public class HelloWorld {
    static class Greeter {
        static {
            System.out.println("Greeter is getting ready!");
        }

        public static void greet() {
            System.out.println("Hello, World!");
        }
    }
    public static void main(String[] args) {
        Greeter.greet();
    }
}

javac HelloWorld.java
java Helloworld
 
 
native-image HelloWorld
./helloWorld
 
# 告诉natvie-image 构建的时候初始化静态类
native-image HelloWorld --initialize-at-build-time=HelloWorld\$Greeter
 ./helloWorld

class Example {
    private static final String message;
    
    static {
        message = System.getProperty("message");
    }

    public static void main(String[] args) {
        System.out.println("Hello, World! My message is: " + message);
    }
}

javac Example.java
java -Dmessage=hi Example
java -Dmessage=hello Example 
java Example

native-image Example --initialize-at-build-time=Example -Dmessage=native
./example 
./example -Dmessage=aNewMessage

native-image
./example -Dmessage=aNewMessage
./example -Dmessage=Hello

class ReflectiveAccess {
    public Class<Foo> fetchFoo() throws ClassNotFoundException {
        return Class.forName("Foo");
    }
}

| src
|   --com/
|      -- example
|          -- App.java

package com.example;

public class App {

    public static void main(String[] args) {
        String str = "Native Image is awesome";
        String reversed = reverseString(str);
        System.out.println("The reversed string is: " + reversed);
    }

    public static String reverseString(String str) {
        if (str.isEmpty())
            return str;
        return reverseString(str.substring(1)) + str.charAt(0);
    }
}

1.  javac -d build src/com/example/App.java
2.  jar --create --file App.jar --main-class com.example.App -C build .
3.  native-image -jar App.jar

========================================================================================================================
GraalVM Native Image: Generating 'App' (executable)...
========================================================================================================================
[1/8] Initializing...                                                                                    (5.9s @ 0.11GB)
 Java version: 21+35, vendor version: Oracle GraalVM 21+35.1
 Graal compiler: optimization level: 2, target machine: armv8-a, PGO: off
 C compiler: cc (apple, arm64, 15.0.0)
 Garbage collector: Serial GC (max heap size: 80% of RAM)
 1 user-specific feature(s):
 - com.oracle.svm.thirdparty.gson.GsonFeature
------------------------------------------------------------------------------------------------------------------------
Build resources:
 - 24.18GB of memory (75.6% of 32.00GB system memory, determined at start)
 - 10 thread(s) (100.0% of 10 available processor(s), determined at start)
[2/8] Performing analysis...  [******]                                                                   (3.5s @ 0.22GB)
    2,085 reachable types   (60.9% of    3,421 total)
    2,000 reachable fields  (45.9% of    4,361 total)
    9,590 reachable methods (38.4% of   24,950 total)
      764 types,   109 fields, and   474 methods registered for reflection
       49 types,    33 fields, and    48 methods registered for JNI access
        4 native libraries: -framework Foundation, dl, pthread, z
[3/8] Building universe...                                                                               (0.7s @ 0.28GB)
[4/8] Parsing methods...      [*]                                                                        (0.5s @ 0.28GB)
[5/8] Inlining methods...     [***]                                                                      (0.4s @ 0.26GB)
[6/8] Compiling methods...    [***]                                                                      (7.9s @ 0.30GB)
[7/8] Layouting methods...    [*]                                                                        (0.7s @ 0.32GB)
[8/8] Creating image...       [*]                                                                        (1.2s @ 0.24GB)
   3.21MB (44.81%) for code area:     4,517 compilation units
   3.75MB (52.33%) for image heap:   57,014 objects and 71 resources
 209.98kB ( 2.86%) for other data
   7.17MB in total
------------------------------------------------------------------------------------------------------------------------
Top 10 origins of code area:                                Top 10 object types in image heap:
   1.71MB java.base                                          839.82kB byte[] for code metadata
   1.23MB svm.jar (Native Image)                             718.58kB byte[] for java.lang.String
  82.86kB com.oracle.svm.svm_enterprise                      438.15kB heap alignment
  40.44kB jdk.proxy3                                         382.41kB java.lang.String
  38.48kB jdk.proxy1                                         330.89kB java.lang.Class
  25.43kB org.graalvm.nativeimage.base                       154.22kB java.util.HashMap$Node
  22.78kB org.graalvm.collections                            114.01kB char[]
  13.92kB jdk.internal.vm.ci                                  99.18kB byte[] for reflection metadata
  13.61kB jdk.internal.vm.compiler                            91.62kB java.lang.Object[]
  11.51kB jdk.proxy2                                          81.45kB com.oracle.svm.core.hub.DynamicHubCompanion
   1.61kB for 2 more packages                                589.69kB for 557 more object types
                              Use '-H:+BuildReport' to create a report with more details.
------------------------------------------------------------------------------------------------------------------------
Security report:
 - Binary does not include Java deserialization.
 - Use '--enable-sbom' to embed a Software Bill of Materials (SBOM) in the binary.
------------------------------------------------------------------------------------------------------------------------
Recommendations:
 PGO:  Use Profile-Guided Optimizations ('--pgo') for improved throughput.
 INIT: Adopt '-H:+StrictImageHeap' to prepare for the next GraalVM release.
 HEAP: Set max heap for improved and more predictable memory usage.
 CPU:  Enable more CPU features with '-march=native' for improved performance.
 QBM:  Use the quick build mode ('-Ob') to speed up builds during development.
------------------------------------------------------------------------------------------------------------------------
                        1.0s (4.8% of total time) in 251 GCs | Peak RSS: 0.82GB | CPU load: 4.95
------------------------------------------------------------------------------------------------------------------------
Produced artifacts:
 /Users/carota/Projects/Java/HelloNativeJar/App (executable)
========================================================================================================================
Finished generating 'App' in 21.1s.

export JAVA_TOOL_OPTIONS="-agentlib:native-image-agent=config-output-dir=/path/to/config-output-dir-{pid}-{datetime}/"

package dream.js.hellospringnative;  
  
import dream.js.hellospringnative.entity.Person;  
import dream.js.hellospringnative.repository.PersonRepository;  
import org.springframework.beans.factory.annotation.Autowired;  
import org.springframework.web.bind.annotation.GetMapping;  
import org.springframework.web.bind.annotation.RestController;  
  
@RestController  
public class CommonController {  
  
    private PersonRepository personRepository;  
  
    public CommonController(@Autowired PersonRepository personRepository) {  
        this.personRepository = personRepository;  
    }  
  
    @GetMapping("/persons")  
    public Iterable<Person> persons() {  
        return personRepository.findAll();  
    }  
  
    @GetMapping("/hello")  
    public String hello() {  
        return "world";  
    }  
}