我们已经看到在Android中创建了一个基本的Intro Slider,可用于向我们的用户告知我们应用程序的功能以及更多其他功能。在本文中,我们将借助Firebase在我们的应用程序中查看动态Intro Slider的实现。借助Firebase Firestore,我们可以从Firebase控制台动态更改所有数据。现在,让我们开始实施。
我们将在这个项目中建立什么?
我们将构建一个简单的Intro滑块,在其中我们将从Firebase控制台加载所有数据,并将这些数据显示在我们的滑块中。借助Firebase,我们可以根据需求动态更新数据。下面给出了一个示例GIF,以了解我们将在本文中做些什么。注意,我们将使用Java语言实现该项目。
分步实施
步骤1:创建一个新项目
要在Android Studio中创建新项目,请参阅如何在Android Studio中创建/启动新项目。请注意,选择Java作为编程语言。
第2步:将您的应用连接到Firebase
创建新项目后。导航到顶部栏上的“工具”选项。在里面单击Firebase。单击Firebase后,您可以在屏幕快照中看到下面提到的右列。
在该列内,导航到Firebase Cloud Firestore。单击该选项,您将在“将应用程序连接到Firebase”和“将Cloud Firestore添加到您的应用程序”中看到两个选项。单击立即连接选项,您的应用程序将连接到Firebase。之后,单击第二个选项,现在您的应用已连接到Firebase。将您的应用程序连接到Firebase后,您将看到以下屏幕。
之后,确认已将Firebase Firestore数据库的依赖项添加到我们的Gradle文件中。导航到该文件内的app> Gradle脚本,检查是否添加了依赖项以下的天气。如果您的build.gradle文件中不存在以下依赖项。在“依赖项”部分中添加以下依赖项。
implementation ‘com.google.firebase:firebase-firestore:22.0.1’
implementation ‘com.squareup.picasso:picasso:2.71828’
添加此依赖项后,同步您的项目,现在我们可以创建我们的应用程序了。如果您想了解更多有关将应用程序连接到Firebase的信息。请参阅本文以详细了解如何将Firebase添加到Android App。当我们从URL加载图像时,我们必须使用毕加索。
步骤3:为Internet添加权限
由于我们将从URL加载图像,因此我们必须在您的AndroidManifest.xml文件中添加Internet权限。用于添加权限。导航到应用程序> AndroidManifest.xml文件,然后添加以下权限。
XML
XML
XML
Java
public class SliderModal {
// string variable for storing title,
// image url and description.
private String title;
private String heading;
private String imgUrl;
public SliderModal() {
// empty constructor is required
// when using firebase
}
// creating getter methods.
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getHeading() {
return heading;
}
// creating setter methods
public void setHeading(String heading) {
this.heading = heading;
}
public String getImgUrl() {
return imgUrl;
}
public void setImgUrl(String imgUrl) {
this.imgUrl = imgUrl;
}
// constructor for our modal class
public SliderModal(String title, String heading, String imgUrl) {
this.title = title;
this.heading = heading;
this.imgUrl = imgUrl;
}
}
Java
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.viewpager.widget.PagerAdapter;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
public class SliderAdapter extends PagerAdapter {
// creating variables for layout inflater,
// context and array list.
LayoutInflater layoutInflater;
Context context;
ArrayList sliderModalArrayList;
// creating constructor.
public SliderAdapter(Context context, ArrayList sliderModalArrayList) {
this.context = context;
this.sliderModalArrayList = sliderModalArrayList;
}
@Override
public int getCount() {
// inside get count method returning
// the size of our array list.
return sliderModalArrayList.size();
}
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
// inside isViewFrombject method we are
// returning our Relative layout object.
return view == (RelativeLayout) object;
}
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
// in this method we will initialize all our layout items
// and inflate our layout file as well.
layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
// below line is use to inflate the layout file which we created.
View view = layoutInflater.inflate(R.layout.slider_layout, container, false);
// initializing our views.
