org.objectweb.asm.ClassAdapter Java Examples

The following examples show how to use org.objectweb.asm.ClassAdapter. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. You may check out the related API usage on the sidebar.
Example #1
Source File: AsmTest.java    From java-master with Apache License 2.0 5 votes vote down vote up 
@Test
public void ModifyClassTest() throws Exception {
    // 读取的Person类的class文件
    ClassReader classReader = new ClassReader("org.javamaster.b2c.bytecode.model.Person");
    ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);
    ClassAdapter classAdapter = new ClassAdapter(classWriter);
    classReader.accept(classAdapter, ClassReader.SKIP_DEBUG);

    // 插入新方法
    // Opcodes.ACC_PUBLIC:方法修饰符为public
    // sayHello:方法名为sayHello
    // ()V:没有入参,返回类型为void
    // new String[]{"javax.validation.ValidationException"}:声明抛出ValidationException异常
    MethodVisitor helloVisitor = classWriter
            .visitMethod(Opcodes.ACC_PUBLIC, "sayHello", "()V", null, new String[]{"javax.validation.ValidationException"});
    // 插入方法体内容,以下涉及到了虚拟机字节码指令
    helloVisitor.visitCode();
    // getstatic 指令:取静态字段
    helloVisitor.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
    // ldc 指令:取"hello world!"常量到操作数栈
    helloVisitor.visitLdcInsn("hello world!");
    // invokevirtual 指令: 调用实例方法println
    helloVisitor.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V");
    // return 指令: 从当前方法返回void
    helloVisitor.visitInsn(Opcodes.RETURN);
    helloVisitor.visitMaxs(1, 1);
    helloVisitor.visitEnd();

    byte[] bytes = classWriter.toByteArray();

    String path = ResourceUtils.getFile("classpath:").getAbsolutePath();
    File file = new File(path, "/org/javamaster/b2c/bytecode/PersonModify.class");
    FileOutputStream fileOutputStream = new FileOutputStream(file);
    fileOutputStream.write(bytes);
    fileOutputStream.close();
}
Example #2
Source File: ClassPatcher.java    From knopflerfish.org with BSD 3-Clause "New" or "Revised" License 5 votes vote down vote up 
public byte[] patch(String className, byte[] classBytes) {

    if(wrappers.size() == 0) {
      return classBytes;
    }

    matchProps.put(PROP_CLASSNAME, className);

    if(patchesFilter != null) {
      boolean b = patchesFilter.match(matchProps);
      
      if(!b) {
        return classBytes;
      }
    }

    try {
      ClassReader  cr    = new ClassReader(classBytes);
      ClassWriter  cw    = new BundleClassWriter(ClassWriter.COMPUTE_MAXS,
                                                 patchedBundle.adapt(BundleWiring.class).getClassLoader());
      ClassAdapter trans = new ClassAdapterPatcher(cw,
                                                   className.replace('.', '/'),
                                                   patchedBundle.adapt(BundleWiring.class).getClassLoader(),
                                                   patchedBundle.getBundleId(),
                                                   this);

      cr.accept(trans, 0);

      byte[] newBytes = cw.toByteArray();

      if(bDumpClasses) {
        dumpClassBytes(className, newBytes);
      }
      classBytes = newBytes;
    } catch (Exception e) {
      throw new RuntimeException("Failed to patch " + className + "/"
                                 + patchedBundle.adapt(BundleWiring.class).getClassLoader() +": " +e);
    }
    return classBytes;
  }
Example #3
Source File: ASMPerfTest.java    From annotation-tools with MIT License 5 votes vote down vote up 
byte[] nullAdaptClass(final InputStream is, final String name)
        throws Exception
{
    ClassReader cr = new ClassReader(is);
    ClassWriter cw = new ClassWriter(compute);
    ClassAdapter ca = new ClassAdapter(cw);
    cr.accept(ca, skipDebug);
    return cw.toByteArray();
}
Example #4
Source File: ASMPerfTest.java    From annotation-tools with MIT License 5 votes vote down vote up 
byte[] counterAdaptClass(final InputStream is, final String name)
        throws Exception
{
    ClassReader cr = new ClassReader(is);
    ClassWriter cw = new ClassWriter(false);
    ClassAdapter ca = new CounterClassAdapter(cw);
    cr.accept(ca, false);
    return cw.toByteArray();
}