AOPSameClass.java

package test.asm.aop;

import java.io.File;
import java.io.FileOutputStream;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

public class AOPSameClass {

	public static void main() throws Exception {
		ClassReader cr = new ClassReader("Account");
		ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
		ClassVisitor classAdapter = new AddSecurityCheckClassAdapter(cw);
		cr.accept(classAdapter, ClassReader.SKIP_DEBUG);
		byte[] data = cw.toByteArray();
		File file = new File("Account.class");
		FileOutputStream fout = new FileOutputStream(file);
		fout.write(data);
		fout.close();
	}

	static class AddSecurityCheckMethodAdapter extends MethodVisitor {
		public AddSecurityCheckMethodAdapter(MethodVisitor mv) {
			super(Opcodes.ASM4, mv);
		}

		public void visitCode() {
			visitMethodInsn(Opcodes.INVOKESTATIC, "SecurityChecker", "checkSecurity", "()V");
		}
	}

	static class AddSecurityCheckClassAdapter extends ClassVisitor {

		public AddSecurityCheckClassAdapter(ClassVisitor cv) {
			// Responsechain 的下一个 ClassVisitor，这里我们将传入 ClassWriter，
			// 负责改写后代码的输出
			super(Opcodes.ASM4, cv);
		}

		// 重写 visitMethod，访问到 "operation" 方法时，
		// 给出自定义 MethodVisitor，实际改写方法内容
		public MethodVisitor visitMethod(final int access, final String name, final String desc,
				final String signature, final String[] exceptions) {
			MethodVisitor mv = cv.visitMethod(access, name, desc, signature, exceptions);
			MethodVisitor wrappedMv = mv;
			if (mv != null) {
				// 对于 "operation" 方法
				if (name.equals("operation")) {
					// 使用自定义 MethodVisitor，实际改写方法内容
					wrappedMv = new AddSecurityCheckMethodAdapter(mv);
				}
			}
			return wrappedMv;
		}
	}

}