Android Studio 图书搜索 Google API

Posted 2023-04-19

【中文标题】Android Studio 图书搜索 Google API

【英文标题】：Android Studio Book search Google API

【发布时间】：2020-07-08 11:48:00

【问题描述】：

OK 这个 android (Java) 应用程序搜索 Google App API 并在列表视图中显示书籍。它使用自定义适配器和异步加载器。我有一个应用程序的骨架，但只有一次搜索。之后，一切都停留在屏幕上，新的搜索没有发生，或者似乎没有发生。

我让它在创建时从 MainActivity 工作，但随后将其移至按钮和 EditText。

我认为问题主要出在这个文件中。

如果有人可以提供帮助，那就太好了！查看 goQuery 按钮单击下的最后一部分。 谢谢。

公共类 MainActivity 扩展 AppCompatActivity 实现 LoaderCallbacks> 私有静态最终字符串 LOG_TAG = MainActivity.class.getName(); 私有字符串 GOOGLE_REQUEST_URL = "https://www.googleapis.com/books/v1/volumes?q=android&maxResults=10"; /** * Book loader ID 的常量值。我们可以选择任何整数。 * 这真的只有在你使用多个加载器时才会起作用。 */ 私有静态最终 int BOOK_LOADER_ID = 1;

/** Adapter for the list of books */
private BookWormAdapter mAdapter;

/** TextView that is displayed when the list is empty */
private TextView mEmptyStateTextView;

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    ListView bookwormListView = (ListView) findViewById(R.id.list);

    mEmptyStateTextView = (TextView) findViewById(R.id.empty_view);
    bookwormListView.setEmptyView(mEmptyStateTextView);

    // Create a new adapter that takes an empty list of books as input
    mAdapter = new BookWormAdapter(this, new ArrayList<Book>());

    // Set the adapter on the @link ListView
    // so the list can be populated in the user interface
    bookwormListView.setAdapter(mAdapter);
    /// End Button search

    // Set an item click listener on the ListView, which sends an intent to a web browser
    // to open a website with more information about the selected book.
    bookwormListView.setOnItemClickListener(new AdapterView.OnItemClickListener() 
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) 
            // Find the current book that was clicked on
            Book currentBook = mAdapter.getItem(position);

            // Convert the String URL into a URI object (to pass into the Intent constructor)
            Uri bookwormUri = Uri.parse(currentBook.getPreviewLink());

            // Create a new intent to view the book URI
            Intent websiteIntent = new Intent(Intent.ACTION_VIEW, bookwormUri);

            // Send the intent to launch a new activity
            startActivity(websiteIntent);
        
    );

    View loadingIndicator = findViewById(R.id.loading_indicator);
    loadingIndicator.setVisibility(View.GONE);



@Override
public Loader<List<Book>> onCreateLoader(int i, Bundle bundle) 
    // Create a new loader for the given URL
    //Log.i(LOG_TAG, "onCreateLoader: TEST Created Loader!");
    return new BookWormLoader(this, GOOGLE_REQUEST_URL);




@Override
public void onLoadFinished(Loader<List<Book>> loader, List<Book> bookworms) 
    // Hide loading indicator because the data has been loaded
    View loadingIndicator = findViewById(R.id.loading_indicator);
    loadingIndicator.setVisibility(View.GONE);
    //  Log.i(LOG_TAG, "onLoadFinished: On Load finished!");
    // Set empty state text to display "No books found."
    mEmptyStateTextView.setText(R.string.no_books);

    // Clear the adapter of previous book data
    mAdapter.clear();

    // If there is a valid list of @link Books, then add them to the adapter's
    // data set. This will trigger the ListView to update.
    if (bookworms != null && !bookworms.isEmpty()) 
        mAdapter.addAll(bookworms);
        //mAdapter.notifyDataSetChanged();
    


@Override
public void onLoaderReset(Loader<List<Book>> loader) 
    // Loader reset, so we can clear out our existing data.
    mAdapter.clear();
    //  Log.i(LOG_TAG, "onLoaderReset: TEST On Loader Reset!");

public void goQuery(View view)
    EditText mySearchTextView = findViewById(R.id.searchEdit);

    `enter code here`if (mySearchTextView.getText().length() < 1) return;

    //mAdapter.clear();
  // mAdapter.notifyDataSetChanged();


    View loadingIndicator = findViewById(R.id.loading_indicator);
    loadingIndicator.setVisibility(View.VISIBLE);

    GOOGLE_REQUEST_URL = "https://www.googleapis.com/books/v1/volumes?q="+mySearchTextView.getText()+"&maxResults=20";

    // Get a reference to the ConnectivityManager to check state of network connectivity
    ConnectivityManager connMgr = (ConnectivityManager)
    getSystemService(Context.CONNECTIVITY_SERVICE);

    // Get details on the currently active default data network
    NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

    // If there is a network connection, fetch data
    if (networkInfo != null && networkInfo.isConnected()) 
        // Get a reference to the LoaderManager, in order to interact with loaders.
        android.app.LoaderManager loaderManager = getLoaderManager();

// 初始化加载器。传入上面定义的 int ID 常量并传入 null for // 捆绑包。为 LoaderCallbacks 参数传入此活动（有效 // 因为这个活动实现了 LoaderCallbacks 接口）。 loaderManager.initLoader(BOOK_LOADER_ID, null, this); 别的 // 否则显示错误 // 首先，隐藏加载指示器，以便显示错误消息 loadingIndicator.setVisibility(View.GONE);

        // Update empty state with no connection error message
        mEmptyStateTextView.setText(R.string.no_internet_connection);
    

【参考方案1】：

我将它添加到 buttonClick 中，现在它正在工作。不知道这是不是真的 Kosher？

loaderManager.destroyLoader(BOOK_LOADER_ID); mAdapter.clear(); mAdapter.notifyDataSetChanged()enter code here;