refactor: use GlobalAppContext to replace App.getApp()

add: Canvas

common/src/main/java/com/stardust/app/GlobalAppContext.java

@@ -0,0 +1,77 @@
+package com.stardust.app;
+
+import android.annotation.SuppressLint;
+import android.app.Application;
+import android.content.Context;
+import android.os.Build;
+import android.os.Handler;
+import android.os.Looper;
+import android.support.annotation.RequiresApi;
+import android.widget.Toast;
+
+/**
+ * Created by Stardust on 2018/3/22.
+ */
+
+public class GlobalAppContext {
+
+    @SuppressLint("StaticFieldLeak")
+    private static Context sApplicationContext;
+    private static Handler sHandler;
+
+    public static void set(Application a) {
+        if (sApplicationContext != null)
+            throw new IllegalStateException();
+        sHandler = new Handler(Looper.getMainLooper());
+        sApplicationContext = a.getApplicationContext();
+    }
+
+    public static Context get() {
+        if (sApplicationContext == null)
+            throw new IllegalStateException("Call GlobalAppContext.set() to set a application context");
+        return sApplicationContext;
+    }
+
+    public static String getString(int resId) {
+        return get().getString(resId);
+    }
+
+    public static String getString(int resId, Object... formatArgs) {
+        return get().getString(resId, formatArgs);
+    }
+
+    @RequiresApi(api = Build.VERSION_CODES.M)
+    public static int getColor(int id) {
+        return get().getColor(id);
+    }
+
+    public static void toast(final String message) {
+        if (Looper.myLooper() == Looper.getMainLooper()) {
+            Toast.makeText(get(), message, Toast.LENGTH_SHORT).show();
+            return;
+        }
+        sHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                Toast.makeText(get(), message, Toast.LENGTH_SHORT).show();
+            }
+        });
+    }
+
+    public static void toast(final int resId) {
+        if (Looper.myLooper() == Looper.getMainLooper()) {
+            Toast.makeText(get(), resId, Toast.LENGTH_SHORT).show();
+            return;
+        }
+        sHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                Toast.makeText(get(), resId, Toast.LENGTH_SHORT).show();
+            }
+        });
+    }
+
+    public static void post(Runnable r) {
+        sHandler.post(r);
+    }
+}