标签:
AndFix原理
AndFix的原理就是通过c++指针进行方法的替换,把有bug的方法替换成补丁文件中的方法。
注:在Native层使用指针替换的方式替换bug方法,已达到修复bug的目的。
使用AndFix修复热修复的整体流程:
方法替换过程:
源码解析
解析源码从使用的方法一一解析。
在自定义Application中初始化PatchManger:
PatchManager mPatchManager = new PatchManager();
直接实例化了一个PatchManger实例对象,接下看PatchManager类源码:
public PatchManager(Context context) {
mContext = context;
mAndFixManager = new AndFixManager(mContext);
mPatchDir = new File(mContext.getFilesDir(), DIR);
mPatchs = new ConcurrentSkipListSet<Patch>();
mLoaders = new ConcurrentHashMap<String, ClassLoader>();
}
然后看AndFixManager的初始化:
public AndFixManager(Context context) {
mContext = context;
mSupport = Compat.isSupport();
if (mSupport) {
mSecurityChecker = new SecurityChecker(mContext);
mOptDir = new File(mContext.getFilesDir(), DIR);
if (!mOptDir.exists() && !mOptDir.mkdirs()) {
mSupport = false;
Log.e(TAG, "opt dir create error.");
} else if (!mOptDir.isDirectory()) {
mOptDir.delete();
mSupport = false;
}
}
}
public static synchronized boolean isSupport() {
if (isChecked)
return isSupport;
isChecked = true;
boolean isYunOs = isYunOS();
boolean setup =AndFix.setup();
boolean isSupportSDKVersion = isSupportSDKVersion();
if (!isYunOs && setup && isSupportSDKVersion) {
isSupport = true;
}
if (inBlackList()) {
isSupport = false;
}
return isSupport;
}
private static boolean isSupportSDKVersion() {
if (android.os.Build.VERSION.SDK_INT >= 8
&& android.os.Build.VERSION.SDK_INT <= 23) {
return true;
}
return false;
}
public static boolean setup() {
try {
final String vmVersion = System.getProperty("java.vm.version");
boolean isArt = vmVersion != null && vmVersion.startsWith("2");
int apilevel = Build.VERSION.SDK_INT;
return setup(isArt, apilevel);
} catch (Exception e) {
Log.e(TAG, "setup", e);
return false;
}
}
public SecurityChecker(Context context) {
mContext = context;
init(mContext);
}
private void init(Context context) {
try {
PackageManager pm = context.getPackageManager();
String packageName = context.getPackageName();
PackageInfo packageInfo = pm.getPackageInfo(packageName,
PackageManager.GET_SIGNATURES);
CertificateFactory certFactory = CertificateFactory
.getInstance("X.509");
ByteArrayInputStream stream = new ByteArrayInputStream(
packageInfo.signatures[0].toByteArray());
X509Certificate cert = (X509Certificate) certFactory
.generateCertificate(stream);
mDebuggable = cert.getSubjectX500Principal().equals(DEBUG_DN);
mPublicKey = cert.getPublicKey();
} catch (NameNotFoundException e) {
Log.e(TAG, "init", e);
} catch (CertificateException e) {
Log.e(TAG, "init", e);
}
}
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接下,看一下版本的初始化:
mPatchManager.init("version")
init方法源码:
public void init(String appVersion) {
if (!mPatchDir.exists() && !mPatchDir.mkdirs()) {
Log.e(TAG, "patch dir create error.");
return;
} else if (!mPatchDir.isDirectory()) {
mPatchDir.delete();
return;
}
SharedPreferences sp = mContext.getSharedPreferences(SP_NAME,
Context.MODE_PRIVATE);
String ver = sp.getString(SP_VERSION, null);
if (ver == null || !ver.equalsIgnoreCase(appVersion)) {
cleanPatch();
sp.edit().putString(SP_VERSION, appVersion).commit();
} else {
initPatchs();
}
}
private void cleanPatch() {
File[] files = mPatchDir.listFiles();
for (File file : files) {
mAndFixManager.removeOptFile(file);
if (!FileUtil.deleteFile(file)) {
Log.e(TAG, file.getName() + " delete error.");
}
}
}
private void initPatchs() {
File[] files = mPatchDir.listFiles();
for (File file : files) {
addPatch(file);
}
}
private Patch addPatch(File file) {
Patch patch = null;
if (file.getName().endsWith(SUFFIX)) {
try {
patch = new Patch(file);
mPatchs.add(patch);
} catch (IOException e) {
Log.e(TAG, "addPatch", e);
}
}
return patch;
}
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Patch文件的加载
public Patch(File file) throws IOException {
mFile = file;
init();
}
@SuppressWarnings("deprecation")
private void init() throws IOException {
