JNI操作Windows注册表(Java核心技术卷2第12章原书例子)

业务介绍

最近项目需要通过Java程序操作Windows注册表(本次测试中使用的是Win64位环境),因为上次使用JNI都是好久前的事情了,重新翻开书(Java核心技术卷2,我这是第8版)又看了一遍,把新遇到的问题记录下.

原书例子

书里的例子Win32Reg的包里面有

• Win32RegKey.java :操作注册表的主要方法类,里面主要有三个类(Win32RegKey;Win32RegKeyException;Win32RegKeyNameEnumeration),这部分实际生产中可以根据自己需要修改
• Win32RegKey.c :JNI部分需要和Windows通信的代码,这里如果修改了包结构,相关的C代码或逻辑需要自己修改
• Win32RegKeyTest.java :测试注册表写入的类

生成头文件

按照JNI调用的基本方式,需要将Win32RegKey.c编译成动态dll文件,然后将dll文件放到jdk>jre的环境中,或者注册到windows的环境中.首先将编译Win32RegKey.java

javac Win32RegKey.java

编译后生成对应的3个class文件Win32RegKey.classWin32RegKeyException.classWin32RegKeyNameEnumeration.class.
在Win32RegKey.c中需要两个头文件,书中原例子代码如下,可根据实际情况修改

/**
   @version 1.00 1997-07-01
   @author Cay Horstmann
*/

#include "Win32RegKey.h"
#include "Win32RegKeyNameEnumeration.h"
#include <string.h>
#include <stdlib.h>
#include <windows.h>

JNIEXPORT jobject JNICALL Java_Win32RegKey_getValue(JNIEnv* env, jobject this_obj, jobject name)
{  
   const char* cname;
   jstring path;
   const char* cpath;
   HKEY hkey;
   DWORD type;
   DWORD size;
   jclass this_class;
   jfieldID id_root;
   jfieldID id_path;
   HKEY root;
   jobject ret;
   char* cret;

   /* get the class */
   this_class = (*env)->GetObjectClass(env, this_obj);

   /* get the field IDs */
   id_root = (*env)->GetFieldID(env, this_class, "root", "I");
   id_path = (*env)->GetFieldID(env, this_class, "path", "Ljava/lang/String;");

   /* get the fields */
   root = (HKEY) (*env)->GetIntField(env, this_obj, id_root);
   path = (jstring)(*env)->GetObjectField(env, this_obj, id_path);
   cpath = (*env)->GetStringUTFChars(env, path, NULL);

   /* open the registry key */
   if (RegOpenKeyEx(root, cpath, 0, KEY_READ, &hkey) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"), 
         "Open key failed");
      (*env)->ReleaseStringUTFChars(env, path, cpath);
      return NULL;
   }

   (*env)->ReleaseStringUTFChars(env, path, cpath);
   cname = (*env)->GetStringUTFChars(env, name, NULL);

   /* find the type and size of the value */
   if (RegQueryValueEx(hkey, cname, NULL, &type, NULL, &size) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Query value key failed");
      RegCloseKey(hkey);
      (*env)->ReleaseStringUTFChars(env, name, cname);
      return NULL;
   }

   /* get memory to hold the value */
   cret = (char*)malloc(size);

   /* read the value */
   if (RegQueryValueEx(hkey, cname, NULL, &type, cret, &size) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Query value key failed");
      free(cret);
      RegCloseKey(hkey);
      (*env)->ReleaseStringUTFChars(env, name, cname);
      return NULL;
   }

   /* depending on the type, store the value in a string,
      integer or byte array */
   if (type == REG_SZ)
   {  
      ret = (*env)->NewStringUTF(env, cret);
   }
   else if (type == REG_DWORD)
   {  
      jclass class_Integer = (*env)->FindClass(env, "java/lang/Integer");
      /* get the method ID of the constructor */
      jmethodID id_Integer = (*env)->GetMethodID(env, class_Integer, "<init>", "(I)V");
      int value = *(int*) cret;
      /* invoke the constructor */
      ret = (*env)->NewObject(env, class_Integer, id_Integer, value);
   }
   else if (type == REG_BINARY)
   {  
      ret = (*env)->NewByteArray(env, size);
      (*env)->SetByteArrayRegion(env, (jarray) ret, 0, size, cret);
   }
   else
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Unsupported value type");
      ret = NULL;
   }

   free(cret);
   RegCloseKey(hkey);
   (*env)->ReleaseStringUTFChars(env, name, cname);

   return ret;
}

JNIEXPORT void JNICALL Java_Win32RegKey_setValue(JNIEnv* env, jobject this_obj, 
   jstring name, jobject value)
{  
   const char* cname;
   jstring path;
   const char* cpath;
   HKEY hkey;
   DWORD type;
   DWORD size;
   jclass this_class;
   jclass class_value;
   jclass class_Integer;
   jfieldID id_root;
   jfieldID id_path;
   HKEY root;
   const char* cvalue;
   int ivalue;

