android ndk 给结构体赋值的方法

转自：http://www.cnweblog.com/fly2700/archive/2012/03/21/320083.html

 

1，java 代码 结构体定义

1 public class  MediaInfo

2 {

3     public int nWidth;

4     public int nHeight;

5     public String strStream;

6 }

java jni接口定义

public native static int       GetMediaInfo(int handle, MediaInfo info); //

c++ ndk 实现代码

 1 JNIEXPORT jint JNICALL Java_src_jni_RtspConnect_GetMediaInfo

 2   (JNIEnv *e, jclass c, jint h, jobject o)

 3 {

 4     //获取Java中的实例类 

 5     jclass objectClass = (e)->FindClass("src/jni/MediaInfo"); 

 6  

 7     //获取类中每一个变量的定义 

 8     jfieldID strStream = (e)->GetFieldID(objectClass, "strStream", "Ljava/lang/String;"); 

 9     jfieldID nHeight = (e)->GetFieldID(objectClass, "nHeight", "I"); 

10     jfieldID nWidth =  (e)->GetFieldID(objectClass, "nWidth", "I");

11  

12  

13     //给每一个实例的变量付值 

14     (e)->SetIntField(o, nHeight, 10); 

15     (e)->SetIntField(o, nWidth, 100);

16     (e)->SetObjectField(o, strStream, (e)->NewStringUTF("my stream"));  

17     

18     return 0; 

19 }

Java 调用

1  MediaInfo info = new MediaInfo();

2         RtspConnect.GetMediaInfo(0, info);

3         Log.i("info", ""+info.nHeight);

4         Log.i("info", ""+info.nWidth);

5         Log.i("info", ""+info.strStream);