Question

我现在正试图在几个小时之后想出这个错误，我真的不知道是什么原因造成的。我试图将代码注入类File。奇怪的是注入适用于ClassWriter.COMPUTE_MAXS，但如果我使用ClassWriter.COMPUTE_FRAMES则抛出ArrayIndexOutOfBoundsException。我需要使用COMPUTE_FRAMES才能运行已编辑的类。我正在使用asm 5.2并且到目前为止只发现COMPUTE_FRAMES的值为2（这可能会对你有所帮助）

我的代码：

    InputStream in = new FileInputStream("Paht/To/Class.class");
    ClassReader classReader = new ClassReader(in);
    ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES){
        @Override
        protected String getCommonSuperClass(final String type1, final String type2){
            return "java/lang/Object";
        }
    };

    ClassVisitor mcw = new ModifierClassWriter(Opcodes.ASM5, cw);
    classReader.accept(mcw, 0);

    File outputDir = new File("Path/To/Output/dir");
    outputDir.mkdirs();
    DataOutputStream dout = new DataOutputStream(new FileOutputStream(new File(outputDir, "NameOfFile.class")));
    dout.write(cw.toByteArray());
    dout.close();

修饰符方法编写器：

    public static class ModifierMethodWriter extends MethodVisitor{

    private String methodName;

    public ModifierMethodWriter(int api, MethodVisitor mv, String methodName) {
        super(api, mv);
        this.methodName = methodName;
    }
    @Override
    public void visitCode() {
        super.visitCode();
    //InjectCodeHere, removed it because it most likely doesnt cause the error
    }
}

ModifierClassWriter：

    public static class ModifierClassWriter extends ClassVisitor{
    private int api;
    public ModifierClassWriter(int api, ClassWriter cv) {
        super(api, cv);
        this.api = api;
    }

    @Override
    public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
        MethodVisitor mv =  super.visitMethod(access, name, desc, signature, exceptions);
        ModifierMethodWriter mvw = new ModifierMethodWriter(api, mv, name);
        return mvw;
    }
}

错误：

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
at org.objectweb.asm.Frame.a(Unknown Source)
at org.objectweb.asm.Frame.a(Unknown Source)
at org.objectweb.asm.MethodWriter.visitMaxs(Unknown Source)
at org.objectweb.asm.MethodVisitor.visitMaxs(Unknown Source)
at org.objectweb.asm.ClassReader.a(Unknown Source)
at org.objectweb.asm.ClassReader.b(Unknown Source)
at org.objectweb.asm.ClassReader.accept(Unknown Source)
at org.objectweb.asm.ClassReader.accept(Unknown Source)
at package.main.ClassMaker.main(ClassMaker.java:28)

Answer 1

感谢@ display-name我发现了错误。

super.visitMaxs(4, 2);

“ModifierMethodWriter”中的

导致错误，我实际上没有在这里显示的代码。

ASM 5.2 ClassReader.accept抛出ArrayIndexOutOfBoundsException：2

1 个答案: