java - 从 Google 图书 api 获取缩略图

Question

我无法在此 Json 响应中提取书籍缩略图的 URL: https://www.googleapis.com/books/v1/volumes?q=java&maxResults=10

当我将链接硬编码到字符串值中时，它可以工作，因此它一定是我获取缩略图的方法。

这是我的代码:

try {

    // Create a JSONObject from the JSON response string
    JSONObject baseJsonResponse = new JSONObject(bookwormJSON);

    // Extract the JSONArray associated with the key called "items",
    // which represents a list of Books.
    JSONArray bookwormArray = baseJsonResponse.getJSONArray("items");

    // For each bookworm in the bookwormArray, create an {@link Book} object
    for (int i = 0; i < bookwormArray.length(); i++) {
        JSONObject volumeInfo = bookwormArray.getJSONObject(i).getJSONObject("volumeInfo");

        String author = "dork";

        // Extract the value for the key called "title"
        String title = volumeInfo.getString("title");

        // Extract the value for the key called "author - I just get first one in array"
        JSONArray authors = volumeInfo.getJSONArray("authors");

        author = authors.getString(0);

        String imgUrl = volumeInfo.getString("smallThumbnail");
        imgUrl = imgUrl.substring(0, 4) + 's' + imgUrl.substring(4);

        // title, author and url from the JSON response.
        Book bookworm = new Book(title, author,imgUrl ); 

        // When url hardcoded and above related code to url is removed it works.

        // Add the new {@link Earthquake} to the list of Books.
        bookworms.add(bookworm);
    }
}

Answer 1

我发现这些嵌套的 Json 文件/字符串很令人困惑，但我确实通过阅读此处的另一篇文章使上述内容正常工作。如果有人感兴趣的话，这是代码:

在此处输入代码尝试{ //从 JSON 响应字符串创建 JSONObject JSONObject baseJsonResponse = new JSONObject(bookwormJSON);

            // Extract the JSONArray associated with the key called "items",
            // which represents a list of Books.
            JSONArray bookwormArray = baseJsonResponse.getJSONArray("items");
            // For each bookworm in the bookwormArray, create an {@link Book} object
            for (int i = 0; i < bookwormArray.length(); i++) {
                JSONObject volumeInfo =  bookwormArray.getJSONObject(i).getJSONObject("volumeInfo");
    //Below is the key line
                          JSONObject imageLinks = volumeInfo.getJSONObject("imageLinks");
               // Extract the value for the key called "title"
                String title = volumeInfo.getString("title");
                // Extract the value for the key called "author - I just get first one in array"
                JSONArray authors = volumeInfo.getJSONArray("authors");
                String author = authors.getString(0);
                // Extract the value for the key called "smallThumbnail"
                String imgUrl= imageLinks.getString("smallThumbnail");
                // insert "s" into http
                imgUrl = imgUrl.substring(0, 4) + 's' + imgUrl.substring(4);
                // title, author and url from the JSON response.
                Book bookworm = new Book(title, author,imgUrl );
                // Add the new {@link Earthquake} to the list of books.
                bookworms.add(bookworm);
            }