如何在Android中使用Google Books API构建图书库应用？

如果您正在寻找构建图书库应用程序，并且想要加载大量图书数据，然后添加此功能，则必须使用Google提供的简单API，并且它是免费的。在本文中，我们将看看我们的Android应用程序中该API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，在其中搜索不同类型的书籍，并在RecyclerView中看到与该主题相关的书籍清单。为了搜索这些图书，我们将使用Google提供的免费API，其中包含大量图书。下面提供了一个示例视频，以使您对我们在本文中将要做的事情有个大概的了解。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。

步骤2：在您的Gradle文件中添加Volley的依赖项

导航至应用程序> Gradle脚本> build.gradle文件，然后在“依赖项”部分中添加以下依赖项。

implementation ‘com.android.volley:volley:1.1.1’

implementation ‘com.squareup.picasso:picasso:2.71828’ 

在gradle文件中添加以下依赖项后，现在同步您的项目，现在我们将移向activity_main.xml文件。因为我们将使用凌空来从API和Picasso图像加载库中获取数据以从URL加载图像。

步骤3：为Internet添加权限

导航至应用程序> AndroidManifest.xml，然后向其添加以下权限。

由于我们将从API加载图书，因此我们必须向用户请求Internet权限。为此，在AndroidManifest.xml中添加互联网的权限。

步骤4：使用activity_main.xml文件

转到activity_main.xml文件，并参考以下代码。以下是activity_main.xml文件的代码。

第5步：创建一个模态类，用于存储来自API的数据。

用于创建新的Modal类。导航到应用程序> Java >您的应用程序的程序包名称>右键单击它，然后单击New> Java类，并为我们的Java类命名为BookInfo并在其中添加以下代码。在代码中添加了注释，以便更详细地了解。

Java

import java.util.ArrayList;
  
public class BookInfo {
  
    // creating string, int and array list 
    // variables for our book details
    private String title;
    private String subtitle;
    private ArrayList authors;
    private String publisher;
    private String publishedDate;
    private String description;
    private int pageCount;
    private String thumbnail;
    private String previewLink;
    private String infoLink;
    private String buyLink;
  
    // creating getter and setter methods
    public String getTitle() {
        return title;
    }
  
    public void setTitle(String title) {
        this.title = title;
    }
  
    public String getSubtitle() {
        return subtitle;
    }
  
    public void setSubtitle(String subtitle) {
        this.subtitle = subtitle;
    }
  
    public ArrayList getAuthors() {
        return authors;
    }
  
    public void setAuthors(ArrayList authors) {
        this.authors = authors;
    }
  
    public String getPublisher() {
        return publisher;
    }
  
    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }
  
    public String getPublishedDate() {
        return publishedDate;
    }
  
    public void setPublishedDate(String publishedDate) {
        this.publishedDate = publishedDate;
    }
  
    public String getDescription() {
        return description;
    }
  
    public void setDescription(String description) {
        this.description = description;
    }
  
    public int getPageCount() {
        return pageCount;
    }
  
    public void setPageCount(int pageCount) {
        this.pageCount = pageCount;
    }
      
    public String getThumbnail() {
        return thumbnail;
    }
  
    public void setThumbnail(String thumbnail) {
        this.thumbnail = thumbnail;
    }
  
    public String getPreviewLink() {
        return previewLink;
    }
  
    public void setPreviewLink(String previewLink) {
        this.previewLink = previewLink;
    }
  
    public String getInfoLink() {
        return infoLink;
    }
  
    public void setInfoLink(String infoLink) {
        this.infoLink = infoLink;
    }
  
    public String getBuyLink() {
        return buyLink;
    }
  
    public void setBuyLink(String buyLink) {
        this.buyLink = buyLink;
    }
  
    // creating a constructor class for our BookInfo
    public BookInfo(String title, String subtitle, ArrayList authors, String publisher,
                    String publishedDate, String description, int pageCount, String thumbnail, 
                    String previewLink, String infoLink, String buyLink) {
        this.title = title;
        this.subtitle = subtitle;
        this.authors = authors;
        this.publisher = publisher;
        this.publishedDate = publishedDate;
        this.description = description;
        this.pageCount = pageCount;
        this.thumbnail = thumbnail;
        this.previewLink = previewLink;
        this.infoLink = infoLink;
        this.buyLink = buyLink;
    }
}

