Android熱修復(fù)筆記
java--->class---jar--->dex
使用方法：1、運(yùn)行修復(fù)的程序，
2、在build-->intermediates-->javac-->debug--->classes 在這個文件夾打開終端窗口運(yùn)行 jar cvf fix.jar qzone/Fix.class
（javac -encoding UTF-8 qzone/Fix.java
或者
studio編譯之后在build-intermediates-javac-debug-classes文件中查找）
3、得到j(luò)ar之后，把classes的jar復(fù)制到sdk->build-tools->版本 中（dx）
使用 dx --dex --output=fix.dex fix.jar 命令 得到dex

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FixUtil工具類

public class FixUtil {

    static String TAG="hotfix";

    public static void installPatch(Context context, String patchPath) {
        PsyP();
        File patchFile = new File(patchPath);
        if (!patchFile.exists()) {
            Log.e(TAG, "installPatch: " + patchPath + "無文件，無需修復(fù)");
            return;
        }
        File optDir = context.getCacheDir();
        try {
            // 1.得到當(dāng)前程序的classLoader
            ClassLoader classLoader = context.getClassLoader();
            // 2.反射獲取類加載器的pathList屬性
            Field pathListField = getField(Class.forName("dalvik.system.BaseDexClassLoader"), "pathList");
            Object pathList = pathListField.get(classLoader);
            // 3.反射獲取DexPathList中的dexElements
            Field dexElementsField = getField(pathList.getClass(), "dexElements");
            Object[] dexElements = (Object[]) dexElementsField.get(pathList);
            // 4.加載自己的dex,并轉(zhuǎn)化為Element[]
            // 通過反射DexPathList 中的makeDexElements() 方法來實現(xiàn)
            // 4.1 反射獲取makeDexElements方法
            Object[] patchElements = null;
            // 版本適配
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                // Android 7.0+ 使用makeDexElements(List,File,List,ClassLoader)
                Method makeDexElementsMethod = getMethod(pathList.getClass(), "makeDexElements", List.class, File.class, List.class, ClassLoader.class);
                List<File> dexFileList = new ArrayList<>();
                dexFileList.add(patchFile);
                ArrayList<IOException> suppressedExceptions = new ArrayList<IOException>();
                patchElements = (Object[]) makeDexElementsMethod.invoke(null, dexFileList, optDir, suppressedExceptions, classLoader);
            } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                // Android 6.0-7.0 使用makePathElements(List,File,List)
                Method makePathElements = getMethod(pathList.getClass(), "makePathElements", List.class, File.class, List.class);
                List<File> dexFileList = new ArrayList<>();
                dexFileList.add(patchFile);
                ArrayList<IOException> suppressedExceptions = new ArrayList<IOException>();
                patchElements = (Object[]) makePathElements.invoke(null, dexFileList, optDir, suppressedExceptions);
            } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                // Android 5.0-6.0 使用makeDexElements(ArrayList,File,ArrayList)  注意這里參數(shù)編程ArrayList類型
                Method makeDexElementsMethod = getMethod(pathList.getClass(), "makeDexElements", ArrayList.class, File.class, ArrayList.class);
                List<File> dexFileList = new ArrayList<>();
                dexFileList.add(patchFile);
                ArrayList<IOException> suppressedExceptions = new ArrayList<IOException>();
                patchElements = (Object[]) makeDexElementsMethod.invoke(null, dexFileList, optDir, suppressedExceptions);
            } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                // Android 4.4-5.0 使用makeDexElements(ArrayList,File,ArrayList)  注意這里參數(shù)編程ArrayList類型
                // 和5.0一樣的方法，注意4.4 會報錯 Class ref in pre-verified class resolved to unexpected implementation
                Log.e(TAG, "installPatch: 當(dāng)前版本：" + Build.VERSION.SDK_INT + "此版本暫未解決 Class ref in pre-verified class resolved to unexpected implementation 的問題");
                return;
            } else {
                Log.e(TAG, "installPatch: 當(dāng)前版本：" + Build.VERSION.SDK_INT + "不支持熱更新");
                return;
            }
            // 5.合并兩個Element[] patchElements要放在前面
            Object[] newElements = (Object[]) Array.newInstance(dexElements.getClass().getComponentType(), dexElements.length + patchElements.length);
            System.arraycopy(patchElements, 0, newElements, 0, patchElements.length);
            System.arraycopy(dexElements, 0, newElements, patchElements.length, dexElements.length);
            // 6.反射替換原來的dexElements
            dexElementsField.set(pathList, newElements);
            Log.e(TAG, "installPatch: 修復(fù)成功");
        } catch (Exception e) {
            e.printStackTrace();
            Log.e(TAG, "installPatch: 修復(fù)失敗!!" + e.getMessage());
        }
    }

