Https下无法抓取只支持TLS1.2的站点 #701
Description
WebMagic默认的HttpClient只会用TLSv1去请求，对于某些只支持TLS1.2的站点（例如 https://juejin.im/） ，就会报错：
javax.net.ssl.SSLException: Received fatal alert: protocol_version
at sun.security.ssl.Alerts.getSSLException(Alerts.java:208)
at sun.security.ssl.Alerts.getSSLException(Alerts.java:154)
at sun.security.ssl.SSLSocketImpl.recvAlert(SSLSocketImpl.java:2023)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1125)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387)
at org.apache.http.conn.ssl.SSLConnectionSocketFactory.createLayeredSocket(SSLConnectionSocketFactory.java:394)
at org.apache.http.conn.ssl.SSLConnectionSocketFactory.connectSocket(SSLConnectionSocketFactory.java:353)
at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:141)
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:353)
at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:380)
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:236)
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)
at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)
at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
at us.codecraft.webmagic.downloader.HttpClientDownloader.download(HttpClientDownloader.java:85)
现在的修改方式是在HttpClientGenerator中构建SSLConnectionSocketFactory时加上支持。