Android热补丁动态修复技术（三）Demo

package com.aitsuki.hotpatchdemo; import android.app.Application; import android.os.Environment; import android.util.Log; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.lang.reflect.Array; import java.lang.reflect.Field; import dalvik.system.DexClassLoader; /** * Created by hp on 2016/4/6. */ public class HotPatchApplication extends Application { @Override public void onCreate() { super.onCreate(); injectHack(); // 获取补丁，如果存在就执行注入操作 String dexPath = Environment.getExternalStorageDirectory().getAbsolutePath().concat("/patch_dex.jar"); File file = new File(dexPath); if (file.exists()) { inject(dexPath); } else { Log.e("HotPatchApplication", dexPath + "不存在"); } } private void injectHack() { try { File hackDir = getDir("hackDir", MODE_PRIVATE); File hackJar = new File(hackDir,"hack.jar"); InputStream in = getAssets().open("hack.jar"); OutputStream out = new FileOutputStream(hackJar); byte[] buf = new byte[1024]; int len; while ((len= in.read(buf)) != -1) { out.write(buf,0,len); } in.close(); out.close(); inject(hackJar.getAbsolutePath()); } catch (IOException e) { e.printStackTrace(); } } /** * 要注入的dex的路径 * * @param path */ private void inject(String path) { try { // 获取classes的dexElements Class<?> cl = Class.forName("dalvik.system.BaseDexClassLoader"); Object pathList = getField(cl, "pathList", getClassLoader()); Object baseElements = getField(pathList.getClass(), "dexElements", pathList); // 获取patch_dex的dexElements（需要先加载dex） String dexopt = getDir("dexopt", 0).getAbsolutePath(); DexClassLoader dexClassLoader = new DexClassLoader(path, dexopt, dexopt, getClassLoader()); Object obj = getField(cl, "pathList", dexClassLoader); Object dexElements = getField(obj.getClass(), "dexElements", obj); // 合并两个Elements Object combineElements = combineArray(dexElements, baseElements); // 将合并后的Element数组重新赋值给app的classLoader setField(pathList.getClass(), "dexElements", pathList, combineElements); //======== 以下是测试是否成功注入 ================= Object object = getField(pathList.getClass(), "dexElements", pathList); int length = Array.getLength(object); Log.e("BugFixApplication", "length = " + length); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (NoSuchFieldException e) { e.printStackTrace(); } } /** * 通过反射获取对象的属性值 */ private Object getField(Class<?> cl, String fieldName, Object object) throws NoSuchFieldException, IllegalAccessException { Field field = cl.getDeclaredField(fieldName); field.setAccessible(true); return field.get(object); } /** * 通过反射设置对象的属性值 */ private void setField(Class<?> cl, String fieldName, Object object, Object value) throws NoSuchFieldException, IllegalAccessException { Field field = cl.getDeclaredField(fieldName); field.setAccessible(true); field.set(object, value); } /** * 通过反射合并两个数组 */ private Object combineArray(Object firstArr, Object secondArr) { int firstLength = Array.getLength(firstArr); int secondLength = Array.getLength(secondArr); int length = firstLength + secondLength; Class<?> componentType = firstArr.getClass().getComponentType(); Object newArr = Array.newInstance(componentType, length); for (int i = 0; i < length; i++) { if (i < firstLength) { Array.set(newArr, i, Array.get(firstArr, i)); } else { Array.set(newArr, i, Array.get(secondArr, i - firstLength)); } } return newArr; } }