ImageView imageView = view.findViewById(R.id.idIV);
TextView titleTV = view.findViewById(R.id.idTVtitle);
TextView headingTV = view.findViewById(R.id.idTVheading);
// setting data to our views.
SliderModal modal = sliderModalArrayList.get(position);
titleTV.setText(modal.getTitle());
headingTV.setText(modal.getHeading());
Picasso.get().load(modal.getImgUrl()).into(imageView);
// after setting the data to our views we
// are adding the view to our container.
container.addView(view);
// at last we are returning the view.
return view;
}
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
// this is a destroy view method which
// is use to remove a view.
container.removeView((RelativeLayout) object);
}
}
Java
import android.os.Bundle;
import android.text.Html;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.QuerySnapshot;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
// creating variables for view pager,
// lineralyout, adapter and our array list.
private ViewPager viewPager;
private LinearLayout dotsLL;
SliderAdapter adapter;
private ArrayList sliderModalArrayList;
private TextView[] dots;
int size;
FirebaseFirestore db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
db = FirebaseFirestore.getInstance();
// initializing all our views.
viewPager = findViewById(R.id.idViewPager);
dotsLL = findViewById(R.id.idLLDots);
// in below line we are creating a new array list.
sliderModalArrayList = new ArrayList<>();
loadDataFromFirebase();
// calling method to add dots indicator
addDots(size, 0);
// below line is use to call on page
// change listener method.
viewPager.addOnPageChangeListener(viewListner);
}
private void loadDataFromFirebase() {
// below line is use to get data from Firebase
// firestore using collection in android.
db.collection("SliderData").get()
.addOnSuccessListener(new OnSuccessListener() {
@Override
public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
// after getting the data we are calling on success method
// and inside this method we are checking if the received
// query snapshot is empty or not.
if (!queryDocumentSnapshots.isEmpty()) {
// if the snapshot is not empty we are hiding our
// progress bar and adding our data in a list.
List list = queryDocumentSnapshots.getDocuments();
for (DocumentSnapshot d : list) {
// after getting this list we are passing
// that list to our object class.
SliderModal sliderModal = d.toObject(SliderModal.class);
// after getting data from Firebase we are
// storing that data in our array list
sliderModalArrayList.add(sliderModal);
}
// below line is use to add our array list to adapter class.
adapter = new SliderAdapter(MainActivity.this, sliderModalArrayList);
// below line is use to set our
// adapter to our viw pager.
viewPager.setAdapter(adapter);
// we are storing the size of our
// array list in a variable.
size = sliderModalArrayList.size();
} else {
// if the snapshot is empty we are displaying a toast message.
Toast.makeText(MainActivity.this, "No data found in Database", Toast.LENGTH_SHORT).show();
}
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
// we are displaying a toast message when
// we get any error from Firebase.
Toast.makeText(MainActivity.this, "Fail to load data..", Toast.LENGTH_SHORT).show();
}
});
}
private void addDots(int size, int pos) {
// inside this method we are
// creating a new text view.
dots = new TextView[size];
// below line is use to remove all
// the views from the linear layout.
dotsLL.removeAllViews();
// running a for loop to add number
// of dots to our slider.
for (int i = 0; i < size; i++) {
// below line is use to add the dots
// and modify its color.
dots[i] = new TextView(this);
dots[i].setText(Html.fromHtml("•"));
dots[i].setTextSize(35);
// below line is called when the
// dots are not selected.
dots[i].setTextColor(getResources().getColor(R.color.white));
dotsLL.addView(dots[i]);
}
if (dots.length > 0) {
// this line is called when the dots
// inside linear layout are selected
dots[pos].setTextColor(getResources().getColor(R.color.purple_200));
}
}
// creating a method for view pager for on page change listener.
