package com.ace.jvm.loader;
import java.io.UnsupportedEncodingException;
import com.ace.jvm.clz.AccessFlag;
import com.ace.jvm.clz.ClassFile;
import com.ace.jvm.clz.ClassIndex;
import com.ace.jvm.constant.ClassInfo;
import com.ace.jvm.constant.ConstantPool;
import com.ace.jvm.constant.FieldRefInfo;
import com.ace.jvm.constant.MethodRefInfo;
import com.ace.jvm.constant.NameAndTypeInfo;
import com.ace.jvm.constant.NullConstantInfo;
import com.ace.jvm.constant.StringInfo;
import com.ace.jvm.constant.UTF8Info;
public class ClassFileParser {
public ClassFile parse(byte[] codes) {
ClassFile clzFile = new ClassFile();
ByteCodeIterator iter = new ByteCodeIterator(codes);
String magicNum = iter.nextU4ToHexString();
if (!"cafebabe".equals(magicNum)) {
return null;
}
clzFile.setMinorVersion(iter.nextU2ToInt());
clzFile.setMajorVersion(iter.nextU2ToInt());
ConstantPool pool = parseConstantPool(iter);
clzFile.setConstPool(pool);
AccessFlag flag = parseAccessFlag(iter);
clzFile.setAccessFlag(flag);
ClassIndex index = parseClassInfex(iter);
clzFile.setClassIndex(index);
return clzFile;
}
private AccessFlag parseAccessFlag(ByteCodeIterator iter) {
int flagValue = iter.nextU2ToInt();
AccessFlag accessFlag = new AccessFlag(flagValue);
return accessFlag;
}
private ClassIndex parseClassInfex(ByteCodeIterator iter) {
ClassIndex classIndex = new ClassIndex();
int thisClassIndex = iter.nextU2ToInt();
classIndex.setThisClassIndex(thisClassIndex);
int superClassIndex = iter.nextU2ToInt();
classIndex.setSuperClassIndex(superClassIndex);
return classIndex;
}
private ConstantPool parseConstantPool(ByteCodeIterator iter) {
ConstantPool pool = new ConstantPool();
int poolCount = iter.nextU2ToInt();
pool.addConstantInfo(new NullConstantInfo());
for (int i = 1; i < poolCount - 1; i++) {
int tag = iter.nextU1ToInt();
if(tag == 7){
int utf8Index = iter.nextU2ToInt();
ClassInfo classInfo = new ClassInfo(pool);
classInfo.setUtf8Index(utf8Index);
pool.addConstantInfo(classInfo);
} else if(tag == 1){
int len = iter.nextU2ToInt();
byte[] data = iter.getBytes(len);
String str = null;
try {
str = new String(data, "UTF-8");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
UTF8Info utf8Info = new UTF8Info(pool);
utf8Info.setLength(len);
utf8Info.setValue(str);
pool.addConstantInfo(utf8Info);
} else if(tag == 8){
StringInfo stringInfo = new StringInfo(pool);
int index = iter.nextU2ToInt();
stringInfo.setIndex(index);
pool.addConstantInfo(stringInfo);
} else if(tag == 9){
FieldRefInfo fieldRefInfo = new FieldRefInfo(pool);
int classInfoIndex = iter.nextU2ToInt();
int nameAndTypeIndex = iter.nextU2ToInt();
fieldRefInfo.setClassInfoIndex(classInfoIndex);
fieldRefInfo.setNameAndTypeIndex(nameAndTypeIndex);
pool.addConstantInfo(fieldRefInfo);
} else if(tag == 10){
MethodRefInfo methodRefInfo = new MethodRefInfo(pool);
int classInfoIndex = iter.nextU2ToInt();
int nameAndTypeIndex = iter.nextU2ToInt();
methodRefInfo.setClassInfoIndex(classInfoIndex);
methodRefInfo.setNameAndTypeIndex(nameAndTypeIndex);
pool.addConstantInfo(methodRefInfo);
} else if(tag == 12){
NameAndTypeInfo nameAndTypeInfo = new NameAndTypeInfo(pool);
int index1 = iter.nextU2ToInt();
int index2 = iter.nextU2ToInt();
nameAndTypeInfo.setIndex1(index1);
nameAndTypeInfo.setIndex2(index2);
pool.addConstantInfo(nameAndTypeInfo);
} else {
throw new RuntimeException("the constant pool tag " + tag + " is not exist.");
}
}
return pool;
}
}