步骤6：创建一个新的布局资源文件

转到应用程序> res>布局>右键单击>新建>布局资源文件，并将文件命名为book_rv_item并将以下代码添加到该文件中。

第7步：创建一个Adapter类，以将我们的数据设置为RecyclerView的项

导航到应用程序> Java >应用程序的程序包名称>右键单击它，然后单击New> Java类，并将其命名为BookAdapter，然后向其添加以下代码。在代码中添加了注释，以便更详细地了解。

Java

import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
  
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
  
import com.squareup.picasso.Picasso;
  
import java.util.ArrayList;
  
public class BookAdapter extends RecyclerView.Adapter {
  
    // creating variables for arraylist and context.
    private ArrayList bookInfoArrayList;
    private Context mcontext;
  
    // creating constructor for array list and context.
    public BookAdapter(ArrayList bookInfoArrayList, Context mcontext) {
        this.bookInfoArrayList = bookInfoArrayList;
        this.mcontext = mcontext;
    }
      
    @NonNull
    @Override
    public BookViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        // inflating our layout for item of recycler view item.
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.book_rv_item, parent, false);
        return new BookViewHolder(view);
    }
  
    @Override
    public void onBindViewHolder(@NonNull BookViewHolder holder, int position) {
          
        // inside on bind view holder method we are 
        // setting ou data to each UI component.
        BookInfo bookInfo = bookInfoArrayList.get(position);
        holder.nameTV.setText(bookInfo.getTitle());
        holder.publisherTV.setText(bookInfo.getPublisher());
        holder.pageCountTV.setText("No of Pages : " + bookInfo.getPageCount());
        holder.dateTV.setText(bookInfo.getPublishedDate());
          
        // below line is use to set image from URL in our image view.
        Picasso.get().load(bookInfo.getThumbnail()).into(holder.bookIV);
  
        // below line is use to add on click listener for our item of recycler view.
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // inside on click listener method we are calling a new activity 
                // and passing all the data of that item in next intent.
                Intent i = new Intent(mcontext, BookDetails.class);
                i.putExtra("title", bookInfo.getTitle());
                i.putExtra("subtitle", bookInfo.getSubtitle());
                i.putExtra("authors", bookInfo.getAuthors());
                i.putExtra("publisher", bookInfo.getPublisher());
                i.putExtra("publishedDate", bookInfo.getPublishedDate());
                i.putExtra("description", bookInfo.getDescription());
                i.putExtra("pageCount", bookInfo.getPageCount());
                i.putExtra("thumbnail", bookInfo.getThumbnail());
                i.putExtra("previewLink", bookInfo.getPreviewLink());
                i.putExtra("infoLink", bookInfo.getInfoLink());
                i.putExtra("buyLink", bookInfo.getBuyLink());
                  
                // after passing that data we are 
                // starting our new  intent.
                mcontext.startActivity(i);
            }
        });
    }
      
    @Override
    public int getItemCount() {
        // inside get item count method we 
        // are returning the size of our array list.
        return bookInfoArrayList.size();
    }
  
    public class BookViewHolder extends RecyclerView.ViewHolder {
        // below line is use to initialize 
        // our text view and image views.
        TextView nameTV, publisherTV, pageCountTV, dateTV;
        ImageView bookIV;
  
        public BookViewHolder(View itemView) {
            super(itemView);
            nameTV = itemView.findViewById(R.id.idTVBookTitle);
            publisherTV = itemView.findViewById(R.id.idTVpublisher);
            pageCountTV = itemView.findViewById(R.id.idTVPageCount);
            dateTV = itemView.findViewById(R.id.idTVDate);
            bookIV = itemView.findViewById(R.id.idIVbook);
        }
    }
}

