jclasslib 查看类信息

电玩女神 2023-01-09 06:12 170阅读 0赞

jclasslib 工具可以查看 class 文件的结构信息

github 下载地址（借助下载工具会快些）：  
[https://github.com/ingokegel/jclasslib/releases/download/5.7/jclasslib\_win64\_5\_7.exe][https_github.com_ingokegel_jclasslib_releases_download_5.7_jclasslib_win64_5_7.exe]

Test.java 代码

public class Test {
        public int test(int i) {
            return i+1;
        }
    }

jclasslib 安装到本地，打开 Test.java 编译后的 Test.class 文件

[![159303d479c774436e56f7eec925b098.png][]][159303d479c774436e56f7eec925b098.png 1]

与我之前手工标记的一张图，结果一致

[![bce51deea926be76d77e230c7c3141b8.png][]][bce51deea926be76d77e230c7c3141b8.png 1]

详细的分析

Test.java 编译的 Test.class 的文件中，包含：

1.  魔数 Magic Number(CAFE BABE)
2.  版本号(Minor:0000，Major：0034)
3.  常量池（14项）
4.  访问标志（public）
5.  类索引、父类索引、接口索引集合（2个：this\_class、super\_class）
6.  字段表(field\_info)集合（0个）
7.  方法表(method\_info)集合（2个）
8.  属性表(attribute\_info)集合（1个）

见这篇文章：

[https://www.javanav.com/val/296686d016a147f5b91d8ad82c6f048d.html][https_www.javanav.com_val_296686d016a147f5b91d8ad82c6f048d.html]

jclasslib 进行了整合

*  一般信息显示了版本号、常量池、访问标志、本类索引、父类索引、接口计数、方法计数、属性计数，汇总了 class 文件的总体情况
 *  常量池、接口、字段、方法、属性，点进各项可以查看对应的具体信息

--------------------

### 【Java学习资源】整理推荐 ###

*  [Centos 7.4 编译 OpenJDK 8][Centos 7.4 _ OpenJDK 8]
 *  [MAT 分析堆内存快照][MAT]
 *  [jclasslib 查看类信息][jclasslib]
 *  [增大 MAT 堆内存][MAT 1]
 *  [JVM 常用配置参数(Java 8)][JVM _Java 8]
 *  [40 道JVM面试题解答][40 _JVM]
 *  [JVM 问题排查常用指令][JVM]
 *  [jvisualvm 远程连接服务器 JVM][jvisualvm _ JVM]
 *  [字节码指令分类][Link 1]
 *  [\-verbose:gc 和 -XX:+PrintGC 的区别][-verbose_gc _ -XX_PrintGC]
 *  [JVM字节码指令表][JVM 1]
 *  [图解 Class 文件结构][https_www.javanav.com_val_296686d016a147f5b91d8ad82c6f048d.html]
 *  [Class 文件的结构][Class]
 *  [JVM 故障处理工具列表][JVM 2]
 *  [HotSpot 内存分配的主要规则][HotSpot]
 *  [开启 GC 日志][GC]
 *  [垃圾收集器及特点][Link 2]
 *  [JVM垃圾回收算法][JVM 3]
 *  [什么样的 Java 对象会被当垃圾回收？][Java]
 *  [内存溢出复现][Link 3]
 *  [HotSpot VM 中对象的内存分析][HotSpot VM]
 *  [JVM 控制的内存区域][JVM 4]
 *  [JVM家族][JVM 5]
 *  [Java 的发展史][Java 1]
 *  [常见 JVM dump 指令][JVM dump]

--------------------

### 【Java面试题与答案】整理推荐 ###

*  [基础与语法][Link 4]
 *  [集合][Link 5]
 *  [网络编程][Link 6]
 *  [并发编程][Link 7]
 *  [Web][]
 *  [安全][Link 8]
 *  [设计模式][Link 9]
 *  [框架][Link 10]
 *  [算法与数据结构][Link 11]
 *  [异常][Link 12]
 *  [文件解析与生成][Link 13]
 *  [Linux][]
 *  [MySQL][]
 *  [Oracle][]
 *  [Redis][]
 *  [Dubbo][]

