The stream: component provides access to the
System.in, System.out and
System.err streams as well as allowing streaming of file and
URL.
stream:in[?options] stream:out[?options] stream:err[?options] stream:header[?options]
In addition, the file and
url endpoint URIs are supported in Apache Camel 2.0:
stream:file?fileName=/foo/bar.txt stream:url[?options]
If the stream:header URI is specified, the
stream header is used to find the stream to write to. This option
is available only for stream producers (that is, it cannot appear in
from()).
You can append query options to the URI in the following format,
?option=value&option=value&...
| Name | Default Value | Description |
|---|---|---|
delay
|
0
|
Initial delay in milliseconds before consuming or producing the stream. |
encoding
|
JVM Default | As of 1.4, you can configure the encoding (is a charset name) to use text-based streams (for example, message body
is a String object). If not provided, Apache Camel uses the JVM default Charset. |
promptMessage
|
null
|
Apache Camel 2.0: Message
prompt to use when reading from
stream:in; for example, you could set
this to Enter a command:
|
promptDelay
|
0
|
Apache Camel 2.0: Optional delay in milliseconds before showing the message prompt. |
initialPromptDelay
|
2000
|
Apache Camel 2.0: Initial delay in milliseconds before showing the message prompt. This delay occurs only once. Can be used during system startup to avoid message prompts being written while other logging is done to the system out. |
fileName
|
null
|
Apache Camel 2.0: When
using the stream:file URI format, this
option specifies the filename to stream to/from. |
scanStream
|
false
|
Apache Camel
2.0: To be used for continuously reading
a stream such as the unix |
retry
|
false
|
Apache Camel 2.7: will
retry opening the file if it's overwritten, somewhat like
tail --retry
|
scanStreamDelay
|
0
|
Apache Camel 2.0: Delay in
milliseconds between read attempts when using
scanStream. |
groupLines
|
0
|
Apache Camel 2.5: To group X number of lines in the consumer. For example to group 10 lines and therefore only spit out an Exchange with 10 lines, instead of 1 Exchange per line. |
The stream: component supports either
String or byte[] for writing to streams. Just
add either String or byte[] content to the
message.in.body. The special stream:header URI
is used for custom output streams. Just add a java.io.OutputStream
object to message.in.header in the key header. See
samples for an example.
In the following sample we route messages from the direct:in
endpoint to the System.out stream:
@Test
public void testStringContent() throws Exception {
template.sendBody("direct:in", "Hello Text World\n");
}
@Test
public void testBinaryContent() {
template.sendBody("direct:in", "Hello Bytes World\n".getBytes());
}
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
public void configure() {
from("direct:in").to("stream:out");
}
};
}The following sample demonstrates how the header type can be used to determine which
stream to use. In the sample we use our own output stream,
MyOutputStream.
private OutputStream mystream = new MyOutputStream();
private StringBuffer sb = new StringBuffer();
@Test
public void testStringContent() {
template.sendBody("direct:in", "Hello");
// StreamProducer appends \n in text mode
assertEquals("Hello\n", sb.toString());
}
@Test
public void testBinaryContent() {
template.sendBody("direct:in", "Hello".getBytes());
// StreamProducer is in binary mode so no \n is appended
assertEquals("Hello", sb.toString());
}
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
public void configure() {
from("direct:in").setHeader("stream", constant(mystream)).
to("stream:header");
}
};
}
private class MyOutputStream extends OutputStream {
public void write(int b) throws IOException {
sb.append((char)b);
}
}The following sample demonstrates how to continuously read a file stream (analogous to
the UNIX tail command):
from("stream:file?fileName=/server/logs/server.log&scanStream=true&scanStreamDelay=1000").to("bean:logService?method=parseLogLine");![]() | Note |
|---|---|
One difficulty with using the combination of |