Java example source code file (ClassWriter.java)
The ClassWriter.java Java example source code
/*
* Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.tools.classfile;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import static com.sun.tools.classfile.Annotation.*;
import static com.sun.tools.classfile.ConstantPool.*;
import static com.sun.tools.classfile.StackMapTable_attribute.*;
import static com.sun.tools.classfile.StackMapTable_attribute.verification_type_info.*;
/**
* Write a ClassFile data structure to a file or stream.
*
* <p>This is NOT part of any supported API.
* If you write code that depends on this, you do so at your own risk.
* This code and its internal interfaces are subject to change or
* deletion without notice.</b>
*/
public class ClassWriter {
public ClassWriter() {
attributeWriter = new AttributeWriter();
constantPoolWriter = new ConstantPoolWriter();
out = new ClassOutputStream();
}
/**
* Write a ClassFile data structure to a file.
*/
public void write(ClassFile classFile, File f) throws IOException {
FileOutputStream f_out = new FileOutputStream(f);
try {
write(classFile, f_out);
} finally {
f_out.close();
}
}
/**
* Write a ClassFile data structure to a stream.
*/
public void write(ClassFile classFile, OutputStream s) throws IOException {
this.classFile = classFile;
out.reset();
write();
out.writeTo(s);
}
protected void write() throws IOException {
writeHeader();
writeConstantPool();
writeAccessFlags(classFile.access_flags);
writeClassInfo();
writeFields();
writeMethods();
writeAttributes(classFile.attributes);
}
protected void writeHeader() {
out.writeInt(classFile.magic);
out.writeShort(classFile.minor_version);
out.writeShort(classFile.major_version);
}
protected void writeAccessFlags(AccessFlags flags) {
out.writeShort(flags.flags);
}
protected void writeAttributes(Attributes attributes) {
int size = attributes.size();
out.writeShort(size);
for (Attribute attr: attributes)
attributeWriter.write(attr, out);
}
protected void writeClassInfo() {
out.writeShort(classFile.this_class);
out.writeShort(classFile.super_class);
int[] interfaces = classFile.interfaces;
out.writeShort(interfaces.length);
for (int i: interfaces)
out.writeShort(i);
}
protected void writeDescriptor(Descriptor d) {
out.writeShort(d.index);
}
protected void writeConstantPool() {
ConstantPool pool = classFile.constant_pool;
int size = pool.size();
out.writeShort(size);
for (CPInfo cpInfo: pool.entries())
constantPoolWriter.write(cpInfo, out);
}
protected void writeFields() throws IOException {
Field[] fields = classFile.fields;
out.writeShort(fields.length);
for (Field f: fields)
writeField(f);
}
protected void writeField(Field f) throws IOException {
writeAccessFlags(f.access_flags);
out.writeShort(f.name_index);
writeDescriptor(f.descriptor);
writeAttributes(f.attributes);
}
protected void writeMethods() throws IOException {
Method[] methods = classFile.methods;
out.writeShort(methods.length);
for (Method m: methods) {
writeMethod(m);
}
}
protected void writeMethod(Method m) throws IOException {
writeAccessFlags(m.access_flags);
out.writeShort(m.name_index);
writeDescriptor(m.descriptor);
writeAttributes(m.attributes);
}
protected ClassFile classFile;
protected ClassOutputStream out;
protected AttributeWriter attributeWriter;
protected ConstantPoolWriter constantPoolWriter;
/**
* Subtype of ByteArrayOutputStream with the convenience methods of
* a DataOutputStream. Since ByteArrayOutputStream does not throw
* IOException, there are no exceptions from the additional
* convenience methods either,
*/
protected static class ClassOutputStream extends ByteArrayOutputStream {
public ClassOutputStream() {
d = new DataOutputStream(this);
}
public void writeByte(int value) {
try {
d.writeByte(value);
} catch (IOException ignore) {
}
}
public void writeShort(int value) {
try {
d.writeShort(value);
} catch (IOException ignore) {
}
}
public void writeInt(int value) {
try {
d.writeInt(value);
} catch (IOException ignore) {
}
}
public void writeLong(long value) {
try {
d.writeLong(value);
} catch (IOException ignore) {
}
}
public void writeFloat(float value) {
try {
d.writeFloat(value);
} catch (IOException ignore) {
}
}
public void writeDouble(double value) {
try {
d.writeDouble(value);
} catch (IOException ignore) {
}
}
public void writeUTF(String value) {
try {
d.writeUTF(value);
} catch (IOException ignore) {
}
}
public void writeTo(ClassOutputStream s) {
try {
super.writeTo(s);
} catch (IOException ignore) {
}
}
private DataOutputStream d;
}
/**
* Writer for the entries in the constant pool.
