JNI开发有时需要Java把对象作为参数传递到C/C++，此篇主要讲解Java传递Student对象到C/C++;
1 定义com.niubashaoye.simple.jni.StuInfo类;
public class StuInfo {
private int stuId;
private String stuName;
private int stuAge;
private String className;
public StuInfo(int stuId, String stuName, int stuAge, String className) {
super();
this.stuId = stuId;
this.stuName = stuName;
this.stuAge = stuAge;
this.className = className;
}
//getter()
//setter()
@Override
public String toString() {
return "StuInfo [stuId=" + stuId + ", stuName=" + stuName + ", stuAge=" + stuAge + ", className=" + className
+ "]";
}
}
2 添加native函数
public class JNITools {
static {
System.loadLibrary("TestDemo");
}
/**
* 设置学生信息
*
* @param stuInfo
* @return
*/
public native void setStuInfo(StuInfo stuInfo);
}
3 C/C++文件
3.1 添加StuInfo结构体
typedef struct {
int stuId;
char stuName[50];
int stuAge;
char className[50];
} StuInfo;
3.2 获取StuInfo对象
JNIEXPORT void JNICALL Java_com_niubashaoye_simple_jni_JNITools_setStuInfo(
JNIEnv *env, jobject obj, jobject jobj) {
StuInfo stuInfo;
LOGI("====setStu===1====");
//获取jclass的实例
jclass jcs = env->FindClass("com/niubashaoye/simple/jni/StuInfo");
//获取StuInfo的字段ID
jfieldID fileId = env->GetFieldID(jcs, "stuId", "I");
jfieldID nameId = env->GetFieldID(jcs, "stuName", "Ljava/lang/String;");
jfieldID ageId = env->GetFieldID(jcs, "stuAge", "I");
jfieldID classId = env->GetFieldID(jcs, "className", "Ljava/lang/String;");
//把字段Id设置到结构体中
stuInfo.stuId = env->GetIntField(jobj, fileId);
jstring nameStr = (jstring) env->GetObjectField(jobj, nameId);
const char *locstr = env->GetStringUTFChars(nameStr, 0);
strcpy(stuInfo.stuName, locstr);
stuInfo.stuAge = getIntByObjInfo(env, jcs, jobj, "stuAge");
jstring classStr = (jstring) env->GetObjectField(jobj, classId);
const char *cstr = env->GetStringUTFChars(classStr, 0);
strcpy(stuInfo.className, cstr);
LOGI("====setStu===4====");
LOGI("传递到C的StuInfo：stuId：%d;stuName：%s;stuAge：%d;className：%s",
stuInfo.stuId, stuInfo.stuName, stuInfo.stuAge, stuInfo.className);
}
4 Java调用native函数
StuInfo stuInfo = new StuInfo(1000, "牛八少爷", 22, "高三一班");
JNITools jniTools= new JNITools();
jniTools.setStuInfo(stuInfo);