GraalVM Native + Base64 编解码命令行小工具开发

初衷：
- 浏览 V 站帖子有很多 Base64 加密的信息，希望能够快速解密。

实现：

v1：直接使用 JShell 命令行运行 Java 代码解密

ant@ant:~$ jshell 
|  Welcome to JShell -- Version 17.0.9
|  For an introduction type: /help intro

jshell> var enc = "c2F2ZW9sZQ=="
enc ==> "c2F2ZW9sZQ=="

jshell> var decodedBytes = Base64.getDecoder().decode(enc.getBytes())
decodedBytes ==> byte[8] { 115, 97, 118, 101, 95, 111, 108, 101 }

jshell> new String(decodedBytes)
$3 ==> "saveole"

v2：GraalVM Native 的方式将 Java 程序编译打包成可执行文件小工具

原 Java 程序：

import java.util.Base64;

public class Base64Tool {
    static String helpMsg = """
		-e Encode input string
		-d Decode input string 
            """;;
    
    public static void main(String[] args) {
        if (args == null || args.length == 0) {
            System.err.println(helpMsg);
            System.exit(1);
        }
        var arg = args[0];
        switch(arg) {
          case "-help":
              System.out.println(helpMsg);
              break;
          case "-e":
              var toEncode = getAndCheckArg(args);
              System.out.println(new String(Base64.getEncoder().encode(toEncode.getBytes())));
              break;
          case "-d":
              var toDecode = getAndCheckArg(args);
              System.out.println(new String(Base64.getDecoder().decode(toDecode.getBytes())));
              break;
          default:
              System.err.println("Unknown command, use -help to see how to use this tool.");
              break;
        }
        System.exit(1);
    }

    static String getAndCheckArg(String[] args) {
        if (args == null || args.length < 2) {
            System.err.println("Please input valid string");
            System.exit(0);
        }
        return args[1];
    }
}

使用 native-image 编译构建可执行程序

ant@ant:~/native$ javac Base64Tool.java 
ant@ant:~/native$ native-image Base64Tool
========================================================================================================================
GraalVM Native Image: Generating 'base64tool' (executable)...
========================================================================================================================
[1/8] Initializing...                                                                                    (1.7s @ 0.14GB)
 Java version: 17.0.9+9, vendor version: GraalVM CE 17.0.9+9.1
 Graal compiler: optimization level: 2, target machine: x86-64-v3
 C compiler: gcc (linux, x86_64, 11.4.0)
 Garbage collector: Serial GC (max heap size: 80% of RAM)
[2/8] Performing analysis...  [****]                                                                     (4.4s @ 0.27GB)
   2,912 (71.67%) of  4,063 types reachable
   3,536 (50.94%) of  6,942 fields reachable
  13,209 (43.86%) of 30,116 methods reachable
     907 types,     0 fields, and   348 methods registered for reflection
      58 types,    58 fields, and    52 methods registered for JNI access
       4 native libraries: dl, pthread, rt, z
[3/8] Building universe...                                                                               (0.9s @ 0.30GB)
[4/8] Parsing methods...      [*]                                                                        (0.6s @ 0.32GB)
[5/8] Inlining methods...     [***]                                                                      (0.5s @ 0.22GB)
[6/8] Compiling methods...    [**]                                                                       (4.5s @ 0.35GB)
[7/8] Layouting methods...    [*]                                                                        (0.7s @ 0.37GB)
[8/8] Creating image...       [*]                                                                        (1.1s @ 0.38GB)
   4.42MB (36.75%) for code area:     7,506 compilation units
   7.04MB (58.46%) for image heap:   89,275 objects and 5 resources
 590.55kB ( 4.79%) for other data
  12.03MB in total
------------------------------------------------------------------------------------------------------------------------
Top 10 origins of code area:                                Top 10 object types in image heap:
   3.37MB java.base                                         1009.70kB byte[] for code metadata
 795.13kB svm.jar (Native Image)                             889.53kB java.lang.String
 112.32kB java.logging                                       836.32kB byte[] for general heap data
  62.07kB org.graalvm.nativeimage.base                       671.94kB java.lang.Class
  24.15kB jdk.internal.vm.ci                                 665.65kB byte[] for java.lang.String
  23.14kB org.graalvm.sdk                                    347.48kB java.util.HashMap$Node
   6.11kB jdk.internal.vm.compiler                           250.25kB com.oracle.svm.core.hub.DynamicHubCompanion
   1.68kB Base64Tool                                         169.02kB java.lang.String[]
   1.35kB jdk.proxy1                                         165.57kB java.lang.Object[]
   1.27kB jdk.proxy3                                         148.84kB byte[] for embedded resources
   1.56kB for 2 more packages                                  1.20MB for 829 more object types
------------------------------------------------------------------------------------------------------------------------
Recommendations:
 HEAP: Set max heap for improved and more predictable memory usage.
 CPU:  Enable more CPU features with '-march=native' for improved performance.
------------------------------------------------------------------------------------------------------------------------
                        0.7s (4.3% of total time) in 164 GCs | Peak RSS: 0.84GB | CPU load: 8.21
------------------------------------------------------------------------------------------------------------------------
Produced artifacts:
 /home/ant/native/base64tool (executable)
========================================================================================================================
Finished generating 'base64tool' in 14.8s.

使用

ant@ant:~/native$ ./base64tool -help
-e Encode input string
-d Decode input string

ant@ant:~/native$ ./base64tool -e saveole
c2F2ZW9sZQ==
ant@ant:~/native$ ./base64tool -d c2F2ZW9sZQ==
saveole
ant@ant:~/native$

注意事项
- 使用 native-image 构建可执行程序时，需要注意当前的执行目录。它默认会扫描当前目录及子目录下的所有文件(不能区分 Java 程序相关的文件)，导致构建失败。建议在单独的文件夹中进行编译构建。