Java example source code file (ClassWriter.java)
The ClassWriter.java Java example source code
/*
* Copyright (c) 2007, 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.javap;
import java.net.URI;
import java.text.DateFormat;
import java.util.Collection;
import java.util.Date;
import java.util.List;
import com.sun.tools.classfile.AccessFlags;
import com.sun.tools.classfile.Attribute;
import com.sun.tools.classfile.Attributes;
import com.sun.tools.classfile.ClassFile;
import com.sun.tools.classfile.Code_attribute;
import com.sun.tools.classfile.ConstantPool;
import com.sun.tools.classfile.ConstantPoolException;
import com.sun.tools.classfile.ConstantValue_attribute;
import com.sun.tools.classfile.Descriptor;
import com.sun.tools.classfile.DescriptorException;
import com.sun.tools.classfile.Exceptions_attribute;
import com.sun.tools.classfile.Field;
import com.sun.tools.classfile.Method;
import com.sun.tools.classfile.Signature;
import com.sun.tools.classfile.Signature_attribute;
import com.sun.tools.classfile.SourceFile_attribute;
import com.sun.tools.classfile.Type;
import com.sun.tools.classfile.Type.ArrayType;
import com.sun.tools.classfile.Type.ClassSigType;
import com.sun.tools.classfile.Type.ClassType;
import com.sun.tools.classfile.Type.MethodType;
import com.sun.tools.classfile.Type.SimpleType;
import com.sun.tools.classfile.Type.TypeParamType;
import com.sun.tools.classfile.Type.WildcardType;
import static com.sun.tools.classfile.AccessFlags.*;
/*
* The main javap class to write the contents of a class file as text.
*
* <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 extends BasicWriter {
static ClassWriter instance(Context context) {
ClassWriter instance = context.get(ClassWriter.class);
if (instance == null)
instance = new ClassWriter(context);
return instance;
}
protected ClassWriter(Context context) {
super(context);
context.put(ClassWriter.class, this);
options = Options.instance(context);
attrWriter = AttributeWriter.instance(context);
codeWriter = CodeWriter.instance(context);
constantWriter = ConstantWriter.instance(context);
}
void setDigest(String name, byte[] digest) {
this.digestName = name;
this.digest = digest;
}
void setFile(URI uri) {
this.uri = uri;
}
void setFileSize(int size) {
this.size = size;
}
void setLastModified(long lastModified) {
this.lastModified = lastModified;
}
protected ClassFile getClassFile() {
return classFile;
}
protected void setClassFile(ClassFile cf) {
classFile = cf;
constant_pool = classFile.constant_pool;
}
protected Method getMethod() {
return method;
}
protected void setMethod(Method m) {
method = m;
}
public void write(ClassFile cf) {
setClassFile(cf);
if ((options.sysInfo || options.verbose) && !options.compat) {
if (uri != null) {
if (uri.getScheme().equals("file"))
println("Classfile " + uri.getPath());
else
println("Classfile " + uri);
}
indent(+1);
if (lastModified != -1) {
Date lm = new Date(lastModified);
DateFormat df = DateFormat.getDateInstance();
if (size > 0) {
println("Last modified " + df.format(lm) + "; size " + size + " bytes");
} else {
println("Last modified " + df.format(lm));
}
} else if (size > 0) {
println("Size " + size + " bytes");
}
if (digestName != null && digest != null) {
StringBuilder sb = new StringBuilder();
for (byte b: digest)
sb.append(String.format("%02x", b));
println(digestName + " checksum " + sb);
}
}
Attribute sfa = cf.getAttribute(Attribute.SourceFile);
if (sfa instanceof SourceFile_attribute) {
println("Compiled from \"" + getSourceFile((SourceFile_attribute) sfa) + "\"");
}
if ((options.sysInfo || options.verbose) && !options.compat) {
indent(-1);
}
String name = getJavaName(classFile);
AccessFlags flags = cf.access_flags;
writeModifiers(flags.getClassModifiers());
if (classFile.isClass())
print("class ");
else if (classFile.isInterface())
print("interface ");
print(name);
Signature_attribute sigAttr = getSignature(cf.attributes);
if (sigAttr == null) {
// use info from class file header
if (classFile.isClass() && classFile.super_class != 0 ) {
String sn = getJavaSuperclassName(cf);
if (!sn.equals("java.lang.Object")) {
print(" extends ");
print(sn);
}
}
for (int i = 0; i < classFile.interfaces.length; i++) {
print(i == 0 ? (classFile.isClass() ? " implements " : " extends ") : ",");
print(getJavaInterfaceName(classFile, i));
}
} else {
try {
Type t = sigAttr.getParsedSignature().getType(constant_pool);
JavaTypePrinter p = new JavaTypePrinter(classFile.isInterface());
// The signature parser cannot disambiguate between a
// FieldType and a ClassSignatureType that only contains a superclass type.