*/
protected static class ConstantPoolWriter
implements ConstantPool.Visitor<Integer,ClassOutputStream> {
protected int write(CPInfo info, ClassOutputStream out) {
out.writeByte(info.getTag());
return info.accept(this, out);
}
public Integer visitClass(CONSTANT_Class_info info, ClassOutputStream out) {
out.writeShort(info.name_index);
return 1;
}
public Integer visitDouble(CONSTANT_Double_info info, ClassOutputStream out) {
out.writeDouble(info.value);
return 2;
}
public Integer visitFieldref(CONSTANT_Fieldref_info info, ClassOutputStream out) {
writeRef(info, out);
return 1;
}
public Integer visitFloat(CONSTANT_Float_info info, ClassOutputStream out) {
out.writeFloat(info.value);
return 1;
}
public Integer visitInteger(CONSTANT_Integer_info info, ClassOutputStream out) {
out.writeInt(info.value);
return 1;
}
public Integer visitInterfaceMethodref(CONSTANT_InterfaceMethodref_info info, ClassOutputStream out) {
writeRef(info, out);
return 1;
}
public Integer visitInvokeDynamic(CONSTANT_InvokeDynamic_info info, ClassOutputStream out) {
out.writeShort(info.bootstrap_method_attr_index);
out.writeShort(info.name_and_type_index);
return 1;
}
public Integer visitLong(CONSTANT_Long_info info, ClassOutputStream out) {
out.writeLong(info.value);
return 2;
}
public Integer visitNameAndType(CONSTANT_NameAndType_info info, ClassOutputStream out) {
out.writeShort(info.name_index);
out.writeShort(info.type_index);
return 1;
}
public Integer visitMethodHandle(CONSTANT_MethodHandle_info info, ClassOutputStream out) {
out.writeByte(info.reference_kind.tag);
out.writeShort(info.reference_index);
return 1;
}
public Integer visitMethodType(CONSTANT_MethodType_info info, ClassOutputStream out) {
out.writeShort(info.descriptor_index);
return 1;
}
public Integer visitMethodref(CONSTANT_Methodref_info info, ClassOutputStream out) {
return writeRef(info, out);
}
public Integer visitString(CONSTANT_String_info info, ClassOutputStream out) {
out.writeShort(info.string_index);
return 1;
}
public Integer visitUtf8(CONSTANT_Utf8_info info, ClassOutputStream out) {
out.writeUTF(info.value);
return 1;
}
protected Integer writeRef(CPRefInfo info, ClassOutputStream out) {
out.writeShort(info.class_index);
out.writeShort(info.name_and_type_index);
return 1;
}
}
/**
* Writer for the different types of attribute.
