JNA結構體參數傳遞，Java數組

 

JNA以結構體數組爲參數進行調用:

 

////// C++
// student 結構體定義
typedef struct
{
    int age;
    char name[20];
}Student;

// 修改java對象的屬性值
JNAAPI bool changeObjs(Student stu[],int size)
{
    for(int i=0;i<size;i++)
    {
        stu[i].age*=10;
        strcpy(stu[i].name,"wokettas");
    }
    return true;
}

/////// Java
// JNA調用方法
Student[] stus=new Students[2];
Student s1=new Student();
Student s2=new Student();
s1.age=1;
s1.name=Arrays.copyOf("k1".getBytes(), 20);
s2.age=2;
s2.name=Arrays.copyOf("k2".getBytes(),20);
stus[0]=s1; //數組賦值
stus[1]=s2;
Gui.gui.changeObjs(stus, stus.length);

 

   運行報錯:

        Structure array elements must use contiguous memory (bad backing address at Structure array index 1)

   結構體數組必須使用連續的內存區域, 上例s1,s2都是new出來的新對象,不可能連續; 也就是說傳統方式的初始化數組不能解決, 查詢JNA api發現裏面提供了:

 

toArray

public Structure[] toArray(int size)

Returns a view of this structure's memory as an array of structures. Note that this Structure must have a public, no-arg constructor. If the structure is currently using a Memory backing, the memory will be resized to fit the entire array. 

 修改後的代碼:

// 測試對象數組
Student student=new Student();
Student[] stus=(Student[]) student.toArray(2); //分配大小爲2的結構體數組
stus[0].age=1;
stus[0].name=Arrays.copyOf("k1".getBytes(), 20);
stus[1].age=2;
stus[1].name=Arrays.copyOf("k2".getBytes(),20);
Gui.gui.changeObjs(stus, stus.length);

 

 

http://tcspecial.iteye.com/blog/1665583  //原文地址