README
《Android开发艺术探索》
任玉刚共15章
第一章 Activity的生命周期和启动模式
四大组件：Activity/Service/Broadcast Receiver/Content Provider
六大布局：RelativeLayout/LinearLayout/FrameLayout/TableLayout/AbsoluteLayout/GridLayout
一个信使：Intent
可见界面：Activity/Toast/Snack/Dialog/Window/Notification
Activity的典型生命周期：onCreate() [onStart() [onResume() onPause() 前台可见] onStop() 后台可见] onDestroy() onRestart()
视图结构：View Parent->ViewGroup-View/ViewGroup树 Activity->Window(PhoneWindow)->DecorView->TitleView/ContentView(setContentView()/setSupportActionBar())
Activity启动：startActivity()->Instrumentation(Binder)->ActivityManagerService(ActivityStack)-ActivityThread
注：ActivityA启动ActivityB，ActivityA的onPause()先于ActivityB的onCreate()执行
Activity的异常生命周期：onSaveInstanceState()->onStop()-onStart()->onRestoreInstanceState() 委托思想
Activity优先级：前台可见 后台可见 不可见
Activity不重建生命周期：onConfigurationChanged() android:configChanges = "orientation|keyboardHidden" //使系统不重建Activity
Activity启动模式：android:launchMode="standard/singTop/singTask/singInstance" onNewIntent()
A task is a stack of activities
Context:Application/Activity/Service 只有Activity有TaskStack
taskAffinity配合singleTask/allowTaskReparenting使用 当allowTaskReparenting="true"时AppA启动AppB的ActivityX会转移到AppB的TaskStack中
Activity的Flags：FLAG_ACTIVITY_NEW_TASK/FLAG_ACTIVITY_SINGLE_TOP/FLAG_ACTIVITY_CLEAR_TOP/FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS
IntentFilter的匹配规则：action/category/data
action的匹配规则（String）：必须有 Intent只有一个 IntentFilter可多个 有一个匹配即可
category的匹配规则（String）：可没有 Intent可多个 IntentFilter可多个 Intent完全匹配
data的匹配规则（mimeType+URI）：必须有 Intent只有一个 IntentFilter可多个 有一个匹配即可
显示调用/隐示调用
隐示判断：PackageManager的resolveActivity()和queryIntentActivities() 或则 Intent的resolveActivity() MATCH_DEFAULT_ONLY
第二章 IPC机制
IPC(Inter-Process Communication):Bundle 文件共享 AIDL Messenger ContentProvider Socket
ANR Application Not Responding
Binder
Android中的进程：android:process 或则JNI Native folk
android:process=":remote" 私有进程
android:process="com.gh.light.remote" 全局进程 ShareUID
问题：静态成员和单例模式完全失效/线程同步机制完全失效/SharedPreferences的可靠性下降/Application会多次创建
Serializable接口：空接口 private static final long serialVersionUID = 1L; 序列化反序列化：ObjectOutputStream/ObjectInputStream 静态变量和transient不参与序列化
Parcelable接口：
public class User implements Parcelable {
public int userId;
public String userName;
public boolean isMale;
public Book book;
public User(int userId, String userName, boolean isMale) {
this.userId = userId;
this.userName = userName;
this.isMale = isMale;
}
/*内容描述*/
public int describeContents() {
return 0;
}
/*序列化*/
public void writeToParcel(Parcel out, int flags) {
out.writeInt(userId);
out.writeString(userName);
out.writeInt(isMale ? 1 : 0);
out.writeParcelable(book, 0);
}
/*反序列化*/
public static final Parcelable.Creator<User> CREATOR = new Parcelable.Creator<User>() {
public User createFromParcel(Parcel in) {
return new User(in);
}
public User[] newArray(int size) {
return new User[size];
}
};
private User(Parcel in) {
userId = in.readInt();
userName = in.readString();
isMale = in.readInt() == 1;
book = in.readParcelable(Thread.currentThread().getContextClassLoader());
}
}
Serializable适用于序列化对象到存储设备和网络传输
Binder implements IBinder /dev/binder
public interface IBookManager extends android.os.IInterface
IBookManager文件详解：
DESCRIPTOR Binder的唯一标识，一般为Binder的类名
asInterface(android.os.IBinder obj) 转化Binder为AIDL
asBinder() 返回当前Binder
public Boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) 运行中服务端 code可以标志请求方法 如果返回false则客户端请求失败
Proxy#getBookList() Proxy#addBook()
linkToDeath() unlinkToDeath()
private IBinder.DeathRecipient mDeathRecipient = new IBinder.DeathRecipient() {
public void binderDied() {
if(mBookManager == null) {
return;
}
mBookManager.asBinder().unlinkToDeath(mDeathRecipient, 0);
mBookManager = null;
}
};
mService = IBookManager.Stub.asInterface(binder);
binder.linkToDeath(mDeathRecipient, 0);
IPC方式：
Bundle/文件共享/SharedPreferences
Messenger信使:Message 服务端 客户端
服务端：
public class MessengerService extends Service {
private static final String TAG = "MessengerService";
private static class MessengerHandler extends Handler {
public void handleMessage(Message msg) {
switch(msg.what) {
case MSG_FROM_CLIENT:
System.out.println(msg.getData().getString("msg"));
Messenger client = msg.replyTo;
... ...