*/
protected static class AttributeWriter implements Attribute.Visitor<Void,ClassOutputStream> {
public void write(Attributes attributes, ClassOutputStream out) {
int size = attributes.size();
out.writeShort(size);
for (Attribute a: attributes)
write(a, out);
}
// Note: due to the use of shared resources, this method is not reentrant.
public void write(Attribute attr, ClassOutputStream out) {
out.writeShort(attr.attribute_name_index);
sharedOut.reset();
attr.accept(this, sharedOut);
out.writeInt(sharedOut.size());
sharedOut.writeTo(out);
}
protected ClassOutputStream sharedOut = new ClassOutputStream();
protected AnnotationWriter annotationWriter = new AnnotationWriter();
public Void visitDefault(DefaultAttribute attr, ClassOutputStream out) {
out.write(attr.info, 0, attr.info.length);
return null;
}
public Void visitAnnotationDefault(AnnotationDefault_attribute attr, ClassOutputStream out) {
annotationWriter.write(attr.default_value, out);
return null;
}
public Void visitBootstrapMethods(BootstrapMethods_attribute attr, ClassOutputStream out) {
out.writeShort(attr.bootstrap_method_specifiers.length);
for (BootstrapMethods_attribute.BootstrapMethodSpecifier bsm : attr.bootstrap_method_specifiers) {
out.writeShort(bsm.bootstrap_method_ref);
int bsm_args_count = bsm.bootstrap_arguments.length;
out.writeShort(bsm_args_count);
for (int i : bsm.bootstrap_arguments) {
out.writeShort(i);
}
}
return null;
}
public Void visitCharacterRangeTable(CharacterRangeTable_attribute attr, ClassOutputStream out) {
out.writeShort(attr.character_range_table.length);
for (CharacterRangeTable_attribute.Entry e: attr.character_range_table)
writeCharacterRangeTableEntry(e, out);
return null;
}
protected void writeCharacterRangeTableEntry(CharacterRangeTable_attribute.Entry entry, ClassOutputStream out) {
out.writeShort(entry.start_pc);
out.writeShort(entry.end_pc);
out.writeInt(entry.character_range_start);
out.writeInt(entry.character_range_end);
out.writeShort(entry.flags);
}
public Void visitCode(Code_attribute attr, ClassOutputStream out) {
out.writeShort(attr.max_stack);
out.writeShort(attr.max_locals);
out.writeInt(attr.code.length);
out.write(attr.code, 0, attr.code.length);
out.writeShort(attr.exception_table.length);
for (Code_attribute.Exception_data e: attr.exception_table)
writeExceptionTableEntry(e, out);
new AttributeWriter().write(attr.attributes, out);
return null;
}
protected void writeExceptionTableEntry(Code_attribute.Exception_data exception_data, ClassOutputStream out) {
out.writeShort(exception_data.start_pc);
out.writeShort(exception_data.end_pc);
out.writeShort(exception_data.handler_pc);
out.writeShort(exception_data.catch_type);
}
public Void visitCompilationID(CompilationID_attribute attr, ClassOutputStream out) {
out.writeShort(attr.compilationID_index);
return null;
}
public Void visitConstantValue(ConstantValue_attribute attr, ClassOutputStream out) {
out.writeShort(attr.constantvalue_index);
return null;
}
public Void visitDeprecated(Deprecated_attribute attr, ClassOutputStream out) {
return null;
}
public Void visitEnclosingMethod(EnclosingMethod_attribute attr, ClassOutputStream out) {
out.writeShort(attr.class_index);
out.writeShort(attr.method_index);
return null;
}
public Void visitExceptions(Exceptions_attribute attr, ClassOutputStream out) {
out.writeShort(attr.exception_index_table.length);
for (int i: attr.exception_index_table)
out.writeShort(i);
return null;
}
public Void visitInnerClasses(InnerClasses_attribute attr, ClassOutputStream out) {
out.writeShort(attr.classes.length);
for (InnerClasses_attribute.Info info: attr.classes)
writeInnerClassesInfo(info, out);
return null;
}
protected void writeInnerClassesInfo(InnerClasses_attribute.Info info, ClassOutputStream out) {
out.writeShort(info.inner_class_info_index);
out.writeShort(info.outer_class_info_index);
out.writeShort(info.inner_name_index);
writeAccessFlags(info.inner_class_access_flags, out);
}
public Void visitLineNumberTable(LineNumberTable_attribute attr, ClassOutputStream out) {
out.writeShort(attr.line_number_table.length);
for (LineNumberTable_attribute.Entry e: attr.line_number_table)
writeLineNumberTableEntry(e, out);
return null;
}
