安卓中使用微光的内容占位符动画
原文:https://www . geesforgeks . org/content-placeholder-animation-using-shimmer-in-Android/
我们看到了一个独特的加载屏幕设计，在脸书可以看到它用于加载目的，它也用于显示加载目的的内容占位符。GitHub 提供了这种类型的加载占位符，它看起来比普通的进度条还要漂亮。在本文中，我们将看一下内容占位符在 Android 中使用 Shimmer 动画的实现。
我们将在本文中构建什么？
我们将构建一个简单的应用程序，其中我们将以 JSON 格式从网址加载数据，在加载过程中，我们将显示一个用于加载的微光布局。下面给出一个视频样本，了解一下在本文中我们要做什么。注意，我们将使用 Java 语言来实现这个项目。
[https://media.geeksforgeeks.org/wp-content/uploads/20210218132459/Screenrecorder-2021-02-18-13-24-13-712.mp4](https://media.geeksforgeeks.org/wp-content/uploads/20210218132459/Screenrecorder-2021-02-18-13-24-13-712.mp4)分步实施
第一步:创建新项目
要在安卓工作室创建新项目，请参考如何在安卓工作室创建/启动新项目。注意选择 Java 作为编程语言。
第二步:添加使用脸书微光布局的依赖关系
导航到应用程序>梯度脚本>构建.梯度文件，并添加以下依赖项。
//下方线用于截击库
实现‘com . Android .凌空:凌空:1 . 1 . 1’
//下面一行用于图像加载库
实现' com.squareup .毕加索:毕加索:2.71828 '
//使用 facebook 微光布局的依赖。
实现' com . Facebook . shimmer:shimmer:0 . 5 . 0 '
现在，同步您的项目并移向您的 XML 文件。
第三步:在安卓中添加互联网权限
导航到应用程序> AndroidManifest.xml ，并在我们从互联网加载数据时为其添加互联网权限。
可扩展标记语言
<uses-permission android:name="android.permission.INTERNET"/>
第 4 步:使用 activity_main.xml 文件
导航到应用程序> res >布局> activity_main.xml 并将下面的代码添加到该文件中。下面是 activity_main.xml 文件的代码。
可扩展标记语言
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<!-- Card view for displaying our card-->
<androidx.cardview.widget.CardView
android:id="@+id/idCVCourse"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:elevation="10dp"
android:visibility="gone"
app:cardCornerRadius="8dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!--Image view for displaying our image-->
<ImageView
android:id="@+id/idIVCourse"
android:layout_width="match_parent"
android:layout_height="300dp"
android:layout_margin="5dp" />
<!--Text view for displaying our course name-->
<TextView
android:id="@+id/idTVCourseName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:padding="5dp"
android:text="Course Name "
android:textColor="@color/black"
android:textSize="18sp"
android:textStyle="bold" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:orientation="horizontal"
android:weightSum="2">
<!--Text view for displaying our batch-->
<TextView
android:id="@+id/idTVBatch"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:padding="5dp"
android:text="Batch"
android:textColor="@color/black" />
<!--Text view for displaying our tracks.-->
<TextView
android:id="@+id/idTVTracks"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:padding="5dp"
android:text="Tracks"
android:textColor="@color/black" />
</LinearLayout>
</LinearLayout>
</androidx.cardview.widget.CardView>
<!--below is the view for our shimmer-->
<com.facebook.shimmer.ShimmerFrameLayout
android:id="@+id/shimmerLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:animateLayoutChanges="true"
android:animationCache="true"
app:shimmer_repeat_mode="restart"
app:shimmer_shape="radial">
<!--For shimmer we are creating a same layout
but setting its background as a gray colour and
not providing any view inside it-->
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:elevation="10dp"
android:visibility="visible"
app:cardCornerRadius="8dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!--Image view for displaying our image-->
<ImageView
android:layout_width="match_parent"
android:layout_height="300dp"
android:layout_margin="5dp"
android:background="#B3B3B3" />
<!--Text view for displaying our course name-->
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:background="#B3B3B3"
android:padding="5dp"
android:textColor="@color/black"
android:textSize="18sp"
android:textStyle="bold" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:orientation="horizontal"
android:weightSum="2">
<!--Text view for displaying our batch-->
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#B3B3B3"
android:padding="5dp"
android:textColor="@color/black" />
<!--Text view for displaying our tracks.-->
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="#B3B3B3"
android:padding="5dp"
android:textColor="@color/black" />
</LinearLayout>
</LinearLayout>
</androidx.cardview.widget.CardView>
</com.facebook.shimmer.ShimmerFrameLayout>
</RelativeLayout>
第五步:使用MainActivity.java 文件
转到MainActivity.java文件，参考以下代码。以下是MainActivity.java文件的代码。代码中添加了注释，以更详细地理解代码。
Java 语言(一种计算机语言，尤用于创建网站)
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.cardview.widget.CardView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.facebook.shimmer.ShimmerFrameLayout;
import com.squareup.picasso.Picasso;
import org.json.JSONException;
import org.json.JSONObject;
public class MainActivity extends AppCompatActivity {
// creating variables for our textview,
// imageview, cardview and progressbar.