   /* get the class */
   this_class = (*env)->GetObjectClass(env, this_obj);

   /* get the field IDs */
   id_root = (*env)->GetFieldID(env, this_class, "root", "I");
   id_path = (*env)->GetFieldID(env, this_class, "path", "Ljava/lang/String;");

   /* get the fields */
   root = (HKEY)(*env)->GetIntField(env, this_obj, id_root);
   path = (jstring)(*env)->GetObjectField(env, this_obj, id_path);
   cpath = (*env)->GetStringUTFChars(env, path, NULL);

   /* open the registry key */
   if (RegOpenKeyEx(root, cpath, 0, KEY_WRITE, &hkey) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Open key failed");
      (*env)->ReleaseStringUTFChars(env, path, cpath);
      return;
   }

   (*env)->ReleaseStringUTFChars(env, path, cpath);
   cname = (*env)->GetStringUTFChars(env, name, NULL);

   class_value = (*env)->GetObjectClass(env, value);
   class_Integer = (*env)->FindClass(env, "java/lang/Integer");
   /* determine the type of the value object */
   if ((*env)->IsAssignableFrom(env, class_value, (*env)->FindClass(env, "java/lang/String")))
   {  
      /* it is a string--get a pointer to the characters */
      cvalue = (*env)->GetStringUTFChars(env, (jstring) value, NULL);
      type = REG_SZ;
      size = (*env)->GetStringLength(env, (jstring) value) + 1;
   }
   else if ((*env)->IsAssignableFrom(env, class_value, class_Integer))
   {  
      /* it is an integer--call intValue to get the value */
      jmethodID id_intValue = (*env)->GetMethodID(env, class_Integer, "intValue", "()I");
      ivalue = (*env)->CallIntMethod(env, value, id_intValue);
      type = REG_DWORD;
      cvalue = (char*)&ivalue;
      size = 4;
   }
   else if ((*env)->IsAssignableFrom(env, class_value, (*env)->FindClass(env, "[B")))
   {  
      /* it is a byte array--get a pointer to the bytes */
      type = REG_BINARY;
      cvalue = (char*)(*env)->GetByteArrayElements(env, (jarray) value, NULL);
      size = (*env)->GetArrayLength(env, (jarray) value);
   }
   else
   {  
      /* we don't know how to handle this type */
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Unsupported value type");
      RegCloseKey(hkey);
      (*env)->ReleaseStringUTFChars(env, name, cname);
      return;
   }

   /* set the value */
   if (RegSetValueEx(hkey, cname, 0, type, cvalue, size) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Set value failed");
   }

   RegCloseKey(hkey);
   (*env)->ReleaseStringUTFChars(env, name, cname);

   /* if the value was a string or byte array, release the pointer */
   if (type == REG_SZ)
   {  
      (*env)->ReleaseStringUTFChars(env, (jstring) value, cvalue);
   }
   else if (type == REG_BINARY)
   {  
      (*env)->ReleaseByteArrayElements(env, (jarray) value, (jbyte*) cvalue, 0);
   }
}

/* helper function to start enumeration of names */
static int startNameEnumeration(JNIEnv* env, jobject this_obj, jclass this_class)
{  
   jfieldID id_index;
   jfieldID id_count;
   jfieldID id_root;
   jfieldID id_path;
   jfieldID id_hkey;
   jfieldID id_maxsize;

   HKEY root;
   jstring path;
   const char* cpath;
   HKEY hkey;
   DWORD maxsize = 0;
   DWORD count = 0;

   /* get the field IDs */
   id_root = (*env)->GetFieldID(env, this_class, "root", "I");
   id_path = (*env)->GetFieldID(env, this_class, "path", "Ljava/lang/String;");
   id_hkey = (*env)->GetFieldID(env, this_class, "hkey", "I");
   id_maxsize = (*env)->GetFieldID(env, this_class, "maxsize", "I");
   id_index = (*env)->GetFieldID(env, this_class, "index", "I");
   id_count = (*env)->GetFieldID(env, this_class, "count", "I");

