Question

我正在尝试在Android应用中使用C ++代码，但我不断收到此错误（无需提及这是我第一次使用NDK）：

com.example.nimashahbazi.mooshak E/art: No implementation found for int com.example.nimashahbazi.mooshak.EncryptingActivity.encrypt(java.lang.String, java.lang.String, java.lang.String) (tried Java_com_example_nimashahbazi_mooshak_EncryptingActivity_encrypt and Java_com_example_nimashahbazi_mooshak_EncryptingActivity_encrypt__Ljava_lang_String_2Ljava_lang_String_2Ljava_lang_String_2)
com.example.nimashahbazi.mooshak D/AndroidRuntime: Shutting down VM
com.example.nimashahbazi.mooshak E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.nimashahbazi.mooshak, PID: 17797
java.lang.UnsatisfiedLinkError: No implementation found for int com.example.nimashahbazi.mooshak.EncryptingActivity.encrypt(java.lang.String, java.lang.String, java.lang.String) (tried Java_com_example_nimashahbazi_mooshak_EncryptingActivity_encrypt and Java_com_example_nimashahbazi_mooshak_EncryptingActivity_encrypt__Ljava_lang_String_2Ljava_lang_String_2Ljava_lang_String_2)
at com.example.nimashahbazi.mooshak.EncryptingActivity.encrypt(Native Method)
at com.example.nimashahbazi.mooshak.EncryptingActivity.onCreate(EncryptingActivity.java:35)
...

这是我的EncryprtingActivity.java：

package com.example.nimashahbazi.mooshak;
import android.content.Intent;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

public class EncryptingActivity extends AppCompatActivity {

static {

    try
    {
        System.loadLibrary("native-lib");
        System.loadLibrary("aes256");


    }
    catch (UnsatisfiedLinkError use)
    {
        Log.e("JNI", "WARNING: Could not load native library");
    }

}
public native int encrypt(String encryptionKey, String inputFile, String outputFile);


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

    String input= Environment.getExternalStoragePublicDirectory("Android/data/"+ getApplicationContext().getPackageName()+"/Files/Download").toString()+"DSC_0001.jpg";
    String output= Environment.getExternalStoragePublicDirectory("Android/data/"+ getApplicationContext().getPackageName()+"/Files/Download").toString()+"DSC_0001.jpg.encr";

    encrypt("12345678",input,output);
}

public void onBackPressed() {
    Intent mainIntent = new Intent(EncryptingActivity.this, HomeActivity.class);
    EncryptingActivity.this.startActivity(mainIntent);
    EncryptingActivity.this.finish();
}
}

这是我的native-lib.cpp：

#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string>
#include "aes256.cpp"

using namespace std;

#define BUFFER_SIZE 1024*1024

JNIEXPORT jint  JNICALL
Java_com_example_nimashahbazi_mooshak_EncryptingActivity_encrypt(JNIEnv *env, jobject obj,
                                                                 jstring encryptionKey,
                                                                 jstring inputFile,
                                                                 jstring outputFile);

JNIEXPORT jint  JNICALL
Java_com_example_nimashahbazi_mooshak_DecryptingActivity_decrypt(JNIEnv *env, jobject obj,
                                                                 jstring encryptionKey,
                                                                 jstring inputFile,
                                                                 jstring outputFile);

JNIEXPORT jint  JNICALL
Java_com_example_nimashahbazi_mooshak_EncryptingActivity_encrypt(JNIEnv *env, jobject obj,
                                                                 jstring encryptionKey,
                                                                 jstring inputFile,
                                                                 jstring outputFile) {

    const char *_encryptionKey = env->GetStringUTFChars(encryptionKey, NULL);
    const char *_inputFile = env->GetStringUTFChars(inputFile, NULL);
    const char *_outputFile = env->GetStringUTFChars(outputFile, NULL);

    ByteArray key, enc;
    size_t file_len;

    FILE *input, *output;

    srand(time(0));

    size_t key_len = 0;
    while (_encryptionKey[key_len] != 0)
        key.push_back(_encryptionKey[key_len++]);

    input = fopen(_inputFile, "rb");
    if (input == 0) {
        fprintf(stderr, "Cannot read file '%s'\n", _inputFile);
        return 1;
    }

    output = fopen(_outputFile, "wb");
    if (output == 0) {
        fprintf(stderr, "Cannot write file '%s'\n", _outputFile);
        return 1;
    }

