打包jar文件 外部调用资源 so等

一个非常好的从jar文件中加载so动态库方法，在android的gif支持开源中用到。这个项目的gif解码是用jni c实现的，避免了OOM等问题。

项目地址：https://github.com/koral--/android-gif-drawable

如果是把java文件生成jar。jni生成的so文件放到使用apk的libs/armeabi/lib_gif.so.....

gifExample.apk:

/libs/gif.jar

/libs/armeabi/lib_gi.so

这样做会报错，提示xml里面找不到GifImageView。

只能用项目之间依赖，so会自动进入生成的apk，不用拷贝。

调用方法：

//开始调用：
    static {
        LibraryLoader.loadLibrary(null, LibraryLoader.BASE_LIBRARY_NAME);
    }

进入这里：

package pl.droidsonroids.gif;

import android.content.Context;
import android.support.annotation.NonNull;

import java.lang.reflect.Method;

/**
 * Helper used to work around native libraries loading on some systems.
 * See <a href="https://medium.com/keepsafe-engineering/the-perils-of-loading-native-libraries-on-android-befa49dce2db">ReLinker</a> for more details.
 */
public class LibraryLoader {
    static final String SURFACE_LIBRARY_NAME = "pl_droidsonroids_gif_surface";
    static final String BASE_LIBRARY_NAME = "pl_droidsonroids_gif";
    private static Context sAppContext;

    /**
     * Intitializes loader with given `Context`. Subsequent calls should have no effect since application Context is retrieved.
     * Libraries will not be loaded immediately but only when needed.
     * @param context any Context except null
     */
    public static void initialize(@NonNull final Context context) {
        sAppContext = context.getApplicationContext();
    }

    static Context getContext() {
        if (sAppContext == null) {
            try {
                final Class<?> activityThread = Class.forName("android.app.ActivityThread");
                final Method currentApplicationMethod = activityThread.getDeclaredMethod("currentApplication");
                sAppContext = (Context) currentApplicationMethod.invoke(null);
            } catch (Exception e) {
                throw new RuntimeException("LibraryLoader not initialized. Call LibraryLoader.initialize() before using library classes.", e);
            }
        }
        return sAppContext;
    }

    static void loadLibrary(Context context, final String library) {
        try {
            System.loadLibrary(library);
        } catch (final UnsatisfiedLinkError e) {
            if (SURFACE_LIBRARY_NAME.equals(library)) {
                loadLibrary(context, BASE_LIBRARY_NAME);
            }
            if (context == null) {
                context = getContext();
            }
            ReLinker.loadLibrary(context, library);
        }
    }
}

最终到这里：

 

/**
 * Copyright 2015 KeepSafe Software, Inc.
 * <p/>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package pl.droidsonroids.gif;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.os.Build;

import java.io.Closeable;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

/**
 * Based on https://github.com/KeepSafe/ReLinker
 * ReLinker is a small library to help alleviate {@link UnsatisfiedLinkError} exceptions thrown due
 * to Android's inability to properly install / load native libraries for Android versions before
 * API 21
 */
class ReLinker {
    private static final String LIB_DIR = "lib";
    private static final int MAX_TRIES = 5;
    private static final int COPY_BUFFER_SIZE = 8192;

    private ReLinker() {
        // No instances
    }

    /**
     * Utilizes the regular system call to attempt to load a native library. If a failure occurs,
     * then the function extracts native .so library out of the app's APK and attempts to load it.
     * <p/>
     * <strong>Note: This is a synchronous operation</strong>
     */
    static void loadLibrary(Context context, final String library) {
        final String libName = System.mapLibraryName(library);
        synchronized (ReLinker.class) {
            final File workaroundFile = unpackLibrary(context, libName);
            System.load(workaroundFile.getAbsolutePath());
        }
    }