JarFile jarFile = null;
InputStream inputStream = null;
try {
jarFile = new JarFile(mFile);
JarEntry entry = jarFile.getJarEntry(ENTRY_NAME);
inputStream = jarFile.getInputStream(entry);
Manifest manifest = new Manifest(inputStream);
Attributes main = manifest.getMainAttributes();
mName = main.getValue(PATCH_NAME);
mTime = new Date(main.getValue(CREATED_TIME));
mClassesMap = new HashMap<String, List<String>>();
Attributes.Name attrName;
String name;
List<String> strings;
for (Iterator<?> it = main.keySet().iterator(); it.hasNext();) {
attrName = (Attributes.Name) it.next();
name = attrName.toString();
if (name.endsWith(CLASSES)) {
strings = Arrays.asList(main.getValue(attrName).split(","));
if (name.equalsIgnoreCase(PATCH_CLASSES)) {
mClassesMap.put(mName, strings);
} else {
mClassesMap.put(
name.trim().substring(0, name.length() - 8),
strings);
}
}
}
} finally {
if (jarFile != null) {
jarFile.close();
}
if (inputStream != null) {
inputStream.close();
}
}
}
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loadPatch方法源码
mPatchManager.loadPatch()
loadPatch源码:
public void loadPatch() {
mLoaders.put("*", mContext.getClassLoader());
Set<String> patchNames;
List<String> classes;
for (Patch patch : mPatchs) {
patchNames = patch.getPatchNames();
for (String patchName : patchNames) {
classes = patch.getClasses(patchName);
mAndFixManager.fix(patch.getFile(), mContext.getClassLoader(),
classes);
}
}
}
fix bug
public synchronized void fix(File file, ClassLoader classLoader,
List<String> classes) {
if (!mSupport) {
return;
}
if (!mSecurityChecker.verifyApk(file)) {
return;
}
try {
File optfile = new File(mOptDir, file.getName());
boolean saveFingerprint = true;
if (optfile.exists()) {
if (mSecurityChecker.verifyOpt(optfile)) {
saveFingerprint = false;
} else if (!optfile.delete()) {
return;
}
}
final DexFile dexFile = DexFile.loadDex(file.getAbsolutePath(),
optfile.getAbsolutePath(), Context.MODE_PRIVATE);
if (saveFingerprint) {
mSecurityChecker.saveOptSig(optfile);
}
ClassLoader patchClassLoader = new ClassLoader(classLoader) {
@Override
protected Class<?> findClass(String className)
throws ClassNotFoundException {
Class<?> clazz = dexFile.loadClass(className, this);
if (clazz == null
&& className.startsWith("com.alipay.euler.andfix")) {
return Class.forName(className);
}
if (clazz == null) {
throw new ClassNotFoundException(className);
}
return clazz;
}
};
Enumeration<String> entrys = dexFile.entries();
Class<?> clazz = null;
while (entrys.hasMoreElements()) {
String entry = entrys.nextElement();
if (classes != null && !classes.contains(entry)) {
continue;
}
clazz = dexFile.loadClass(entry, patchClassLoader);
if (clazz != null) {
fixClass(clazz, classLoader);
}
}
} catch (IOException e) {
Log.e(TAG, "pacth", e);
}
}
private void fixClass(Class<?> clazz, ClassLoader classLoader) {
Method[] methods = clazz.getDeclaredMethods();
MethodReplace methodReplace;
String clz;
String meth;
for (Method method : methods) {
methodReplace = method.getAnnotation(MethodReplace.class);
if (methodReplace == null)
continue;
clz = methodReplace.clazz();
meth = methodReplace.method();
if (!isEmpty(clz) && !isEmpty(meth)) {
replaceMethod(classLoader, clz, meth, method);
}
}
}
private void replaceMethod(ClassLoader classLoader, String clz,
String meth, Method method) {
try {
String key = clz + "@" + classLoader.toString();
Class<?> clazz = mFixedClass.get(key);
if (clazz == null) {
Class<?> clzz = classLoader.loadClass(clz);
clazz = AndFix.initTargetClass(clzz);
}
if (clazz != null) {
mFixedClass.put(key, clazz);
Method src = clazz.getDeclaredMethod(meth,
method.getParameterTypes());
AndFix.addReplaceMethod(src, method);
}
} catch (Exception e) {
Log.e(TAG, "replaceMethod", e);
}
}
public static void addReplaceMethod(Method src, Method dest) {
try {
replaceMethod(src, dest);
initFields(dest.getDeclaringClass());
} catch (Throwable e) {