   /* get the field values */
   root = (HKEY)(*env)->GetIntField(env, this_obj, id_root);
   path = (jstring)(*env)->GetObjectField(env, this_obj, id_path);
   cpath = (*env)->GetStringUTFChars(env, path, NULL);

   /* open the registry key */
   if (RegOpenKeyEx(root, cpath, 0, KEY_READ, &hkey) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Open key failed");
      (*env)->ReleaseStringUTFChars(env, path, cpath);
      return -1;
   }
   (*env)->ReleaseStringUTFChars(env, path, cpath);

   /* query count and max length of names */
   if (RegQueryInfoKey(hkey, NULL, NULL, NULL, NULL, NULL, NULL, &count, &maxsize, 
          NULL, NULL, NULL) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Query info key failed");
      RegCloseKey(hkey);
      return -1;
   }

   /* set the field values */
   (*env)->SetIntField(env, this_obj, id_hkey, (DWORD) hkey);
   (*env)->SetIntField(env, this_obj, id_maxsize, maxsize + 1);
   (*env)->SetIntField(env, this_obj, id_index, 0);
   (*env)->SetIntField(env, this_obj, id_count, count);
   return count;
}

JNIEXPORT jboolean JNICALL Java_Win32RegKeyNameEnumeration_hasMoreElements(JNIEnv* env, 
   jobject this_obj)
{  jclass this_class;
   jfieldID id_index;
   jfieldID id_count;
   int index;
   int count;
   /* get the class */
   this_class = (*env)->GetObjectClass(env, this_obj);

   /* get the field IDs */
   id_index = (*env)->GetFieldID(env, this_class, "index", "I");
   id_count = (*env)->GetFieldID(env, this_class, "count", "I");

   index = (*env)->GetIntField(env, this_obj, id_index);
   if (index == -1) /* first time */
   {  
      count = startNameEnumeration(env, this_obj, this_class);
      index = 0;
   }
   else
      count = (*env)->GetIntField(env, this_obj, id_count);
   return index < count;
}

JNIEXPORT jobject JNICALL Java_Win32RegKeyNameEnumeration_nextElement(JNIEnv* env, 
   jobject this_obj)
{  
   jclass this_class;
   jfieldID id_index;
   jfieldID id_hkey;
   jfieldID id_count;
   jfieldID id_maxsize;

   HKEY hkey;
   int index;
   int count;
   DWORD maxsize;

   char* cret;
   jstring ret;

   /* get the class */
   this_class = (*env)->GetObjectClass(env, this_obj);

   /* get the field IDs */
   id_index = (*env)->GetFieldID(env, this_class, "index", "I");
   id_count = (*env)->GetFieldID(env, this_class, "count", "I");
   id_hkey = (*env)->GetFieldID(env, this_class, "hkey", "I");
   id_maxsize = (*env)->GetFieldID(env, this_class, "maxsize", "I");

   index = (*env)->GetIntField(env, this_obj, id_index);
   if (index == -1) /* first time */
   {  
      count = startNameEnumeration(env, this_obj, this_class);
      index = 0;
   }
   else
      count = (*env)->GetIntField(env, this_obj, id_count);

   if (index >= count) /* already at end */
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "java/util/NoSuchElementException"),
         "past end of enumeration");
      return NULL;
   }

   maxsize = (*env)->GetIntField(env, this_obj, id_maxsize);
   hkey = (HKEY)(*env)->GetIntField(env, this_obj, id_hkey);
   cret = (char*)malloc(maxsize);

   /* find the next name */
   if (RegEnumValue(hkey, index, cret, &maxsize, NULL, NULL, NULL, NULL) != ERROR_SUCCESS)
   {  
      (*env)->ThrowNew(env, (*env)->FindClass(env, "Win32RegKeyException"),
         "Enum value failed");
      free(cret);
      RegCloseKey(hkey);
      (*env)->SetIntField(env, this_obj, id_index, count);
      return NULL;
   }

   ret = (*env)->NewStringUTF(env, cret);
   free(cret);

