《jdk8u源码分析》3.InitLauncher

src/windows/bin/java_md.c::InitLauncher

void
InitLauncher(boolean javaw)
{
    INITCOMMONCONTROLSEX icx;

    /*
     * Required for javaw mode MessageBox output as well as for
     * HotSpot -XX:+ShowMessageBoxOnError in java mode, an empty
     * flag field is sufficient to perform the basic UI initialization.
     */
    memset(&icx, 0, sizeof(INITCOMMONCONTROLSEX));
    icx.dwSize = sizeof(INITCOMMONCONTROLSEX);
    InitCommonControlsEx(&icx);
    _isjavaw = javaw;
    
    JLI_SetTraceLauncher();
}

src/share/bin/jli_util.h::JLDEBUG_ENV_ENTRY

#define JLDEBUG_ENV_ENTRY "_JAVA_LAUNCHER_DEBUG"

src/share/bin/jli_util.c::JLI_SetTraceLauncher

void
JLI_SetTraceLauncher()
{
   if (getenv(JLDEBUG_ENV_ENTRY) != 0) {
        _launcher_debug = JNI_TRUE;
        //----_JAVA_LAUNCHER_DEBUG----
        JLI_TraceLauncher("----%s----\n", JLDEBUG_ENV_ENTRY);
   }
}

添加环境变量：_JAVA_LAUNCHER_DEBUG=1 即可通过 JLI_SetTraceLauncher() 设置 _launcher_debug = JNI_TRUE 在命令行输出JVM启动的详细信息。