if (t instanceof Type.ClassSigType) {
print(p.print(t));
} else if (options.verbose || !t.isObject()) {
print(" extends ");
print(p.print(t));
}
} catch (ConstantPoolException e) {
print(report(e));
}
}
if (options.verbose) {
println();
indent(+1);
attrWriter.write(cf, cf.attributes, constant_pool);
println("minor version: " + cf.minor_version);
println("major version: " + cf.major_version);
if (!options.compat)
writeList("flags: ", flags.getClassFlags(), "\n");
indent(-1);
constantWriter.writeConstantPool();
} else {
print(" ");
}
println("{");
indent(+1);
writeFields();
writeMethods();
indent(-1);
println("}");
}
// where
class JavaTypePrinter implements Type.Visitor<StringBuilder,StringBuilder> {
boolean isInterface;
JavaTypePrinter(boolean isInterface) {
this.isInterface = isInterface;
}
String print(Type t) {
return t.accept(this, new StringBuilder()).toString();
}
String printTypeArgs(List<? extends TypeParamType> typeParamTypes) {
StringBuilder builder = new StringBuilder();
appendIfNotEmpty(builder, "<", typeParamTypes, "> ");
return builder.toString();
}
public StringBuilder visitSimpleType(SimpleType type, StringBuilder sb) {
sb.append(getJavaName(type.name));
return sb;
}
public StringBuilder visitArrayType(ArrayType type, StringBuilder sb) {
append(sb, type.elemType);
sb.append("[]");
return sb;
}
public StringBuilder visitMethodType(MethodType type, StringBuilder sb) {
appendIfNotEmpty(sb, "<", type.typeParamTypes, "> ");
append(sb, type.returnType);
append(sb, " (", type.paramTypes, ")");
appendIfNotEmpty(sb, " throws ", type.throwsTypes, "");
return sb;
}
public StringBuilder visitClassSigType(ClassSigType type, StringBuilder sb) {
appendIfNotEmpty(sb, "<", type.typeParamTypes, ">");
if (isInterface) {
appendIfNotEmpty(sb, " extends ", type.superinterfaceTypes, "");
} else {
if (type.superclassType != null
&& (options.verbose || !type.superclassType.isObject())) {
sb.append(" extends ");
append(sb, type.superclassType);
}
appendIfNotEmpty(sb, " implements ", type.superinterfaceTypes, "");
}
return sb;
}
public StringBuilder visitClassType(ClassType type, StringBuilder sb) {
if (type.outerType != null) {
append(sb, type.outerType);
sb.append(".");
}
sb.append(getJavaName(type.name));
appendIfNotEmpty(sb, "<", type.typeArgs, ">");
return sb;
}
public StringBuilder visitTypeParamType(TypeParamType type, StringBuilder sb) {
sb.append(type.name);
String sep = " extends ";
if (type.classBound != null
&& (options.verbose || !type.classBound.isObject())) {
sb.append(sep);
append(sb, type.classBound);
sep = " & ";
}
if (type.interfaceBounds != null) {
for (Type bound: type.interfaceBounds) {
sb.append(sep);
append(sb, bound);
sep = " & ";
}
}
return sb;
}
public StringBuilder visitWildcardType(WildcardType type, StringBuilder sb) {
switch (type.kind) {
case UNBOUNDED:
sb.append("?");
break;
case EXTENDS:
sb.append("? extends ");
