Examples of org.objectweb.asm.commons.GeneratorAdapter

org.objectweb.asm.commons.GeneratorAdapter

A {@link org.objectweb.asm.MethodVisitor} with convenient methods to generatecode. For example, using this adapter, the class below

 public class Example { public static void main(String[] args) { System.out.println("Hello world!"); } }

can be generated as follows:

 ClassWriter cw = new ClassWriter(true); cw.visit(V1_1, ACC_PUBLIC, "Example", null, "java/lang/Object", null); Method m = Method.getMethod("void <init> ()"); GeneratorAdapter mg = new GeneratorAdapter(ACC_PUBLIC, m, null, null, cw); mg.loadThis(); mg.invokeConstructor(Type.getType(Object.class), m); mg.returnValue(); mg.endMethod(); m = Method.getMethod("void main (String[])"); mg = new GeneratorAdapter(ACC_PUBLIC + ACC_STATIC, m, null, null, cw); mg.getStatic(Type.getType(System.class), "out", Type.getType(PrintStream.class)); mg.push("Hello world!"); mg.invokeVirtual(Type.getType(PrintStream.class), Method.getMethod("void println (String)")); mg.returnValue(); mg.endMethod(); cw.visitEnd();

@author Juozas Baliuka @author Chris Nokleberg @author Eric Bruneton @author Prashant Deva

    }
    MethodVisitor mv;
    mv = cv.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
    if (mv != null) {
      Method m = Method.getMethod("void <init>()");
      GeneratorAdapter ga = new GeneratorAdapter(ACC_PUBLIC, m, mv);
      ga.visitCode();
      ga.loadThis();
      ga.invokeConstructor(Type.getType("Ljava/lang/Object;"), m);
      ga.returnValue();
      ga.endMethod();
    }
    mv = cv.visitMethod(ACC_PUBLIC, "getF", "()I", null, null);
    if (mv != null) {
      Type bean = Type.getType("Lpkg/Bean;");
      Method m = Method.getMethod("int getF()");
      GeneratorAdapter ga = new GeneratorAdapter(ACC_PUBLIC, m, mv);
      ga.visitCode();
      ga.loadThis();
      ga.getField(bean, "f", Type.INT_TYPE);
      ga.returnValue();
      ga.endMethod();
    }
    mv = cv.visitMethod(ACC_PUBLIC, "setF", "(I)V", null, null);
    if (mv != null) {
      Type bean = Type.getType("Lpkg/Bean;");
      Method m = Method.getMethod("void setF(int)");
      GeneratorAdapter ga = new GeneratorAdapter(ACC_PUBLIC, m, mv);
      ga.visitCode();
      ga.loadThis();
      ga.loadArg(0);
      ga.putField(bean, "f", Type.INT_TYPE);
      ga.returnValue();
      ga.endMethod();
    }
    mv = cv.visitMethod(ACC_PUBLIC, "checkAndSetF", "(I)V", null, null);
    if (mv != null) {
      Type bean = Type.getType("Lpkg/Bean;");
      Method m = Method.getMethod("void checkAndSetF(int)");
      GeneratorAdapter ga = new GeneratorAdapter(ACC_PUBLIC, m, mv);
      ga.visitCode();
      ga.loadArg(0);
      Label label = new Label();
      ga.ifZCmp(GeneratorAdapter.LT, label);
      ga.loadThis();
      ga.loadArg(0);
      ga.putField(bean, "f", Type.INT_TYPE);
      Label end = new Label();
      ga.goTo(end);
      ga.mark(label);
      ga.throwException(Type.getType(IllegalArgumentException.class),
          "f");
      ga.mark(end);
      ga.returnValue();
      ga.endMethod();
    }
    cv.visitEnd();
    byte[] b = cw.toByteArray();
    return b;
  }

View Full Code Here

        .getInternalName() });


