java URLConnection 没有得到字符集
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/3934251/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
URLConnection does not get the charset
提问by Bart van Heukelom
I'm using URL.openConnection()to download something from a server. The server says
我正在使用URL.openConnection()从服务器下载一些东西。服务员说
Content-Type: text/plain; charset=utf-8
But connection.getContentEncoding()returns null. What up?
但connection.getContentEncoding()返回null。怎么了？
采纳答案by Waldheinz
This is documented behaviour as the getContentEncoding()method is specified to return the contents of the Content-EncodingHTTP header, which is not set in your example. You could use the getContentType()method and parse the resulting String on your own, or possibly go for a more advancedHTTP client library like the one from Apache.
这是记录在案的行为，因为该getContentEncoding()方法被指定为返回Content-EncodingHTTP 标头的内容，这在您的示例中未设置。您可以使用该getContentType()方法并自行解析生成的 String，或者可能使用更高级的HTTP 客户端库，例如来自Apache 的库。
回答by Buhake Sindi
The value returned from URLConnection.getContentEncoding()returns the value from header Content-Encoding
从返回的值URLConnection.getContentEncoding()返回从报头中的值Content-Encoding
Code from URLConnection.getContentEncoding()
代码来自 URLConnection.getContentEncoding()
/**
* Returns the value of the <code>content-encoding</code> header field.
*
* @return the content encoding of the resource that the URL references,
* or <code>null</code> if not known.
* @see java.net.URLConnection#getHeaderField(java.lang.String)
*/
public String getContentEncoding() {
return getHeaderField("content-encoding");
}
Instead, rather do a connection.getContentType()to retrieve the Content-Type and retrieve the charset from the Content-Type. I've included a sample code on how to do this....
相反，而是执行 aconnection.getContentType()来检索 Content-Type 并从 Content-Type 中检索字符集。我已经包含了一个关于如何做到这一点的示例代码......
String contentType = connection.getContentType();
String[] values = contentType.split(";"); // values.length should be 2
String charset = "";
for (String value : values) {
value = value.trim();
if (value.toLowerCase().startsWith("charset=")) {
charset = value.substring("charset=".length());
}
}
if ("".equals(charset)) {
charset = "UTF-8"; //Assumption
}
回答by Juan M. Rivero
Just as an addition to the answer from @Buhake Sindi. If you are using Guava, instead of the manual parsing you can do:
就像对@Buhake Sindi 的回答的补充一样。如果您使用的是 Guava，您可以执行以下操作，而不是手动解析：
MediaType mediaType = MediaType.parse(httpConnection.getContentType());
Optional<Charset> typeCharset = mediaType.charset();