   /* increment index */
   index++;
   (*env)->SetIntField(env, this_obj, id_index, index);

   if (index == count) /* at end */
   {  
      RegCloseKey(hkey);
   }

   return ret;
}

此时需要使用javah命令来生成对应的头文件,注意如果java代码没有在src的根目录下,有包路径的话javah命令需要在src目录中执行,并指定全路径.此时对应的上述C代码也需要进行响应的修改,如生成后的文件名参数名等

src>javah Win32RegKey
src>javah Win32RegKeyNameEnumeration

如果修改了包路径为src.a.b.c.Win32RegKey,则需要

src>javah a.b.c.Win32RegKey

此时对应生成两个头文件Win32RegKey.h 及Win32RegKeyNameEnumeration.h

编译DLL

将Win32RegKey.c/Win32RegKey.h/Win32RegKeyNameEnumeration.h三个文件放在同一个路径中,因为是在windows平台编译,所以需要gcc环境.此次遇到一个问题,之前按照书中都是用cygwin的,然后通过gcc -mno-cygwin来去掉最后生成的dll中依赖的cygwin1.dll库.但是gcc更新了,将此参数去掉了,所以本次采用了MinGW-64的环境,如果还需要32位环境需要单独用MinGW来编译.具体安装gcc及相关配置略.
配置好gcc后,进行编译,命令中的jdk是自己机器中使用的jdk的环境的路径

gcc -D __int64="long long" -Wl,--kill-at -I jdk/include -I  jdk/include/win32  -shared Win32RegKey.c -o Win32RegKey.dll

此处-D __int64="long long"在书中有具体说明,因为typedef __int64 long 是专门用于微软编译器的，如果使用Gnu编译器可以使用-D __int64="long long"方式.
编译好后,将生成的dll放到jdk/jre/bin目录中,最后运行测试类Win32RegKeyTest.java 即可.

其他代码

Win32RegKey.java

import java.util.Enumeration;

/**
 * A Win32RegKey object can be used to get and set values of a registry key in the Windows registry.
 *
 * @author Cay Horstmann
 * @version 1.00 1997-07-01
 */
public class Win32RegKey {
	/**
	 * Construct a registry key object.
	 *
	 * @param theRoot one of HKEY_CLASSES_ROOT, HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE, HKEY_USERS,
	 *                HKEY_CURRENT_CONFIG, HKEY_DYN_DATA
	 * @param thePath the registry key path
	 */
	public Win32RegKey(int theRoot, String thePath) {
		root = theRoot;
		path = thePath;
	}

	/**
	 * Enumerates all names of registry entries under the path that this object describes.
	 *
	 * @return an enumeration listing all entry names
	 */
	public Enumeration<String> names() {
		return new Win32RegKeyNameEnumeration(root, path);
	}

	/**
	 * Gets the value of a registry entry.
	 *
	 * @param name the entry name
	 * @return the associated value
	 */
	public native Object getValue(String name);

	/**
	 * Sets the value of a registry entry.
	 *
	 * @param name  the entry name
	 * @param value the new value
	 */
	public native void setValue(String name, Object value);

	public static final int HKEY_CLASSES_ROOT = 0x80000000;
	public static final int HKEY_CURRENT_USER = 0x80000001;
	public static final int HKEY_LOCAL_MACHINE = 0x80000002;
	public static final int HKEY_USERS = 0x80000003;
	public static final int HKEY_CURRENT_CONFIG = 0x80000005;
	public static final int HKEY_DYN_DATA = 0x80000006;

	private int root;
	private String path;

	static {
		System.loadLibrary("Win32RegKey");
	}
}

class Win32RegKeyNameEnumeration implements Enumeration<String> {
	Win32RegKeyNameEnumeration(int theRoot, String thePath) {
		root = theRoot;
		path = thePath;
	}

	public native String nextElement();

	public native boolean hasMoreElements();

	private int root;
	private String path;
	private int index = -1;
	private int hkey = 0;
	private int maxsize;
	private int count;
}

class Win32RegKeyException extends RuntimeException {
	public Win32RegKeyException() {
	}

	public Win32RegKeyException(String why) {
		super(why);
	}
}

Win32RegKeyTest.java

import java.util.Enumeration;

/**
 * @author Cay Horstmann
 * @version 1.02 2007-10-26
 */
public class Win32RegKeyTest {

	public static void main(String[] args) {
		Win32RegKey key = new Win32RegKey(
				Win32RegKey.HKEY_CURRENT_USER, "Software\JavaSoft\Java Runtime Environment");
		System.out.println(111);
		key.setValue("Default user", "Harry Hacker");
		key.setValue("Lucky number", new Integer(13));
		key.setValue("Small primes", new byte[]{2, 3, 5, 7, 11});

		Enumeration<String> e = key.names();

		while (e.hasMoreElements()) {
			String name = e.nextElement();
			System.out.print(name + "=");

			Object value = key.getValue(name);

			if (value instanceof byte[])
				for (byte b : (byte[]) value) System.out.print((b & 0xFF) + " ");
			else
				System.out.print(value);

			System.out.println();
		}
	}
}