    Aes256 aes(key);

    fseek(input, 0, SEEK_END);
    file_len = ftell(input);
    fseek(input, 0, SEEK_SET);
    printf("File is %zd bytes\n", file_len);

    enc.clear();
    aes.encrypt_start(file_len, enc);
    fwrite(enc.data(), enc.size(), 1, output);

    while (!feof(input)) {
        unsigned char buffer[BUFFER_SIZE];
        size_t buffer_len;

        buffer_len = fread(buffer, 1, BUFFER_SIZE, input);
        printf("Read %zd bytes\n", buffer_len);
        if (buffer_len > 0) {
            enc.clear();
            aes.encrypt_continue(buffer, buffer_len, enc);
            fwrite(enc.data(), enc.size(), 1, output);
        }
    }

    enc.clear();
    aes.encrypt_end(enc);
    fwrite(enc.data(), enc.size(), 1, output);

    fclose(input);
    fclose(output);

    return 0;
}

JNIEXPORT jint  JNICALL
Java_com_example_nimashahbazi_mooshak_DecryptingActivity_decrypt(JNIEnv *env, jobject obj,
                                                                 jstring encryptionKey,
                                                                 jstring inputFile,
                                                                 jstring outputFile) {

    const char *_encryptionKey = env->GetStringUTFChars(encryptionKey, NULL);
    const char *_inputFile = env->GetStringUTFChars(inputFile, NULL);
    const char *_outputFile = env->GetStringUTFChars(outputFile, NULL);

    ByteArray key, dec;
    size_t file_len;

    FILE *input, *output;

    srand(time(0));

    size_t key_len = 0;
    while (_encryptionKey[key_len] != 0)
        key.push_back(_encryptionKey[key_len++]);

    input = fopen(_inputFile, "rb");
    if (input == 0) {
        fprintf(stderr, "Cannot read file '%s'\n", inputFile);
        return 1;
    }

    output = fopen(_outputFile, "wb");
    if (output == 0) {
        fprintf(stderr, "Cannot write file '%s'\n", outputFile);
        return 1;
    }

    Aes256 aes(key);

    fseek(input, 0, SEEK_END);
    file_len = ftell(input);
    fseek(input, 0, SEEK_SET);
    printf("File is %zd bytes\n", file_len);

    aes.decrypt_start(file_len);

    while (!feof(input)) {
        unsigned char buffer[BUFFER_SIZE];
        size_t buffer_len;

        buffer_len = fread(buffer, 1, BUFFER_SIZE, input);
        printf("Read %zd bytes\n", buffer_len);
        if (buffer_len > 0) {
            dec.clear();
            aes.decrypt_continue(buffer, buffer_len, dec);
            fwrite(dec.data(), dec.size(), 1, output);
        }
    }

    dec.clear();
    aes.decrypt_end(dec);
    fwrite(dec.data(), dec.size(), 1, output);

    fclose(input);
    fclose(output);

    return 0;
}

这是我的android.mk：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := native-lib
LOCAL_SRC_FILES := native-lib.cpp\
                   aes256.cpp

LOCAL_C_INCLUDES := aes256.hpp

include $(BUILD_SHARED_LIBRARY)

这是我的CMakeLists.txt

cmake_minimum_required(VERSION 3.4.1)

add_library(native-lib SHARED src/main/cpp/native-lib.cpp)
add_library(aes256 SHARED src/main/cpp/aes256.cpp)

find_library(log-libd log )

target_link_libraries(native-lib ${log-lib})

target_link_libraries(aes256 ${log-lib})

这是我的build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion '25.0.2'
    defaultConfig {
        applicationId "com.example.nimashahbazi.mooshak"
        minSdkVersion 16
        targetSdkVersion 20
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags "-frtti -fexceptions"
            }
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    externalNativeBuild {
        cmake {
            path 'CMakeLists.txt'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })

    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.github.angads25:filepicker:1.1.1'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    compile 'de.hdodenhof:circleimageview:2.1.0'
    compile 'com.daimajia.numberprogressbar:library:1.4@aar'
    compile 'com.theartofdev.edmodo:android-image-cropper:2.4.+'
    compile 'com.github.johnkil.android-appmsg:appmsg:1.2.0'
    compile 'com.android.support:recyclerview-v7:25.3.1'
    compile 'com.google.code.gson:gson:2.7'
    compile group: 'net.lingala.zip4j', name: 'zip4j', version: '1.2.4'
    testCompile 'junit:junit:4.12'
}

还有一些名为aes256.cpp和aes256.hpp的文件来自here。

我已经检查了关于该主题的每个提议的解决方案，它们主要是关于C ++函数的名称和格式，但我在这里找不到问题。有人可以帮我吗？提前谢谢。

Answer 1

您似乎正在尝试加载错误的库 - 您的Android.mk声明您的库名称为Mooshak（通过LOCAL_MODULE），但您使用的是System.loadLibrary("native-lib");

您应该使用：System.loadLibrary("Mooshak");代替。

Answer 2

我正在写这篇文章，因为Alex已经在评论中解释了接受的答案。我不得不添加＆＃34; extern C＆＃34;到native-lib中函数的定义：

./emulator64-x86 -avd Android_Wear_Square_API_23

没有找到int com.example.nimashahbazi.mooshak.EncryptingActivity.encrypt的实现

2 个答案: