JNA中的未知源错误（C中的Return Struct Array函数）
[英]Unknown Source Error in JNA ( Return Struct Array function in C)
问题描述
I try to make JNA application. 
我尝试制作JNA应用程序。 However , I can not get sturct array from C. I get error in java side ( com.sun.Proxy.$Proxy0.fill(Unknown Source) ) 但是，我不能从C获取sturct数组。我在Java端遇到错误（ com.sun.Proxy。$ Proxy0.fill（Unknown Source） ）
This is my part of c code below. 这是我下面的c代码的一部分。 I compiled as shared libary and I can use other functions. 我编译为共享库，并且可以使用其他功能。 Just giving error when I call fill function . 调用fill函数时仅给出错误。
typedef struct A{
double Value;
char Type;
char Name[100];
char SymbolTableName[100];
int updateMode;
int dataType;
char ulSize;
} A;
typedef struct B{
int numAs;
struct A* as;
} B;
B fill(void){
B sVal;
sVal.numAs=100;
int i=0;
sVal.as = (A*)malloc(sizeof(A) * sVal.numAs);
memset(sVal.as, 0, sizeof(A) * sVal.numAs);
//X in scope , everything is ok here.
X= ReadShared(); // It return struct array , X is struct same type.
for(i=0; i<sVal.numAs; i++)
{
sVal.as[i].Value=X->datas[i].Value;
sVal.as[i].Type=X->datas[i].Type;
strcpy(sVal.as[i].Name,X->datas[i].Name);
strcpy(sVal.as[i].SymbolTableName,X->datas[i].SymbolTableName);
sVal.as[i].updateMode=X->datas[i].updateMode;
sVal.as[i].dataType=X->datas[i].dataType;
sVal.as[i].ulSize=X->datas[i].ulSize;
}
return sVal;
}
This is my Java Part below. 这是我下面的Java部分。
public class TestClass {
public interface Test extends Library {
public static class A extends Structure {
public static class ByReference extends A implements Structure.ByReference{}
double Value;
char Type;
char Name;
char SymbolTableName;
int updateMode;
int dataType;
char ulSize;
protected List getFieldOrder() {
// TODO Auto-generated method stub
return null;
}
}
public static class B extends Structure {
public static class ByValue extends B implements Structure.ByValue {}
public int numAs;
public A.ByReference as;
protected List getFieldOrder() {
// TODO Auto-generated method stub
return null;
}
}
public B.ByValue fill();
}
/**
* @param args
*/
public TestClass(){
}
static void funcc(){
NativeLibrary.addSearchPath("tester", "/root/Desktop/");//Path is true
Test test=(Test)Native.loadLibrary("tester", Test.class);
Test.B.ByValue jig=test.fill();
Test.A[] Avals = (Test.A[])jig.as.toArray(jig.numAs);
}
}
How will I correct this error ? 我将如何纠正此错误？ Why it happens? 为什么会发生？ Maybe there is something missing what ı can not see( Java side or c side ). 也许有一些缺少我看不到的东西（Java端或c端）。 Thanks for any helps. 感谢您的帮助。
at com.sun.jna.Structure.getFields(Structure.java:911) at com.sun.jna.Structure.deriveLayout(Structure.java:1058) at com.sun.jna.Structure.calculateSize(Structure.java:982) at com.sun.jna.Structure.calculateSize(Structure.java:949) at com.sun.jna.Structure.allocateMemory(Structure.java:375) at com.sun.jna.Structure.(Structure.java:184) at com.sun.jna.Structure.(Structure.java:172) at com.sun.jna.Structure.(Structure.java:159) at com.sun.jna.Structure.(Structure.java:151) at MyTest.TestClass$Test$B.(TestClass.java:38) at MyTest.TestClass$Test$B$ByValue.(TestClass.java:39) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526) at java.lang.Class.newInstance(Class.java:379) at com.sun.jna.Structure.newInstanc
1 个解决方案
解决方案1
0 2015-06-15 14:44:57
You haven't defined the order of structure fields within your Structure classes. 您尚未在Structure类中定义结构字段的顺序。 JNA needs this information in order to properly read and write from native memory. JNA需要此信息以便正确地从本机内存读取和写入。
You have also incorrectly mapped native char and char[] . 您还错误地映射了本地char和char[] 。
For class A , you need this: 对于A类，您需要：
double Value;
byte Type;
byte[] Name = new byte[100];
byte[] SymbolTableName = new byte[100];
int updateMode;
int dataType;
byte ulSize;
protected List getFieldOrder() {
return Arrays.asList("Value", "Type", "Name", "SymbolTableName", "updateMode", "dataType", "ulSize");
}
For class B , you need this: 对于B类，您需要：
protected List getFieldOrder() {
return Arrays.asList("numAs", "as");
}
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