wu-sheng · January 17, 2018 03:09 · Dec 23, 2016 · Feb 29, 2016
diff --git a/BootstrapAgent.java b/BootstrapAgent.java
@@ -32,6 +32,7 @@ public static void premain(String arg, Instrumentation inst) throws Exception {
                 new TypeDescription.ForLoadedType(MyInterceptor.class),
                 ClassFileLocator.ForClassLoader.read(MyInterceptor.class).resolve()));
         new AgentBuilder.Default()
+                .ignore(ElementMatchers.nameStartsWith("net.bytebuddy."))
                 .enableBootstrapInjection(temp, inst)
                 .type(ElementMatchers.nameEndsWith(".HttpURLConnection"))
                 .transform(new AgentBuilder.Transformer() {

diff --git a/BootstrapAgent.java b/BootstrapAgent.java
@@ -0,0 +1,52 @@
+package net.bytebuddy;
+
+import net.bytebuddy.agent.ByteBuddyAgent;
+import net.bytebuddy.agent.builder.AgentBuilder;
+import net.bytebuddy.description.type.TypeDescription;
+import net.bytebuddy.dynamic.ClassFileLocator;
+import net.bytebuddy.dynamic.DynamicType;
+import net.bytebuddy.dynamic.loading.ClassInjector;
+import net.bytebuddy.implementation.MethodDelegation;
+import net.bytebuddy.implementation.bind.annotation.SuperCall;
+import net.bytebuddy.matcher.ElementMatchers;
+
+import java.io.File;
+import java.lang.instrument.Instrumentation;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.nio.file.Files;
+import java.util.Collections;
+import java.util.concurrent.Callable;
+
+public class BootstrapAgent {
+
+    public static void main(String[] args) throws Exception {
+        premain(null, ByteBuddyAgent.install());
+        HttpURLConnection urlConnection = (HttpURLConnection) new URL("http://www.google.com").openConnection();
+        System.out.println(urlConnection.getRequestMethod());
+    }
+
+    public static void premain(String arg, Instrumentation inst) throws Exception {
+        File temp = Files.createTempDirectory("tmp").toFile();
+        ClassInjector.UsingInstrumentation.of(temp, ClassInjector.UsingInstrumentation.Target.BOOTSTRAP, inst).inject(Collections.singletonMap(
+                new TypeDescription.ForLoadedType(MyInterceptor.class),
+                ClassFileLocator.ForClassLoader.read(MyInterceptor.class).resolve()));
+        new AgentBuilder.Default()
+                .enableBootstrapInjection(temp, inst)
+                .type(ElementMatchers.nameEndsWith(".HttpURLConnection"))
+                .transform(new AgentBuilder.Transformer() {
+                    @Override
+                    public DynamicType.Builder<?> transform(DynamicType.Builder<?> builder, TypeDescription typeDescription, ClassLoader classLoader) {
+                        return builder.method(ElementMatchers.named("getRequestMethod")).intercept(MethodDelegation.to(MyInterceptor.class));
+                    }
+                }).installOn(inst);
+    }
+
+    public static class MyInterceptor {
+
+        public static String intercept(@SuperCall Callable<String> zuper) throws Exception {
+            System.out.println("Intercepted!");
+            return zuper.call();
+        }
+    }
+}