init

javaagent/pom.xml

@@ -0,0 +1,80 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+
+	<groupId>org.kreyssel.tools.loggingagent</groupId>
+	<artifactId>loggingagent</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<name>Java Instrument API Example</name>
+	<description>
+		Example of how to use the Java Instrument API (Java Agent) to add own logging capabilities.
+
+		http://download.oracle.com/javase/6/docs/api/java/lang/instrument/package-summary.html
+	</description>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<version>2.3.2</version>
+				<configuration>
+					<source>1.5</source>
+					<target>1.5</target>
+				</configuration>
+			</plugin>
+
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-jar-plugin</artifactId>
+				<version>2.3.1</version>
+				<configuration>
+					<archive>
+						<manifestFile>src/main/resources/META-INF/MANIFEST.MF</manifestFile>
+					</archive>
+				</configuration>
+			</plugin>
+
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-assembly-plugin</artifactId>
+				<version>2.2</version>
+				<executions>
+					<execution>
+						<goals>
+							<goal>attached</goal>
+						</goals>
+						<phase>package</phase>
+					</execution>
+				</executions>
+				<configuration>
+					<descriptors>
+						<descriptor>src/main/assembly/package.xml</descriptor>
+					</descriptors>
+					<archive>
+						<manifestFile>src/main/resources/META-INF/MANIFEST.MF</manifestFile>
+					</archive>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+	<dependencies>
+		<!-- used to modify classes at runtime -->
+		<dependency>
+			<groupId>javassist</groupId>
+			<artifactId>javassist</artifactId>
+			<version>3.12.1.GA</version>
+		</dependency>
+
+		<!-- only for using org.slf4j.instrumentation.JavassistHelper class -->
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>slf4j-ext</artifactId>
+			<version>1.6.1</version>
+		</dependency>
+	</dependencies>
+</project>

javaagent/src/main/assembly/package.xml

@@ -0,0 +1,40 @@
+<!-- 
+	Pack a full jar inclusive javassist and slf4j classes.
+ -->
+<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 http://maven.apache.org/xsd/assembly-1.1.0.xsd">
+
+	<id>jar-with-dependencies</id>
+
+	<formats>
+		<format>jar</format>
+	</formats>
+
+	<includeBaseDirectory>false</includeBaseDirectory>
+
+	<dependencySets>
+		<dependencySet>
+			<outputDirectory>/</outputDirectory>
+			<useProjectArtifact>true</useProjectArtifact>
+			<useStrictFiltering>true</useStrictFiltering>
+			<unpack>true</unpack>
+			<includes>
+				<include>org.kreyssel.tools.loggingagent:*</include>
+				<include>javassist:javassist</include>
+			</includes>			
+		</dependencySet>
+		<dependencySet>
+			<outputDirectory>/</outputDirectory>
+			<unpack>true</unpack>
+			<includes>
+				<include>org.slf4j:slf4j-ext</include>
+			</includes>
+			<unpackOptions>
+				<includes>
+					<include>org/slf4j/instrumentation/JavassistHelper.class</include>
+					<include>org/slf4j/instrumentation/ToStringHelper.class</include>
+				</includes>
+			</unpackOptions>	
+		</dependencySet>
+	</dependencySets>
+</assembly>

javaagent/src/main/java/org/kreyssel/tools/loggingagent/LoggerAgent.java

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+package org.kreyssel.tools.loggingagent;
+
+import javassist.CannotCompileException;
+import javassist.ClassPool;
+import javassist.CtBehavior;
+import javassist.CtClass;
+import javassist.CtField;
+import javassist.NotFoundException;
+
+import org.slf4j.instrumentation.JavassistHelper;
+
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.Instrumentation;
+
+
+/**
+ * LoggerAgent add java.util.logging statements to classes at runtime using 
+ * <a href="http://www.javassist.org/">javassist</a>.
+ *  
+ * <p>inspired by http://today.java.net/article/2008/04/22/add-logging-class-load-time-java-instrumentation</p>
+ */
+public class LoggerAgent implements ClassFileTransformer {
+
+    /** classes to always not to instrument */
+    static final String[] DEFAULT_EXCLUDES = new String[] {"com/sun/", "sun/", "java/", "javax/", "org/slf4j" };
+
+    /** only this classes should instrument or leave empty to instrument all classes that not excluded */
+    static final String[] INCLUDES = new String[] {
+           // "org/bouncycastle/crypto/encodings/", "org/bouncycastle/jce/provider/JCERSACipher"
+        };
+
+    /** the jul logger definition */
+    static final String def = "private static java.util.logging.Logger _log;";
+
+    /** the jul logging if statement  */
+    static final String ifLog = "if (_log.isLoggable(java.util.logging.Level.INFO))";
+
+    /**
+     * add agent
+     */
+    public static void premain( final String agentArgument, final Instrumentation instrumentation ) {
+        instrumentation.addTransformer( new LoggerAgent() );
+    }
+
+    /**
+     * instrument class
+     */
+    public byte[] transform( final ClassLoader loader, final String className, final Class clazz,
+        final java.security.ProtectionDomain domain, final byte[] bytes ) {
+
+        for( String include : INCLUDES ) {
+
+            if( className.startsWith( include ) ) {
+                return doClass( className, clazz, bytes );
+            }
+        }
+
+        for( int i = 0; i < DEFAULT_EXCLUDES.length; i++ ) {
+
+            if( className.startsWith( DEFAULT_EXCLUDES[i] ) ) {
+                return bytes;
+            }
+        }
+
+        return doClass( className, clazz, bytes );
+    }
+
+    /**
+     * instrument class with javasisst
+     */
+    private byte[] doClass( final String name, final Class clazz, byte[] b ) {
+        ClassPool pool = ClassPool.getDefault();
+        CtClass cl = null;
+
+        try {
+            cl = pool.makeClass( new java.io.ByteArrayInputStream( b ) );
+
+            if( cl.isInterface() == false ) {
+
+                CtField field = CtField.make( def, cl );
+                String getLogger = "java.util.logging.Logger.getLogger(" + name.replace( '/', '.' ) +
+                    ".class.getName());";
+                cl.addField( field, getLogger );
+
+                CtBehavior[] methods = cl.getDeclaredBehaviors();
+
+                for( int i = 0; i < methods.length; i++ ) {
+
+                    if( methods[i].isEmpty() == false ) {
+                        doMethod( methods[i] );
+                    }
+                }
+
+                b = cl.toBytecode();
+            }
+        } catch( Exception e ) {
+            System.err.println( "Could not instrument  " + name + ",  exception : " + e.getMessage() );
+        } finally {
+
+            if( cl != null ) {
+                cl.detach();
+            }
+        }
+
+        return b;
+    }
+
+    /**
+     * modify code and add log statements
+     */
+    private void doMethod( final CtBehavior method ) throws NotFoundException, CannotCompileException {
+
+        String signature = JavassistHelper.getSignature( method );
+        String returnValue = JavassistHelper.returnValue( method );
+
+        method.insertBefore( ifLog + "_log.info(\">> " + signature + "\");" );
+
+        method.insertAfter( ifLog + "_log.info(\"<< " + signature + returnValue + "\");" );
+    }
+}

javaagent/src/main/resources/META-INF/MANIFEST.MF

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+Premain-Class: org.kreyssel.tools.loggingagent.LoggerAgent