Android对话框之Context

new AlertDialog.Builder(getApplicationContext(),R.style.MyAlertDialogStyle)
        .setTitle("温柔")
        .setMessage("不知道 不明了 不想要\n" +
                "为什么 我的心")
        .setPositiveButton("确定",null)
        .setNegativeButton("取消",null)
        .show();

 /**
     * Create a Dialog window that uses the default dialog frame style.
     * 
     * @param context The Context the Dialog is to run it.  In particular, it
     *                uses the window manager and theme in this context to
     *                present its UI.
     */
    public Dialog(Context context) {
        this(context, 0, true);
    }

    /**
     * Create a Dialog window that uses a custom dialog style.
     * 
     * @param context The Context in which the Dialog should run. In particular, it
     *                uses the window manager and theme from this context to
     *                present its UI.
     * @param theme A style resource describing the theme to use for the 
     * window. See <a href="{@docRoot}guide/topics/resources/available-resources.html#stylesandthemes">Style 
     * and Theme Resources</a> for more information about defining and using 
     * styles.  This theme is applied on top of the current theme in 
     * <var>context</var>.  If 0, the default dialog theme will be used.
     */
    public Dialog(Context context, int theme) {
        this(context, theme, true);
    }

    Dialog(Context context, int theme, boolean createContextThemeWrapper) {
        if (createContextThemeWrapper) {
            if (theme == 0) {
                TypedValue outValue = new TypedValue();
                context.getTheme().resolveAttribute(com.android.internal.R.attr.dialogTheme,
                        outValue, true);
                theme = outValue.resourceId;
            }
            mContext = new ContextThemeWrapper(context, theme);
        } else {
            mContext = context;
        }

        mWindowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
        Window w = PolicyManager.makeNewWindow(mContext);
        mWindow = w;
        w.setCallback(this);
        w.setOnWindowDismissedCallback(this);
        w.setWindowManager(mWindowManager, null, null);
        w.setGravity(Gravity.CENTER);
        mListenersHandler = new ListenersHandler(this);
    }

    public ContextThemeWrapper() {
        super(null);
    }
    
    public ContextThemeWrapper(Context base, int themeres) {
        super(base);
        mThemeResource = themeres;
    }

    @Override protected void attachBaseContext(Context newBase) {
        super.attachBaseContext(newBase);
    }

    ...

    @
    Override public void setTheme(int resid) {
        mThemeResource = resid;
        initializeTheme();
    }