    MethodVisitor mv = cv.visitMethod(ACC_PUBLIC, INIT.getName(), INIT
        .getDescriptor(), null, null);
    if (mv != null) {
      GeneratorAdapter init = new GeneratorAdapter(ACC_PUBLIC, INIT, mv);
      init.visitCode();
      init.loadThis();
      init.loadArg(0);
      init.invokeConstructor(PROXY, INIT);
      init.returnValue();
      init.endMethod();
    }


    GeneratorAdapter clinit = null;
    mv = cv.visitMethod(ACC_STATIC, CLINIT.getName(), CLINIT
        .getDescriptor(), null, null);
    if (mv != null) {
      clinit = new GeneratorAdapter(ACC_STATIC, CLINIT, mv);
      clinit.visitCode();
    }


    for (int i = 0; i < itf.getMethods().length; ++i) {
      Method m = getMethod(itf.getMethods()[i]);


      mv = cv.visitMethod(ACC_PUBLIC, m.getName(), m.getDescriptor(),
          null, null);
      if (mv != null) {
        String field = "_M" + i;
        FieldVisitor fv = cv.visitField(ACC_PRIVATE + ACC_STATIC,
            field, METHOD.getDescriptor(), null, null);
        if (fv != null) {
          fv.visitEnd();
        }


        if (clinit != null) {
          Type[] formals = m.getArgumentTypes();
          clinit.push(Type.getType(itf));
          clinit.push(m.getName());
          clinit.push(formals.length);
          clinit.newArray(CLASS);
          for (int j = 0; j < formals.length; ++j) {
            clinit.dup();
            clinit.push(j);
            clinit.push(formals[j]);
            clinit.arrayStore(CLASS);
          }
          clinit.invokeVirtual(CLASS, GET_METHOD);
          clinit.putStatic(type, field, METHOD);
        }


        GeneratorAdapter ga = new GeneratorAdapter(ACC_PUBLIC, m, mv);
        ga.visitCode();
        ga.loadThis();
        ga.getField(PROXY, "h", HANDLER);
        ga.loadThis();
        ga.getStatic(type, field, METHOD);
        ga.loadArgArray();
        ga.invokeInterface(HANDLER, INVOKE);
        if (m.getReturnType() != Type.VOID_TYPE) {
          ga.unbox(m.getReturnType());
        }
        ga.returnValue();
        ga.endMethod();
      }
    }


    if (clinit != null) {
      clinit.returnValue();

View Full Code Here

            final String targetClassName, final Class superClass,
            final Class[] interfaces, final Map methods, final Type selfType) {
        ClassWriter cw = beginProxyClass(targetClassName, superClass,
                interfaces);


        GeneratorAdapter clazzInit = createClassInitializer(selfType, cw);


        generateConstructors(superClass, selfType, cw);


        generateGetProxyClass(selfType, cw);


        generateGetInvocationHandler(selfType, cw);


        generateProxyMethods(superClass, methods, selfType, cw, clazzInit);


        // finish class initializer
        clazzInit.returnValue();
        clazzInit.endMethod();


        // end class
        cw.visitEnd();


        byte[] data = cw.toByteArray();

View Full Code Here

    }


    private static void generateGetInvocationHandler(Type selfType,
            ClassVisitor cw) {
        // make getter for handler
        GeneratorAdapter gh = new GeneratorAdapter(Opcodes.ACC_PUBLIC,
                new org.objectweb.asm.commons.Method("___getInvocationHandler",
                        INVOCATION_HANDLER_TYPE, EMPTY_TYPE_ARR), null,
                EMPTY_TYPE_ARR, cw);


        gh.loadThis();
        gh.getField(selfType, INVOCATION_HANDLER_FIELD_NAME,
                INVOCATION_HANDLER_TYPE);
        gh.returnValue();
        gh.endMethod();
    }

