add

spring-boot-agent/src/main/java/com/qianglu/agent/AgentStartup.java

+package com.qianglu.agent;
+
+
+import com.qianglu.agent.service.DumpClassesService;
+
+import java.lang.instrument.Instrumentation;
+
+/**
+ * @author qianglu
+ */
+public class AgentStartup {
+
+	public static void premain(String arg, Instrumentation instrumentation) {
+		System.err.println("agent startup , args is " + arg);
+		// 注册我们的文件下载函数
+		instrumentation.addTransformer(new DumpClassesService());	}
+}

spring-boot-agent/src/main/java/com/qianglu/agent/service/DumpClassesService.java

+package com.qianglu.agent.service;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.IllegalClassFormatException;
+import java.security.ProtectionDomain;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * 测试下载
+ *
+ * @author QIANGLU on 2019-08-15
+ */
+public class DumpClassesService implements ClassFileTransformer {
+
+    private static final List<String> SYSTEM_CLASS_PREFIX = Arrays.asList("java", "sum", "jdk");
+
+
+    @Override
+    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
+        if (!isSystemClass(className)) {
+            System.out.println("load class " + className);
+            FileOutputStream fos = null;
+            try {
+                // 将类名统一命名为classNamedump.class格式
+                fos = new FileOutputStream(className + "dump.class");
+                fos.write(classfileBuffer);
+                fos.flush();
+            } catch (IOException ioe) {
+                ioe.printStackTrace();
+            } finally {
+                // 关闭文件输出流
+                if (null != fos) {
+                    try {
+                        fos.close();
+                    } catch (IOException e) {
+                        e.printStackTrace();
+                    }
+                }
+            }
+        }
+        return classfileBuffer;
+    }
+
+    /**
+     * 判断一个类是否为系统类
+     *
+     * @param className 类名
+     * @return System Class then return true,else return false
+     */
+    private boolean isSystemClass(String className) {
+        // 假设系统类的类名不为NULL而且不为空
+        if (null == className || className.isEmpty()) {
+            return false;
+        }
+
+        for (String prefix : SYSTEM_CLASS_PREFIX) {
+            if (className.startsWith(prefix)) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
\ No newline at end of file