Log.e(TAG, "addReplaceMethod", e);
}
}
private static native void replaceMethod(Method dest, Method src);
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由于Android4.4后才用的Art虚拟机,之前的系统都是Dalvik虚拟机,因此Natice层写了2个方法,对不同的系统做不同的处理方式。
extern void dalvik_replaceMethod(JNIEnv* env, jobject src, jobject dest);
extern void art_replaceMethod(JNIEnv* env, jobject src, jobject dest);
Dalvik replaceMethod的实现:
extern void __attribute__ ((visibility ("hidden"))) dalvik_replaceMethod(
JNIEnv* env, jobject src, jobject dest) {
jobject clazz = env->CallObjectMethod(dest, jClassMethod);
ClassObject* clz = (ClassObject*) dvmDecodeIndirectRef_fnPtr(
dvmThreadSelf_fnPtr(), clazz);
clz->status = CLASS_INITIALIZED;
Method* meth = (Method*) env->FromReflectedMethod(src);
Method* target = (Method*) env->FromReflectedMethod(dest);
LOGD("dalvikMethod: %s", meth->name);
meth->jniArgInfo = 0x80000000;
meth->accessFlags |= ACC_NATIVE;
int argsSize = dvmComputeMethodArgsSize_fnPtr(meth);
if (!dvmIsStaticMethod(meth))
argsSize++;
meth->registersSize = meth->insSize = argsSize;
meth->insns = (void*) target;
meth->nativeFunc = dalvik_dispatcher;
}
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Art replaceMethod的实现:
extern void __attribute__ ((visibility ("hidden"))) art_replaceMethod(
JNIEnv* env, jobject src, jobject dest) {
if (apilevel > 22) {
replace_6_0(env, src, dest);
} else if (apilevel > 21) {
replace_5_1(env, src, dest);
} else {
replace_5_0(env, src, dest);
}
}
void replace_5_0(JNIEnv* env, jobject src, jobject dest) {
art::mirror::ArtMethod* smeth =
(art::mirror::ArtMethod*) env->FromReflectedMethod(src);
art::mirror::ArtMethod* dmeth =
(art::mirror::ArtMethod*) env->FromReflectedMethod(dest);
dmeth->declaring_class_->class_loader_ =
smeth->declaring_class_->class_loader_;
dmeth->declaring_class_->clinit_thread_id_ =
smeth->declaring_class_->clinit_thread_id_;
dmeth->declaring_class_->status_ = (void *)((int)smeth->declaring_class_->status_-1);
smeth->declaring_class_ = dmeth->declaring_class_;
smeth->access_flags_ = dmeth->access_flags_;
smeth->frame_size_in_bytes_ = dmeth->frame_size_in_bytes_;
smeth->dex_cache_initialized_static_storage_ =
dmeth->dex_cache_initialized_static_storage_;
smeth->dex_cache_resolved_types_ = dmeth->dex_cache_resolved_types_;
smeth->dex_cache_resolved_methods_ = dmeth->dex_cache_resolved_methods_;
smeth->vmap_table_ = dmeth->vmap_table_;
smeth->core_spill_mask_ = dmeth->core_spill_mask_;
smeth->fp_spill_mask_ = dmeth->fp_spill_mask_;
smeth->mapping_table_ = dmeth->mapping_table_;
smeth->code_item_offset_ = dmeth->code_item_offset_;
smeth->entry_point_from_compiled_code_ =
dmeth->entry_point_from_compiled_code_;
smeth->entry_point_from_interpreter_ = dmeth->entry_point_from_interpreter_;
smeth->native_method_ = dmeth->native_method_;
smeth->method_index_ = dmeth->method_index_;
smeth->method_dex_index_ = dmeth->method_dex_index_;
LOGD("replace_5_0: %d , %d", smeth->entry_point_from_compiled_code_,
dmeth->entry_point_from_compiled_code_);
}
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添加Patch
mPatchManager.addPatch(path)
源码:
public void addPatch(String path) throws IOException {
File src = new File(path);
File dest = new File(mPatchDir, src.getName());
if (!src.exists()) {
throw new FileNotFoundException(path);
}
if (dest.exists()) {
Log.d(TAG, "patch [" + path + "] has be loaded.");
return;
}
FileUtil.copyFile(src, dest);
Patch patch = addPatch(dest);
if (patch != null) {
loadPatch(patch);
}
}
移除Patch
mPatchManager.removeAllPatch()
源码:
public void removeAllPatch() {
cleanPatch();
SharedPreferences sp = mContext.getSharedPreferences(SP_NAME,
Context.MODE_PRIVATE);
sp.edit().clear().commit();
}
到此源代码就解析结束。
反编译Patch dex文件代码
patch文件中.dex文件反编译后,看到源码效果如下:
红框标注的部分,就是补丁方法。方法的注解部分写了clazz和method的值,对应着apk包中的类名和方法名称。
Android-AndFix 热修复框架原理及源码解析
标签:
原文地址:http://blog.csdn.net/walid1992/article/details/51558162