Android 11 ，Android Studio 三方APP调用系统 system/lib 目录下so库使用过程中的BUG(坑)。
背景介绍：最近在做文件管理器，需要把图库的功能集成到文件管理器中，实现在文件管理器中打开图片、切换图片的功能。在实现gif图片打开功能的时候，需要用到系统现成的gifplayer so库，导入Android studio的时候遇到了一堆问题，解决了感觉有必要记录一下主要的两个问题。
一、Android studio 导入so库。
按照下图创建目录导入。
java代码中使用System.loadLibrary导入so库使用：
package com.xuhao;
import android.graphics.Bitmap;
import android.os.Handler;
import android.os.HandlerThread;
import java.io.File;
public class GifPlayer {
static {
System.loadLibrary("gifplayer");
System.loadLibrary("gifplayer_jni");
}
private native long native_create();
private native boolean native_load(long ptr,String gifPath);
private native void native_play(long ptr, boolean loop, Bitmap bitmap,Runnable runnable);
private native int native_getWidth(long ptr);
private native int native_getHeight(long ptr);
private native void native_pause(long ptr);
private native void native_resume(long ptr);
private native void native_stop(long ptr);
private native void native_release(long ptr);
public interface OnDrawGifCallBack {
void onDrawFrame(Bitmap bitmap);
}
private Bitmap mBitmap;
private OnDrawGifCallBack mOnDrawGifCallBack;
private long mGifPlayerPtr = 0L;
private final static String TAG = "GifPlayer";
private HandlerThread mHandlerThread;
private Handler mWorkHandler;
public GifPlayer() {
mHandlerThread = new HandlerThread("GifPlayer");
mHandlerThread.start();
mWorkHandler = new Handler(mHandlerThread.getLooper());
mGifPlayerPtr = native_create();
}
public void setOnDrawGifCallBack(OnDrawGifCallBack onDrawGifCallBack) {
this.mOnDrawGifCallBack = onDrawGifCallBack;
}
public void play(final String gifPath, final boolean loop){
boolean ret = checkIfFileExist(gifPath);
if (!ret) {
throw new IllegalArgumentException("This isn't a valid gif path");
} else {
mWorkHandler.post(new Runnable() {
@Override
public void run() {
if (native_load(mGifPlayerPtr, gifPath)) {
mBitmap = Bitmap.createBitmap(native_getWidth(mGifPlayerPtr), native_getHeight(mGifPlayerPtr), Bitmap.Config.ARGB_8888);
native_play(mGifPlayerPtr, loop, mBitmap, new Runnable() {
@Override
public void run() {
if (mOnDrawGifCallBack != null) {
mOnDrawGifCallBack.onDrawFrame(mBitmap);
}
}
});
}
}
});
}
}
public void pause() {
native_pause(mGifPlayerPtr);
}
public void resume() {
native_resume(mGifPlayerPtr);
}
public void stop() {
native_stop(mGifPlayerPtr);
}
public void release() {
native_stop(mGifPlayerPtr);
mWorkHandler.post(new Runnable() {
@Override
public void run() {
native_release(mGifPlayerPtr);
mBitmap = null;
mWorkHandler = null;
mHandlerThread.quit();
mHandlerThread = null;
}
});
}
private boolean checkIfFileExist(String gifPath) {
if (gifPath != null && gifPath.length() != 0) {
File file = new File(gifPath);
if (file.exists() && _getFormatName(gifPath).equals("gif")) {
return true;
}
}
return false;
}
private String _getFormatName(String gifPath) {
if (gifPath != null && gifPath.length() != 0) {
gifPath = gifPath.trim();
String s[] = gifPath.split("\\.");
if (s.length >= 2) {
return s[s.length - 1];
}
}
return "";
}
}
注：java文件所在的包名必须和系统中so库源码jni的名字路径相同，这一点非常重要，是规则必须遵守。比如系统中的jni文件叫com_xuhao_GifPlayer.cpp，那么Android Studio 中必须把GifPlayer.java放在路径com.xuhao下才行。
到目前为止都是在按流程走。
二、解决报错
1、第一个报错
E AndroidRuntime: java.lang.UnsatisfiedLinkError: dlopen failed: library "/system/lib/libgifplayer_jni.so" needed or dlopened by "/apex/com.android.art/lib/libnativeloader.so" is not accessible for the namespace "classloader-namespace"
解决方法：
上面的报错，意思是无法导入system/lib/目录下的libgifplayer_jni.so库，libgifplayer_jni.so不是public的，需要加入白名单，Android 11 的白名单文件位置为：system\core\rootdir\etc\public.libraries.android.txt ，在该文件末尾加上要使用的so库名字：
2、第二个报错
08-28 21:35:04.482 6950 6950 I ilicon.explore: The ClassLoaderContext is a special shared library.
