1

所以我正在玩弄 JNI，看看它在系统调用方面的限制是什么。我第一个学习 JNI 如何工作的 C 文件仍然运行良好。我正在尝试添加另一个读取 uname 并连接成单个字符串然后返回的 C++ 文件。但是，链接器实际上无法找到新的函数定义 (getKernelInfo())。我已经尝试过很明显的方法，比如仔细检查函数/java 包的类型和名称。但是我似乎找不到问题所在。

以下是相关文件：

安卓.mk

LOCAL_PATH:= $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := example
LOCAL_CFLAGS    := -Werror
LOCAL_SRC_FILES := \
    example.c \
    kernel.cpp
LOCAL_LDLIBS    := -llog 

include $(BUILD_SHARED_LIBRARY)

应用程序.mk

APP_STL                 := stlport_static

内核.cpp

#include <jni.h>
#include <sys/utsname.h>
#include <string>

using namespace std;

JNIEXPORT jstring JNICALL
Java_com_test_myjniapp_MainActivity_getKernelInfo(JNIEnv * env, jobject  obj)
{
    struct utsname info;
    uname(&info);

    string sysInfo = "";
    char** names = (char**)&(info.sysname);
    for(int i = 0; i < 5; i++, names++) {
        sysInfo = sysInfo + string(*names);
        if(i != 4)
            sysInfo = sysInfo + ", ";
    }

    jstring res = env->NewStringUTF((const char*)sysInfo.c_str());

    return res;
}

MainActivity.java

package com.test.myjniapp;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends Activity {
    static {
        System.loadLibrary("example");
    }

    private TextView textUID;
    private Button btnPress;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textUID = (TextView) findViewById(R.id.txtUID);
        btnPress = (Button) findViewById(R.id.btnUID);


    }

    @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;
    }

    public void onUIDClick(View v) {
        textUID.setText(Integer.toString(getUID()));
    }

    public void onPIDClick(View v) {
        textUID.setText(Integer.toString(getPID()));
    }

    public void onTimeClick(View v) {
        textUID.setText(Long.toString(getTime()));
    }

    public void onKernelClick(View v) {
        textUID.setText(getKernelInfo());
    }

    private native int getUID();
    private native int getPID();
    private native long getTime();
    private native String getKernelInfo();
}
4

0 回答 0