private TextView courseNameTV, courseTracksTV, courseBatchTV;
private ImageView courseIV;
private CardView courseCV;
// variable for our shimmer frame layout
private ShimmerFrameLayout shimmerFrameLayout;
// below line is the variable for url from
// where we will be querying our data.
String url = "https://jsonkeeper.com/b/63OH";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// initializing our shimmer layout.
shimmerFrameLayout = findViewById(R.id.shimmerLayout);
// on below line we are
// starting our shimmer layout.
shimmerFrameLayout.startShimmer();
// in below line we are
// initializing our all views.
courseCV = findViewById(R.id.idCVCourse);
courseNameTV = findViewById(R.id.idTVCourseName);
courseTracksTV = findViewById(R.id.idTVTracks);
courseBatchTV = findViewById(R.id.idTVBatch);
courseIV = findViewById(R.id.idIVCourse);
// creating a new variable for our request queue
RequestQueue queue = Volley.newRequestQueue(MainActivity.this);
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
// inside the on response method.
// in below line we are making our card
// view visible after we get all the data.
// on below line we are making our shimmer
// layout visibility to gone.
// on below line we are stopping our shimmer.
shimmerFrameLayout.stopShimmer();
courseCV.setVisibility(View.VISIBLE);
try {
// now we get our response from API in json object format.
// in below line we are extracting a string with its key
// value from our json object.
// similarly we are extracting all the strings from our json object.
String courseName = response.getString("courseName");
String courseTracks = response.getString("courseTracks");
String courseMode = response.getString("courseMode");
String courseImageURL = response.getString("courseimg");
// after extracting all the data we are
// setting that data to all our views.
courseNameTV.setText(courseName);
courseTracksTV.setText(courseTracks);
courseBatchTV.setText(courseMode);
// we are using picasso to load the image from url.
Picasso.get().load(courseImageURL).into(courseIV);
} catch (JSONException e) {
// if we do not extract data from json object properly.
// below line of code is use to handle json exception
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
// this is the error listener method which
// we will call if we get any error from API.
@Override
public void onErrorResponse(VolleyError error) {
// below line is use to display a toast message along with our error.
Toast.makeText(MainActivity.this, "Fail to get data..", Toast.LENGTH_SHORT).show();
}
});
// at last we are adding our json
// object request to our request
// queue to fetch all the json data.
queue.add(jsonObjectRequest);
}
}
现在运行您的应用程序，并查看应用程序的输出。
输出:
[https://media.geeksforgeeks.org/wp-content/uploads/20210218132459/Screenrecorder-2021-02-18-13-24-13-712.mp4](https://media.geeksforgeeks.org/wp-content/uploads/20210218132459/Screenrecorder-2021-02-18-13-24-13-712.mp4)版权属于：月萌API www.moonapi.com，转载请注明出处
