Difference between revisions of "JGridstart/Java user agents"
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It is possible to detect on the server-side something about the user's Java environment by inspecting the request headers that Java sends. There are differences when a connection is made from the Java program using [http://java.sun.com/javase/6/docs/api/java/net/URLConnection.html URLConnection], or when a [http://en.wikipedia.org/wiki/Java_web_start Java Web Start] application is being downloaded. | It is possible to detect on the server-side something about the user's Java environment by inspecting the request headers that Java sends. There are differences when a connection is made from the Java program using [http://java.sun.com/javase/6/docs/api/java/net/URLConnection.html URLConnection], or when a [http://en.wikipedia.org/wiki/Java_web_start Java Web Start] application is being downloaded. | ||
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| <tt>Java/1.6.0_0</tt> | | <tt>Java/1.6.0_0</tt> | ||
|} | |} | ||
| + | |||
| + | == Setting the user-agent from Java == | ||
| + | jGridstart sets the user-agent so that it can be recognised by the web server, including its version number. This is done by setting the system property <tt>[http://java.sun.com/j2se/1.4.2/docs/guide/net/properties.html#ncnt http.agent]</tt> (Java still appends something like <tt>Java/1.6.0_10</tt> to it). | ||
| + | |||
| + | There is a little problem with java web start. When the system property <tt>http.agent</tt> is set from within a java web start application, it is not actually used when a http connection is made. This can be remedied by either setting the property from the <tt>JNLP</tt> file, or by setting the request property <tt>User-Agent</tt> on the <tt>URLConnection</tt>. jGridstart uses this as a workaround: | ||
| + | <code> | ||
| + | static URLConnection URLopenConnection(URL url) throws IOException { | ||
| + | URLConnection conn = url.openConnection(); | ||
| + | if (conn instanceof HttpURLConnection) { | ||
| + | String agent = System.getProperty("http.agent") + | ||
| + | " Java/"+System.getProperty("java.version"); | ||
| + | if (agent != null) | ||
| + | ((HttpURLConnection)conn).setRequestProperty("User-Agent", agent); | ||
| + | } | ||
| + | return conn; | ||
| + | } | ||
| + | </code> | ||
| + | See also [http://www.noizeramp.com/article.php?article=se-networking_specifics_under_Java_Web_StartNetworking specifics under Java Web Start]. | ||
Latest revision as of 12:39, 29 March 2012
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</sidebar> It is possible to detect on the server-side something about the user's Java environment by inspecting the request headers that Java sends. There are differences when a connection is made from the Java program using URLConnection, or when a Java Web Start application is being downloaded.
Java Web Start
| Vendor | HTTP Header | |
|---|---|---|
| User-Agent | UA-Java-Version | |
| Sun | JNLP/1.5 javaws/1.5.0_19 (b02) J2SE/1.5.0_19 | 1.5.0_19 |
| Sun | JNLP/6.0 javaws/1.6.0_17 (b04) Java/1.6.0_17 | 1.6.0_17 |
| OpenJDK | Java/1.6.0_0 | (not supplied) |
URLConnection
| Vendor | HTTP header User-Agent |
|---|---|
| Sun | Java/1.5.0_19 |
| Sun | Java/1.6.0_17 |
| OpenJDK | Java/1.6.0_0 |
Setting the user-agent from Java
jGridstart sets the user-agent so that it can be recognised by the web server, including its version number. This is done by setting the system property http.agent (Java still appends something like Java/1.6.0_10 to it).
There is a little problem with java web start. When the system property http.agent is set from within a java web start application, it is not actually used when a http connection is made. This can be remedied by either setting the property from the JNLP file, or by setting the request property User-Agent on the URLConnection. jGridstart uses this as a workaround:
static URLConnection URLopenConnection(URL url) throws IOException {
URLConnection conn = url.openConnection();
if (conn instanceof HttpURLConnection) {
String agent = System.getProperty("http.agent") +
" Java/"+System.getProperty("java.version");
if (agent != null)
((HttpURLConnection)conn).setRequestProperty("User-Agent", agent);
}
return conn;
}
See also specifics under Java Web Start.