08-28 21:35:04.504 6950 6950 I chatty : uid=1000(system) com.hisilicon.explorer identical 2 lines
08-28 21:35:04.512 6950 6950 I ilicon.explore: The ClassLoaderContext is a special shared library.
08-28 21:35:04.537 6950 6950 D NetworkSecurityConfig: Using Network Security Config from resource network_security_config debugBuild: false
08-28 21:35:04.554 6950 6950 W ContextImpl: Calling a method in the system process without a qualified user: android.app.ContextImpl.startService:1669 android.content.ContextWrapper.startService:720 com.hisilicon.explorer.contentprovider.ServerDataProvider.f:3 com.hisilicon.explorer.contentprovider.ServerDataProvider.onCreate:4 android.content.ContentProvider.attachInfo:2388
08-28 21:35:04.556 6950 6950 W ContextImpl: Calling a method in the system process without a qualified user: android.app.ContextImpl.bindService:1748 android.content.ContextWrapper.bindService:756 com.hisilicon.explorer.contentprovider.ServerDataProvider.f:7 com.hisilicon.explorer.contentprovider.ServerDataProvider.onCreate:4 android.content.ContentProvider.attachInfo:2388
08-28 21:35:04.539 6950 6950 D NetworkSecurityConfig: Using Network Security Config from resource network_security_config debugBuild: false
08-28 21:35:04.576 6950 6950 E ilicon.explore: ----- class 'Lcom/softwinner/GifPlayer;' cl=0x12d11a28 -----
08-28 21:35:04.576 6950 6950 E ilicon.explore: objectSize=176 (172 from super)
08-28 21:35:04.576 6950 6950 E ilicon.explore: access=0x0008.0001
08-28 21:35:04.576 6950 6950 E ilicon.explore: super='java.lang.Class<java.lang.Object>' (cl=0x0)
08-28 21:35:04.576 6950 6950 E ilicon.explore: vtable (1 entries, 11 in super):
08-28 21:35:04.576 6950 6950 E ilicon.explore: 0: void com.softwinner.GifPlayer.g()
08-28 21:35:04.576 6950 6950 E ilicon.explore: direct methods (11 entries):
08-28 21:35:04.576 6950 6950 E ilicon.explore: 0: void com.softwinner.GifPlayer.<clinit>()
08-28 21:35:04.576 6950 6950 E ilicon.explore: 1: void com.softwinner.GifPlayer.<init>()
08-28 21:35:04.576 6950 6950 E ilicon.explore: 2: long com.softwinner.GifPlayer.a(com.softwinner.GifPlayer)
08-28 21:35:04.576 6950 6950 E ilicon.explore: 3: android.graphics.Bitmap com.softwinner.GifPlayer.b(com.softwinner.GifPlayer, android.graphics.Bitmap)
08-28 21:35:04.576 6950 6950 E ilicon.explore: 4: void com.softwinner.GifPlayer.c(com.softwinner.GifPlayer, long)
08-28 21:35:04.576 6950 6950 E ilicon.explore: 5: android.os.Handler com.softwinner.GifPlayer.d(com.softwinner.GifPlayer, android.os.Handler)
08-28 21:35:04.576 6950 6950 E ilicon.explore: 6: android.os.HandlerThread com.softwinner.GifPlayer.e(com.softwinner.GifPlayer)
08-28 21:35:04.576 6950 6950 E ilicon.explore: 7: android.os.HandlerThread com.softwinner.GifPlayer.f(com.softwinner.GifPlayer, android.os.HandlerThread)
08-28 21:35:04.576 6950 6950 E ilicon.explore: 8: long com.softwinner.GifPlayer.native_create()
08-28 21:35:04.576 6950 6950 E ilicon.explore: 9: void com.softwinner.GifPlayer.native_release(long)
08-28 21:35:04.576 6950 6950 E ilicon.explore: 10: void com.softwinner.GifPlayer.native_stop(long)
08-28 21:35:04.576 6950 6950 E ilicon.explore: instance fields (4 entries):