    /**
     * 10.0以上反射調(diào)用隱蔽方法
     */
    static void PsyP() {
        if (SDK_INT < Build.VERSION_CODES.P) {
            return;
        }
        try {
            //設(shè)置豁免所有hide api  https://developer.android.google.cn/about/versions/10/non-sdk-q
            Method forName = Class.class.getDeclaredMethod("forName", String.class);
            Method getDeclaredMethod = Class.class.getDeclaredMethod("getDeclaredMethod", String.class, Class[].class);
            Class<?> vmRuntimeClass = (Class<?>) forName.invoke(null, "dalvik.system.VMRuntime");
            Method getRuntime = (Method) getDeclaredMethod.invoke(vmRuntimeClass, "getRuntime", null);
            Method setHiddenApiExemptions = (Method) getDeclaredMethod.invoke(vmRuntimeClass, "setHiddenApiExemptions", new Class[]{String[].class});
            Object sVmRuntime = getRuntime.invoke(null);
            setHiddenApiExemptions.invoke(sVmRuntime, new Object[]{new String[]{"L"}});
        } catch (
                Throwable e) {
            Log.e("[error]", "reflect bootstrap failed:", e);
        }
    }

    /**
     * 反射獲取屬性 會從所有父類中找，不區(qū)分private
     */
    public static Field getField(Class cls, String fieldName) {
        // 如果自己類中找不到 就去父類中遞歸查找
        Field declaredField = null;
        while (cls != null) {
            Log.e(TAG, "getField: 當(dāng)前類" + cls.getName());
            try {
                declaredField = cls.getDeclaredField(fieldName);
                if (declaredField != null) {
                    declaredField.setAccessible(true);
                    return declaredField;
                }
            } catch (NoSuchFieldException e) {
                e.printStackTrace();
            }
            cls = cls.getSuperclass();
        }
        // 沒有找到
        return null;
    }

    /**
     * 反射獲取方法 會從所有父類中找，不區(qū)分private  注意方法需要傳入?yún)?shù)
     */
    public static Method getMethod(Class cls, String methodName, Class<?>... paramTypes) {

        // 如果自己類中找不到 就去父類中遞歸查找
        Method declaredMethod = null;
        while (cls != null) {
            try {
                declaredMethod = cls.getDeclaredMethod(methodName, paramTypes);
                if (declaredMethod != null) {
                    declaredMethod.setAccessible(true);
                    return declaredMethod;
                }
                cls = cls.getSuperclass();
            } catch (NoSuchMethodException e) {
                e.printStackTrace();
            }
        }

        // 沒有找到
        return null;
    }
}

Fix修復(fù)類(要修復(fù)的類)

public class Fix {
    public static String getMessage() {
//        return "程序出bug了，趕緊叫人來修補(bǔ)?。?！";
        return "程序的問題已經(jīng)修復(fù)完成(這是修復(fù)之后的類文件及方法)";
    }
}

AppLication

public class App extends Application {

  @Override
  public void onCreate() {
      super.onCreate();
      Log.e("Application", "----------path:" + Environment.getExternalStorageDirectory().getAbsolutePath() + "/fix.dex");
      FixUtil.installPatch(this, Environment.getExternalStorageDirectory().getAbsolutePath() + "/fix.dex");
//            FixUtil.installPatch(this, getFilesDir()+ File.separator+"patch.dex");
  }
}