ViewPager.OnPageChangeListener viewListner = new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
// we are calling our dots method to
// change the position of selected dots.
addDots(size, position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
};
}
步骤4:使用activity_main.xml文件
导航到应用程序> res>布局> activity_main.xml,然后将以下代码添加到该文件中。以下是activity_main.xml文件的代码。
XML格式
步骤5:为我们的滑块项目创建布局文件
现在,我们将创建一个要显示在滑块中的项目。因此,要创建新的布局,请导航至应用程序> res>布局>右键单击它>单击New>布局资源文件,并将其命名为slider_layout ,并向其添加以下代码。
XML格式
步骤6:创建一个Modal类来存储Slider项的所有数据
要创建新的Modal类,请导航至应用程序> Java >应用程序的包名称>右键单击它,然后单击New> Java class并将其命名为SliderModal 。创建此类后,将以下代码添加到其中。
Java
public class SliderModal {
// string variable for storing title,
// image url and description.
private String title;
private String heading;
private String imgUrl;
public SliderModal() {
// empty constructor is required
// when using firebase
}
// creating getter methods.
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getHeading() {
return heading;
}
// creating setter methods
public void setHeading(String heading) {
this.heading = heading;
}
public String getImgUrl() {
return imgUrl;
}
public void setImgUrl(String imgUrl) {
this.imgUrl = imgUrl;
}
// constructor for our modal class
public SliderModal(String title, String heading, String imgUrl) {
this.title = title;
this.heading = heading;
this.imgUrl = imgUrl;
}
}
步骤7:创建一个Adapter类,用于将数据设置到每个视图
用于创建新的Adapter类。导航到应用程序> Java >应用程序的程序包名称>右键单击它> New Java类>将其命名为SliderAdapter并将以下代码添加到其中。在代码内部添加了注释,以更详细地了解代码。
Java
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.viewpager.widget.PagerAdapter;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
public class SliderAdapter extends PagerAdapter {
// creating variables for layout inflater,
// context and array list.
LayoutInflater layoutInflater;
Context context;
ArrayList sliderModalArrayList;
// creating constructor.
public SliderAdapter(Context context, ArrayList sliderModalArrayList) {
this.context = context;
this.sliderModalArrayList = sliderModalArrayList;
}
@Override
public int getCount() {
// inside get count method returning
// the size of our array list.
return sliderModalArrayList.size();
}
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
// inside isViewFrombject method we are
// returning our Relative layout object.
return view == (RelativeLayout) object;
}
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
// in this method we will initialize all our layout items
// and inflate our layout file as well.
layoutInflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
// below line is use to inflate the layout file which we created.
View view = layoutInflater.inflate(R.layout.slider_layout, container, false);
// initializing our views.
ImageView imageView = view.findViewById(R.id.idIV);
TextView titleTV = view.findViewById(R.id.idTVtitle);
TextView headingTV = view.findViewById(R.id.idTVheading);
// setting data to our views.
SliderModal modal = sliderModalArrayList.get(position);
titleTV.setText(modal.getTitle());
headingTV.setText(modal.getHeading());
Picasso.get().load(modal.getImgUrl()).into(imageView);
// after setting the data to our views we
// are adding the view to our container.
container.addView(view);
// at last we are returning the view.
return view;
}
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
// this is a destroy view method which
// is use to remove a view.
container.removeView((RelativeLayout) object);
}
}
步骤8:使用MainActivity。 Java文件
转到MainActivity。 Java文件并参考以下代码。下面是MainActivity的代码。 Java文件。在代码内部添加了注释,以更详细地了解代码。
Java
import android.os.Bundle;
import android.text.Html;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.QuerySnapshot;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
// creating variables for view pager,
// lineralyout, adapter and our array list.
private ViewPager viewPager;
private LinearLayout dotsLL;
SliderAdapter adapter;
private ArrayList sliderModalArrayList;
private TextView[] dots;
int size;
FirebaseFirestore db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
db = FirebaseFirestore.getInstance();
// initializing all our views.
viewPager = findViewById(R.id.idViewPager);
dotsLL = findViewById(R.id.idLLDots);
// in below line we are creating a new array list.
