blocks|key|903593|text|从URLConnection.getContentEncoding()返回的值返回来自头Content-Encoding的值|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|903594|来自URLConnection.getContentEncoding()的代码|903595|/**
+++++*+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");
++++}|code-block|syntax|javascript|903596|相反，应该执行一个connection.getContentType()来检索Content-Type并从Content-Type检索字符集。我已经包含了一个如何做到这一点的示例代码……|903597|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
}|903598|entityMap^0|1|Y|18|G|0|2|Y|0|0|9|R|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|R|$]]

The value returned from <code>URLConnection.getContentEncoding()</code> returns the value from header <code>Content-Encoding</code>

Code from <code>URLConnection.getContentEncoding()</code>

<pre><code>/**
 * Returns the value of the &lt;code&gt;content-encoding&lt;/code&gt; header field.
 *
 * @return the content encoding of the resource that the URL references,
 * or &lt;code&gt;null&lt;/code&gt; if not known.
 * @see java.net.URLConnection#getHeaderField(java.lang.String)
 */
 public String getContentEncoding() {
 return getHeaderField("content-encoding");
 }
</code></pre>

Instead, rather do a <code>connection.getContentType()</code> to retrieve the Content-Type and retrieve the charset from the Content-Type. I've included a sample code on how to do this....

<pre><code>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
}
</code></pre>

blocks|key|1118446|text|这是记录在案的行为，因为getContentEncoding()方法被指定为返回Content-Encoding+header的内容，而本例中没有对其进行设置。您可以使用getContentType()方法并自己解析结果字符串，也可以使用一个更像Apache的advanced+HTTP客户端库。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1118447|entityMap|0|LINK|mutability|MUTABLE|url|http://hc.apache.org/httpcomponents-client-ga/|1|http://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/org/apache/http/entity/ContentType.html#getCharset%2528%2529^0|C|K|14|G|2D|G|3F|6|0|3M|8|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@$9|W|A|X|1|Y]|$9|Z|A|10|1|11]]|E|$]]|$1|F|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]|N|$5|I|J|K|E|$L|O]]]]

This is documented behaviour as the <code>getContentEncoding()</code> method is specified to return the contents of the <code>Content-Encoding</code> HTTP header, which is not set in your example. You could use the <code>getContentType()</code> method and parse the resulting String on your own, or possibly go for a more <a href="http://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/org/apache/http/entity/ContentType.html#getCharset%28%29" rel="noreferrer">advanced</a> HTTP client library like the one from <a href="http://hc.apache.org/httpcomponents-client-ga/" rel="noreferrer">Apache</a>.

blocks|key|1118491|text|只是对@Buhake+Sindi的回答的补充。如果您使用的是Guava，则可以执行以下操作，而不是手动解析：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1118492|MediaType+mediaType+=+MediaType.parse(httpConnection.getContentType());
Optional<Charset>+typeCharset+=+mediaType.charset();|code-block|syntax|javascript|1118493|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Just as an addition to the answer from @Buhake Sindi. If you are using Guava, instead of the manual parsing you can do:

<pre><code>MediaType mediaType = MediaType.parse(httpConnection.getContentType());
Optional&lt;Charset&gt; typeCharset = mediaType.charset();
</code></pre>

I'm using <code>URL.openConnection()</code> to download something from a server. The server says

<pre><code>Content-Type: text/plain; charset=utf-8
</code></pre>

But <code>connection.getContentEncoding()</code> returns <code>null</code>. What up?

URLConnection does not get the charset

服务器

我正在使用URL.openConnection()从服务器上下载一些东西。服务器说Content-Type: text/plain; charset=utf-8但是connection.getContentEncoding()返回null。怎么了？

问URLConnection未获取字符集
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