Question

我一直试图获取并打印数据表。我认为我在servlet中正确设置了请求但是当我尝试获取test.jsp中的book列表时，它说服务器遇到意外情况，导致它无法完成请求。他们应该去哪里？我觉得我错过了什么或者他们完全错了，但我无法弄清楚是什么。谢谢你的帮助。

servletTest中的

public class TestServlet extends HttpServlet {

protected void doPost(HttpServletRequest request,
                      HttpServletResponse response)
        throws ServletException, IOException {

}

protected void doGet(HttpServletRequest request,
                     HttpServletResponse response)
        throws ServletException, IOException {

        String userPath="/test";
        String url = "/WEB-INF/jsp"+userPath+".jsp";


        String categoryName = request.getParameter("category");
        request.setAttribute("selectedCategoryName", categoryName);

        CategoryDao categoryDao = 
        ApplicationContext.INSTANCE.getCategoryDao();

        BookDao bookDao = ApplicationContext.INSTANCE.getBookDao();
        request.setAttribute("bookList",bookDao);


        request.getRequestDispatcher(url).forward(request,response);
}

在test.jsp

中

<body>

  <ul>
      <li><a href="test?category=architecture">architecture</a></li>
      <li><a href="test?category=fine art">fine art</a></li>
      <li><a href="test?category=fashion">fashion</a></li>
      <li><a href="test?category=photography">photography</a></li>
      <li><a href="test?category=graphic">graphic</a></li>
 </ul>
 <c:set var="categoryName">${selectedCategoryName}</c:set>
 <h1><span style="size: 14px">${categoryName}</span> </h1>
 <table border="1">

 <tr>
    <th>book_id</th>
    <th>title</th>
    <th>author</th>
    <th>price</th>
    <th>is_public</th>
    <th>category_id</th>
 </tr>

    <c:forEach var="book" items="${bookList}">
        <tr>
            <td>${book.bookId}</td>
            <td>${book.title}</td>
            <td>${book.author}</td>
            <td>${book.price}</td>
            <td>${book.is_public}</td>
            <td>${book.category_id}</td>
        </tr>
    </c:forEach>
</table>
</body>
</html>

预订课程

public class Book {

private long bookId;
private String title;
private String author;
private int price;
private boolean isPublic;
private Long categoryId;


public Book(long bookId, String title, String author, int price,
            boolean isPublic, long categoryId) {
    this.bookId = bookId;
    this.title = title;
    this.author = author;
    this.price = price;
    this.isPublic = isPublic;
    this.categoryId = categoryId;
}

public long getBookId() {
    return bookId;
}

public String getTitle() {
    return title;
}

public String getAuthor() {
    return author;
}

public int getPrice() {
    return price;
}

public boolean getIsPublic() {
    return isPublic;
}

@Override
public String toString() {
    return "Book{" +
            "bookId=" + bookId +
            ", title='" + title + '\'' +
            ", author='" + author + '\'' +
            ", price=" + price +
            ", isPublic=" + isPublic +
            ", categoryId=" + categoryId +
            '}';
    }
}

Answer 1

错误是因为您没有调用正确的名称。在您的图书课程中，您有以下变量：

private boolean isPublic;
private Long categoryId;

但是在你的jsp中，你可以调用这些变量：

 <td>${book.is_public}</td>
 <td>${book.category_id}</td>

哪个错了。你需要打电话：

 <td>${book.isPublic}</td>
 <td>${book.categoryId}</td>

然后它会起作用。确保名称始终相同。

无法从DAO获取数据列表

1 个答案: