Clean up the execution mechanism of examples

Motivation:

- There's no way to pass an argument to an example.
- Assigning a Maven profile for each example is an overkill.
  It makes the pom.xml crowded.

Modifications:

- Remove example profiles from example/pom.xml
- Keep the list of examples in run-example.sh
- run-example.sh passes all options to exec-maven-plugin.
  For example, we can now do this:

    ./run-example.sh -Dssl -Dport=443 http-server

Result:

- It's much easier to add a new example and provide an easy way to
  launch it.
- We can still pass an arbitrary argument to the example being launched.
  (I'll update all examples to make them get their options from system
  properties rather than from args[].

example/pom.xml

@@ -105,34 +105,6 @@
     </dependency>
   </dependencies>
 
-  <profiles>
-    <profile>
-      <id>spdy-server</id>
-      <properties>
-        <exampleClass>io.netty.example.spdy.server.SpdyServer</exampleClass>
-      </properties>
-    </profile>
-    <profile>
-      <id>spdy-client</id>
-      <properties>
-        <exampleClass>io.netty.example.spdy.client.SpdyClient</exampleClass>
-      </properties>
-    </profile>
-
-    <profile>
-      <id>http2-server</id>
-      <properties>
-        <exampleClass>io.netty.example.http2.server.Http2Server</exampleClass>
-      </properties>
-    </profile>
-    <profile>
-      <id>http2-client</id>
-      <properties>
-        <exampleClass>io.netty.example.http2.client.Http2Client</exampleClass>
-      </properties>
-    </profile>
-  </profiles>
-
   <build>
     <plugins>
       <plugin>
@@ -146,6 +118,7 @@
             ${argLine.leak}
             ${argLine.coverage}
             -classpath %classpath
+            ${argLine.example}
             ${exampleClass}
           </commandlineArgs>
           <classpathScope>runtime</classpathScope>

run-example.sh

@@ -1,15 +1,44 @@
 #!/bin/bash -e
-cd "`dirname "$0"`"/example
-if [[ $# -ne 1 ]]; then
-  echo "Usage: $0 <example-name>" >&2
+declare -A EXAMPLE_MAP=(
+  ['spdy-server']='io.netty.example.spdy.server.SpdyServer'
+  ['spdy-client']='io.netty.example.spdy.client.SpdyClient'
+  ['http2-server']='io.netty.example.http2.server.Http2Server'
+  ['http2-client']='io.netty.example.http2.client.Http2Client'
+)
+
+EXAMPLE=''
+EXAMPLE_CLASS=''
+EXAMPLE_ARGS=''
+I=0
+
+while [[ $# -gt 0 ]]; do
+  ARG="$1"
+  shift
+  if [[ "$ARG" =~ (^-.+) ]]; then
+    if [[ -z "$EXAMPLE_ARGS" ]]; then
+      EXAMPLE_ARGS="$ARG"
+    else
+      EXAMPLE_ARGS="$EXAMPLE_ARGS $ARG"
+    fi
+  else
+    EXAMPLE="$ARG"
+    EXAMPLE_CLASS="${EXAMPLE_MAP["$EXAMPLE"]}"
+    break
+  fi
+done
+
+if [[ -z "$EXAMPLE" ]] || [[ -z "$EXAMPLE_CLASS" ]] || [[ $# -ne 0 ]]; then
+  echo "  Usage: $0 [-D<name>[=<value>] ...] <example-name>" >&2
+  echo "Example: $0 -Dport=8443 -Dssl http-server" >&2
   echo >&2
   echo "Available examples:" >&2
-  grep -E '^      <id>[-a-z0-9]*</id>' pom.xml | sed -e 's#\(^.*<id>\|</id>.*$\)##g' | sed -e 's#^#  #' >&2
+  for E in "${!EXAMPLE_MAP[@]}"; do
+    echo "  $E"
+  done | sort >&2
   exit 1
 fi
 
-EXAMPLE_NAME="$1"
-
-echo "[INFO] Running: $EXAMPLE_NAME"
-mvn -X -P "$EXAMPLE_NAME" compile exec:exec
+cd "`dirname "$0"`"/example
+echo "[INFO] Running: $EXAMPLE ($EXAMPLE_CLASS $EXAMPLE_ARGS)"
+exec mvn -nsu compile exec:exec -DargLine.example="$EXAMPLE_ARGS" -DexampleClass="$EXAMPLE_CLASS"