View Full Code Here

        gh.endMethod();
    }


    private static void generateGetProxyClass(Type selfType, ClassVisitor cw) {
        // make getter for proxy class
        GeneratorAdapter gpc = new GeneratorAdapter(Opcodes.ACC_PUBLIC,
                new org.objectweb.asm.commons.Method("___getProxyClass",
                        PROXY_CLASS_TYPE, EMPTY_TYPE_ARR), null,
                EMPTY_TYPE_ARR, cw);
        gpc.getStatic(selfType, PROXY_CLASS_FIELD_NAME, PROXY_CLASS_TYPE);
        gpc.returnValue();
        gpc.endMethod();
    }

View Full Code Here

        }
    }


    private static GeneratorAdapter createClassInitializer(Type selfType,
            ClassVisitor cw) {
        GeneratorAdapter clazzInit;
        clazzInit = new GeneratorAdapter(Opcodes.ACC_PRIVATE
                | Opcodes.ACC_STATIC, new org.objectweb.asm.commons.Method(
                "<clinit>", Type.VOID_TYPE, EMPTY_TYPE_ARR), null,
                EMPTY_TYPE_ARR, cw);


        clazzInit.visitLdcInsn(selfType.getClassName());
        clazzInit.invokeStatic(JAVA_LANG_CLASS_TYPE, CLASS_FORNAME_METHOD);
        clazzInit
                .invokeStatic(PROXY_HELPER_TYPE, HELPER_GET_PROXY_CLASS_METHOD);
        clazzInit.dup();
        clazzInit.putStatic(selfType, PROXY_CLASS_FIELD_NAME, PROXY_CLASS_TYPE);
        return clazzInit;
    }

View Full Code Here

                        .getArgumentTypes());


        //
        // construct the proxy method
        //
        GeneratorAdapter ga = new GeneratorAdapter(Opcodes.ACC_PUBLIC, m, null,
                ex, cw);


        ga.loadThis();
        ga.getField(selfType, INVOCATION_HANDLER_FIELD_NAME,
                INVOCATION_HANDLER_TYPE);


        // if the method is extending something, then we have
        // to test if the handler is initialized...


        if (md.isImplemented()) {
            ga.dup();
            Label ok = ga.newLabel();
            ga.ifNonNull(ok);


            ga.loadThis();
            ga.loadArgs();
            ga.invokeConstructor(superType, m);
            ga.returnValue();
            ga.mark(ok);
        }


        ga.loadThis();
        ga.getStatic(selfType, field_name, PROXY_METHOD_TYPE);


        if (m.getArgumentTypes().length == 0) {
            // load static empty array
            ga.getStatic(JAVA_PROXY_TYPE, "NO_ARGS", Type
                    .getType(Object[].class));
        } else {
            // box arguments
            ga.loadArgArray();
        }


        Label before = ga.mark();


        ga.invokeInterface(INVOCATION_HANDLER_TYPE,
                INVOCATION_HANDLER_INVOKE_METHOD);


        Label after = ga.mark();


        ga.unbox(m.getReturnType());
        ga.returnValue();


        // this is a simple rethrow handler
        Label rethrow = ga.mark();
        ga.visitInsn(Opcodes.ATHROW);


        for (int i = 0; i < ex.length; i++) {
            ga.visitTryCatchBlock(before, after, rethrow, ex[i]
                    .getInternalName());
        }


        ga.visitTryCatchBlock(before, after, rethrow, "java/lang/Error");
        ga.visitTryCatchBlock(before, after, rethrow,
                "java/lang/RuntimeException");


        Type thr = Type.getType(Throwable.class);
        Label handler = ga.mark();
        Type udt = Type.getType(UndeclaredThrowableException.class);
        int loc = ga.newLocal(thr);
        ga.storeLocal(loc, thr);
        ga.newInstance(udt);
        ga.dup();
        ga.loadLocal(loc, thr);
        ga.invokeConstructor(udt, org.objectweb.asm.commons.Method
                .getMethod("void <init>(java.lang.Throwable)"));
        ga.throwException();


        ga.visitTryCatchBlock(before, after, handler, "java/lang/Throwable");


        ga.endMethod();


        //
        // construct the super-proxy method
        //
        if (md.isImplemented()) {


