根据本教程，我尝试让 java 代理工作。 https://www.baeldung.com/java-instrumentation#loading-a-java-agent
我确实知道[Agent] Transforming class TestApplication
我没有错误，但我看不到转换类的任何效果。
最终我想让静态负载和动态负载都工作，但现在我专注于静态方式。
public class Static_Agent {
public static void premain(String agentArgs, Instrumentation inst) {
String[] tokens = agentArgs.split(";");
String className = tokens[0];
String methodName = tokens[1];
System.out.println(">> "+className);
System.out.println(">> "+methodName);
transformClass(className, methodName, inst);
}
public static void transformClass(String className, String methodName, Instrumentation instrumentation) {
Class<?> targetCls = null;
ClassLoader targetClassLoader = null;
// see if we can get the class using forName
try {
targetCls = Class.forName(className);
targetClassLoader = targetCls.getClassLoader();
transform(targetCls, methodName, targetClassLoader, instrumentation);
return;
} catch (Exception ex) {
ex.printStackTrace();
}
// otherwise iterate all loaded classes and find what we want
for(Class<?> clazz: instrumentation.getAllLoadedClasses()) {
if(clazz.getName().equals(className)) {
targetCls = clazz;
targetClassLoader = targetCls.getClassLoader();
transform(targetCls, methodName, targetClassLoader, instrumentation);
return;
}
}
throw new RuntimeException("Failed to find class [" + className + "]");
}
public static void transform(Class<?> clazz, String methodName, ClassLoader classLoader, Instrumentation instrumentation) {
Transformer dt = new Transformer(clazz.getName(), methodName, classLoader);
instrumentation.addTransformer(dt, true);
try {
instrumentation.retransformClasses(clazz);
} catch (Exception ex) {
throw new RuntimeException("Transform failed for class: [" + clazz.getName() + "]", ex);
}
}
}
public class Transformer implements ClassFileTransformer {
/** The internal form class name of the class to transform */
private String targetClassName;
/** The class loader of the class we want to transform */
private ClassLoader targetClassLoader;
private String targetMethodName;
public Transformer(String targetClassName, String targetMethodName, ClassLoader targetClassLoader) {
this.targetClassName = targetClassName;
this.targetClassLoader = targetClassLoader;
this.targetMethodName = targetMethodName;
}
@Override
public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
byte[] byteCode = classfileBuffer;
String finalTargetClassName = this.targetClassName.replaceAll("\\.", "/");
if (!className.equals(finalTargetClassName)) {
return byteCode;
}
if (className.equals(finalTargetClassName) && loader.equals(targetClassLoader)) {
System.out.println("[Agent] Transforming class TestApplication");
try {
ClassPool cp = ClassPool.getDefault();
CtClass cc = cp.get(targetClassName);
CtMethod m = cc.getDeclaredMethod(targetMethodName);
m.addLocalVariable("startTime", CtClass.longType);
m.insertBefore("startTime = System.currentTimeMillis();");
StringBuilder endBlock = new StringBuilder();
m.addLocalVariable("endTime", CtClass.longType);
m.addLocalVariable("opTime", CtClass.longType);
endBlock.append("endTime = System.currentTimeMillis();");
endBlock.append("opTime = (endTime-startTime)/1000;");
endBlock.append("System.out.println(\"[Application] Withdrawal operation completed in:\" + opTime + \" seconds!\");");
m.insertAfter(endBlock.toString());
byteCode = cc.toBytecode();
cc.detach();
} catch (Exception e) {
System.out.println("Exception"+e);
}
}
return byteCode;
}
}
public class TestApplication {
public static void main(String[] args) {
try {
TestApplication.run();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void run() throws Exception {
System.out.println("--- start ---");
while (true) {
test();
Thread.sleep(4_000);
}
}
static int count = 0;
public static void test() {
System.out.println(count++);
}
}
我启动：
java -javaagent:static_agent.jar="doeke.application.TestApplication;test" -jar application.jar
如果有帮助，该项目在这里： https ://github.com/clankill3r/java_agent
编辑：
在我现在使用的文件末尾附近的 Transformer.java 中e.printStackTrace();。
我收到以下错误：
[代理] 转换类 TestApplication javassist.NotFoundException: doeke.application.TestApplication at javassist.ClassPool.get(ClassPool.java:436) at doeke.transformer.Transformer.transform(Transformer.java:48) at java.instrument/java。 lang.instrument.ClassFileTransformer.transform(ClassFileTransformer.java:246) 在 java.instrument/sun.instrument.TransformerManager.transform(TransformerManager.java:188) 在 java.instrument/sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java: 563) 在 java.instrument/sun.instrument.InstrumentationImpl.retransformClasses0(Native Method) 在 java.instrument/sun.instrument.InstrumentationImpl.retransformClasses(InstrumentationImpl.java:167) 在 doeke.static_agent.Static_Agent.transform(Static_Agent.java: 56) 在 doeke.static_agent.Static_Agent。在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 在 java.base/jdk.internal 的 doeke.static_agent.Static_Agent.premain(Static_Agent.java:22) 的 transformClass(Static_Agent.java:34)。 reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/java.lang.reflect.Method.invoke(Method. java:566) 在 java.instrument/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:513) 在 java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:525)在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/jdk.internal.reflect.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 的 invoke0(Native Method)。 base/java.lang.reflect.Method.invoke(Method.java:566) at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:513) at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain( InstrumentationImpl.java:525)在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 的 invoke0(Native Method)。 base/java.lang.reflect.Method.invoke(Method.java:566) at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:513) at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain( InstrumentationImpl.java:525)仪器/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:513) 在 java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:525)仪器/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:513) 在 java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:525)
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