Java ClassVisitor类代码示例

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
static void addGetter(final ClassVisitor cv, final String owner, final MemberInfo memInfo) {
    final int access = ACC_PUBLIC;
    final String name = GETTER_PREFIX + memInfo.getJavaName();
    final String desc = getterDesc(memInfo);
    final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
    final MethodGenerator mi = new MethodGenerator(mv, access, name, desc);
    mi.visitCode();
    if (memInfo.isStatic() && memInfo.getKind() == Kind.PROPERTY) {
        mi.getStatic(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
    } else {
        mi.loadLocal(0);
        mi.getField(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
    }
    mi.returnValue();
    mi.computeMaxs();
    mi.visitEnd();
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
static void addSetter(final ClassVisitor cv, final String owner, final MemberInfo memInfo) {
    final int access = ACC_PUBLIC;
    final String name = SETTER_PREFIX + memInfo.getJavaName();
    final String desc = setterDesc(memInfo);
    final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
    final MethodGenerator mi = new MethodGenerator(mv, access, name, desc);
    mi.visitCode();
    if (memInfo.isStatic() && memInfo.getKind() == Kind.PROPERTY) {
        mi.loadLocal(1);
        mi.putStatic(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
    } else {
        mi.loadLocal(0);
        mi.loadLocal(1);
        mi.putField(owner, memInfo.getJavaName(), memInfo.getJavaDesc());
    }
    mi.returnVoid();
    mi.computeMaxs();
    mi.visitEnd();
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
public ClassVisitor make(ClassVisitor cv) {
    return new ClassVisitor(Opcodes.ASM5, cv) {

        @Override
        public void visitInnerClass(String name, String outerName,
                String innerName, int access) {
            if (whenVisitInner) {
                int access_ = (ACC_PROTECTED | access) & ~(ACC_PRIVATE | ACC_PUBLIC);
                System.out.println("visitInnerClass: name = " + name
                        + ", outerName = " + outerName
                        + ", innerName = " + innerName
                        + ", access original = 0x" + Integer.toHexString(access)
                        + ", access modified to 0x" + Integer.toHexString(access_));
                access = access_;
            }
            super.visitInnerClass(name, outerName, innerName, access);
        }
    };
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
boolean hasModulePackages() throws IOException {
    Set<String> attrTypes = new HashSet<>();
    ClassVisitor cv = new ClassVisitor(Opcodes.ASM5) {
        @Override
        public void visitAttribute(Attribute attr) {
            attrTypes.add(attr.type);
        }
    };

    // prototype of attributes that should be parsed
    Attribute[] attrs = new Attribute[] {
        new ClassFileAttributes.ModulePackagesAttribute()
    };

    try (InputStream in = getInputStream()) {
        // parse module-info.class
        ClassReader cr = new ClassReader(in);
        cr.accept(cv, attrs, 0);
        return attrTypes.contains(ClassFileConstants.MODULE_PACKAGES);
    }
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
public static ModuleTarget read(InputStream in) throws IOException {
    ModuleTargetAttribute[] modTargets = new ModuleTargetAttribute[1];
    ClassVisitor cv = new ClassVisitor(Opcodes.ASM5) {
        @Override
        public void visitAttribute(Attribute attr) {
            if (attr instanceof ModuleTargetAttribute) {
                modTargets[0] = (ModuleTargetAttribute)attr;
            }
        }
    };

    // prototype of attributes that should be parsed
    Attribute[] attrs = new Attribute[] {
        new ModuleTargetAttribute()
    };

    // parse module-info.class
    ClassReader cr = new ClassReader(in);
    cr.accept(cv, attrs, 0);
    if (modTargets[0] != null) {
        return new ModuleTarget(modTargets[0].targetPlatform());
    }

    return null;
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
private static boolean hasModuleTarget(InputStream in) throws IOException {
    ModuleTargetAttribute[] modTargets = new ModuleTargetAttribute[1];
    ClassVisitor cv = new ClassVisitor(Opcodes.ASM5) {
        @Override
        public void visitAttribute(Attribute attr) {
            if (attr instanceof ModuleTargetAttribute) {
                modTargets[0] = (ModuleTargetAttribute)attr;
            }
        }
    };

    // prototype of attributes that should be parsed
    Attribute[] attrs = new Attribute[] {
        new ModuleTargetAttribute()
    };