sliderModalArrayList = new ArrayList<>();
loadDataFromFirebase();
// calling method to add dots indicator
addDots(size, 0);
// below line is use to call on page
// change listener method.
viewPager.addOnPageChangeListener(viewListner);
}
private void loadDataFromFirebase() {
// below line is use to get data from Firebase
// firestore using collection in android.
db.collection("SliderData").get()
.addOnSuccessListener(new OnSuccessListener() {
@Override
public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
// after getting the data we are calling on success method
// and inside this method we are checking if the received
// query snapshot is empty or not.
if (!queryDocumentSnapshots.isEmpty()) {
// if the snapshot is not empty we are hiding our
// progress bar and adding our data in a list.
List list = queryDocumentSnapshots.getDocuments();
for (DocumentSnapshot d : list) {
// after getting this list we are passing
// that list to our object class.
SliderModal sliderModal = d.toObject(SliderModal.class);
// after getting data from Firebase we are
// storing that data in our array list
sliderModalArrayList.add(sliderModal);
}
// below line is use to add our array list to adapter class.
adapter = new SliderAdapter(MainActivity.this, sliderModalArrayList);
// below line is use to set our
// adapter to our viw pager.
viewPager.setAdapter(adapter);
// we are storing the size of our
// array list in a variable.
size = sliderModalArrayList.size();
} else {
// if the snapshot is empty we are displaying a toast message.
Toast.makeText(MainActivity.this, "No data found in Database", Toast.LENGTH_SHORT).show();
}
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
// we are displaying a toast message when
// we get any error from Firebase.
Toast.makeText(MainActivity.this, "Fail to load data..", Toast.LENGTH_SHORT).show();
}
});
}
private void addDots(int size, int pos) {
// inside this method we are
// creating a new text view.
dots = new TextView[size];
// below line is use to remove all
// the views from the linear layout.
dotsLL.removeAllViews();
// running a for loop to add number
// of dots to our slider.
for (int i = 0; i < size; i++) {
// below line is use to add the dots
// and modify its color.
dots[i] = new TextView(this);
dots[i].setText(Html.fromHtml("•"));
dots[i].setTextSize(35);
// below line is called when the
// dots are not selected.
dots[i].setTextColor(getResources().getColor(R.color.white));
dotsLL.addView(dots[i]);
}
if (dots.length > 0) {
// this line is called when the dots
// inside linear layout are selected
dots[pos].setTextColor(getResources().getColor(R.color.purple_200));
}
}
// creating a method for view pager for on page change listener.
ViewPager.OnPageChangeListener viewListner = new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
// we are calling our dots method to
// change the position of selected dots.
addDots(size, position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
};
}
添加上述代码后,将数据添加到Android中的Firebase Firestore。
第9步:将数据添加到Android中的Firebase Firestore
在浏览器中搜索Firebase并转到该网站,您将看到以下屏幕。
单击“转到控制台”选项后。单击您的项目,如下所示。
单击您的项目后,您将看到以下屏幕。单击该项目后,您将看到以下屏幕。
单击创建数据库选项后,您将看到以下屏幕。
在此屏幕内,我们必须选择“以测试模式启动”选项。我们正在使用测试模式,因为我们未在应用内设置身份验证。因此,我们选择在测试模式下启动。选择测试模式后,单击下一步选项,您将看到以下屏幕。
在此屏幕内,我们只需单击“启用”按钮即可启用我们的Firebase Firestore数据库。完成此过程后,我们必须在Firebase控制台中添加数据。用于将数据添加到我们的Firebase控制台。
您必须单击“开始收集选项”,并将收集名称指定为SliderData 。创建集合后,您必须单击“自动识别”选项以创建第一个文档。在其中创建三个字段,分别是title , heading和imgUrl,并在该字段中添加值。在Firebase控制台内以类似的方式添加多个文档。之后,运行您的应用程序,并查看该应用程序的输出。
将这些数据添加到Firebase后,运行您的应用程序并查看该应用程序的输出。