            GeneratorAdapter ga2 = new GeneratorAdapter(Opcodes.ACC_PUBLIC, sm,
                    null, ex, cw);


            ga2.loadThis();
            ga2.loadArgs();
            ga2.invokeConstructor(superType, m);
            ga2.returnValue();
            ga2.endMethod();
        }
    }

View Full Code Here

        org.objectweb.asm.commons.Method super_m = new org.objectweb.asm.commons.Method(
                name1, Type.VOID_TYPE, toType(superConstructorParameterTypes));
        org.objectweb.asm.commons.Method m = new org.objectweb.asm.commons.Method(
                name1, Type.VOID_TYPE, toType(newConstructorParameterTypes));


        GeneratorAdapter ga = new GeneratorAdapter(access, m, signature,
                toType(superConstructorExceptions), cw);


        ga.loadThis();
        ga.loadArgs(0, superConstructorParameterTypes.length);
        ga.invokeConstructor(Type.getType(constructor.getDeclaringClass()),
                super_m);


        ga.loadThis();
        ga.loadArg(superConstructorParameterTypes.length);
        ga.putField(selfType, INVOCATION_HANDLER_FIELD_NAME,
                INVOCATION_HANDLER_TYPE);


        // do a void return
        ga.returnValue();
        ga.endMethod();
        return newConstructorParameterTypes;
    }

View Full Code Here

    generateField(DISPATCHER_FIELD, Type.getDescriptor(Callable.class));
    generateField(LISTENER_FIELD, Type.getDescriptor(InvocationListener.class));


    // a general methodAdapter field that we will use to with GeneratorAdapters
    // to create the methods required to implement WovenProxy
    GeneratorAdapter methodAdapter;


    // add a method for unwrapping the dispatcher
    methodAdapter = getMethodGenerator(PUBLIC_GENERATED_METHOD_ACCESS, new Method(
        "org_apache_aries_proxy_weaving_WovenProxy_unwrap", DISPATCHER_TYPE,
        NO_ARGS));


    // /////////////////////////////////////////////////////
    // Implement the method


    // load this to get the field
    methodAdapter.loadThis();
    // get the dispatcher field and return
    methodAdapter.getField(typeBeingWoven, DISPATCHER_FIELD, DISPATCHER_TYPE);
    methodAdapter.returnValue();
    methodAdapter.endMethod();


    // /////////////////////////////////////////////////////


    // add a method for checking if the dispatcher is set
    methodAdapter = getMethodGenerator(PUBLIC_GENERATED_METHOD_ACCESS, new Method(
        "org_apache_aries_proxy_weaving_WovenProxy_isProxyInstance",
        Type.BOOLEAN_TYPE, NO_ARGS));


    // /////////////////////////////////////////////////////
    // Implement the method


    // load this to get the field
    methodAdapter.loadThis();
    // make a label for return true
    Label returnTrueLabel = methodAdapter.newLabel();
    // get the dispatcher field for the stack
    methodAdapter.getField(typeBeingWoven, DISPATCHER_FIELD, DISPATCHER_TYPE);
    // check if the dispatcher was non-null and goto return true if it was
    methodAdapter.ifNonNull(returnTrueLabel);
    methodAdapter.loadThis();
    // get the listener field for the stack
    methodAdapter.getField(typeBeingWoven, LISTENER_FIELD, LISTENER_TYPE);
    // check if the listener field was non-null and goto return true if it was
    methodAdapter.ifNonNull(returnTrueLabel);
    // return false if we haven't jumped anywhere
    methodAdapter.push(false);
    methodAdapter.returnValue();
    // mark the returnTrueLable
    methodAdapter.mark(returnTrueLabel);
    methodAdapter.push(true);
    methodAdapter.returnValue();
    // end the method
    methodAdapter.endMethod();


