[Android] 高速实现一个通用EmptyView
好的APP应当具备良好的交互, 最好能贴心的满足用户的需求. 而人性化的提醒就是当中之中的一个. 某些APP中常常会看到这种场景, 当载入内容失败, 或者获取内容失败时, 界面会变成一个可与用后交互的场景. 同意用户点击屏幕或者界面中某个button, 尝试又一次获取内容或者检測网络连接等等. Android的ListView中有类似setEmptyView(...) 的方法, 当列表中没有数据, 就会显示该 emptyView. 但并不是全部的View都有这种接口方法, 为此我们能够自己去实现可通用的"emptyView".
这里通过简单的样例提供一种思路, 当然不是唯一的. 我们能够依据自己的想法实现各种各样的emptyView本质还是调用view.setVisibility(...).
效果图例如以下, 看起来好简单吧!
So 直接上代码喇!
将EmptyView封装在某个经常使用布局文件里, 比方RelativeLayout, 当然也能够是LinearLayout等等.
public class CustomRelativeLayout extends RelativeLayout{
public static interface RetryListener{
void retry();
}
private ProgressBar progressBar = null;
private Button btn_refresh = null;
private TextView tv_tip = null;
private boolean isNormal = true;
private RetryListener retryListener = null;
private final static int tvTipId = 0x1001;
public CustomRelativeLayout(Context context) {
this(context, null);
}
public CustomRelativeLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomRelativeLayout(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
}
/**
* 设置载入界面
*/
protected void setInProgress()
{
if(progressBar == null)
{
int size = (int) TypedValue
.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 45, getResources().getDisplayMetrics());
progressBar = new ProgressBar(getContext());
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(size,size);
lp.addRule(RelativeLayout.CENTER_IN_PARENT);
progressBar.setLayoutParams(lp);
addView(progressBar);
}
if(getChildCount() > 0)
{
int childCount = getChildCount();
if(childCount >0)
{
for(int i=(childCount-1); i>=0; i--)
{
getChildAt(i).setVisibility(View.GONE);
}
}
}
if(btn_refresh != null)
btn_refresh.setVisibility(View.GONE);
if(tv_tip != null)
tv_tip.setVisibility(View.GONE);
progressBar.setVisibility(View.VISIBLE);
}
/**
* 显示载入失败界面,隐藏全部正常的View元素
*/
protected void setChildrenGone()
{
if(btn_refresh == null)
{
btn_refresh = new Button(getContext());
tv_tip = new TextView(getContext());
tv_tip.setText("网络连接失败");
tv_tip.setGravity(Gravity.CENTER);
tv_tip.setTextSize(TypedValue.COMPLEX_UNIT_SP, 16);
btn_refresh.setText("刷新");
btn_refresh.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if(retryListener != null)
{
retryListener.retry();
}
else
{
Toast.makeText(getContext(), "暂无数据", Toast.LENGTH_SHORT).show();
}
}
});
int btnWidth = (int)TypedValue
.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 80, getResources().getDisplayMetrics());
RelativeLayout.LayoutParams lp
= new RelativeLayout.LayoutParams(btnWidth, LayoutParams.WRAP_CONTENT);
lp.addRule(RelativeLayout.CENTER_IN_PARENT);
lp.setMargins(0, 10, 0, 0);
btn_refresh.setLayoutParams(lp);
btn_refresh.setId(tvTipId);
btn_refresh.setVisibility(View.GONE);
addView(btn_refresh);
RelativeLayout.LayoutParams lp_tv
= new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
lp_tv.addRule(RelativeLayout.ABOVE, tvTipId);
tv_tip.setLayoutParams(lp_tv);
addView(tv_tip);
}
if(getChildCount() > 0)
{
int childCount = getChildCount();
if(childCount >0)
{
for(int i=(childCount-1); i>=0; i--)
{
getChildAt(i).setVisibility(View.GONE);
}
}
}
if(progressBar != null)
progressBar.setVisibility(View.GONE);
isNormal = false;
btn_refresh.setVisibility(View.VISIBLE);
tv_tip.setVisibility(View.VISIBLE);
}
/**
* 显示正常View元素
*/
protected void setChildrenVisible()
{
if(getChildCount() > 0)
{
int childCount = getChildCount();
if(childCount >0)
{
for(int i=(childCount-1); i>=0; i--)
{
getChildAt(i).setVisibility(View.VISIBLE);
}
}
if(progressBar != null)
progressBar.setVisibility(View.GONE);
if(btn_refresh != null)
btn_refresh.setVisibility(View.GONE);
if(tv_tip != null)
tv_tip.setVisibility(View.GONE);
isNormal = true;
}
}
protected boolean isNormalView()
{
return isNormal;
}
public void setRetryListener(RetryListener listener)
{
this.retryListener = listener;
}
}提供一个RetryListener接口, 作为点击 "刷新" button后的事件.
然后模拟载入中而且载入失败的界面, 点击button后拖延3秒, 如果获取数据成功, 更新view后显示正常的界面.
public class MainActivity extends Activity {
private Button btn_start = null;
private static CustomRelativeLayout cuLayout = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}
private static Handler mHandler = new Handler()
{
@Override
public void handleMessage(Message msg)
{
if(msg.what == 0x1)
{
cuLayout.setChildrenVisible();
}
else if(msg.what == 0x2)
{
cuLayout.setChildrenGone();
}
super.handleMessage(msg);
}
};
private void init()
{
btn_start = (Button) findViewById(R.id.btn_start);
cuLayout = (CustomRelativeLayout) findViewById(R.id.container);
cuLayout.setRetryListener(new CustomRelativeLayout.RetryListener(){
public void retry()
{
cuLayout.setInProgress();
mHandler.sendEmptyMessageDelayed(0x1,3000);
}
});
btn_start.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
cuLayout.setChildrenGone();
}
});
cuLayout.setInProgress();
mHandler.sendEmptyMessageDelayed(0x2,2000);
}
}
布局文件:
<com.alextam.progressview.CustomRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF"
>
<ImageView
android:layout_width="match_parent"
android:layout_height="250dp"
android:src="@mipmap/movie"
/>
<Button
android:id="@+id/btn_start"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="ACTION"
/>
</RelativeLayout>
</com.alextam.progressview.CustomRelativeLayout>
就是这么简单喇, 相信看完后也能定制出自己喜爱的界面哦! 另外, 作为EmptyView和载入view, 并不推荐使用复杂的元素. 最好简单而好看的View元素就够了. 由于不过充当辅助的作用, 轻量化, 差点儿不占内存是前提.
