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Java example source code file (java.h)

This example Java source code file (java.h) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

char_bit, createjavavm_t, getcreatedjavavms_t, getdefaultjavavminitargs_t, getprogramname, invocationfunctions, jli_reporterrormessage, jnicall, ncrv_return_value, null_check_return_value, setjavalauncherplatformprops

The java.h Java example source code

/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

#ifndef _JAVA_H_
#define _JAVA_H_

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

#include <jni.h>
#include <jvm.h>

/*
 * Get system specific defines.
 */
#include "emessages.h"
#include "java_md.h"
#include "jli_util.h"

#include "manifest_info.h"
#include "version_comp.h"
#include "wildcard.h"
#include "splashscreen.h"

# define KB (1024UL)
# define MB (1024UL * KB)
# define GB (1024UL * MB)

#define CURRENT_DATA_MODEL (CHAR_BIT * sizeof(void*))

/*
 * The following environment variable is used to influence the behavior
 * of the jre exec'd through the SelectVersion routine.  The command line
 * options which specify the version are not passed to the exec'd version,
 * because that jre may be an older version which wouldn't recognize them.
 * This environment variable is known to this (and later) version and serves
 * to suppress the version selection code.  This is not only for efficiency,
 * but also for correctness, since any command line options have been
 * removed which would cause any value found in the manifest to be used.
 * This would be incorrect because the command line options are defined
 * to take precedence.
 *
 * The value associated with this environment variable is the MainClass
 * name from within the executable jar file (if any). This is strictly a
 * performance enhancement to avoid re-reading the jar file manifest.
 *
 */
#define ENV_ENTRY "_JAVA_VERSION_SET"

#define SPLASH_FILE_ENV_ENTRY "_JAVA_SPLASH_FILE"
#define SPLASH_JAR_ENV_ENTRY "_JAVA_SPLASH_JAR"

/*
 * Pointers to the needed JNI invocation API, initialized by LoadJavaVM.
 */
typedef jint (JNICALL *CreateJavaVM_t)(JavaVM **pvm, void **env, void *args);
typedef jint (JNICALL *GetDefaultJavaVMInitArgs_t)(void *args);
typedef jint (JNICALL *GetCreatedJavaVMs_t)(JavaVM **vmBuf, jsize bufLen, jsize *nVMs);

typedef struct {
    CreateJavaVM_t CreateJavaVM;
    GetDefaultJavaVMInitArgs_t GetDefaultJavaVMInitArgs;
    GetCreatedJavaVMs_t GetCreatedJavaVMs;
} InvocationFunctions;

int
JLI_Launch(int argc, char ** argv,              /* main argc, argc */
        int jargc, const char** jargv,          /* java args */
        int appclassc, const char** appclassv,  /* app classpath */
        const char* fullversion,                /* full version defined */
        const char* dotversion,                 /* dot version defined */
        const char* pname,                      /* program name */
        const char* lname,                      /* launcher name */
        jboolean javaargs,                      /* JAVA_ARGS */
        jboolean cpwildcard,                    /* classpath wildcard */
        jboolean javaw,                         /* windows-only javaw */
        jint     ergo_class                     /* ergnomics policy */
);

/*
 * Prototypes for launcher functions in the system specific java_md.c.
 */

jboolean
LoadJavaVM(const char *jvmpath, InvocationFunctions *ifn);

void
GetXUsagePath(char *buf, jint bufsize);

jboolean
GetApplicationHome(char *buf, jint bufsize);

#define GetArch() GetArchPath(CURRENT_DATA_MODEL)

/*
 * Different platforms will implement this, here
 * pargc is a pointer to the original argc,
 * pargv is a pointer to the original argv,
 * jrepath is an accessible path to the jre as determined by the call
 * so_jrepath is the length of the buffer jrepath
 * jvmpath is an accessible path to the jvm as determined by the call
 * so_jvmpath is the length of the buffer jvmpath
 */
void CreateExecutionEnvironment(int *argc, char ***argv,
                                char *jrepath, jint so_jrepath,
                                char *jvmpath, jint so_jvmpath,
                                char *jvmcfg,  jint so_jvmcfg);

/* Reports an error message to stderr or a window as appropriate. */
void JLI_ReportErrorMessage(const char * message, ...);

