// Windows平臺下的Java程序啟動器
// 適用于1.2或更高版本的VM
#include <windows.h>
#include <jni.h>
#include <string>
using namespace std;

void vShowError(string sErrorMessage);
void vShowLastError(string sErrorMessage);
void vDestroyVM(JNIEnv *env, JavaVM *jvm);
void vAddOption(string& sName);

JavaVMOption* vm_options;
int mctOptions = 0;
int mctOptionCapacity = 0;
boolean GetApplicationHome(char *buf, jint sz);
typedef jint (CALLBACK *CreateJavaVM)(JavaVM **pvm, JNIEnv **penv, void *args);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow){
    JNIEnv *env;
    JavaVM *jvm;
    jint jintVMStartupReturnValue;
    jclass jclassStartup;
    jmethodID midStartup;

    // 確定各種文件所在的路徑
    // -應用的主目錄
    char home[2000];
    if (!GetApplicationHome(home, sizeof(home))) {
        vShowError("不能確定應用的主目錄。");
        return 0;
    }
    string sAppHome(home);
    string sOption_AppHome = "-Dapplication.home=" + sAppHome;
    string sJREPath = sAppHome + "\\jre";
    // -VM路徑
    string sRuntimePath = sJREPath + "\\bin\\classic\\";
    string sJVMpath = sRuntimePath + "jvm.dll";
    // -啟動路徑
    string sBootPath = sJREPath + "\\lib";
    string sOption_BootPath = "-Dsun.boot.class.path=" + sBootPath;
    // -CLASSPATH
    string sClassPath = sAppHome + "\\classes";
    string sOption_ClassPath = "-Djava.class.path=" + sClassPath;
    // 設置VM參數(shù)
    // vAddOption(string("-verbose"));
    vAddOption(sOption_ClassPath);
    vAddOption(sOption_AppHome);
    // VM初始化參數(shù)
    JavaVMInitArgs vm_args;
    vm_args.version = 0x00010002;
    vm_args.options = vm_options;
    vm_args.nOptions = mctOptions;
    vm_args.ignoreUnrecognized = JNI_TRUE;
    // 裝入JVM庫
    HINSTANCE hJVM = LoadLibrary(sJVMpath.c_str());
    if( hJVM == NULL ){
        vShowLastError("不能從下面的路徑裝入JVM：" + sJVMpath);
        return 0;
    }
    // 啟動1.2/3/4 VM
    CreateJavaVM lpfnCreateJavaVM = (CreateJavaVM) GetProcAddress(hJVM, "JNI_CreateJavaVM");
    jintVMStartupReturnValue = (*lpfnCreateJavaVM) (&jvm, &env, &vm_args);
    // 是否成功？
    if (jintVMStartupReturnValue < 0) {
        string sErrorMessage = "創(chuàng)建VM失敗。";
        vShowError(sErrorMessage);
        vDestroyVM(env, jvm);
        return 0;
    }
    // 要啟動的類
    string sStartupClass = "javabunny/JavaBunny";
    // 注意句點符號已經(jīng)被轉換成斜杠
    jclassStartup = env->FindClass(sStartupClass.c_str());
    if (jclassStartup == NULL) {
        string sErrorMessage ="找不到啟動類[" +sStartupClass + "]";
        vShowError(sErrorMessage);
        vDestroyVM(env, jvm);
        return 0;
    }
    // 要啟動的方法
    string sStartupMethod_Identifier = "main";
    string sStartupMethod_TypeDescriptor ="([Ljava/lang/String;)V";
    midStartup = env->GetStaticMethodID(jclassStartup,
    sStartupMethod_Identifier.c_str(),
    sStartupMethod_TypeDescriptor.c_str());
    if (midStartup == NULL) {
        string sErrorMessage = "找不到啟動方法["+ sStartupClass + "."+ sStartupMethod_Identifier
        + "]，類型描述符是[" + sStartupMethod_TypeDescriptor + "]";
        vShowError(sErrorMessage);
        vDestroyVM(env, jvm);
        return 0;
    }
    // 構造啟動方法的參數(shù)
    jstring jstringExampleArg;
    jclass jclassString;
    jobjectArray jobjectArray_args;
    jstringExampleArg = env->NewStringUTF("string1");
    if (jstringExampleArg == NULL){
        vDestroyVM(env, jvm);
        return 0;
    }
    jclassString = env->FindClass("java/lang/String");
    jobjectArray_args = env->NewObjectArray(1, jclassString, jstringExampleArg);
    if (jobjectArray_args == NULL){
        vDestroyVM(env, jvm);
        return 0;
    }
    // 調用啟動方法啟動Java程序
    env->CallStaticVoidMethod(jclassStartup, midStartup, jobjectArray_args);
    // 在退出之前嘗試分離主線程
    if (jvm->DetachCurrentThread() != 0) {
        vShowError("分離主線程失敗。\n");
    }
    // 只要還有非守護線程，下面的調用將一直被掛起
    jvm->DestroyJavaVM();
    return 0;
}
void vDestroyVM(JNIEnv *env, JavaVM *jvm){
    if (env->ExceptionOccurred()) {
        env->ExceptionDescribe();
    }
    jvm->DestroyJavaVM();
}

void vShowError(string sError) {
    MessageBox(NULL, sError.c_str(), "錯誤", MB_OK);
}

/* 在對話框中顯示錯誤信息，括號內包含
的GetLastError錯誤信息 */
void vShowLastError(string sLocalError) {
    LPVOID lpSystemMsgBuf;
    FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER |
    FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
    NULL, GetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
    (LPTSTR) &lpSystemMsgBuf, 0, NULL );
    string sSystemError = string((LPTSTR)lpSystemMsgBuf);
    vShowError(sLocalError + " [" + sSystemError + "]");
}

void vAddOption(string& sValue) {
    mctOptions++;
    if (mctOptions >= mctOptionCapacity) {
        if (mctOptionCapacity == 0) {
            mctOptionCapacity = 3;
            vm_options = (JavaVMOption*)malloc(mctOptionCapacity * sizeof(JavaVMOption));
        } else {
            JavaVMOption *tmp;
            mctOptionCapacity *= 2;
            tmp = (JavaVMOption*)malloc(mctOptionCapacity * sizeof(JavaVMOption));
            memcpy(tmp, vm_options, (mctOptions-1) * sizeof(JavaVMOption));
            free(vm_options);
            vm_options = tmp;
        }
    }
    vm_options[mctOptions-1].optionString = (char*)sValue.c_str();
}

/* 如果緩沖區(qū)是"c:\app\bin\java"，則把"c:\app"放入buf。*/
jboolean GetApplicationHome(char *buf, jint sz) {
    char *cp;
    GetModuleFileName(0, buf, sz);
    *strrchr(buf, '\\') = '\0';
    if ((cp = strrchr(buf, '\\')) == 0) {
        // 如果應用程序放在驅動器的根目錄下，且不存在bin目錄
        // 會出現(xiàn)這種情形
        buf[0] = '\0';
        return JNI_FALSE;
    }
    return JNI_TRUE;
}