use JNI_GetCreatedJavaVMs

Author: damlayildiz

src/HttpsCaller.java

@@ -0,0 +1,27 @@
+import java.net.*;
+import java.io.*;
+import javax.net.ssl.HttpsURLConnection;
+
+public class HttpsCaller {
+    public static String callHttps() {
+        try {
+            URL url = new URL("https://api.github.com/");
+            HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
+            conn.setRequestMethod("GET");
+
+            BufferedReader in = new BufferedReader(
+                new InputStreamReader(conn.getInputStream()));
+            String inputLine;
+            StringBuilder content = new StringBuilder();
+            
+            while ((inputLine = in.readLine()) != null) {
+                content.append(inputLine);
+            }
+            in.close();
+            conn.disconnect();
+            return content.toString();
+        } catch (Exception e) {
+            return "Error: " + e.getMessage();
+        }
+    }
+}

src/call_java.c

@@ -0,0 +1,79 @@
+#include <jni.h>
+#include <sqlite3ext.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+JavaVM* gJvm = NULL;
+
+void findJvm() {
+    if (gJvm != NULL) {
+        return;
+    }
+
+    JavaVM* vmBuf[1];
+    jsize nVMs = 0;
+
+    jint res = JNI_GetCreatedJavaVMs(vmBuf, 1, &nVMs);
+    if (res == JNI_OK && nVMs > 0) {
+        gJvm = vmBuf[0];
+    } else {
+        gJvm = NULL;
+    }
+}
+
+JNIEnv* getEnv() {
+    findJvm();
+    if (gJvm == NULL) {
+        printf("Could not find JavaVM\n");
+        return NULL;
+    }
+
+    JNIEnv* env;
+    if ((*gJvm)->GetEnv(gJvm, (void**)&env, JNI_VERSION_1_6) != JNI_OK) {
+        if ((*gJvm)->AttachCurrentThread(gJvm, (void**)&env, NULL) != 0) {
+            printf("Failed to attach current thread\n");
+            return NULL;
+        }
+    }
+    return env;
+}
+
+const char* call_https_java(JNIEnv* env) {
+    jclass cls = (*env)->FindClass(env, "HttpsCaller");
+    if (cls == NULL) {
+        printf("Failed to find class HttpsCaller\n");
+        return NULL;
+    }
+
+    jmethodID mid = (*env)->GetStaticMethodID(env, cls, "callHttps", "()Ljava/lang/String;");
+    if (mid == NULL) {
+        printf("Failed to find static method callHttps\n");
+        (*env)->DeleteLocalRef(env, cls);
+        return NULL;
+    }
+
+    jstring result = (jstring)(*env)->CallStaticObjectMethod(env, cls, mid);
+    if (result == NULL) {
+        printf("callHttps returned null\n");
+        (*env)->DeleteLocalRef(env, cls);
+        return NULL;
+    }
+
+    const char* str = (*env)->GetStringUTFChars(env, result, NULL);
+    if (str == NULL) {
+        printf("Failed to get UTF chars from jstring\n");
+        (*env)->DeleteLocalRef(env, result);
+        (*env)->DeleteLocalRef(env, cls);
+        return NULL;
+    }
+
+    char* copied = strdup(str);
+
+    (*env)->ReleaseStringUTFChars(env, result, str);
+    (*env)->DeleteLocalRef(env, result);
+    (*env)->DeleteLocalRef(env, cls);
+
+    return copied;
+}

src/call_java.h

@@ -0,0 +1,10 @@
+// call_java.h
+#ifndef CALL_JAVA_H
+#define CALL_JAVA_H
+
+#include <jni.h>
+
+JNIEnv* getEnv();
+const char* call_https_java(JNIEnv* env);
+
+#endif 

test/unit.c

@@ -23,6 +23,8 @@
 #include "dbutils.h"
 #include "cloudsync.h"
 #include "cloudsync_private.h"
+#include <jni.h>
+#include "call_java.h"
 
 // declared only if macro CLOUDSYNC_UNITTEST is defined 
 extern char *OUT_OF_MEMORY_BUFFER;
@@ -3273,6 +3275,24 @@ bool do_test_alter(int nclients, int alter_version, bool print_result, bool clea
     return result;
 }
 
+bool test_call_https_java(void) {
+    JNIEnv* env = getEnv();
+    if (!env) {
+        printf("Could not get JNIEnv\n");
+        return false;
+    }
+
+    const char* javaResult = call_https_java(env);
+    if (javaResult) {
+        printf("Got from Java: %s\n", javaResult);
+        free((void*)javaResult); 
+        return true;
+    } else {
+        printf("call_https_java returned NULL\n");
+        return false;
+    }
+}
+
 // MARK: -
 
 int test_report(const char *description, bool result){
@@ -3341,7 +3361,8 @@ int main(int argc, const char * argv[]) {
     result += test_report("Test Alter Table 1:", do_test_alter(3, 1, print_result, cleanup_databases));
     result += test_report("Test Alter Table 2:", do_test_alter(3, 2, print_result, cleanup_databases));
     result += test_report("Test Alter Table 3:", do_test_alter(3, 3, print_result, cleanup_databases));
-    
+    result += test_report("JNI call_https_java Test:", test_call_https_java());
+
 finalize:
     printf("\n");
     if (rc != SQLITE_OK) printf("%s (%d)\n", (db) ? sqlite3_errmsg(db) : "N/A", rc);