JNI开发-C/C++传递对象到Java

       JNI开发有时需要C/C++传递对象到Java，此篇主要讲解C/C++传递Student对象到Java;

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");
	 }	
       /**
	 * 获取学生信息
	 * 
	 * @param stuInfo
	 * @return
	 */
	public native StuInfo getStuInfo();
}	 * 获取学生信息
	 * 
	 * @param stuInfo
	 * @return
	 */
	public native StuInfo getStuInfo();
}

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 jobject JNICALL Java_com_niubashaoye_simple_jni_JNITools_getStuInfo(
		JNIEnv *env, jobject obj) {
	//给StuInfo结构体赋值
	StuInfo stuInfo;
	stuInfo.stuId = 100123;
	const char *name = "我是我自己!";
	strcpy(stuInfo.stuName, name);
	const char *className = "高三六班";
	strcpy(stuInfo.className, className);


	//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;");


	//创建StuInfo对象
	jobject stuObje = env->AllocObject(jcs);
	//设置变量值
	env->SetIntField(stuObje, fileId, stuInfo.stuId);
	env->SetIntField(stuObje, ageId, stuInfo.stuAge);
	env->SetObjectField(stuObje, nameId, env->NewStringUTF(stuInfo.stuName));
	env->SetObjectField(stuObje, classId, env->NewStringUTF(stuInfo.className));
	return stuObje;
}
		JNIEnv *env, jobject obj) {
	//给StuInfo结构体赋值
	StuInfo stuInfo;
	stuInfo.stuId = 100123;
	const char *name = "我是我自己!";
	strcpy(stuInfo.stuName, name);
	const char *className = "高三六班";
	strcpy(stuInfo.className, className);


	//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;");


	//创建StuInfo对象
	jobject stuObje = env->AllocObject(jcs);
	//设置变量值
	env->SetIntField(stuObje, fileId, stuInfo.stuId);
	env->SetIntField(stuObje, ageId, stuInfo.stuAge);
	env->SetObjectField(stuObje, nameId, env->NewStringUTF(stuInfo.stuName));
	env->SetObjectField(stuObje, classId, env->NewStringUTF(stuInfo.className));
	return stuObje;
}

4. Java调用native函数

StuInfo stuInfo = jniTools.getStuInfo();
Toast.makeText(getApplicationContext(), stuInfo.toString(), Toast.LENGTH_SHORT).show();

代码下载：https://download.csdn.net/download/niuba123456/10533705