    // parse module-info.class
    ClassReader cr = new ClassReader(in);
    cr.accept(cv, attrs, 0);
    return modTargets[0] != null && modTargets[0].targetPlatform() != null;
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
public synchronized Instrumentor addMethodEntryInjection(String methodName, Consumer<InstrHelper> injector) {
    instrumentingVisitor = new ClassVisitor(Opcodes.ASM5, instrumentingVisitor) {
        @Override
        public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
            MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);

            if (name.equals(methodName)) {
                matches.getAndIncrement();

                mv = new MethodVisitor(Opcodes.ASM5, mv) {
                    @Override
                    public void visitCode() {
                        injector.accept(new InstrHelper(mv, name));
                    }
                };
            }
            return mv;
        }
    };
    return this;
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
@Override
public ClassWriter visit(ClassReader reader) {
    if ((amount++ % 2) == 0) {
        String className = reader.getClassName();
        if (className.endsWith("module-info")) {
            return null;
        }
        ClassWriter cw = new ClassWriter(reader, ClassWriter.COMPUTE_FRAMES);
        reader.accept(new ClassVisitor(Opcodes.ASM5, cw) {
            @Override
            public void visit(int i, int i1, String s, String s1, String s2, String[] strings) {
                super.visit(i, i1, s + "Changed", s1, s2, strings);
            }
        }, ClassReader.EXPAND_FRAMES);
        ++changed;
        return cw;
    } else {
        return null;
    }
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 * Makes the given class visitor visit this method.
 *
 * @param cv
 *            a class visitor.
 */
public void accept(final ClassVisitor cv) {
    String[] exceptions = new String[this.exceptions.size()];
    this.exceptions.toArray(exceptions);
    MethodVisitor mv = cv.visitMethod(access, name, desc, signature,
            exceptions);
    if (mv != null) {
        accept(mv);
    }
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
static MethodGenerator makeConstructor(final ClassVisitor cv) {
    final int access = 0;
    final String name = INIT;
    final String desc = DEFAULT_INIT_DESC;
    final MethodVisitor mv = cv.visitMethod(access, name, desc, null, null);
    return new MethodGenerator(mv, access, name, desc);
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
static void addMapField(final ClassVisitor cv) {
    // add a PropertyMap static field
    final FieldVisitor fv = cv.visitField(ACC_PRIVATE | ACC_STATIC | ACC_FINAL,
        PROPERTYMAP_FIELD_NAME, PROPERTYMAP_DESC, null, null);
    if (fv != null) {
        fv.visitEnd();
    }
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
ScriptClassInstrumentor(final ClassVisitor visitor, final ScriptClassInfo sci) {
    super(Opcodes.ASM4, visitor);
    if (sci == null) {
        throw new IllegalArgumentException("Null ScriptClassInfo, is the class annotated?");
    }
    this.scriptClassInfo = sci;
    this.memberCount = scriptClassInfo.getInstancePropertyCount();
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
public Method(ClassConstruct ownerClass, ClassVisitor cv, String name, String descriptor, int access,
              ClassBuilder.ExecutionMode execMode) {
    this.ownerClassName = ownerClass.getName();
    this.ownerClass = ownerClass;
    this.execMode = execMode;
    this.cv = cv;
    mv = cv.visitMethod(access, name, descriptor, null, null);
    mv.visitCode();
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
public byte[] asm(ClassLoader loader, String className,
        Class<?> classBeingRedefined,
        ProtectionDomain protectionDomain, byte[] classfileBuffer)
    throws IllegalClassFormatException {

    ClassWriter cw = new ClassWriter(0);
    ClassVisitor cv = new ReAddDummyFieldsClassVisitor(ASM5, cw) { };
    ClassReader cr = new ClassReader(classfileBuffer);
    cr.accept(cv, 0);
    return cw.toByteArray();
}
 

import jdk.internal.org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
private static void generateTestMethod(ClassVisitor cv,
        Label unstableIfLocation) {
    MethodVisitor mv = cv.visitMethod(ACC_PUBLIC | ACC_STATIC, METHOD_NAME,
            "(Z)V", null, null);
    mv.visitCode();

    Label end = new Label();
    Label falseBranch = new Label();

    // push "field" field's value and 1 to stack
    mv.visitFieldInsn(GETSTATIC, CLASS_NAME, FIELD_NAME, "I");
    mv.visitInsn(ICONST_1);
    // load argument's value
    mv.visitVarInsn(ILOAD, 0); // alwaysTrue
    // here is our unstable if
    mv.visitLabel(unstableIfLocation);
    mv.visitJumpInsn(IFEQ, falseBranch);
    // increment on "true"
    mv.visitInsn(IADD);
    mv.visitJumpInsn(GOTO, end);
    // decrement on "false"
    mv.visitLabel(falseBranch);
    mv.visitInsn(ISUB);
    mv.visitLabel(end);
    // bye bye
    mv.visitInsn(RETURN);

    mv.visitMaxs(0, 0);
    mv.visitEnd();
}