第8步：创建一个新活动以详细显示我们的图书信息

导航到应用程序> Java >应用程序的包名称>右键单击它，然后单击新建>活动>选择空活动并将其命名为BookDetails 。确保选择清空活动。

使用activity_book_details.xml文件：

转到activity_book_details.xml文件，并参考以下代码。以下是activity_book_details.xml文件的代码。

使用BookDetails。 Java文件：

转到BookDetails。 Java文件并参考以下代码。下面是BookDetails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.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
  
import androidx.appcompat.app.AppCompatActivity;
  
import com.squareup.picasso.Picasso;
  
import java.util.ArrayList;
  
public class BookDetails extends AppCompatActivity {
      
    // creating variables for strings,text view, image views and button.
    String title, subtitle, publisher, publishedDate, description, thumbnail, previewLink, infoLink, buyLink;
    int pageCount;
    private ArrayList authors;
  
    TextView titleTV, subtitleTV, publisherTV, descTV, pageTV, publishDateTV;
    Button previewBtn, buyBtn;
    private ImageView bookIV;
      
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_book_details);
          
        // initializing our views..
        titleTV = findViewById(R.id.idTVTitle);
        subtitleTV = findViewById(R.id.idTVSubTitle);
        publisherTV = findViewById(R.id.idTVpublisher);
        descTV = findViewById(R.id.idTVDescription);
        pageTV = findViewById(R.id.idTVNoOfPages);
        publishDateTV = findViewById(R.id.idTVPublishDate);
        previewBtn = findViewById(R.id.idBtnPreview);
        buyBtn = findViewById(R.id.idBtnBuy);
        bookIV = findViewById(R.id.idIVbook);
  
        // getting the data which we have passed from our adapter class.
        title = getIntent().getStringExtra("title");
        subtitle = getIntent().getStringExtra("subtitle");
        publisher = getIntent().getStringExtra("publisher");
        publishedDate = getIntent().getStringExtra("publishedDate");
        description = getIntent().getStringExtra("description");
        pageCount = getIntent().getIntExtra("pageCount", 0);
        thumbnail = getIntent().getStringExtra("thumbnail");
        previewLink = getIntent().getStringExtra("previewLink");
        infoLink = getIntent().getStringExtra("infoLink");
        buyLink = getIntent().getStringExtra("buyLink");
  
        // after getting the data we are setting 
        // that data to our text views and image view.
        titleTV.setText(title);
        subtitleTV.setText(subtitle);
        publisherTV.setText(publisher);
        publishDateTV.setText("Published On : " + publishedDate);
        descTV.setText(description);
        pageTV.setText("No Of Pages : " + pageCount);
        Picasso.get().load(thumbnail).into(bookIV);
  
        // adding on click listener for our preview button.
        previewBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (previewLink.isEmpty()) {
                    // below toast message is displayed when preview link is not present.
                    Toast.makeText(BookDetails.this, "No preview Link present", Toast.LENGTH_SHORT).show();
                    return;
                }
                // if the link is present we are opening 
                // that link via an intent.
                Uri uri = Uri.parse(previewLink);
                Intent i = new Intent(Intent.ACTION_VIEW, uri);
                startActivity(i);
            }
        });
  
        // initializing on click listener for buy button.
        buyBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (buyLink.isEmpty()) {
                    // below toast message is displaying when buy link is empty.
                    Toast.makeText(BookDetails.this, "No buy page present for this book", Toast.LENGTH_SHORT).show();
                    return;
                }
                // if the link is present we are opening
                // the link via an intent.
                Uri uri = Uri.parse(buyLink);
                Intent i = new Intent(Intent.ACTION_VIEW, uri);
                startActivity(i);
            }
        });
    }
}

步骤9：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.view.View;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ProgressBar;
import android.widget.Toast;
  
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
  
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 org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
  
import java.util.ArrayList;
  
public class MainActivity extends AppCompatActivity {
  
    // creating variables for our request queue,
    // array list, progressbar, edittext,
    // image button and our recycler view. 
    private RequestQueue mRequestQueue;
    private ArrayList bookInfoArrayList;
    private ProgressBar progressBar;
    private EditText searchEdt;
    private ImageButton searchBtn;
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
          
        // initializing our views. 
        progressBar = findViewById(R.id.idLoadingPB);
        searchEdt = findViewById(R.id.idEdtSearchBooks);
        searchBtn = findViewById(R.id.idBtnSearch);
  
        // initializing on click listener for our button.
        searchBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                progressBar.setVisibility(View.VISIBLE);
                  