client.send(msg);
break;
default:
super.handleMessage(msg);
}
}
}
private final Messenger mMessenger = new Messenger(new MessengerHandler());
public IBinder onBind(Intent intent) {
return mMessenger.getBinder();
}
}
客户端：
private Messenger mService;
// public void onServiceConnected(ComponentName className, IBinder service)
mService = new Messenger(service);
Message msg = Message.obtain(null, MSG_FROM_CLIENT);
Bundle data = new Bundle();
data.putString("msg", "Hello, this is client.");
msg.setData(data);
msg.replyTo = mGetReplyMessenger;//同服务端创建一个Messenger
mService.send(msg);
AIDL(Android Interface Defination Language)
步骤：
1 创建.aidl文件 byte short int long float double boolean char String CharSequence List(ArrayList) Map(HashMap) Parcelable AIDL
Book.java 同名Book.aidl parcelable Book;
in out inout 不支持静态常量
2 服务端实现 CopyOnWriteArrayList/ConcurrentHashMap
private CopyOnWriteArrayList<Book> mBookList = new CopyOnWriteArrayList<Book>();
private Binder mBinder = new IBookManager.Stub() {};
3 客户端实现
IBookManager bookManager = IBookManager.Stub.asInterface(service);
观察者模式 RemoteCallbackList
binderDied()肯onServiceDisconnected()区别 不可访问UI
ContentProvider
CRUD(insert() delete() update() query()) + onCreate() getType()
ContentResolver MediaStore SQLite
注册：
<provider
android:name".provider.BookProvider"
android:authorities="com.study.mm.book.provider"
android:permission="com.study.PROVIDER"
android:progress=":provider" />
访问：
Uri uri = Uri.parse("content://com.study.mm.book.provider");
getContentResolver().query(uri, null, null, null, null);
五大存储：SharedPreferences/File/SQLite/ContentProvider/Network
SQLiteOpenHelper Constructors() onCreate() onUpgrade()
UriMatcher
Socket TCP/UDP
Binder连接池
interface ISecurityCenter {
String encrypt(String content);
String decrypt(String password);
}
interface ICompute {
int add(int a, int b);
}
public class SecurityCenterImpl extends ISecurityCenter.Stub
public class ComputeImpl extends ICompute.Stub
interface IBinderPool {
IBinder queryBinder(int binderCode);
}
Service里返回：new BinderPool.BinderPoolImpl();
第三章 View的事件体系
View是一个矩形区域
ViewParent->ViewGroup->(View/ViewGroup) View树
Activity->Window(PhoneWindow)->DecorView(TittleView+ContentView) setSupportActionBar() setContentView()
View坐标系：左上角为0点 右下为正方向 getLeft()/getRight()/getTop()/getBottom() left right top bottom x y translationX translationY
MotionEvent ACTION_DOWN ACTION_MOVE ACTION_UP getX() getY() (相对于当前View) getRawX() getRawY() (相对于手机屏幕)
TouchSlop ViewConfiguration.get(getContext()).getScaledTouchSlop()
VelocityTracker
VelocityTracker velocityTracker = VelocityTracker.obtain();
velocityTracker.addMovement(event);
velocityTracker.computeCurrentVelocity(1000);
int xVelocity = velocityTracker.getXVelocity();
velocityTracker.clear();velocityTracker.recycle();
GestureDetector
GestureDetector mGestureDetector = new GestureDetector(this);
mGestureDetector.setIsLongPressEnable(false);
boolean consume = mGestureDetector.onTouchEvent(event); return consume;
实现：OnGesureListener OnDoubleTapListener的方法
Scroller弹性滑动
scrollTo() scrollBy()
Scroller scroller = new Scroller(mContext);
View的滑动：
使用scrollTo()/scrollBy() 操作简单 适合对View内容的滑动
使用动画 操作简单 适用于没有交互的View和实现复杂的动画效果
改变布局参数 操作复杂 适用于有交互的View
使用Scroller进行弹性滑动
View事件的分发处理（委托思想）：先分发 再拦截 谁拦截 谁处理 不处理 就回调 处理完 就结束
public boolean dispatchTouchEvent(MotionEvent ev)
public boolean onInterceptTouchEvent(MotionEvent ev)
public boolean onTouchEvent(MotionEvent ev)
互动冲突：外部拦截法 内部拦截法
第十二章 Bitmap的加载和Cache
OOM(Out Of Memory)
16M Bitmap
LruCache 内存缓存
DisLruCache 磁盘缓存
LRU(Least Recently Used)最近最少使用
ListView GridView RecyclerView
Bitmap
BitmapFactory decodeFile/decodeResource/decodeStream/decodeByteArray
BitmapFactory.Options inJustDecodeBounds inSampleSize outWidth outHeight 2
public Bitmap compressBitmap(Resources res, int id, int requireWidth, int requireHeight) {
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inJustDecodeBounds = true;
BitmapFactory.decodeResources(res, id, opts);
int outWidth = opts.outWidth;
int outHeight = opts.outHeight;
int inSampleSize = 1;
while(outWidth > requireWidth || outHeight >requireHeight) {