append(sb, type.boundType);
break;
case SUPER:
sb.append("? super ");
append(sb, type.boundType);
break;
default:
throw new AssertionError();
}
return sb;
}
private void append(StringBuilder sb, Type t) {
t.accept(this, sb);
}
private void append(StringBuilder sb, String prefix, List<? extends Type> list, String suffix) {
sb.append(prefix);
String sep = "";
for (Type t: list) {
sb.append(sep);
append(sb, t);
sep = ", ";
}
sb.append(suffix);
}
private void appendIfNotEmpty(StringBuilder sb, String prefix, List<? extends Type> list, String suffix) {
if (!isEmpty(list))
append(sb, prefix, list, suffix);
}
private boolean isEmpty(List<? extends Type> list) {
return (list == null || list.isEmpty());
}
}
protected void writeFields() {
for (Field f: classFile.fields) {
writeField(f);
}
}
protected void writeField(Field f) {
if (!options.checkAccess(f.access_flags))
return;
AccessFlags flags = f.access_flags;
writeModifiers(flags.getFieldModifiers());
Signature_attribute sigAttr = getSignature(f.attributes);
if (sigAttr == null)
print(getJavaFieldType(f.descriptor));
else {
try {
Type t = sigAttr.getParsedSignature().getType(constant_pool);
print(getJavaName(t.toString()));
} catch (ConstantPoolException e) {
// report error?
// fall back on non-generic descriptor
print(getJavaFieldType(f.descriptor));
}
}
print(" ");
print(getFieldName(f));
if (options.showConstants && !options.compat) { // BUG 4111861 print static final field contents
Attribute a = f.attributes.get(Attribute.ConstantValue);
if (a instanceof ConstantValue_attribute) {
print(" = ");
ConstantValue_attribute cv = (ConstantValue_attribute) a;
print(getConstantValue(f.descriptor, cv.constantvalue_index));
}
}
print(";");
println();
indent(+1);
if (options.showDescriptors)
println("descriptor: " + getValue(f.descriptor));
if (options.verbose && !options.compat)
writeList("flags: ", flags.getFieldFlags(), "\n");
if (options.showAllAttrs) {
for (Attribute attr: f.attributes)
attrWriter.write(f, attr, constant_pool);
println();
}
indent(-1);
if (options.showDisassembled || options.showLineAndLocalVariableTables)
println();
}
protected void writeMethods() {
for (Method m: classFile.methods)
writeMethod(m);
setPendingNewline(false);
}
protected void writeMethod(Method m) {
if (!options.checkAccess(m.access_flags))
return;
method = m;
AccessFlags flags = m.access_flags;
Descriptor d;
Type.MethodType methodType;
List<? extends Type> methodExceptions;
Signature_attribute sigAttr = getSignature(m.attributes);
if (sigAttr == null) {
d = m.descriptor;
methodType = null;
methodExceptions = null;
} else {
Signature methodSig = sigAttr.getParsedSignature();
d = methodSig;
try {
methodType = (Type.MethodType) methodSig.getType(constant_pool);
methodExceptions = methodType.throwsTypes;
if (methodExceptions != null && methodExceptions.isEmpty())
methodExceptions = null;
} catch (ConstantPoolException e) {
// report error?
