java - 解析 Jar 文件并查找类之间的关系？

Question

如何检测 jar 文件中的类是否扩展了其他类，或者是否有对其他类对象的方法调用或创建了其他类对象？然后系统找出哪个类扩展了哪个类，哪个类调用了哪个类的方法。

我正在使用 Classparser 来解析 jar。这是我的部分代码:

        String jarfile = "C:\\Users\\OOOO\\Desktop\\Sample.Jar";

        jar = new JarFile(jarfile);
        Enumeration<JarEntry> entries = jar.entries();
        while (entries.hasMoreElements()) {
            JarEntry entry = entries.nextElement();
            if (!entry.getName().endsWith(".class")) {
                continue;
            }

            ClassParser parser = new ClassParser(jarfile, entry.getName());
            JavaClass javaClass = parser.parse();

Answer 1

_{有人投票结束这个问题，因为它“过于宽泛”。我不确定这是否是这里适当的关闭原因，但它可能是，因为可以将这个问题(这是 your previous question 的后续问题)视为只是要求其他人为您做一些工作。}

但是，要回答如何使用 BCEL 检测单个 JAR 文件中类之间的引用这一基本问题:

您可以从JarFile 中获取JavaClass 对象的列表。对于这些 JavaClass 对象中的每一个，您可以检查 Method 对象及其 InstructionList。在这些指令中，您可以选择 InvokeInstruction 对象并进一步检查它们以找出实际调用了哪个类的哪个方法。

以下程序打开一个 JAR 文件(很明显，它是 bcel-5.2.jar - 无论如何您都需要它...)并按上述方式处理它。对于 JAR 文件的每个 JavaClass，它都会创建一个从所有引用的 JavaClass 对象到在这些对象上调用的 Method 列表的映射类，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;
    }
}

但是请注意，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，您可能不会总是检测到某个方法在某个类的对象上被调用，因为它“隐藏”在多态抽象之后。例如，在这样的代码片段中

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。但是由于多态性，它只能被识别为在“some Object”上调用这个方法。