inSampleSize *= 2;
outWidth /= 2;
outHeight /= 2;
}
opts.inSampleSize = inSampleSize;
opts.inJustDecodeBounds = false;
return BitmapFactory.decodeResources(res, id, opts);
}
LruCache Android 3.1 support-v4 Android 2.2 LinkedHashMap
强引用：不被GC
软引用：内存不足GC
弱引用：随时GC
int maxSize = (int)(Runtime.getRuntime().maxMemory() / 8);
LruCache<String, Bitmap> mLruCache = new LruCache<String, Bitmap>(maxSize) {
protected int sizeOf(String key, Bitmap bitmap) {
return bitmap.getRowBytes() * bitmap.getHeight();
}
create()
entryRemoved()
};
mLruCache.get(key);
mLruCache.put(key, bitmap);
mLruCache.remove(key);
/sdcard/Android/data/package_name/cache
/data/data/package_name/cache
File directory = getCacheDirectory(context, "bitmap");
if (!directory.exists()) {
directory.mkdir();
}
int version = getAppVersion(context);
int maxSize = 10 * 1024 * 1024;
mDiskLruCache = DiskLruCache.open(directory, version, 1, maxSize);
private int getAppVersion(Context context) {
String packageName = context.getPackageName();
PackageManager packageManager = context.getPackageManager();
try {
PackageInfo packageInfo = packageManager.getPackageInfo(packageName, 0);
return packageInfo.versionCode;
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
}
return 1;
}
private File getCacheDirectory(Context context, String uniqueName) {
String cachePath;
String state = Environment.getExternalStorageState();
boolean isRemovable = Environment.isExternalStorageRemovable();
if (TextUtils.equals(state, Environment.MEDIA_MOUNTED) || !isRemovable) {
cachePath = context.getExternalCacheDir().toString();
} else {
cachePath = context.getCacheDir().toString();
}
return new File(cachePath + File.separator + uniqueName);
}
private String getKey(String src) {
String key;
try {
MessageDigest digest = MessageDigest.getInstance("MD5");
digest.update(src.getBytes());
byte[] bytes = digest.digest();
key = bytes2HexString(bytes);
} catch (NoSuchAlgorithmException e) {
key = String.valueOf(src.hashCode());
}
return key;
}
private String bytes2HexString(byte[] bytes) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < bytes.length; i++) {
String string = Integer.toHexString(0xFF & bytes[i]);
if (string.length() == 1) {
sb.append('0');
}
sb.append(string);
}
return sb.toString();
}
public void put(String key) {
try {
DiskLruCache.Editor editor = mDiskLruCache.edit(key);
OutputStream os = editor.newOutputStream(0);
} catch (IOException e) {
e.printStackTrace();
}
}
public void get(String key) {
try {
DiskLruCache.Snapshot snapshot = mDiskLruCache.get(key);
InputStream is = snapshot.getInputStream(0);
} catch (IOException e) {
e.printStackTrace();
}
}
public boolean remove(String key) {
try {
return mDiskLruCache.remove(key);
} catch (IOException e) {
e.printStackTrace();
}
return false;
}
public void delete() {
try {
mDiskLruCache.delete();
} catch (IOException e) {
e.printStackTrace();
}
}
public long size() {
return mDiskLruCache.size();
}
public void close() {
try {
mDiskLruCache.close();
} catch (IOException e) {
e.printStackTrace();
}
}
ImageLoader 先从内存缓存加载，再从磁盘缓存加载，最后从网络加载写入缓存
优化卡顿：
不在getView()执行耗时操作
控制异步任务的执行频率
开启硬件加速android:hardwareAccelerated="true"
第十四章 JNI和NDK编程
JNI Java Native Interface
NDK Native Development Kit
代码保护
提高效率
引用开源库
libc libm libz liblog
static {
System.loadLibrary("libHelloJNI");
}
public native static String print(String name);
public static native String print(String name);
native public static String print(String name);
jstring Java_com_study_hellojni_MainActivity_print(JNIEnv* env, jobject thiz, jstring name);
#include<jni.h>
env JVM指针 obj调用该方法的对象
Application.mk Android.mk jni目录
APP_ABI := armeabi
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := helloJNI
LOCAL_SRC_FILES := hello.cpp
include $(BUILD_SHARED_LIBRARY)
jbyte jshort jint jlong jfloat jdouble jboolean jchar
jclass jobject jsarray jsring void jobjectArray jbooleanArray ... jthrowable
Java call C/C++
C/C++ call Java
第十五章 Android性能优化
OOM SOF ANR
布局优化
减少层级
include merge ViewStub
16ms 60fps
内存优化
ListView Bitmap
MAT
Debug.startMethodTracing();
Debug.stopMethodTracing();