                // checking if our edittext field is empty or not.
                if (searchEdt.getText().toString().isEmpty()) {
                    searchEdt.setError("Please enter search query");
                    return;
                }
                // if the search query is not empty then we are 
                // calling get book info method to load all 
                // the books from the API.
                getBooksInfo(searchEdt.getText().toString());
            }
        });
    }
  
    private void getBooksInfo(String query) {
          
        // creating a new array list.
        bookInfoArrayList = new ArrayList<>();
          
        // below line is use to initialize
        // the variable for our request queue.
        mRequestQueue = Volley.newRequestQueue(MainActivity.this);
          
        // below line is use to clear cache this 
        // will be use when our data is being updated.
        mRequestQueue.getCache().clear();
          
        // below is the url for getting data from API in json format.
        String url = "https://www.googleapis.com/books/v1/volumes?q=" + query;
          
        // below line we are  creating a new request queue.
        RequestQueue queue = Volley.newRequestQueue(MainActivity.this);
  
          
        // below line is use to make json object request inside that we 
        // are passing url, get method and getting json object. .
        JsonObjectRequest booksObjrequest = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener() {
            @Override
            public void onResponse(JSONObject response) {
                progressBar.setVisibility(View.GONE);
                // inside on response method we are extracting all our json data.
                try {
                    JSONArray itemsArray = response.getJSONArray("items");
                    for (int i = 0; i < itemsArray.length(); i++) {
                        JSONObject itemsObj = itemsArray.getJSONObject(i);
                        JSONObject volumeObj = itemsObj.getJSONObject("volumeInfo");
                        String title = volumeObj.optString("title");
                        String subtitle = volumeObj.optString("subtitle");
                        JSONArray authorsArray = volumeObj.getJSONArray("authors");
                        String publisher = volumeObj.optString("publisher");
                        String publishedDate = volumeObj.optString("publishedDate");
                        String description = volumeObj.optString("description");
                        int pageCount = volumeObj.optInt("pageCount");
                        JSONObject imageLinks = volumeObj.optJSONObject("imageLinks");
                        String thumbnail = imageLinks.optString("thumbnail");
                        String previewLink = volumeObj.optString("previewLink");
                        String infoLink = volumeObj.optString("infoLink");
                        JSONObject saleInfoObj = itemsObj.optJSONObject("saleInfo");
                        String buyLink = saleInfoObj.optString("buyLink");
                        ArrayList authorsArrayList = new ArrayList<>();
                        if (authorsArray.length() != 0) {
                            for (int j = 0; j < authorsArray.length(); j++) {
                                authorsArrayList.add(authorsArray.optString(i));
                            }
                        }
                        // after extracting all the data we are 
                        // saving this data in our modal class. 
                        BookInfo bookInfo = new BookInfo(title, subtitle, authorsArrayList, publisher, publishedDate, description, pageCount, thumbnail, previewLink, infoLink, buyLink);
                          
                        // below line is use to pass our modal 
                        // class in our array list.
                        bookInfoArrayList.add(bookInfo);
                          
                        // below line is use to pass our 
                        // array list in adapter class.
                        BookAdapter adapter = new BookAdapter(bookInfoArrayList, MainActivity.this);
                          
                        // below line is use to add linear layout
                        // manager for our recycler view.
                        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(MainActivity.this, RecyclerView.VERTICAL, false);
                        RecyclerView mRecyclerView = (RecyclerView) findViewById(R.id.idRVBooks);
                          
                        // in below line we are setting layout manager and 
                        // adapter to our recycler view.
                        mRecyclerView.setLayoutManager(linearLayoutManager);
                        mRecyclerView.setAdapter(adapter);
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                    // displaying a toast message when we get any error from API
                    Toast.makeText(MainActivity.this, "No Data Found" + e, Toast.LENGTH_SHORT).show();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                // also displaying error message in toast.
                Toast.makeText(MainActivity.this, "Error found is " + error, Toast.LENGTH_SHORT).show();
            }
        });
        // at last we are adding our json object
        // request in our request queue.
        queue.add(booksObjrequest);
    }
}

输出：

在以下链接上查看项目： https : //github.com/ChaitanyaMunje/LibraryApp

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