发表更新Android / 手撸Android源码1 小时读完 (大约11066个字)

基础05-Navigation

简介

NavController是中央导航 API。它会跟踪用户访问过的目的地，并允许用户在目的地之间移动。

获取NavController

  • fragment

如果是NavHostFragment

1
val navController = this.navController
阅读更多
发表更新Android / 手撸Android源码23 分钟读完 (大约3407个字)

基础04-LiveData

LiveData

LiveData的观察者

1
2
3
4
5
6
7
fun interface Observer<T> {

    /**
     * Called when the data is changed to [value].
     */
    fun onChanged(value: T)
}
  • 通过onChanged函数分派数据变化

成员

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
@SuppressWarnings("WeakerAccess") /* synthetic access */
final Object mDataLock = new Object();
static final int START_VERSION = -1;
@SuppressWarnings("WeakerAccess") /* synthetic access */
static final Object NOT_SET = new Object();

private SafeIterableMap<Observer<? super T>, ObserverWrapper> mObservers =
        new SafeIterableMap<>();

// how many observers are in active state
@SuppressWarnings("WeakerAccess") /* synthetic access */
int mActiveCount = 0;
// to handle active/inactive reentry, we guard with this boolean
private boolean mChangingActiveState;
private volatile Object mData; // 1️⃣：当前的data
// when setData is called, we set the pending data and actual data swap happens on the main
// thread
@SuppressWarnings("WeakerAccess") /* synthetic access */
volatile Object mPendingData = NOT_SET; // 2️⃣：给多线程使用的，在4️⃣mPostValueRunnable中使用
private int mVersion; // 3️⃣：mVersion是数据版本

private boolean mDispatchingValue;
@SuppressWarnings("FieldCanBeLocal")
private boolean mDispatchInvalidated;
private final Runnable mPostValueRunnable = new Runnable() {// 4️⃣mPostValueRunnable，在主线程中将mPendingData设置为当前值
    @SuppressWarnings("unchecked")
    @Override
    public void run() {
        Object newValue;
        synchronized (mDataLock) {
            newValue = mPendingData;
            mPendingData = NOT_SET;
        }
        setValue((T) newValue);
    }
};
阅读更多
发表更新Android / 手撸Android源码18 分钟读完 (大约2687个字)

基础03-Lifecycle

lifeCycle的Observer

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
public interface LifecycleObserver

public interface DefaultLifecycleObserver : LifecycleObserver {
    /**
     * Notifies that `ON_CREATE` event occurred.
     *
     *
     * This method will be called after the [LifecycleOwner]'s `onCreate`
     * method returns.
     *
     * @param owner the component, whose state was changed
     */
    public fun onCreate(owner: LifecycleOwner) {}

    /**
     * Notifies that `ON_START` event occurred.
     *
     *
     * This method will be called after the [LifecycleOwner]'s `onStart` method returns.
     *
     * @param owner the component, whose state was changed
     */
    public fun onStart(owner: LifecycleOwner) {}

    /**
     * Notifies that `ON_RESUME` event occurred.
     *
     *
     * This method will be called after the [LifecycleOwner]'s `onResume`
     * method returns.
     *
     * @param owner the component, whose state was changed
     */
    public fun onResume(owner: LifecycleOwner) {}

    /**
     * Notifies that `ON_PAUSE` event occurred.
     *
     *
     * This method will be called before the [LifecycleOwner]'s `onPause` method
     * is called.
     *
     * @param owner the component, whose state was changed
     */
    public fun onPause(owner: LifecycleOwner) {}

    /**
     * Notifies that `ON_STOP` event occurred.
     *
     *
     * This method will be called before the [LifecycleOwner]'s `onStop` method
     * is called.
     *
     * @param owner the component, whose state was changed
     */
    public fun onStop(owner: LifecycleOwner) {}

