add jni tutorial

24.06/jni/Main.c

@@ -0,0 +1,27 @@
+#include <jni.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "Main.h"
+
+JNIEXPORT void JNICALL Java_Main_native_1hello
+  (JNIEnv * env, jclass cls) {
+    printf("Hello JNI!\n");
+}
+
+JNIEXPORT jint JNICALL Java_Main_add
+    (JNIEnv * env, jobject instance, jint a, jint b) {
+    return a + b;
+}
+
+JNIEXPORT jstring JNICALL Java_Main_hi
+  (JNIEnv * env, jobject instance, jstring javaString) {
+    char* hello = "Hello,";
+    const char* name = (*env)->GetStringUTFChars(env, javaString, 0);
+    size_t len = strlen(hello) + strlen(name) + 1;
+    char* result = (char*)malloc(len);
+    strcpy(result, hello);
+    strcat(result, name);
+    (*env)->ReleaseStringUTFChars(env, javaString, name);
+    return (*env)->NewStringUTF(env, result);
+}

24.06/jni/Main.java

@@ -0,0 +1,16 @@
+public class Main {
+    static {
+        System.load("C:/Users/sunwu/Desktop/base/gateway/notebook/24.06/jni/libMyJNI.dll");
+    }
+
+    public static native void native_hello();
+    public native int add(int a, int b);
+
+    public native String hi(String name);
+
+    public static void main(String[] args) {
+        native_hello();
+        System.out.println(new Main().add(1, 1));
+        System.out.println(new Main().hi("frank"));
+    }
+}