protected void writeLineNumberTableEntry(LineNumberTable_attribute.Entry entry, ClassOutputStream out) {
out.writeShort(entry.start_pc);
out.writeShort(entry.line_number);
}
public Void visitLocalVariableTable(LocalVariableTable_attribute attr, ClassOutputStream out) {
out.writeShort(attr.local_variable_table.length);
for (LocalVariableTable_attribute.Entry e: attr.local_variable_table)
writeLocalVariableTableEntry(e, out);
return null;
}
protected void writeLocalVariableTableEntry(LocalVariableTable_attribute.Entry entry, ClassOutputStream out) {
out.writeShort(entry.start_pc);
out.writeShort(entry.length);
out.writeShort(entry.name_index);
out.writeShort(entry.descriptor_index);
out.writeShort(entry.index);
}
public Void visitLocalVariableTypeTable(LocalVariableTypeTable_attribute attr, ClassOutputStream out) {
out.writeShort(attr.local_variable_table.length);
for (LocalVariableTypeTable_attribute.Entry e: attr.local_variable_table)
writeLocalVariableTypeTableEntry(e, out);
return null;
}
protected void writeLocalVariableTypeTableEntry(LocalVariableTypeTable_attribute.Entry entry, ClassOutputStream out) {
out.writeShort(entry.start_pc);
out.writeShort(entry.length);
out.writeShort(entry.name_index);
out.writeShort(entry.signature_index);
out.writeShort(entry.index);
}
public Void visitMethodParameters(MethodParameters_attribute attr, ClassOutputStream out) {
out.writeByte(attr.method_parameter_table.length);
for (MethodParameters_attribute.Entry e : attr.method_parameter_table) {
out.writeShort(e.name_index);
out.writeShort(e.flags);
}
return null;
}
public Void visitRuntimeVisibleAnnotations(RuntimeVisibleAnnotations_attribute attr, ClassOutputStream out) {
annotationWriter.write(attr.annotations, out);
return null;
}
public Void visitRuntimeInvisibleAnnotations(RuntimeInvisibleAnnotations_attribute attr, ClassOutputStream out) {
annotationWriter.write(attr.annotations, out);
return null;
}
public Void visitRuntimeVisibleTypeAnnotations(RuntimeVisibleTypeAnnotations_attribute attr, ClassOutputStream out) {
annotationWriter.write(attr.annotations, out);
return null;
}
public Void visitRuntimeInvisibleTypeAnnotations(RuntimeInvisibleTypeAnnotations_attribute attr, ClassOutputStream out) {
annotationWriter.write(attr.annotations, out);
return null;
}
public Void visitRuntimeVisibleParameterAnnotations(RuntimeVisibleParameterAnnotations_attribute attr, ClassOutputStream out) {
out.writeByte(attr.parameter_annotations.length);
for (Annotation[] annos: attr.parameter_annotations)
annotationWriter.write(annos, out);
return null;
}
public Void visitRuntimeInvisibleParameterAnnotations(RuntimeInvisibleParameterAnnotations_attribute attr, ClassOutputStream out) {
out.writeByte(attr.parameter_annotations.length);
for (Annotation[] annos: attr.parameter_annotations)
annotationWriter.write(annos, out);
return null;
}
public Void visitSignature(Signature_attribute attr, ClassOutputStream out) {
out.writeShort(attr.signature_index);
return null;
}
public Void visitSourceDebugExtension(SourceDebugExtension_attribute attr, ClassOutputStream out) {
out.write(attr.debug_extension, 0, attr.debug_extension.length);
return null;
}
public Void visitSourceFile(SourceFile_attribute attr, ClassOutputStream out) {
out.writeShort(attr.sourcefile_index);
return null;
}
public Void visitSourceID(SourceID_attribute attr, ClassOutputStream out) {
out.writeShort(attr.sourceID_index);
return null;
}
public Void visitStackMap(StackMap_attribute attr, ClassOutputStream out) {
if (stackMapWriter == null)
stackMapWriter = new StackMapTableWriter();
out.writeShort(attr.entries.length);
for (stack_map_frame f: attr.entries)
stackMapWriter.write(f, out);
return null;
}
public Void visitStackMapTable(StackMapTable_attribute attr, ClassOutputStream out) {
if (stackMapWriter == null)
stackMapWriter = new StackMapTableWriter();
out.writeShort(attr.entries.length);
for (stack_map_frame f: attr.entries)
stackMapWriter.write(f, out);
return null;
}
public Void visitSynthetic(Synthetic_attribute attr, ClassOutputStream out) {
return null;
}
protected void writeAccessFlags(AccessFlags flags, ClassOutputStream p) {
sharedOut.writeShort(flags.flags);
}
protected StackMapTableWriter stackMapWriter;
}
/**
* Writer for the frames of StackMap and StackMapTable attributes.
