS, redirectLocations);
        }
        if (!config.isCircularRedirectsAllowed()) {
            if (redirectLocations.contains(uri)) {
                throw new CircularRedirectException("Circular redirect to '" + uri + "'");
            }
        }
        redirectLocations.add(uri);
        return uri;
    }