有人投票认为这个问题“太宽泛”了。我不确定这是否是适当的关闭原因，但它可能是，因为人们可以认为这个问题（这是your previous question 的后续问题）只是要求其他人为你做一些工作。
但是，要回答如何使用 BCEL 检测单个 JAR 文件中的类之间的引用这一基本问题：
您可以从JarFile 获取JavaClass 对象的列表。对于每个JavaClass 对象，您可以检查Method 对象及其InstructionList。从这些说明中，您可以选择InvokeInstruction 对象并进一步检查它们以找出实际调用哪个类的哪个方法。
以下程序打开一个 JAR 文件（出于显而易见的原因，它是 bcel-5.2.jar - 无论如何你都需要它......）并以上述方式处理它。对于 JAR 文件的每个 JavaClass，它会创建一个从所有引用的 JavaClass 对象到在这些类上调用的 Methods 列表的映射，并相应地打印信息：
import java.io.IOException;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import org.apache.bcel.classfile.ClassFormatException;
import org.apache.bcel.classfile.ClassParser;
import org.apache.bcel.classfile.ConstantPool;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.InvokeInstruction;
import org.apache.bcel.generic.MethodGen;
import org.apache.bcel.generic.ObjectType;
import org.apache.bcel.generic.ReferenceType;
import org.apache.bcel.generic.Type;
public class BCELRelationships
{
public static void main(String[] args) throws Exception
{
JarFile jarFile = null;
try
{
String jarName = "bcel-5.2.jar";
jarFile = new JarFile(jarName);
findReferences(jarName, jarFile);
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
if (jarFile != null)
{
try
{
jarFile.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
}
private static void findReferences(String jarName, JarFile jarFile)
throws ClassFormatException, IOException, ClassNotFoundException
{
Map<String, JavaClass> javaClasses =
collectJavaClasses(jarName, jarFile);
for (JavaClass javaClass : javaClasses.values())
{
System.out.println("Class "+javaClass.getClassName());
Map<JavaClass, Set<Method>> references =
computeReferences(javaClass, javaClasses);
for (Entry<JavaClass, Set<Method>> entry : references.entrySet())
{
JavaClass referencedJavaClass = entry.getKey();
Set<Method> methods = entry.getValue();
System.out.println(
" is referencing class "+
referencedJavaClass.getClassName()+" by calling");
for (Method method : methods)
{
System.out.println(
" "+method.getName()+" with arguments "+
Arrays.toString(method.getArgumentTypes()));
}
}
}
}
private static Map<String, JavaClass> collectJavaClasses(
String jarName, JarFile jarFile)
throws ClassFormatException, IOException
{
Map<String, JavaClass> javaClasses =
new LinkedHashMap<String, JavaClass>();
Enumeration<JarEntry> entries = jarFile.entries();
while (entries.hasMoreElements())
{
JarEntry entry = entries.nextElement();
if (!entry.getName().endsWith(".class"))
{
continue;
}
ClassParser parser =
new ClassParser(jarName, entry.getName());
JavaClass javaClass = parser.parse();
javaClasses.put(javaClass.getClassName(), javaClass);
}
return javaClasses;
}
public static Map<JavaClass, Set<Method>> computeReferences(
JavaClass javaClass, Map<String, JavaClass> knownJavaClasses)
throws ClassNotFoundException
{
Map<JavaClass, Set<Method>> references =
new LinkedHashMap<JavaClass, Set<Method>>();
ConstantPool cp = javaClass.getConstantPool();
ConstantPoolGen cpg = new ConstantPoolGen(cp);
for (Method m : javaClass.getMethods())
{
String fullClassName = javaClass.getClassName();
String className =
fullClassName.substring(0, fullClassName.length()-6);
MethodGen mg = new MethodGen(m, className, cpg);
InstructionList il = mg.getInstructionList();
if (il == null)
{
continue;
}
InstructionHandle[] ihs = il.getInstructionHandles();
for(int i=0; i < ihs.length; i++)
{
InstructionHandle ih = ihs[i];
Instruction instruction = ih.getInstruction();
if (!(instruction instanceof InvokeInstruction))
{
continue;
}
InvokeInstruction ii = (InvokeInstruction)instruction;
ReferenceType referenceType = ii.getReferenceType(cpg);
if (!(referenceType instanceof ObjectType))
{
continue;
}
ObjectType objectType = (ObjectType)referenceType;
String referencedClassName = objectType.getClassName();
JavaClass referencedJavaClass =
knownJavaClasses.get(referencedClassName);
if (referencedJavaClass == null)
{
continue;
}
String methodName = ii.getMethodName(cpg);
Type[] argumentTypes = ii.getArgumentTypes(cpg);
Method method =
findMethod(referencedJavaClass, methodName, argumentTypes);
Set<Method> methods = references.get(referencedJavaClass);
if (methods == null)
{
methods = new LinkedHashSet<Method>();
references.put(referencedJavaClass, methods);
}
methods.add(method);
}
}
return references;
}
private static Method findMethod(
JavaClass javaClass, String methodName, Type argumentTypes[])
throws ClassNotFoundException
{
for (Method method : javaClass.getMethods())
{
if (method.getName().equals(methodName))
{
if (Arrays.equals(argumentTypes, method.getArgumentTypes()))
{
return method;
}
}
}
for (JavaClass superClass : javaClass.getSuperClasses())
{
Method method = findMethod(superClass, methodName, argumentTypes);
if (method != null)
{
return method;
}
}
return null;
}
}
但请注意，此信息可能并非在所有意义上都是完整的。例如，由于多态性，您可能并不总是检测到某个类的对象上调用了方法，因为它“隐藏”在多态抽象后面。例如，在一个类似sn-p的代码中
void call() {
MyClass m = new MyClass();
callToString(m);
}
void callToString(Object object) {
object.toString();
}
对toString 的调用实际上发生在MyClass 的实例上。但由于多态性，只能识别为在“someObject”上调用该方法。