我试图使用JNA查询Windows中文件的有效权限。最后,我计划使用GetEffectiveRightsFromAcl函数,但要做到这一点,我需要提供一个指向已填充的受托人结构的指针。JNA平台(platform.jar)并没有定义这个结构,所以我尝试自己来定义它。到目前为止,我的情况如下:
public static class TRUSTEE extends Structure {
public TRUSTEE() {
super();
}
public TRUSTEE(Pointer p) {
super(p);
read();
}
public Pointer pMultipleTrustee;
public int MultipleTrusteeOperation;
public int TrusteeForm;
public int TrusteeType;
public Pointer ptstrName;
}我试图像这样填充这个结构:
private TRUSTEE createTrusteeForCurrentUser() {
TRUSTEE result = new TRUSTEE();
result.TrusteeForm = TRUSTEE_FORM.TRUSTEE_IS_NAME;
result.TrusteeType = TRUSTEE_TYPE.TRUSTEE_IS_USER;
String strName = "CURRENT_USER";
// How can I set result.ptstrName using strName?
}这个Google组线程建议在调用char *时在结构中使用String字段。但是,考虑到ptstrName字段允许指向不同类型的事物,这在我的情况下是不合适的,这取决于TrusteeForm的值。因此,我认为我需要从String转换为Pointer。我在JNA中找到了NativeString类,它可以工作,只是它是一个包-私有类。
将Java转换为本机格式并获得String的Pointer的推荐方法是什么?我是否为TRUSTEE结构使用了正确的数据类型?我对JNA有点陌生,所以如果我错过了一些明显的东西,请原谅。
更新
我找到了解决问题的办法,但如果有人有更好的解决办法,我还是想听听。
发布于 2012-04-15 21:48:22
我通过复制包私有NativeString类的源代码并在我的项目中创建一个公共副本来解决这个问题。由于在构造函数中使用了包-私有方法,我不得不做一个小改动。
更新: As @fragorl在注释中指出,下面显示的NativeString的实现现在已经过时了。
用法:
private static TRUSTEE createTrusteeForCurrentUser() {
TRUSTEE result = new TRUSTEE();
result.TrusteeForm = TRUSTEE_FORM.TRUSTEE_IS_NAME;
result.TrusteeType = TRUSTEE_TYPE.TRUSTEE_IS_USER;
result.ptstrName = new NativeString("CURRENT_USER",true).getPointer();
result.write();
return result;
}NativeString.java:
/** Provides a temporary allocation of an immutable C string
* (<code>const char*</code> or <code>const wchar_t*</code>) for use when
* converting a Java String into a native memory function argument.
*
* @author Todd Fast, todd.fast@sun.com
* @author twall@users.sf.net
*/
public class NativeString implements CharSequence, Comparable {
private Pointer pointer;
private boolean wide;
/** Create a native string (NUL-terminated array of <code>char</code>).<p>
* If the system property <code>jna.encoding</code> is set, its value will
* be used to encode the native string. If not set or if the encoding
* is unavailable, the default platform encoding will be used.
*/
public NativeString(String string) {
this(string, false);
}
/** Create a native string as a NUL-terminated array of <code>wchar_t</code>
* (if <code>wide</code> is true) or <code>char</code>.<p>
* If the system property <code>jna.encoding</code> is set, its value will
* be used to encode the native <code>char</code>string.
* If not set or if the encoding is unavailable, the default platform
* encoding will be used.
*
* @param string value to write to native memory
* @param wide whether to store the String as <code>wchar_t</code>
*/
public NativeString(String string, boolean wide) {
if (string == null) {
throw new NullPointerException("String must not be null");
}
// Allocate the memory to hold the string. Note, we have to
// make this 1 element longer in order to accommodate the terminating
// NUL (which is generated in Pointer.setString()).
this.wide = wide;
if (wide) {
int len = (string.length() + 1 ) * Native.WCHAR_SIZE;
pointer = new Memory(len);
pointer.setString(0, string, true);
}
else {
byte[] data = Native.toByteArray(string);
pointer = new Memory(data.length + 1);
pointer.write(0, data, 0, data.length);
pointer.setByte(data.length, (byte)0);
}
}
public int hashCode() {
return toString().hashCode();
}
public boolean equals(Object other) {
if (other instanceof CharSequence) {
return compareTo(other) == 0;
}
return false;
}
public String toString() {
String s = wide ? "const wchar_t*" : "const char*";
s += "(" + pointer.getString(0, wide) + ")";
return s;
}
public Pointer getPointer() {
return pointer;
}
public char charAt(int index) {
return toString().charAt(index);
}
public int length() {
return toString().length();
}
public CharSequence subSequence(int start, int end) {
return CharBuffer.wrap(toString()).subSequence(start, end);
}
public int compareTo(Object other) {
if (other == null)
return 1;
return toString().compareTo(other.toString());
}
}发布于 2012-04-18 13:37:59
假设您希望char *位于本机端(如果字符串包含非ascii字符,则可能需要分配更多内存),
String myString = "CURRENT_USER";
Pointer m = new Memory(myString.length() + 1); // WARNING: assumes ascii-only string
m.setString(0, myString); 然后,您可以在任何需要引用“本机”字符串的地方使用m。
对于宽字符串(wchar_t *),
String myString = "CURRENT_USER";
Pointer m = new Memory(Native.WCHAR_SIZE * (myString.length() + 1));
m.setWideString(0, myString);发布于 2012-04-15 04:09:07
尝试在http://jna.java.net/javadoc/com/sun/jna/Pointer.html中使用指针类。
https://stackoverflow.com/questions/10158582
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