    /**
     * Notifies that `ON_DESTROY` event occurred.
     *
     *
     * This method will be called before the [LifecycleOwner]'s `onDestroy` method
     * is called.
     *
     * @param owner the component, whose state was changed
     */
    public fun onDestroy(owner: LifecycleOwner) {}
}

public fun interface LifecycleEventObserver : LifecycleObserver {
    /**
     * Called when a state transition event happens.
     *
     * @param source The source of the event
     * @param event The event
     */
    public fun onStateChanged(source: LifecycleOwner, event: Lifecycle.Event)
}
  • 可以看到，我们在使用lifecycle.addObserver()时，可以传入LifecycleEventObserver或DefaultLifecycleObserver，一个通过event获取当前状态，一个通过不同的回调函数获取当前状态

Activity树

1
2
3
4
5
6
7
8
9
10
11
Activity -- AccountAuthenticatorActivity
         |- ActivityGroup -- TabActivity
         |- ExpandableListActivity
         |- LauncherActivity
         |- ListActivity -- PreferenceActivity
         |- NativeActivity
         |- androidx.core.app.ComponentActivity -- androidx.activity.ComponentActivity -- FragmentActivity -- AppCompatActivity
                                                |- PreviewActivity
         |- BootstrapActivity
         |- EmptyActivity
         |- EmptyFloatingActivity

LifecycleOwner

阅读更多
发表更新Android / 手撸Android源码21 分钟读完 (大约3102个字)

基础02-viewModel

ViewModel简介

在了解ViewModel之前，我们先来了解一下MVC, MVP, MVVM的发展Difference Between MVC, MVP and MVVM Architecture Pattern in Android

ViewModelStoreOwner

1
2
3
4
5
6
7
interface ViewModelStoreOwner {

    /**
     * The owned [ViewModelStore]
     */
    val viewModelStore: ViewModelStore
}

ViewModelStore

阅读更多
发表更新Android / 手撸Android源码27 分钟读完 (大约3993个字)

基础01-Context

大纲

  • Context类
    • 注解
      • 用于标注文件、SharedPreferences、数据库的打开方式的注解
      • 用于标注bindService时，service的flags的注解
      • 用于标注registerReceiver时，receiver的flags的注解
      • 用于标注getService时，servicesName的注解
      • 用于标注createPackageContext、createPackageContextAsUser、createContextAsUser、createApplicationContext时的flags的注解
    • 常量定义
      • 对应上面注解中限制的常量
      • WAL

Context类

Context是抽象类，具体实现在ContextImpl，Application，Service，Activity都直接或间接继承自ContextWrapper，ContextWrapper通过代理的方式调用真正的ContextImpl。

注解

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
/** @hide */
@IntDef(flag = true, prefix = { "MODE_" }, value = {
        MODE_PRIVATE,
        MODE_WORLD_READABLE,
        MODE_WORLD_WRITEABLE,
        MODE_APPEND,
})
@Retention(RetentionPolicy.SOURCE)
public @interface FileMode {}

/** @hide */
@IntDef(flag = true, prefix = { "MODE_" }, value = {
        MODE_PRIVATE,
        MODE_WORLD_READABLE,
        MODE_WORLD_WRITEABLE,
        MODE_MULTI_PROCESS,
})
@Retention(RetentionPolicy.SOURCE)
public @interface PreferencesMode {}

/** @hide */
@IntDef(flag = true, prefix = { "MODE_" }, value = {
        MODE_PRIVATE,
        MODE_WORLD_READABLE,
        MODE_WORLD_WRITEABLE,
        MODE_ENABLE_WRITE_AHEAD_LOGGING,
        MODE_NO_LOCALIZED_COLLATORS,
})
@Retention(RetentionPolicy.SOURCE)
public @interface DatabaseMode {}
阅读更多
关注我

链接

分类

最新文章

归档

标签

6.8242
Android1
Android FrameWork1
Android 高级开发瓶颈突破系列课11
Android-官方文档1
Android-官方源码5
Android面试查漏补缺2
C/C++1
Flutter1
Java基础1
Kotlin-Android21
Kotlin-Android 实习25
LeetCode45
LeetCode 1013
LeetCode周赛1
Linux/UNIX系统编程手册38
OI KIWI2
OS4
PAT-(Advanced-Level)-Practice2
PAT-(Basic-Level)-Practice44
blockchain1
fedfab13
gallery1
geth1
git1
gradle1
hexo2
linux2
misc1
projects1
shell2
刷题2
动态规划1
多线程1
排序1
数据库2
牛客2
算法43
×