    /**
     * Attempts to unpack the given library to the workaround directory. Implements retry logic for
     * IO operations to ensure they succeed.
     *
     * @param context {@link Context} to describe the location of the installed APK file
     * @param libName The name of the library to load
     */
    private static File unpackLibrary(final Context context, final String libName) {
        File outputFile = new File(context.getDir(LIB_DIR, Context.MODE_PRIVATE), libName);// + BuildConfig.VERSION_NAME);
        if (outputFile.isFile()) {
            return outputFile;
        }

        final File cachedLibraryFile = new File(context.getCacheDir(), libName );//+ BuildConfig.VERSION_NAME);
        if (cachedLibraryFile.isFile()) {
            return cachedLibraryFile;
        }

        final FilenameFilter filter = new FilenameFilter() {
            @Override
            public boolean accept(File dir, String filename) {
                return filename.startsWith(libName);
            }
        };
        clearOldLibraryFiles(outputFile, filter);
        clearOldLibraryFiles(cachedLibraryFile, filter);

        final ApplicationInfo appInfo = context.getApplicationInfo();
        final File apkFile = new File(appInfo.sourceDir);
        ZipFile zipFile = null;
        try {
            zipFile = openZipFile(apkFile);

            int tries = 0;
            while (tries++ < MAX_TRIES) {
                ZipEntry libraryEntry = getLibraryEntry(libName, zipFile);

                InputStream inputStream = null;
                FileOutputStream fileOut = null;
                try {
                    inputStream = zipFile.getInputStream(libraryEntry);
                    fileOut = new FileOutputStream(outputFile);
                    copy(inputStream, fileOut);
                } catch (IOException e) {
                    if (tries > MAX_TRIES / 2) {
                        outputFile = cachedLibraryFile;
                    }
                    continue;
                } finally {
                    closeSilently(inputStream);
                    closeSilently(fileOut);
                }
                setFilePermissions(outputFile);
                break;
            }
        } finally {
            closeSilently(zipFile);
        }
        return outputFile;
    }

    @SuppressWarnings("deprecation") //required for old API levels
    private static ZipEntry getLibraryEntry(final String libName, final ZipFile zipFile) {
        String jniNameInApk;

        ZipEntry libraryEntry = null;
//        if (Build.VERSION.SDK_INT >= 21 && Build.SUPPORTED_ABIS.length > 0) {
//            for (final String ABI : Build.SUPPORTED_ABIS) {
//                jniNameInApk = "lib/" + ABI + "/" + libName;
//                libraryEntry = zipFile.getEntry(jniNameInApk);
//
//                if (libraryEntry != null) {
//                    break;
//                }
//            }
//        } else 
        
        {
            jniNameInApk = "lib/" + Build.CPU_ABI + "/" + libName;
            libraryEntry = zipFile.getEntry(jniNameInApk);
        }

        if (libraryEntry == null) {
            throw new IllegalStateException("Library " + libName + " for supported ABIs not found in APK file");
        }
        return libraryEntry;
    }

    private static ZipFile openZipFile(final File apkFile) {
        int tries = 0;
        ZipFile zipFile = null;
        while (tries++ < MAX_TRIES) {
            try {
                zipFile = new ZipFile(apkFile, ZipFile.OPEN_READ);
                break;
            } catch (IOException ignored) {
            }
        }

        if (zipFile == null) {
            throw new RuntimeException("Could not open APK file: " + apkFile.getAbsolutePath());
        }
        return zipFile;
    }

    @SuppressWarnings("ResultOfMethodCallIgnored") //intended, nothing useful can be done
    private static void clearOldLibraryFiles(final File outputFile, final FilenameFilter filter) {
        final File[] fileList = outputFile.getParentFile().listFiles(filter);
        if (fileList != null) {
            for (File file : fileList) {
                file.delete();
            }
        }
    }

    @SuppressWarnings("ResultOfMethodCallIgnored") //intended, nothing useful can be done
    @SuppressLint("SetWorldReadable") //intended, default permission
    private static void setFilePermissions(File outputFile) {
        // Try change permission to rwxr-xr-x
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
            outputFile.setReadable(true, false);
            outputFile.setExecutable(true, false);
            outputFile.setWritable(true);
        }
    }

