我们的业务代码里有需要用爬虫爬取商品的图片地址，然后在转到我们的服务器里的过程，中间当然少不了下载图片的过程，最近目标网站有些改变，就是之前http前缀的图片地址部分改成了https，然后就造成了一个问题，图片下载不了，查看log，发现一个java的SSLException.

异常是： java.lang.RuntimeException:Received fatal alert: protocol_version

异常的根源是：javax.net.ssl.SSLException:  Received fatal alert: protocol_version.

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原因是： https的请求需要加上ssl的验证，但是代码里一般只用到http，即使用到https也只是换了个前缀，并没有带上ssl验证的过程。

源代码：

private static final PoolingHttpClientConnectionManager HTTP_CLIENT_CONNECTION_MANAGER;

private static final CloseableHttpClient HTTP_CLIENT;

static {

HTTP_CLIENT_CONNECTION_MANAGER = new PoolingHttpClientConnectionManager(RegistryBuilder

. create().register("http", PlainConnectionSocketFactory.getSocketFactory())

.register("https", SSLConnectionSocketFactory.getSocketFactory()).build());

HTTP_CLIENT_CONNECTION_MANAGER.setDefaultMaxPerRoute(100);

HTTP_CLIENT_CONNECTION_MANAGER.setMaxTotal(200);

RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(60000).setConnectTimeout(60000)

.setSocketTimeout(60000).build();

HTTP_CLIENT = HttpClientBuilder.create().setConnectionManager(HTTP_CLIENT_CONNECTION_MANAGER)

.setDefaultRequestConfig(requestConfig).build();

}

HttpGet httpGet = new HttpGet(url + (StringUtils.contains(url, "?") ? "&" : "?")

+ EntityUtils.toString(new UrlEncodedFormEntity(nameValuePairs, "UTF-8")));

CloseableHttpResponse httpResponse = HTTP_CLIENT.execute(httpGet);

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解决方法：加上SSL的验证，加上协议

修改后可用的代码：

private static final PoolingHttpClientConnectionManager HTTP_CLIENT_CONNECTION_MANAGER;

private static final CloseableHttpClient HTTP_CLIENT;

static {

SSLContext ctx = SSLContexts.createSystemDefault();

SSLConnectionSocketFactory fac =

new SSLConnectionSocketFactory(ctx, new String[]{"SSLv2Hello", "TLSv1.2"}, null, SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);

HTTP_CLIENT_CONNECTION_MANAGER = new PoolingHttpClientConnectionManager(RegistryBuilder

. create().register("http", PlainConnectionSocketFactory.getSocketFactory())

.register("https", fac).build());

HTTP_CLIENT_CONNECTION_MANAGER.setDefaultMaxPerRoute(100);

HTTP_CLIENT_CONNECTION_MANAGER.setMaxTotal(200);

RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(60000).setConnectTimeout(60000)

.setSocketTimeout(60000).build();

HTTP_CLIENT = HttpClientBuilder.create().setConnectionManager(HTTP_CLIENT_CONNECTION_MANAGER)

.setDefaultRequestConfig(requestConfig).build();

}

HttpGet httpGet = new HttpGet(url + (StringUtils.contains(url, "?") ? "&" : "?")

+ EntityUtils.toString(new UrlEncodedFormEntity(nameValuePairs, "UTF-8")));

CloseableHttpResponse httpResponse = HTTP_CLIENT.execute(httpGet);

希望能帮到你。。。