BCELって何?

解析プログラムのひな形

package com.example.quiz7;

import java.io.File;
import java.io.FileInputStream;
import java.util.jar.JarEntry;
import java.util.jar.JarInputStream;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.bcel.classfile.ClassParser;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.JavaClass;

public class BcelExam {
    
    public static void main(final String[] args) {
        try {
            BcelExam thisClass = new BcelExam();
            thisClass.dirWalk(new File("target/classes"));
        } catch (Exception ex) {
            Logger.getLogger(BcelExam.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private void dirWalk(File path) throws Exception {
        if (path.isDirectory()) {
            for (File child : path.listFiles()) {
                dirWalk(child);
            }
        } else if (path.getName().endsWith("jar") || path.getName().endsWith("zip")) {
            jarWalk(path);
        } else if (path.getName().endsWith("class")) {
            JavaClass javaClass = new ClassParser(path.getAbsolutePath()).parse();
            classWalk(javaClass);
        }
    }

    private void jarWalk(File jarFile) throws Exception {
        try (JarInputStream jarIn = new JarInputStream(new FileInputStream(jarFile));) {
            JarEntry entry;
            while ((entry = jarIn.getNextJarEntry()) != null) {
                if (!entry.isDirectory()) {
                    String fileName = entry.getName();
                    if (fileName.endsWith("class")) {
                        JavaClass javaClass = new ClassParser(jarFile.getAbsolutePath(), fileName).parse();
                        classWalk(javaClass);
                    }
                }
            }
        }
    }

    private void classWalk(final JavaClass javaClass) {
        final org.apache.bcel.classfile.Method[] methods = javaClass.getMethods();
        for (org.apache.bcel.classfile.Method method : methods) {
            methodWalk(javaClass.getClassName(), method);
        }
    }

    private void methodWalk(final String clazz, final org.apache.bcel.classfile.Method method) {
        codeWalk(clazz + "#" + method.getName(), method.getCode());
    }

    private void codeWalk(final String method, final Code code) {
        System.out.println(method);
        
        if (code == null) {
            // Interfaceの場合
            return;
        }
        for (String line : code.toString().split("\n")) {
            System.out.println(line);
        }
    }
}

自分を読み込んだ結果

com.example.quiz7.BcelExam#main
Code(max_stack = 4, max_locals = 2, code_length = 43)
0:    new		<com.example.quiz7.BcelExam> (2)
3:    dup
4:    invokespecial	com.example.quiz7.BcelExam.<init> ()V (3)
7:    astore_1
8:    aload_1
9:    new		<java.io.File> (4)
12:   dup
13:   ldc		"target/classes" (5)
15:   invokespecial	java.io.File.<init> (Ljava/lang/String;)V (6)
18:   invokespecial	com.example.quiz7.BcelExam.dirWalk (Ljava/io/File;)V (7)
21:   goto		#42
24:   astore_1
25:   ldc_w		com.example.quiz7.BcelExam (2)
28:   invokevirtual	java.lang.Class.getName ()Ljava/lang/String; (9)
31:   invokestatic	java.util.logging.Logger.getLogger (Ljava/lang/String;)Ljava/util/logging/Logger; (10)
34:   getstatic		java.util.logging.Level.SEVERE Ljava/util/logging/Level; (11)
37:   aconst_null
38:   aload_1
39:   invokevirtual	java.util.logging.Logger.log (Ljava/util/logging/Level;Ljava/lang/String;Ljava/lang/Throwable;)V (12)
42:   return

Exception handler(s) = 
From	To	Handler	Type
0	21	24	java.lang.Exception(8)

Attribute(s) = 
LineNumber(0, 21), LineNumber(8, 22), LineNumber(21, 25), LineNumber(24, 23), 
LineNumber(25, 24), LineNumber(42, 26)
LocalVariable(start_pc = 8, length = 13, index = 1:com.example.quiz7.BcelExam thisClass)
LocalVariable(start_pc = 25, length = 17, index = 1:Exception ex)
LocalVariable(start_pc = 0, length = 43, index = 0:String[] args)
(Unknown attribute StackMapTable: 00 02 58 07 00 45 11)
com.example.quiz7.BcelExam#dirWalk
Code(max_stack = 3, max_locals = 6, code_length = 110)
0:    aload_1
1:    invokevirtual	java.io.File.isDirectory ()Z (13)
4:    ifeq		#45
7:    aload_1
8:    invokevirtual	java.io.File.listFiles ()[Ljava/io/File; (14)
11:   astore_2
12:   aload_2
13:   arraylength
14:   istore_3
15:   iconst_0
16:   istore		%4
18:   iload		%4
20:   iload_3
21:   if_icmpge		#42
24:   aload_2
25:   iload		%4
27:   aaload
28:   astore		%5
30:   aload_0
31:   aload		%5
33:   invokespecial	com.example.quiz7.BcelExam.dirWalk (Ljava/io/File;)V (7)
36:   iinc		%4	1
39:   goto		#18
42:   goto		#109
45:   aload_1
46:   invokevirtual	java.io.File.getName ()Ljava/lang/String; (15)
49:   ldc		"jar" (16)
51:   invokevirtual	java.lang.String.endsWith (Ljava/lang/String;)Z (17)
54:   ifne		#69
57:   aload_1
58:   invokevirtual	java.io.File.getName ()Ljava/lang/String; (15)
61:   ldc		"zip" (18)
63:   invokevirtual	java.lang.String.endsWith (Ljava/lang/String;)Z (17)
66:   ifeq		#77
69:   aload_0
70:   aload_1
71:   invokespecial	com.example.quiz7.BcelExam.jarWalk (Ljava/io/File;)V (19)
74:   goto		#109
77:   aload_1
78:   invokevirtual	java.io.File.getName ()Ljava/lang/String; (15)
81:   ldc		"class" (20)
83:   invokevirtual	java.lang.String.endsWith (Ljava/lang/String;)Z (17)
86:   ifeq		#109
89:   new		<org.apache.bcel.classfile.ClassParser> (21)
92:   dup
93:   aload_1
94:   invokevirtual	java.io.File.getAbsolutePath ()Ljava/lang/String; (22)
97:   invokespecial	org.apache.bcel.classfile.ClassParser.<init> (Ljava/lang/String;)V (23)
100:  invokevirtual	org.apache.bcel.classfile.ClassParser.parse ()Lorg/apache/bcel/classfile/JavaClass; (24)
103:  astore_2
104:  aload_0
105:  aload_2
106:  invokespecial	com.example.quiz7.BcelExam.classWalk (Lorg/apache/bcel/classfile/JavaClass;)V (25)
109:  return
...

Java#Jakarta


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Last-modified: 2014-01-06 (月) 22:39:42 (1061d)
ISBN10
ISBN13
9784061426061