    /**
     * Copies all data from an {@link InputStream} to an {@link OutputStream}.
     *
     * @param in  The stream to read from.
     * @param out The stream to write to.
     * @throws IOException when a stream operation fails.
     */
    private static void copy(InputStream in, OutputStream out) throws IOException {
        final byte[] buf = new byte[COPY_BUFFER_SIZE];
        while (true) {
            final int bytesRead = in.read(buf);
            if (bytesRead == -1) {
                break;
            }
            out.write(buf, 0, bytesRead);
        }
    }

    /**
     * Closes a {@link Closeable} silently (without throwing or handling any exceptions)
     *
     * @param closeable {@link Closeable} to close
     */
    private static void closeSilently(final Closeable closeable) {
        try {
            if (closeable != null) {
                closeable.close();
            }
        } catch (IOException ignored) {
        }
    }
}

获取当前apk路径

final ApplicationInfo appInfo = context.getApplicationInfo();
Log.d("zhibin","appInfo.sourceDir: "+ appInfo.sourceDir);
输出：/system/app/xxx.apk

---

对应sdk 5.0以下版本，修正一些不支持的变量：

    @SuppressWarnings("deprecation") //required for old API levels
    private static ZipEntry getLibraryEntry(final String libName, final ZipFile zipFile) {
        String jniNameInApk;

        ZipEntry libraryEntry = null;
//        if (Build.VERSION.SDK_INT >= 21 && Build.SUPPORTED_ABIS.length > 0) {
//            for (final String ABI : Build.SUPPORTED_ABIS) {
//                jniNameInApk = "lib/" + ABI + "/" + libName;
//                libraryEntry = zipFile.getEntry(jniNameInApk);
//
//                if (libraryEntry != null) {
//                    break;
//                }
//            }
//        } else 
        
        {
            jniNameInApk = "lib/" + Build.CPU_ABI + "/" + libName;
            Log.d("zhibin","Search directory for jniNameInApk: "+ jniNameInApk);
            libraryEntry = zipFile.getEntry(jniNameInApk);
            
            
            //直接指定
            if(libraryEntry == null){
                jniNameInApk = "lib/armeabi" + "/" + libName;
                Log.d("zhibin","Correct it to  jniNameInApk: "+ jniNameInApk);
                libraryEntry = zipFile.getEntry(jniNameInApk);
            }
        }

        if (libraryEntry == null) {
            throw new IllegalStateException("Library " + libName + " for supported ABIs not found in APK file");
        }
        return libraryEntry;
    }

共外部调用资源：

背景：工作中需要开发一个广告插件，并提供给其它人使用。这里就需要把自己的插件程序，打成jar来提供给他人引用。
但是遇到一个问题：插件程序中无法使用资源文件。

试过以下几种方式解决：

1、从插件程序中导出jar包
论坛上有人说导出的jar包中无法包含Drawable等资源文件，一些图片等数据，需要放到Assert文件中使用。
其实，关于这个问题，我做了尝试：
首先，需要说明导出jar包含什么文件是由你导出时选择来决定的，比如下图：

如果你选择了res文件夹，则打包出的jar文件是可以包含res文件到。

但是包含文件并不代表可以使用。如果你想当然在插件程序中使用R.drawable.XXXX等方式获取
资源会报错！
当然别人通过R.XX.XX也只能看到自己的资源文件，而无法获取jar中的资源文件。

2、获取jar包中的文件

虽然无法直接引用资源文件，但是如果外边程序想获取某个资源文件时，也是可行的。
其原理是以数据流读取jar中指定的文件。
比如读取Assert文件下的icon.jpg文件：
你可以在插件中封装一个对外的方法：
    publicstatic Drawable getAssertDrawable(Context context,StringfileName){
       try {
          InputStreaminStream=context.getAssets().open(fileName);
          return newBitmapDrawable(BitmapFactory.decodeStream(inStream));
       } catch(IOException e) {
         Log.e(LOG_TAG, "Assert中"+fileName+"不存在");
       }
       returnnull;
    }
直接使用该方法可以得到文件。
后来又尝试在外部程序，直接使用context.getAssets().open(fileName)方法获取jar中文件，
让人喜出望外的是竟然成功了。呵呵！
后来分析，外部程序编译时，其实连同jar包中内容一起混编。jar包中的Assert文件会同外部程序的Assert一起
由AssertManager管理。
所以当你jar包中Assert内部文件和外部Assert中的文件有命名冲突时，编译器会报错的。