/* Reports a system error message to stderr or a window */
void JLI_ReportErrorMessageSys(const char * message, ...);

/* Reports an error message only to stderr. */
void JLI_ReportMessage(const char * message, ...);

/*
 * Reports an exception which terminates the vm to stderr or a window
 * as appropriate.
 */
void JLI_ReportExceptionDescription(JNIEnv * env);
void PrintMachineDependentOptions();

const char *jlong_format_specifier();

/*
 * Block current thread and continue execution in new thread
 */
int ContinueInNewThread0(int (JNICALL *continuation)(void *),
                        jlong stack_size, void * args);

/* sun.java.launcher.* platform properties. */
void SetJavaLauncherPlatformProps(void);
void SetJavaCommandLineProp(char* what, int argc, char** argv);
void SetJavaLauncherProp(void);

/*
 * Functions defined in java.c and used in java_md.c.
 */
jint ReadKnownVMs(const char *jvmcfg, jboolean speculative);
char *CheckJvmType(int *argc, char ***argv, jboolean speculative);
void AddOption(char *str, void *info);

enum ergo_policy {
   DEFAULT_POLICY = 0,
   NEVER_SERVER_CLASS,
   ALWAYS_SERVER_CLASS
};

const char* GetProgramName();
const char* GetDotVersion();
const char* GetFullVersion();
jboolean IsJavaArgs();
jboolean IsJavaw();
jint GetErgoPolicy();

jboolean ServerClassMachine();

int ContinueInNewThread(InvocationFunctions* ifn, jlong threadStackSize,
                   int argc, char** argv,
                   int mode, char *what, int ret);

int JVMInit(InvocationFunctions* ifn, jlong threadStackSize,
                   int argc, char** argv,
                   int mode, char *what, int ret);

/*
 * Initialize platform specific settings
 */
void InitLauncher(jboolean javaw);

/*
 * For MacOSX and Windows/Unix compatibility we require these
 * entry points, some of them may be stubbed out on Windows/Unixes.
 */
void     PostJVMInit(JNIEnv *env, jstring mainClass, JavaVM *vm);
void     ShowSplashScreen();
void     RegisterThread();
/*
 * this method performs additional platform specific processing and
 * should return JNI_TRUE to indicate the argument has been consumed,
 * otherwise returns JNI_FALSE to allow the calling logic to further
 * process the option.
 */
jboolean ProcessPlatformOption(const char *arg);

/*
 * This allows for finding classes from the VM's bootstrap class loader directly,
 * FindClass uses the application class loader internally, this will cause
 * unnecessary searching of the classpath for the required classes.
 *
 */
typedef jclass (JNICALL FindClassFromBootLoader_t(JNIEnv *env,
                                                  const char *name));
jclass FindBootStrapClass(JNIEnv *env, const char *classname);

jobjectArray CreateApplicationArgs(JNIEnv *env, char **strv, int argc);
jobjectArray NewPlatformStringArray(JNIEnv *env, char **strv, int strc);
jclass GetLauncherHelperClass(JNIEnv *env);

int JNICALL JavaMain(void * args); /* entry point                  */

enum LaunchMode {               // cf. sun.launcher.LauncherHelper
    LM_UNKNOWN = 0,
    LM_CLASS,
    LM_JAR
};

static const char *launchModeNames[]
    = { "Unknown", "Main class", "JAR file" };

typedef struct {
    int    argc;
    char **argv;
    int    mode;
    char  *what;
    InvocationFunctions ifn;
} JavaMainArgs;

#define NULL_CHECK_RETURN_VALUE(NCRV_check_pointer, NCRV_return_value) \
    do { \
        if ((NCRV_check_pointer) == NULL) { \
            JLI_ReportErrorMessage(JNI_ERROR); \
            return NCRV_return_value; \
        } \
    } while (JNI_FALSE)

#define NULL_CHECK0(NC0_check_pointer) \
    NULL_CHECK_RETURN_VALUE(NC0_check_pointer, 0)

#define NULL_CHECK(NC_check_pointer) \
    NULL_CHECK_RETURN_VALUE(NC_check_pointer, )

#endif /* _JAVA_H_ */

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