*/
protected static class StackMapTableWriter
implements stack_map_frame.Visitor<Void,ClassOutputStream> {
public void write(stack_map_frame frame, ClassOutputStream out) {
out.write(frame.frame_type);
frame.accept(this, out);
}
public Void visit_same_frame(same_frame frame, ClassOutputStream p) {
return null;
}
public Void visit_same_locals_1_stack_item_frame(same_locals_1_stack_item_frame frame, ClassOutputStream out) {
writeVerificationTypeInfo(frame.stack[0], out);
return null;
}
public Void visit_same_locals_1_stack_item_frame_extended(same_locals_1_stack_item_frame_extended frame, ClassOutputStream out) {
out.writeShort(frame.offset_delta);
writeVerificationTypeInfo(frame.stack[0], out);
return null;
}
public Void visit_chop_frame(chop_frame frame, ClassOutputStream out) {
out.writeShort(frame.offset_delta);
return null;
}
public Void visit_same_frame_extended(same_frame_extended frame, ClassOutputStream out) {
out.writeShort(frame.offset_delta);
return null;
}
public Void visit_append_frame(append_frame frame, ClassOutputStream out) {
out.writeShort(frame.offset_delta);
for (verification_type_info l: frame.locals)
writeVerificationTypeInfo(l, out);
return null;
}
public Void visit_full_frame(full_frame frame, ClassOutputStream out) {
out.writeShort(frame.offset_delta);
out.writeShort(frame.locals.length);
for (verification_type_info l: frame.locals)
writeVerificationTypeInfo(l, out);
out.writeShort(frame.stack.length);
for (verification_type_info s: frame.stack)
writeVerificationTypeInfo(s, out);
return null;
}
protected void writeVerificationTypeInfo(verification_type_info info,
ClassOutputStream out) {
out.write(info.tag);
switch (info.tag) {
case ITEM_Top:
case ITEM_Integer:
case ITEM_Float:
case ITEM_Long:
case ITEM_Double:
case ITEM_Null:
case ITEM_UninitializedThis:
break;
case ITEM_Object:
Object_variable_info o = (Object_variable_info) info;
out.writeShort(o.cpool_index);
break;
case ITEM_Uninitialized:
Uninitialized_variable_info u = (Uninitialized_variable_info) info;
out.writeShort(u.offset);
break;
default:
throw new Error();
}
}
}
/**
* Writer for annotations and the values they contain.
