在Android Toast基礎與原理中，我們對Toast的原始碼進行了分析。我們也對Toast的實現原理有了一定的瞭解。接下來我們將編寫一個工具類，來完成Toast的自定義檢視和動畫。

一、實現原理分析

通過上篇文章，我們知道Toast是通過內部類TN（一個ITransientNotification物件）進行實現。通過與INotificationManager進行管理。在原始碼中，我們在TN的建構函式中：

TN() {
    // XXX This should be changed to use a Dialog, with a Theme.Toast
    // defined that sets up the layout params appropriately.
 

    final WindowManager.LayoutParams params = mParams;
    params.height = WindowManager.LayoutParams.WRAP_CONTENT;
    params.width = WindowManager.LayoutParams.WRAP_CONTENT;
    params.format = PixelFormat.TRANSLUCENT;
    params.windowAnimations = com.android.internal.R.style.Animation_Toast;
    params.
 
type = WindowManager.LayoutParams.TYPE_TOAST;
    params.setTitle("Toast");
    params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
            | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
            | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE;
}

看到在params中設定Toast的顯示動畫。

params.windowAnimations =
 
 com.android.internal.R.style.Animation_Toast;

所以我們的實現思路就是通過反射獲取到對應的WindowManager.LayoutParams物件，然後進行設定我們的動畫即可。

二、工具類的實現

/**
 * Created by Iflytek_dsw on 2017/7/4.
 */
public class ToastManager {

    private Toast toast;
    private Context context;
    private static ToastManager instance;


    private ToastManager(Context context){
        this.context = context;
        toast = new Toast(context);
    }

    /**
     * 構造ToastManager物件
     * @param context 上下文物件
     * @return
     */
    public static ToastManager getInstance(Context context) {
        if(instance == null){
            instance = new ToastManager(context);
        }
        return instance;
    }

    /**
     * 自定義View和顯示位置的Toast
     * @param view  Toast的View檢視
     * @param gravity   Toast的顯示位置
     * @param xOffset   Toast在x方向上偏移量,x大於0往右，x小於0往左
     * @param yOffset   Toast在y方向上偏移量,y值大於0往上，小於0往下
     */
    public void makeToastSelfView(View view, int gravity,int xOffset, int yOffset){
        if(toast == null){
            toast = new Toast(context);
        }

        toast.setView(view);
        toast.setGravity(gravity, xOffset, yOffset);
        toast.setDuration(Toast.LENGTH_SHORT);
        toast.show();
    }

    /**
     * 構造帶有動畫的Toast
     * @param tText 提示的文字
     * @param animationID   style封裝的動畫資源id
     */
    public void makeToastSelfAnimation(String tText,int animationID){
        toast = Toast.makeText(context, tText, Toast.LENGTH_SHORT);
        try {
            Field mTNField = toast.getClass().getDeclaredField("mTN");
            mTNField.setAccessible(true);
            Object mTNObject = mTNField.get(toast);
            Class tnClass = mTNObject.getClass();
            Field paramsField = tnClass.getDeclaredField("mParams");
            /**由於WindowManager.LayoutParams mParams的許可權是private*/
            paramsField.setAccessible(true);
            WindowManager.LayoutParams layoutParams = (WindowManager.LayoutParams) paramsField.get(mTNObject);
            layoutParams.windowAnimations = animationID;
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        toast.show();
    }

    /**
     * 設定自定義View和Animation
     * @param view  自定義View
     * @param animationID   動畫資源id
     */
    public void makeToastSelfViewAnim(View view, int animationID){
        if(toast == null){
            toast = new Toast(context);
        }

        toast.setView(view);
        try {
            Field mTNField = toast.getClass().getDeclaredField("mTN");
            mTNField.setAccessible(true);
            Object mTNObject = mTNField.get(toast);
            Class tnClass = mTNObject.getClass();
            Field paramsField = tnClass.getDeclaredField("mParams");
            /**由於WindowManager.LayoutParams mParams的許可權是private*/
            paramsField.setAccessible(true);
            WindowManager.LayoutParams layoutParams = (WindowManager.LayoutParams) paramsField.get(mTNObject);
            layoutParams.windowAnimations = animationID;
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        toast.show();
    }
}

三、體驗Sample

1、自定義Toast的layout佈局

首先我們自定義一個Toast的檢視layout佈局。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="wrap_content"
    android:gravity="center_vertical"
    android:background="#000000"
    android:padding="10dp"
    android:layout_height="wrap_content">
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@mipmap/dicus"/>
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:text="發表評論+10松果"
        android:textColor="#FFFFFF"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20dp"
        android:text="檢視"
        android:textColor="#E8C84A"/>
</LinearLayout>

2、自定義實現動畫

1、新建anim資料夾，用於儲存我們的enter和out動畫。

enter

<?xml version="1.0" encoding="utf-8"?>
<scale xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromXScale="0"
    android:toXScale="1"
    android:pivotX="50%"
    android:pivotY="50%"
    android:fromYScale="1"
    android:toYScale="1"
    android:duration="1000">
</scale>

out

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
    <scale
        android:fromXScale="1"
        android:toXScale="0"
        android:pivotX="50%"
        android:pivotY="50%"
        android:fromYScale="1"
        android:toYScale="1"
        android:duration="1000"
        />
</set>

style樣式

    <style name="MyToast" parent="Base.Animation.AppCompat.Dialog">
        <item name="android:windowEnterAnimation">@anim/enter</item>
        <item name="android:windowExitAnimation">@anim/out</item>
    </style>

3、呼叫工具類實現

public class MainActivity extends AppCompatActivity {
    private Button btn_toast;
    private View toastView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        LayoutInflater inflater = LayoutInflater.from(MainActivity.this);
        toastView = inflater.inflate(R.layout.toastlayout, null);
        btn_toast = (Button) findViewById(R.id.btn_toast);
        btn_toast.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ToastManager.getInstance(getApplicationContext()).
                        makeToastSelfViewAnim(toastView,R.style.MyToast);
            }
        });
    }
}

效果圖：