[英]URLConnection does not get the charset
I'm using URL.openConnection()
to download something from a server. 我正在使用URL.openConnection()
从服务器下载内容。 The server says 服务器说
Content-Type: text/plain; charset=utf-8
But connection.getContentEncoding()
returns null
. 但是connection.getContentEncoding()
返回null
。 What up? 怎么了?
The value returned from URLConnection.getContentEncoding()
returns the value from header Content-Encoding
从URLConnection.getContentEncoding()
返回的值返回标头Content-Encoding
的值
Code from URLConnection.getContentEncoding()
来自URLConnection.getContentEncoding()
代码
/**
* 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. 相反,请执行connection.getContentType()
以检索Content-Type并从Content-Type检索charset。 I've included a sample code on how to do this.... 我已经包含了如何执行此操作的示例代码....
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
}
This is documented behaviour as the getContentEncoding()
method is specified to return the contents of the Content-Encoding
HTTP header, which is not set in your example. 这是记录的行为,因为指定了getContentEncoding()
方法以返回Content-Encoding
HTTP标头的内容,该标头未在您的示例中设置。 You could use the getContentType()
method and parse the resulting String on your own, or possibly go for a more advanced HTTP client library like the one from Apache . 您可以使用getContentType()
方法并自行解析生成的String,也可以使用Apache中更高级的 HTTP客户端库。
Just as an addition to the answer from @Buhake Sindi. 正如@Buhake Sindi的回答一样。 If you are using Guava, instead of the manual parsing you can do: 如果您使用的是Guava,而不是手动解析,您可以执行以下操作:
MediaType mediaType = MediaType.parse(httpConnection.getContentType());
Optional<Charset> typeCharset = mediaType.charset();
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