另外，还有人提供另外一种方法来读取诸如Drawable等文件夹下的文件。
    publicstatic Drawable getDrawableForJar(String resName，Classclass){
       InputStreaminStream=class.getResourceAsStream(resName);
       return newBitmapDrawable(BitmapFactory.decodeStream(inStream));
    }
使用class.getResourceAsStream()方法读取，注意这里resName是文件的相对路径，比如jar根目录下res/drawable/icon.png，
则调用方法为：class.getResourceAsStream(/res/drawable/icon.png);

这里主要是采用ClassLoader的下面几个方法来实现：

　　public URL getResource(String name);

　　public InputStream getResourceAsStream(String name)

　　public static InputStreamgetSystemResourceAsStream(String name)

　　public static URL getSystemResource(String name)

　　后两个方法可以看出是静态的方法，这几个方法都可以从Jar中读取图片资源，但是对与动画的gif文件，笔者在尝试过程中发现，存在一些差异。

　　String gifName为Gif文件在Jar中的相对路径。

　　(1)使用了两个静态方法

　　BufferedImageimage = ImageIO.read(ClassLoader.getSystemResourceAsStream(gifName));

　　或者

　　Image image = Toolkit.getDefaultToolkit().getImage(ClassLoader.getSystemResource(gifName));

　　这两种方式可以成功地读取gif文件，但是对于gif动画，显示出来地是静态的。

　　(2)使用其他两个方法

　　Image image = Toolkit.getDefaultToolkit().getImage( this .getClass.getClassLoader()

.getResource(gifName));

　　再这种方式下动画可以正常显示了。

3、使用library方法加载资源文件 

在论坛中看到帖子讲述如何把工程作为libarary,让其他工程添加library，编译后会自动生成jar，然后在哪来使用。 
当时看到此贴，喜出望外，所以赶紧尝试下！ 

方法：选择插件工程，右键选择属性，选择Android，勾选下面Is Liabrary选项。 
然后，选择我们现有的工程，右键属性，选择Android，在library下add相应的库。你会看到，刚才我们设置的插件项目，就在其中。最后，点击应用，完成。 

详细步骤： 

按如下方法设置：

1. 假设要引用的android工程叫LibProject，引入到的工程叫MainProject；

2.设置LibProject，右键->Properties->Android，将Islibrary项选中，然后Apply；

3.设置MainProject，右键->->Properties->Android,在Library中，点击Add按钮，将LibProject工程加入，Apply即可。

你会看到我们的工程中多出插件工程的引用，而且可以使用R.XXX.XXX获取资源文件。 

以为可以解决了，但是发现并没有生成想要的jar文件。在插件工程中，倒是有编译的class文件，却没有jar包。 
而我们往往是不能像这样把原工程给别人直接引用的。 
经过多次试验，始终没有生成jar,非常奇怪别人怎么弄得。。。 

另外，拿以前通过这种方式生成的jar文件看，里面也不包含资源文件夹。。 
可以把生成的类共享出去。

把.so文件打包到jar中

查了一些方法，其中一个我比较喜欢，再load动态库的时候，把so文件复制到tmp目录下，然后删掉

//modify the static block

static {
  try {
    Class c = HelloJNI.class;
    URL location = 
      c.getProtectionDomain().getCodeSource().getLocation();
    ZipFile zf = new ZipFile(location.getPath());
    // libhellojni.so is put in the lib folder
    InputStream in = zf.getinputStream(zf.getEntry("lib/libhellojni.so"));
    File f = File.createTempFile("JNI-", "Temp");
    FileOutputStream out = new FileOutputStream(f);
    byte [] buf = new byte[1024];
    int len;
    while ((len = in.read(buf)) > 0)
      out.write(buf, 0, len);
    in.close();
    out.close();
    System.load(f.getAbsolutePath());
    f.delete();
  } catch (Exception e) { // I am still lazy ~~~
    e.printStackTrace();
  }
}