// fall back on standard descriptor
methodType = null;
methodExceptions = null;
}
}
writeModifiers(flags.getMethodModifiers());
if (methodType != null) {
print(new JavaTypePrinter(false).printTypeArgs(methodType.typeParamTypes));
}
if (getName(m).equals("<init>")) {
print(getJavaName(classFile));
print(getJavaParameterTypes(d, flags));
} else if (getName(m).equals("<clinit>")) {
print("{}");
} else {
print(getJavaReturnType(d));
print(" ");
print(getName(m));
print(getJavaParameterTypes(d, flags));
}
Attribute e_attr = m.attributes.get(Attribute.Exceptions);
if (e_attr != null) { // if there are generic exceptions, there must be erased exceptions
if (e_attr instanceof Exceptions_attribute) {
Exceptions_attribute exceptions = (Exceptions_attribute) e_attr;
print(" throws ");
if (methodExceptions != null) { // use generic list if available
writeList("", methodExceptions, "");
} else {
for (int i = 0; i < exceptions.number_of_exceptions; i++) {
if (i > 0)
print(", ");
print(getJavaException(exceptions, i));
}
}
} else {
report("Unexpected or invalid value for Exceptions attribute");
}
}
println(";");
indent(+1);
if (options.showDescriptors) {
println("descriptor: " + getValue(m.descriptor));
}
if (options.verbose && !options.compat) {
writeList("flags: ", flags.getMethodFlags(), "\n");
}
Code_attribute code = null;
Attribute c_attr = m.attributes.get(Attribute.Code);
if (c_attr != null) {
if (c_attr instanceof Code_attribute)
code = (Code_attribute) c_attr;
else
report("Unexpected or invalid value for Code attribute");
}
if (options.showDisassembled && !options.showAllAttrs) {
if (code != null) {
println("Code:");
codeWriter.writeInstrs(code);
codeWriter.writeExceptionTable(code);
}
}
if (options.showLineAndLocalVariableTables) {
if (code != null) {
attrWriter.write(code, code.attributes.get(Attribute.LineNumberTable), constant_pool);
attrWriter.write(code, code.attributes.get(Attribute.LocalVariableTable), constant_pool);
}
}
if (options.showAllAttrs) {
Attribute[] attrs = m.attributes.attrs;
for (Attribute attr: attrs)
attrWriter.write(m, attr, constant_pool);
}
indent(-1);
// set pendingNewline to write a newline before the next method (if any)
// if a separator is desired
setPendingNewline(
options.showDisassembled ||
options.showAllAttrs ||
options.showDescriptors ||
options.showLineAndLocalVariableTables ||
options.verbose);
}
void writeModifiers(Collection<String> items) {
for (Object item: items) {
print(item);
print(" ");
}
}
void writeList(String prefix, Collection<?> items, String suffix) {
print(prefix);
String sep = "";
for (Object item: items) {
print(sep);
print(item);
sep = ", ";
}
print(suffix);
}
void writeListIfNotEmpty(String prefix, List<?> items, String suffix) {
if (items != null && items.size() > 0)
writeList(prefix, items, suffix);
}
Signature_attribute getSignature(Attributes attributes) {
if (options.compat) // javap does not recognize recent attributes
return null;
return (Signature_attribute) attributes.get(Attribute.Signature);
}
String adjustVarargs(AccessFlags flags, String params) {
if (flags.is(ACC_VARARGS) && !options.compat) {
int i = params.lastIndexOf("[]");
if (i > 0)
return params.substring(0, i) + "..." + params.substring(i+2);
}
return params;
}
String getJavaName(ClassFile cf) {
try {
return getJavaName(cf.getName());
} catch (ConstantPoolException e) {
return report(e);
}
}
String getJavaSuperclassName(ClassFile cf) {
try {
return getJavaName(cf.getSuperclassName());
} catch (ConstantPoolException e) {
return report(e);
}
}
String getJavaInterfaceName(ClassFile cf, int index) {
try {
return getJavaName(cf.getInterfaceName(index));
} catch (ConstantPoolException e) {
return report(e);
}
}
String getJavaFieldType(Descriptor d) {
try {
return getJavaName(d.getFieldType(constant_pool));
