问题
A few days ago I asked about an UnsatisfiedLinkError from running non-native OpenCV code. I thought the problem was solved after reinstalling Eclipse and closing/reopening all the packages, but it's back again after I put the OpenCV code into the existing onCreate() method.
I created a new Android application with an activity called Start. I then went to project properties and added OpenCV as a library. Here's the code for the activity (Start.java):
package com.test;
import org.opencv.core.Mat;
import org.opencv.highgui.Highgui;
import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.view.Menu;
public class Start extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
Mat Image = Highgui.imread("/image.jpg");
if (Image == null) {
AlertDialog ad = new AlertDialog.Builder(this).create();
ad.setMessage("Fatal error: can't open /image.jpg!");
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_start, menu);
return true;
}
}
And here's the log:
08-13 12:26:14.791: E/Trace(1067): error opening trace file: No such file or directory (2)
08-13 12:26:15.191: W/dalvikvm(1067): No implementation found for native Lorg/opencv/highgui/Highgui;.imread_1:(Ljava/lang/String;)J
08-13 12:26:15.191: D/AndroidRuntime(1067): Shutting down VM
08-13 12:26:15.191: W/dalvikvm(1067): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
08-13 12:26:15.201: E/AndroidRuntime(1067): FATAL EXCEPTION: main
08-13 12:26:15.201: E/AndroidRuntime(1067): java.lang.UnsatisfiedLinkError: Native method not found: org.opencv.highgui.Highgui.imread_1:(Ljava/lang/String;)J
08-13 12:26:15.201: E/AndroidRuntime(1067): at org.opencv.highgui.Highgui.imread_1(Native Method)
08-13 12:26:15.201: E/AndroidRuntime(1067): at org.opencv.highgui.Highgui.imread(Highgui.java:324)
08-13 12:26:15.201: E/AndroidRuntime(1067): at com.test.Start.onCreate(Start.java:18)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.app.Activity.performCreate(Activity.java:5008)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.app.ActivityThread.access$600(ActivityThread.java:130)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.os.Handler.dispatchMessage(Handler.java:99)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.os.Looper.loop(Looper.java:137)
08-13 12:26:15.201: E/AndroidRuntime(1067): at android.app.ActivityThread.main(ActivityThread.java:4745)
08-13 12:26:15.201: E/AndroidRuntime(1067): at java.lang.reflect.Method.invokeNative(Native Method)
08-13 12:26:15.201: E/AndroidRuntime(1067): at java.lang.reflect.Method.invoke(Method.java:511)
08-13 12:26:15.201: E/AndroidRuntime(1067): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-13 12:26:15.201: E/AndroidRuntime(1067): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-13 12:26:15.201: E/AndroidRuntime(1067): at dalvik.system.NativeStart.main(Native Method)
Again, this is non-native code, so having an Unsatisfied Link Error doesn't make much sense.
回答1:
After a bunch of searching, I found this:
"3. If your application project doesn’t have a JNI part, just copy the corresponding OpenCV native libs from /sdk/native/libs/ to your project directory to folder libs/."
So that means copy the \armeabi, \armeabi-v7a, and \x86 folders.
"4. The last step of enabling OpenCV in your application is Java initialization code before call to OpenCV API. It can be done, for example, in the static section of the Activity class, which gets executed only once, before any instance of the class is created:
static {
if (!OpenCVLoader.initDebug()) {
// Handle initialization error
}
}
Alternatively, you can put it inside the onCreate method:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_load_image);
if (!OpenCVLoader.initDebug()) {
// Handle initialization error
}
[...]
}
Now it works!
回答2:
you should use
if (!OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_2, this, mOpenCVCallBack))
{
Log.e("TEST", "Cannot connect to OpenCV Manager");
}
in OnCreate() And use
private BaseLoaderCallback mOpenCVCallBack = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS:
{
Mat Image = Highgui.imread("/image.jpg");
if (Image == null) {
AlertDialog ad = new AlertDialog.Builder(this).create();
ad.setMessage("Fatal error: can't open /image.jpg!");
}
} break;
default:
{
super.onManagerConnected(status);
} break;
}
}
};
回答3:
In most situations, a line like this before calling openCV is enough: "System.loadLibrary(Core.NATIVE_LIBRARY_NAME);"
回答4:
I was adding opencv in my project in Android Studio. This error occurs when native files are not available at run time. So you have to copy native files at correct location.
First create the jniLibs at this location /app/src/main/ location and copy the all the folder with *.so files (armeabi, armeabi-v7a, mips, x86) in the jniLibs from the OpenCV SDK and make your gradle plugin above 0.7.2+
回答5:
The problem is that you are using Highgui.imread method before the OpenCV4Android library even finishes loading. Android calls the "onCreate" method before loading the OpenCV4Android library. So, create a separate method for your OpenCV code like this :-
public class Start extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_start, menu);
return true;
}
public void readImage {
Mat Image = Highgui.imread("/image.jpg");
if(Image=null) {
Log.i("Start", "--------Image Cannot be Loaded--------");
else if(!Image=null) {
Log.i("Start", "--------Image Loaded Successfully--------");
}
}
回答6:
The link in the answer was not working and i had to dig around for sometime for the solution that worked for me.
I first had a BaseLoaderCallback defined in the class
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS:
{
Log.i(TAG, "OpenCV loaded successfully");
// any immediate code for using OpenCV
} break;
default:
{
super.onManagerConnected(status);
} break;
}
}
};
Then in onResume function i had:
@Override
public void onResume()
{
super.onResume();
if (!OpenCVLoader.initDebug()) {
Log.d(TAG, "Internal OpenCV library not found. Using OpenCV Manager for initialization");
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
} else {
Log.d(TAG, "OpenCV library found inside package. Using it!");
mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
}
}
Make sure of the following
1.You are changing the OPENCV_VERSION_3_0_0 as per your version
- Not to run any opencv library before loading. Even in
onCreate(), opencv has not yet loaded. Better to put it in theonManagerConnected()function in the switch case where OpenCV has loaded successfully.
回答7:
In my case I paste the opencv classes in wrong package name
Wrong one
I paste the opencv classes into com.opencv -> all classes
Correct one
org.opencv -> all classes
After change this right package name it will works.
Reason - they may refer "org.opencv.."
来源：https://stackoverflow.com/questions/11939192/unsatisfied-link-error-opencv-for-android-non-native