android jni 结构体_Android——- jni返回结构体-Fun言

1.创建工程，添加jni

2. main.cpp

#include

struct test_data

{

char name[256];

int num;

double average;

};

extern "C" {

JNIEXPORT jobject JNICALL Java_com_re_struct_MainActivity_call(JNIEnv * env, jobject obj, jobject classobj);

};

JNIEXPORT jobject JNICALL Java_com_re_struct_MainActivity_call(JNIEnv * env, jobject obj, jobject classobj)

{

jclass objectClass = env->FindClass("com/re/struct/test_data");

jfieldID name = env->GetFieldID(objectClass, "name", "Ljava/lang/String;");

jfieldID num = env->GetFieldID(objectClass, "num", "I");

jfieldID average = env->GetFieldID(objectClass, "average", "D");

env->SetObjectField(classobj, name, env->NewStringUTF("hello world"));

env->SetIntField(classobj, num, 10);

env->SetDoubleField(classobj, average, 2.5);

return classobj;

}

3. test_data.java

package com.re.struct;

public class test_data {

public String name;

public int num;

public double average;

}

4. MainActivity.java

package com.re.struct;

import android.app.Activity;

import android.os.Bundle;

import android.util.Log;

import android.view.Menu;

public class MainActivity extends Activity {

static{

System.loadLibrary("main");

}

private native test_data call(test_data data);

private test_data data = new test_data();

private static final String TAG="######";

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

data = call(data);

Log.e(TAG, "name:" + data.name);

Log.e(TAG, "num:" + data.num);

Log.e(TAG, "average:" + data.average);

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

}

5. 效果：

6. 补充：

Java类型

符号

boolean

Z

byte

B

char

C

short

S

int

I

long

L

float

F

double

D

void

V

objects对象

Lfully-qualified-class-name;        L类名;

Arrays数组

[array-type [数组类型

methods方法

(argument-types)return-type(参数类型)返回类型

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