BottomSheetDialogFragment、DialogFragment内存泄漏记录

项目开发中大多会使用leakcanary内存泄漏检测工具检测内存泄漏，leakcanary检测会发现BottomSheetDialogFragment、DialogFragment有内存泄漏情况。如果还不清楚为什么出现内存泄漏，请移步Google或百度；这里不详细描述为什么内存泄露了，默认你已经知道了为什么BottomSheetDialogFragment、DialogFragment有内存泄漏情况。（如有问题欢迎指正！）

解决步骤：(已真机测试)

1、新建一个DialogInterfaceProxy类，用来持有Dialog中DialogInterface接口下的OnCancelListener、OnDismissListener、OnShowListener真正的回调，代码如下：

public class DialogInterfaceProxy {
    public static DialogInterface.OnCancelListener proxy(DialogInterface.OnCancelListener onCancelListener) {
        return new ProxyOnCancelListener(onCancelListener);
    }

    public static DialogInterface.OnDismissListener proxy(DialogInterface.OnDismissListener onDismissListener) {
        return new ProxyOnDismissListener(onDismissListener);
    }

    public static DialogInterface.OnShowListener proxy(DialogInterface.OnShowListener onShowListener) {
        return new ProxyOnShowListener(onShowListener);
    }

    /**
     * 使用弱引用持有Dialog真正的DialogInterface.OnCancelListener,
     * 

     * 即使Message.obj未被正常释放，最终它持有的也只是ProxyOnCancelListener的一个空壳实例
     */
    public static class ProxyOnCancelListener implements DialogInterface.OnCancelListener {
        private WeakReference<DialogInterface.OnCancelListener> mProxyRef;

        public ProxyOnCancelListener(DialogInterface.OnCancelListener onCancelListener) {
            mProxyRef = new WeakReference<>(onCancelListener);
        }

        @Override
        public void onCancel(DialogInterface dialog) {
            DialogInterface.OnCancelListener onCancelListener = mProxyRef.get();
            if (onCancelListener != null) {
                onCancelListener.onCancel(dialog);
            }
        }
    }

    /**
     * 使用弱引用持有Dialog真正的DialogInterface.OnDismissListener,
     * 

     * 即使Message.obj未被正常释放，最终它持有的也只是ProxyOnDismissListener的一个空壳实例
     */
    public static class ProxyOnDismissListener implements DialogInterface.OnDismissListener {
        private WeakReference<DialogInterface.OnDismissListener> mProxyRef;

        public ProxyOnDismissListener(DialogInterface.OnDismissListener onDismissListener) {
            mProxyRef = new WeakReference<>(onDismissListener);
        }

        @Override
        public void onDismiss(DialogInterface dialog) {
            DialogInterface.OnDismissListener onDismissListener = mProxyRef.get();
            if (onDismissListener != null) {
                onDismissListener.onDismiss(dialog);
            }
        }
    }

    /**
     * 使用弱引用持有Dialog真正的DialogInterface.OnShowListener,
     * 

     * 即使Message.obj未被正常释放，最终它持有的也只是ProxyOnShowListener的一个空壳实例
     */
    public static class ProxyOnShowListener implements DialogInterface.OnShowListener {
        private WeakReference<DialogInterface.OnShowListener> mProxyRef;

        public ProxyOnShowListener(DialogInterface.OnShowListener onShowListener) {
            mProxyRef = new WeakReference<>(onShowListener);
        }

        @Override
        public void onShow(DialogInterface dialog) {
            DialogInterface.OnShowListener onShowListener = mProxyRef.get();
            if (onShowListener != null) {
                onShowListener.onShow(dialog);
            }
        }
    }
}

2、新建ProxyBottomSheetDialog继承BottomSheetDialog，将其中super.setOnCancelListener、super.setOnDismissListener、super.setOnShowListener参数使用DialogInterfaceProxy类包裹起来，代码如下：

public class ProxyBottomSheetDialog extends BottomSheetDialog {

    public ProxyBottomSheetDialog(@NonNull Context context) {
        super(context);
    }

    public ProxyBottomSheetDialog(@NonNull Context context, int theme) {
        super(context, theme);
    }

    protected ProxyBottomSheetDialog(@NonNull Context context, boolean cancelable, OnCancelListener cancelListener) {
        super(context, cancelable, cancelListener);
    }

    @Override
    public void setOnCancelListener(@Nullable OnCancelListener listener) {
        super.setOnCancelListener(DialogInterfaceProxy.proxy(listener));
    }

    @Override
    public void setOnDismissListener(@Nullable OnDismissListener listener) {
        super.setOnDismissListener(DialogInterfaceProxy.proxy(listener));
    }

    @Override
    public void setOnShowListener(@Nullable OnShowListener listener) {
        super.setOnShowListener(DialogInterfaceProxy.proxy(listener));
    }
}

3、新建ProxyBottomSheetDialogFragment继承BottomSheetDialogFragment，重写onCreateDialog方法，该方法中改为自定义的ProxyBottomSheetDialog，代码如下：

public class ProxyBottomSheetDialogFragment extends BottomSheetDialogFragment {

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        if (getContext() == null) {
            return super.onCreateDialog(savedInstanceState);
        }
        return new ProxyBottomSheetDialog(getContext(), getTheme());
    }
}

4、DialogFragment处理同上2、3步骤！！！