} catch (ConstantPoolException e) {
return report(e);
} catch (DescriptorException e) {
return report(e);
}
}
String getJavaReturnType(Descriptor d) {
try {
return getJavaName(d.getReturnType(constant_pool));
} catch (ConstantPoolException e) {
return report(e);
} catch (DescriptorException e) {
return report(e);
}
}
String getJavaParameterTypes(Descriptor d, AccessFlags flags) {
try {
return getJavaName(adjustVarargs(flags, d.getParameterTypes(constant_pool)));
} catch (ConstantPoolException e) {
return report(e);
} catch (DescriptorException e) {
return report(e);
}
}
String getJavaException(Exceptions_attribute attr, int index) {
try {
return getJavaName(attr.getException(index, constant_pool));
} catch (ConstantPoolException e) {
return report(e);
}
}
String getValue(Descriptor d) {
try {
return d.getValue(constant_pool);
} catch (ConstantPoolException e) {
return report(e);
}
}
String getFieldName(Field f) {
try {
return f.getName(constant_pool);
} catch (ConstantPoolException e) {
return report(e);
}
}
String getName(Method m) {
try {
return m.getName(constant_pool);
} catch (ConstantPoolException e) {
return report(e);
}
}
static String getJavaName(String name) {
return name.replace('/', '.');
}
String getSourceFile(SourceFile_attribute attr) {
try {
return attr.getSourceFile(constant_pool);
} catch (ConstantPoolException e) {
return report(e);
}
}
/**
* Get the value of an entry in the constant pool as a Java constant.
* Characters and booleans are represented by CONSTANT_Intgere entries.
* Character and string values are processed to escape characters outside
* the basic printable ASCII set.
* @param d the descriptor, giving the expected type of the constant
* @param index the index of the value in the constant pool
* @return a printable string containing the value of the constant.
*/
String getConstantValue(Descriptor d, int index) {
try {
ConstantPool.CPInfo cpInfo = constant_pool.get(index);
switch (cpInfo.getTag()) {
case ConstantPool.CONSTANT_Integer: {
ConstantPool.CONSTANT_Integer_info info =
(ConstantPool.CONSTANT_Integer_info) cpInfo;
String t = d.getValue(constant_pool);
if (t.equals("C")) { // character
return getConstantCharValue((char) info.value);
} else if (t.equals("Z")) { // boolean
return String.valueOf(info.value == 1);
} else { // other: assume integer
return String.valueOf(info.value);
}
}
case ConstantPool.CONSTANT_String: {
ConstantPool.CONSTANT_String_info info =
(ConstantPool.CONSTANT_String_info) cpInfo;
return getConstantStringValue(info.getString());
}
default:
return constantWriter.stringValue(cpInfo);
}
} catch (ConstantPoolException e) {
return "#" + index;
}
}
private String getConstantCharValue(char c) {
StringBuilder sb = new StringBuilder();
sb.append('\'');
sb.append(esc(c, '\''));
sb.append('\'');
return sb.toString();
}
private String getConstantStringValue(String s) {
StringBuilder sb = new StringBuilder();
sb.append("\"");
for (int i = 0; i < s.length(); i++) {
sb.append(esc(s.charAt(i), '"'));
}
sb.append("\"");
return sb.toString();
}
private String esc(char c, char quote) {
if (32 <= c && c <= 126 && c != quote)
return String.valueOf(c);
else switch (c) {
case '\b': return "\\b";
case '\n': return "\\n";
case '\t': return "\\t";
case '\f': return "\\f";
case '\r': return "\\r";
case '\\': return "\\\\";
case '\'': return "\\'";
case '\"': return "\\\"";
default: return String.format("\\u%04x", (int) c);
}
}
private Options options;
private AttributeWriter attrWriter;
private CodeWriter codeWriter;
private ConstantWriter constantWriter;
private ClassFile classFile;
private URI uri;
private long lastModified;
private String digestName;
private byte[] digest;
private int size;
private ConstantPool constant_pool;
private Method method;
}
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