安卓动态加载jar实现类似热更新功能
1.将类转换成jar包，具体见 AndroidStudio 将类打包成jar
2.将打包好的jar转换成可以被Dalvik虚拟机识别的dex文件
拷贝jar文件到
build-tools下面
shift + 鼠标右键打开命令行，输入dx --dex --output=qula_dex.jar qula.jar
执行成功后
qula_dex.jar就是我们要动态加载的dex
3.创建assets目录将我们的qula_dex.jar文件放到此目录下面
4.创建一个FileUtils工具类用来将assets目录下的qula_dex.jar copy到app/data/cache目录下 源码如下
public class FileUtils {
public static void copyFiles(Context context, String fileName, File desFile) {
InputStream in =null;
OutputStream out =null;
try {
in = context.getApplicationContext().getAssets().open(fileName);
out =new FileOutputStream(desFile.getAbsolutePath());
byte[] bytes =new byte[1024];
int i;
while ((i = in.read(bytes)) != -1){
out.write(bytes,0, i);
}
}catch (IOException e) {
e.printStackTrace();
}finally {
try {
if (in !=null)
in.close();
if (out !=null)
out.close();
}catch (IOException e) {
e.printStackTrace();
}
}
}
public static boolean hasExternalStorage() {
return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
}
/**
* 获取缓存路径
* @param context
* @return 返回缓存文件路径
*/
public static File getCacheDir(Context context) {
File cache;
if (hasExternalStorage()) {
cache = context.getExternalCacheDir();
}else {
cache = context.getCacheDir();
}
if (!cache.exists()){
cache.mkdirs();
}
return cache;
}
}
5.执行测试
/**
* 加载dex文件中的class，并调用其中的sayHello方法
*/
private void loadDexClass() {
File cacheFile = FileUtils.getCacheDir(context);
String internalPath = cacheFile.getAbsolutePath() + File.separator +"qula_dex.jar";
File desFile =new File(internalPath);
try {
if (!desFile.exists()) {
desFile.createNewFile();
FileUtils.copyFiles(context,"qula_dex.jar", desFile);
}
}catch (IOException e) {
e.printStackTrace();
}
//下面开始加载dex class
DexClassLoader dexClassLoader =new DexClassLoader(internalPath,
cacheFile.getAbsolutePath(),null,context.getClassLoader());
try {
//加载的类名为jar文件里面完整类名，写错会找不到此类hh
Class libClazz = dexClassLoader.loadClass("com.justcodeit.xiaoshuo.netbook.BookFactory_qula");
loadBook = (IBookLoadFactory) libClazz.newInstance();
if (loadBook !=null)
Toast.makeText(context,"版本号" +loadBook.getVersion(), Toast.LENGTH_LONG).show();
}catch (Exception e) {
e.printStackTrace();
}
}