08-28 21:35:04.576 6950 6950 E ilicon.explore: 0: android.graphics.Bitmap com.softwinner.GifPlayer.a
08-28 21:35:04.576 6950 6950 E ilicon.explore: 1: long com.softwinner.GifPlayer.b
08-28 21:35:04.576 6950 6950 E ilicon.explore: 2: android.os.HandlerThread com.softwinner.GifPlayer.c
08-28 21:35:04.576 6950 6950 E ilicon.explore: 3: android.os.Handler com.softwinner.GifPlayer.d
08-28 21:35:04.576 6950 6950 E ilicon.explore: Failed to register native method com.softwinner.GifPlayer.native_load(JLjava/lang/String;)Z in /data/app/~~r-FMElIYiOMGNg22Rt8Mqg==/com.hisilicon.explorer-hzeXaFdGb6EVm8n37HswcA==/base.apk
08-28 21:35:04.576 6950 6950 D AndroidRuntime: Shutting down VM
08-28 21:35:04.578 6950 6950 E AndroidRuntime: FATAL EXCEPTION: main
08-28 21:35:04.578 6950 6950 E AndroidRuntime: Process: com.hisilicon.explorer, PID: 6950
08-28 21:35:04.578 6950 6950 E AndroidRuntime: java.lang.NoSuchMethodError: no static or non-static method "Lcom/softwinner/GifPlayer;.native_load(JLjava/lang/String;)Z"
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at java.lang.Runtime.nativeLoad(Native Method)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at java.lang.Runtime.nativeLoad(Runtime.java:1131)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at java.lang.Runtime.loadLibrary0(Runtime.java:1085)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at java.lang.Runtime.loadLibrary0(Runtime.java:1008)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at java.lang.System.loadLibrary(System.java:1664)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at com.softwinner.GifPlayer.<clinit>(GifPlayer.java:2)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at com.hisilicon.explorer.ExplorerApplication.onCreate(ExplorerApplication.java:8)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1192)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6743)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at android.app.ActivityThread.access$1300(ActivityThread.java:237)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1921)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:106)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at android.os.Looper.loop(Looper.java:223)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:7695)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
08-28 21:35:04.578 6950 6950 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
提取关键报错：
java.lang.NoSuchMethodError: no static or non-static method "Lcom/softwinner/GifPlayer;.native_load(JLjava/lang/String;)Z"
意思就是so库加载进去了，但是GifPlayer 中声明的native_load方法找不到。。。。。。，奇怪了，看了一圈都没有任何问题，把人整麻了。
解决方法：
后面发现so库的Android.mk中有如下配置：
LOCAL_PROGUARD_ENABLED:= disabled
这个配置的意思就是关闭代码混淆，那么我的Android studio中的配置是不是也要把代码混淆关闭才能正常使用呢？试了一下，果然。build.gradle如下修改：把和代码混淆相关的功能都注释关闭。
buildTypes {
release {
// minifyEnabled true //是否启动混淆 true:打开 false:关闭 混淆后无法联网 ,无法使用libgifplayer so库
// shrinkResources true//去掉无用资源
// proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
这里我大概分析一下BUG产生的原因：java调so库是能调到的，但是so库返回结果的时候，由于APK使用了代码混淆，就不知道该返回给谁了。
后记：本文只针对Android 11 三方APP导入system/lib 目录下so库使用的情况，其它版本读者请细细斟酌一下，本文只做个参考。