（转）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

public class  MediaInfo
{
    public int nWidth;
    public int nHeight;
    public String strStream;
}

java jni接口定义

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

c++ ndk 实现代码

JNIEXPORT jint JNICALL Java_src_jni_RtspConnect_GetMediaInfo
  (JNIEnv *e, jclass c, jint h, jobject o)
{
    //获取Java中的实例类 
    jclass objectClass = (e)->FindClass("src/jni/MediaInfo"); 
 
    //获取类中每一个变量的定义 
    jfieldID strStream = (e)->GetFieldID(objectClass, "strStream", "Ljava/lang/String;"); 
    jfieldID nHeight = (e)->GetFieldID(objectClass, "nHeight", "I"); 
    jfieldID nWidth =  (e)->GetFieldID(objectClass, "nWidth", "I");
 
 
    //给每一个实例的变量付值 
    (e)->SetIntField(o, nHeight, 10); 
    (e)->SetIntField(o, nWidth, 100);
    (e)->SetObjectField(o, strStream, (e)->NewStringUTF("my stream"));  
    
    return 0; 
}

Java 调用

 MediaInfo info = new MediaInfo();
        RtspConnect.GetMediaInfo(0, info);
        Log.i("info", ""+info.nHeight);
        Log.i("info", ""+info.nWidth);
        Log.i("info", ""+info.strStream);