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| © Copyright 2015 Contributors. |
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| |
| <h1>AspectJ 1.8.7 Readme</h1> |
| |
| <p>The full list of resolved issues in 1.8.7 is available |
| <a href="https://bugs.eclipse.org/bugs/buglist.cgi?query_format=advanced;bug_status=RESOLVED;bug_status=VERIFIED;bug_status=CLOSED;product=AspectJ;target_milestone=1.8.7;">here</a></h2>.</p> |
| |
| <ul> |
| <li>1.8.7 available 9-Sep-2015 |
| </ul> |
| |
| |
| <h2>Notable changes</h2> |
| |
| <h3>ajdoc</h3> |
| <p>The ajdoc tool has been fixed! It is now working again if run on a 1.7 JDK.</p> |
| |
| <h3>Dynamic weaver attachment</h3> |
| <p>The AspectJ loadtime weaving agent can now be dynamically attached to a JVM after it has started |
| (you don't need to use -javaagent). This offers extra flexibility but obviously any |
| classes loaded before attachment will not be woven.</p> |
| |
| <p>Here is a simple aspect:</p> |
| <code><pre> |
| public aspect Azpect { |
| before(): execution(* *(..)) { |
| System.out.println(thisJoinPointStaticPart); |
| } |
| } |
| </pre></code> |
| |
| <p>Compiled via:</p> |
| |
| <code><pre>ajc -1.8 Azpect.java -outxml</pre></code> |
| |
| <p>This produces a compiled class <tt>Azpect.class</tt> and a file <tt>META-INF/aop-ajc.xml</tt>.</p> |
| |
| <p>I then have this sample application (same directory):</p> |
| |
| <code><pre> |
| import java.lang.management.ManagementFactory; |
| import org.aspectj.weaver.loadtime.Agent; |
| import com.sun.tools.attach.VirtualMachine; |
| |
| public class Application { |
| |
| public static void main(String[] args) { |
| if (!isAspectJAgentLoaded()) |
| System.err.println("WARNING: AspectJ weaving agent not loaded"); |
| new Sample().doSomething(); |
| } |
| |
| public static boolean isAspectJAgentLoaded() { |
| try { |
| Agent.getInstrumentation(); |
| } catch (NoClassDefFoundError e) { |
| System.out.println(e); |
| return false; |
| } catch (UnsupportedOperationException e) { |
| System.out.println(e); |
| return dynamicallyLoadAspectJAgent(); |
| } |
| return true; |
| } |
| |
| public static boolean dynamicallyLoadAspectJAgent() { |
| String nameOfRunningVM = ManagementFactory.getRuntimeMXBean().getName(); |
| int p = nameOfRunningVM.indexOf('@'); |
| String pid = nameOfRunningVM.substring(0, p); |
| try { |
| VirtualMachine vm = VirtualMachine.attach(pid); |
| String jarFilePath = System.getProperty("AGENT_PATH"); |
| vm.loadAgent(jarFilePath); |
| vm.detach(); |
| } catch (Exception e) { |
| System.out.println(e); |
| return false; |
| } |
| return true; |
| } |
| } |
| </pre></code> |
| |
| <p>And this Sample class:</p> |
| <code><pre> |
| public class Sample { |
| public void doSomething() { |
| System.out.println("Do something"); |
| System.out.println("Square of 7 = " + square(7)); |
| } |
| |
| private int square(int i) { |
| return i * i; |
| } |
| } |
| </pre></code> |
| |
| <p>Compile these with javac, <b>but you must have the aspectjweaver and the JDK tools.jar on your classpath</b>.</p> |
| |
| <p>Once compiled we can run it:</p> |
| |
| <code><pre>java -DAGENT_PATH=<path-to>/aspectjweaver.jar Application</pre></code> |
| |
| <p>What does it do? The main method calls the function that detects whether the agent is attached, if it is not then |
| it programmatically attaches it using the <tt>VirtualMachine</tt> class. Then the main method accesses the |
| Sample class. At this point in program execution the Sample class is loaded and because the agent has been |
| attached it gets woven. Notice that the <tt>Application</tt> class itself is not woven because it was loaded prior |
| to agent attachment.</p> |
| |
| <p>Thanks to Alexander Kriegisch for the sample code and the patch to add this behaviour to AspectJ.</p> |
| |
| |
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