    // ///////////////////////////////////////////////////////
  }

View Full Code Here

   * We write createNewProxyInstance separately because it isn't final, and is
   * overridden on each class, we also write a constructor for this method to
   * use if we don't have one.
   */
  private final void writeCreateNewProxyInstanceAndConstructor() {
    GeneratorAdapter methodAdapter = getMethodGenerator(ACC_PUBLIC, new Method(
        "org_apache_aries_proxy_weaving_WovenProxy_createNewProxyInstance",
        WOVEN_PROXY_IFACE_TYPE, DISPATCHER_LISTENER_METHOD_ARGS));


    // /////////////////////////////////////////////////////
    // Implement the method


    // Create and instantiate a new instance, then return it
    methodAdapter.newInstance(typeBeingWoven);
    methodAdapter.dup();
    methodAdapter.loadArgs();
    methodAdapter.invokeConstructor(typeBeingWoven, new Method("<init>",
        Type.VOID_TYPE, DISPATCHER_LISTENER_METHOD_ARGS));
    methodAdapter.returnValue();
    methodAdapter.endMethod();
    //////////////////////////////////////////////////////////


    
    // Write a protected no-args constructor for this class
    methodAdapter = getMethodGenerator(ACC_PROTECTED | ACC_SYNTHETIC, ARGS_CONSTRUCTOR);


    // /////////////////////////////////////////////////////
    // Implement the constructor


    // For the top level supertype we need to invoke a no-args super, on object 
    //if we have to
    
    if(implementWovenProxy) {
      methodAdapter.loadThis();


      if (superHasNoArgsConstructor)
        methodAdapter.invokeConstructor(superType, NO_ARGS_CONSTRUCTOR);
      else {
        if(hasNoArgsConstructor)
          methodAdapter.invokeConstructor(typeBeingWoven, NO_ARGS_CONSTRUCTOR);
        else
          throw new RuntimeException(new UnableToProxyException(typeBeingWoven.getClassName(), 
              NLS.MESSAGES.getMessage("type.lacking.no.arg.constructor", typeBeingWoven.getClassName(), superType.getClassName())));
      }
      methodAdapter.loadThis();
      methodAdapter.loadArg(0);
      methodAdapter.putField(typeBeingWoven, DISPATCHER_FIELD, DISPATCHER_TYPE);
      
      methodAdapter.loadThis();
      methodAdapter.loadArg(1);
      methodAdapter.putField(typeBeingWoven, LISTENER_FIELD, LISTENER_TYPE);
    } else {
      //We just invoke the super with args
      methodAdapter.loadThis();
      methodAdapter.loadArgs();
      methodAdapter.invokeConstructor(superType, ARGS_CONSTRUCTOR);
    }
    
    //Throw an NPE if the dispatcher is null, return otherwise
    methodAdapter.loadArg(0);
    Label returnValue = methodAdapter.newLabel();
    methodAdapter.ifNonNull(returnValue);
    methodAdapter.newInstance(NPE_TYPE);
    methodAdapter.dup();
    methodAdapter.push("The dispatcher must never be null!");
    methodAdapter.invokeConstructor(NPE_TYPE, NPE_CONSTRUCTOR);
    methodAdapter.throwException();
    
    methodAdapter.mark(returnValue);
    methodAdapter.returnValue();
    methodAdapter.endMethod();
    //////////////////////////////////////////////////////////
  }

View Full Code Here

0 1 2 3 4 5 6 7 8 9

TOP

Related Classes of org.objectweb.asm.commons.GeneratorAdapter

ch3.sec2.BeanGenerator2

ch3.sec2.ProxyGenerator

co.cask.cdap.internal.app.runtime.service.http.HttpHandlerGenerator

co.cask.cdap.internal.app.runtime.service.http.HttpHandlerGenerator$HandlerMethodVisitor

co.cask.cdap.internal.io.DatumWriterGenerator

co.cask.cdap.internal.io.FieldAccessorGenerator

co.cask.tigon.internal.io.DatumWriterGenerator

co.cask.tigon.internal.io.FieldAccessorGenerator

com.onpositive.instrumentation.processors.ClassProcessor

com.sun.ejb.codegen.EjbOptionalIntfGenerator

All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.