[https_github.com_ingokegel_jclasslib_releases_download_5.7_jclasslib_win64_5_7.exe]: https://github.com/ingokegel/jclasslib/releases/download/5.7/jclasslib_win64_5_7.exe
[159303d479c774436e56f7eec925b098.png]: /images/20221119/2e9df0861409459ea06e80b6c9e27d4e.png
[159303d479c774436e56f7eec925b098.png 1]: https://www.javanav.com/aimgs/image__20201231094704.png
[bce51deea926be76d77e230c7c3141b8.png]: /images/20221119/8d644416ddce418593023a58e179598e.png
[bce51deea926be76d77e230c7c3141b8.png 1]: https://www.javanav.com/aimgs/image__20201123121959.png
[https_www.javanav.com_val_296686d016a147f5b91d8ad82c6f048d.html]: https://www.javanav.com/val/296686d016a147f5b91d8ad82c6f048d.html
[Centos 7.4 _ OpenJDK 8]: https://www.javanav.com/val/9ab53ed895974be8986d79ef64aa1087.html
[MAT]: https://www.javanav.com/val/c3466d5a4ae54cbbacff48a77764eefc.html
[jclasslib]: https://www.javanav.com/val/f6c5cf9df8554a788b403bdc4c711564.html
[MAT 1]: https://www.javanav.com/val/60b1b34a85474c9ba01858ff435c0abe.html
[JVM _Java 8]: https://www.javanav.com/val/d76fe4761aa64973b6ae730326aa6d34.html
[40 _JVM]: https://www.javanav.com/val/93550f179edb4a77bbf4d35faa6d560c.html
[JVM]: https://www.javanav.com/val/731835b642a548e8a7d7c14aeab161e6.html
[jvisualvm _ JVM]: https://www.javanav.com/val/925604ea926e42aa9f936df96b6c69d0.html
[Link 1]: https://www.javanav.com/val/ecd6c327f9164c358ee168a8f4d6cdfa.html
[-verbose_gc _ -XX_PrintGC]: https://www.javanav.com/val/3159ceb444204e0a830b921dee94d9d1.html
[JVM 1]: https://www.javanav.com/val/2e69020292844506ac038fa6942f359f.html
[Class]: https://www.javanav.com/val/b21a17ddecf543239060a2af5ed9c21e.html
[JVM 2]: https://www.javanav.com/val/a52a3d4ee8df4a7b9d2262572ed303dd.html
[HotSpot]: https://www.javanav.com/val/6b9865caa5f84c348f9485c558df4551.html
[GC]: https://www.javanav.com/val/acbb4071b64240b49145a1baf7856551.html
[Link 2]: https://www.javanav.com/val/391b81f602e74370aa62b8e1b5d84d83.html
[JVM 3]: https://www.javanav.com/val/bbee490647d7459984be9d612dc4b75e.html
[Java]: https://www.javanav.com/val/00c98517d5e940248f6c50403d184dd5.html
[Link 3]: https://www.javanav.com/val/2a7fd81371534120a3e86935cc1ecb01.html
[HotSpot VM]: https://www.javanav.com/val/49e9ce5857744a39a88b1977d84086c7.html
[JVM 4]: https://www.javanav.com/val/34d7eadd6bdb4f179913fe172c4a144b.html
[JVM 5]: https://www.javanav.com/val/c850f57e1cee4024a12e3ac449d2757d.html
[Java 1]: https://www.javanav.com/val/f6a20dc008d6431bb54ba6afc71cbefe.html
[JVM dump]: https://www.javanav.com/val/200700af5dfe459d957e04e93c813a0c.html
[Link 4]: https://www.javanav.com/interview/93b0069472fd479393006c0e73043fc4.html
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[Web]: https://www.javanav.com/interview/4e27cb63adb440c6825a159d35cf4010.html
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[Link 13]: https://www.javanav.com/interview/67a50996c28f418e83b109ea42fc3eff.html
[Linux]: https://www.javanav.com/interview/00cccb81729540d1923bd0a0ef49533a.html
[MySQL]: https://www.javanav.com/interview/d311e78502a845f1a4bb307bd6aec2b3.html
[Oracle]: https://www.javanav.com/interview/5f29e9677edf4a16be3dce30d257c9ab.html
[Redis]: https://www.javanav.com/interview/066c62b3af4d4827b2243a822c3084a9.html
[Dubbo]: https://www.javanav.com/interview/9a3e7a7740324757abaab953f7ebc455.html