JNA：无法创建结构子类的对象 - 无效的结构字段

Question

我正在将 C typedef 映射到 JNA 结构。下面如果 C typedef:

typedef struct _GLYCOUNTERS {
unsigned int ulArraySize;
LPGLYCOUNTER lpCounters;
}GLYCOUNTERS, *LPGLYCOUNTERS;

这是我的 JNA 结构子class:

public class GlyCounters extends Structure{
    public class ByReference extends GlyCounters implements Structure.ByReference {};
    public class ByValue extends GlyCounters implements Structure.ByValue {};
    public int ulArraySize;
    public GlyCounter lpCounters;

    @Override
    protected List<String> getFieldOrder() {
        return Arrays.asList(new String[] { "ulArraySize", "lpCounters"});
}
    }

我正在尝试使用代码创建和对象 GlyCounters class：

lppCounters = glyTypes.new GlyCounters();

如您所见，我正在另一个 class 中创建对象，GlyCounters 是另一个 class.

的嵌套 class

这是我收到的错误消息：

Exception in thread "main" java.lang.IllegalArgumentException: Invalid Structure field in class btc_dll.GloryTypeDef$GlyCounters, field name 'lpCounters' (class btc_dll.GloryTypeDef$GlyCounter): Can't instantiate class btc_dll.GloryTypeDef$GlyCounter (java.lang.InstantiationException: btc_dll.GloryTypeDef$GlyCounter)
at com.sun.jna.Structure.validateField(Structure.java:1038)
at com.sun.jna.Structure.validateFields(Structure.java:1048)
at com.sun.jna.Structure.<init>(Structure.java:179)
at com.sun.jna.Structure.<init>(Structure.java:172)
at com.sun.jna.Structure.<init>(Structure.java:159)
at com.sun.jna.Structure.<init>(Structure.java:151)
at btc_dll.GloryTypeDef$GlyCounters.<init>(GloryTypeDef.java:298)
at btc_gui.Btc_gui.main(Btc_gui.java:54)
Java Result: 1

导致问题的字段是另一个 C typedef 结构的另一个 JNA 结构 class。谷歌搜索错误消息后，我尝试向这两个 classes 添加无参数构造函数，但错误仍然存在。

有没有人遇到过类似的问题？

Answer 1

如果您想要在结构中使用类型为 struct * 的字段，则需要使用带有接口 Structure.ByReference.

标记的 Structure

已编辑

最常用的方法：

public class GlyCounter extends Structure {
    public class ByReference extends GlyCounter implements Structure.ByReference {};
    // More definition here...
}
public class GlyCounters extends Structure{
    public int ulArraySize;
    public GlyCounter.ByReference lpCounters;

    public GlyCounters(Pointer p) {
        super(p);
        read();
    }

    @Override
    protected List<String> getFieldOrder() {
        return Arrays.asList(new String[] { "ulArraySize", "lpCounters"});
    }
}

// To obtain the full array (assuming they're allocated as a block)
GlyCounters gc = new GlyCounters(pointer);
GlyCounter[] counters = gc.lpCounters.toArray(gc.ulArraySize());

字段 lpCounters 现在是指针类型而不是内联（即共享封闭 struct 的内存）。

JNA：无法创建结构子类的对象 - 无效的结构字段

JNA: Can't create object of structure subclass - Invalid structure field

java

jna