*/
protected static class AnnotationWriter
implements Annotation.element_value.Visitor<Void,ClassOutputStream> {
public void write(Annotation[] annos, ClassOutputStream out) {
out.writeShort(annos.length);
for (Annotation anno: annos)
write(anno, out);
}
public void write(TypeAnnotation[] annos, ClassOutputStream out) {
out.writeShort(annos.length);
for (TypeAnnotation anno: annos)
write(anno, out);
}
public void write(Annotation anno, ClassOutputStream out) {
out.writeShort(anno.type_index);
out.writeShort(anno.element_value_pairs.length);
for (element_value_pair p: anno.element_value_pairs)
write(p, out);
}
public void write(TypeAnnotation anno, ClassOutputStream out) {
write(anno.position, out);
write(anno.annotation, out);
}
public void write(element_value_pair pair, ClassOutputStream out) {
out.writeShort(pair.element_name_index);
write(pair.value, out);
}
public void write(element_value ev, ClassOutputStream out) {
out.writeByte(ev.tag);
ev.accept(this, out);
}
public Void visitPrimitive(Primitive_element_value ev, ClassOutputStream out) {
out.writeShort(ev.const_value_index);
return null;
}
public Void visitEnum(Enum_element_value ev, ClassOutputStream out) {
out.writeShort(ev.type_name_index);
out.writeShort(ev.const_name_index);
return null;
}
public Void visitClass(Class_element_value ev, ClassOutputStream out) {
out.writeShort(ev.class_info_index);
return null;
}
public Void visitAnnotation(Annotation_element_value ev, ClassOutputStream out) {
write(ev.annotation_value, out);
return null;
}
public Void visitArray(Array_element_value ev, ClassOutputStream out) {
out.writeShort(ev.num_values);
for (element_value v: ev.values)
write(v, out);
return null;
}
// TODO: Move this to TypeAnnotation to be closer with similar logic?
private void write(TypeAnnotation.Position p, ClassOutputStream out) {
out.writeByte(p.type.targetTypeValue());
switch (p.type) {
// instanceof
case INSTANCEOF:
// new expression
case NEW:
// constructor/method reference receiver
case CONSTRUCTOR_REFERENCE:
case METHOD_REFERENCE:
out.writeShort(p.offset);
break;
// local variable
case LOCAL_VARIABLE:
// resource variable
case RESOURCE_VARIABLE:
int table_length = p.lvarOffset.length;
out.writeShort(table_length);
for (int i = 0; i < table_length; ++i) {
out.writeShort(1); // for table length
out.writeShort(p.lvarOffset[i]);
out.writeShort(p.lvarLength[i]);
out.writeShort(p.lvarIndex[i]);
}
break;
// exception parameter
case EXCEPTION_PARAMETER:
out.writeShort(p.exception_index);
break;
// method receiver
case METHOD_RECEIVER:
// Do nothing
break;
// type parameters
case CLASS_TYPE_PARAMETER:
case METHOD_TYPE_PARAMETER:
out.writeByte(p.parameter_index);
break;
// type parameters bounds
case CLASS_TYPE_PARAMETER_BOUND:
case METHOD_TYPE_PARAMETER_BOUND:
out.writeByte(p.parameter_index);
out.writeByte(p.bound_index);
break;
// class extends or implements clause
case CLASS_EXTENDS:
out.writeShort(p.type_index);
break;
// throws
case THROWS:
out.writeShort(p.type_index);
break;
// method parameter
case METHOD_FORMAL_PARAMETER:
out.writeByte(p.parameter_index);
break;
// type cast
case CAST:
// method/constructor/reference type argument
case CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT:
case METHOD_INVOCATION_TYPE_ARGUMENT:
case CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT:
case METHOD_REFERENCE_TYPE_ARGUMENT:
out.writeShort(p.offset);
out.writeByte(p.type_index);
break;
// We don't need to worry about these
case METHOD_RETURN:
case FIELD:
break;
case UNKNOWN:
throw new AssertionError("ClassWriter: UNKNOWN target type should never occur!");
default:
throw new AssertionError("ClassWriter: Unknown target type for position: " + p);
}
{ // Append location data for generics/arrays.
// TODO: check for overrun?
out.writeByte((byte)p.location.size());
for (int i : TypeAnnotation.Position.getBinaryFromTypePath(p.location))
out.writeByte((byte)i);
}
}
}
}
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