Question

即使我使用了inputstream，也没有为参数2指定值并使用了setBlob方法- 即使我使用了inputstream，也没有为参数2指定值和使用setBlob方法- 即使我使用了inputstream，也没有为参数2指定值并使用了setBlob方法---

这是我的jsp代码：

<form  method="post" enctype="multipart/form-data" action="insertbooks">
<p>Title<p>
<input type="text" style="width:300px;height:25px" name="title" placeholder="Type Book Title"/>
<p>Insert image</p>
<input name="image" type="file">
<p>Author</p>
<input type="text" style="width:300px;height:25px" name="author" placeholder="Author Name"/>
<p>Price</p>
<input type="text" style="width:300px;height:25px" name="price" placeholder="Enter price"/>
<br>

<br><br>
<input style="width:100px;height:35px;font-size:1.3em" type="submit" name="submitb" value="submit" />
</form>

这是我的insertbooks.java代码：

public class insertbooks extends HttpServlet {

private String dbURL = "jdbc:mysql://localhost:3306/bookecom";    
private String dbUser = "root";
private String dbPass = "";

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");

     // for error handling in file
    File file=new File("D://Study//programming//servlet//bookecom//insertbookserror.txt");
    FileWriter fw = new FileWriter(file);
    PrintWriter pw = new PrintWriter(fw);

    PrintWriter out = response.getWriter();
    //retrieving image
   InputStream inputStream = null; // input stream of the upload file
    String Title = request.getParameter("title");

     // obtains the upload file part in this multipart request
    Part filePart = request.getPart("image");
    if (filePart != null) {
        // prints out some information for debugging
        System.out.println(filePart.getName());
        System.out.println(filePart.getSize());
        System.out.println(filePart.getContentType());

        // obtains input stream of the upload file
         inputStream = filePart.getInputStream();
        pw.println("Got photooo");
    }

//    System.out.println(" filename:  "+filePart.getName());
  //  pw.println(filePart.getName());
    String Author = request.getParameter("author");
    String Pricef = request.getParameter("price");

    //float Pricef = Float.valueOf(Price);
      pw.println("Got parameters");

      System.out.println("price value"+Pricef);

  Connection conn = null;


  try{
        Class.forName("com.mysql.cj.jdbc.Driver");
        pw.println("Driver Loaded");
        conn = DriverManager.getConnection(dbURL, dbUser, dbPass); 
        pw.println("Connection Established_1");


 // String query = "Insert into books(title,image,author,price) values('"+Title +"','"+inputStream +"','"+Author+"','"+Pricef +"')" ;
 String query = "Insert into books(title,image,author,price) values(?,?,?,?)" ;

 PreparedStatement ps =conn.prepareStatement(query);
 ps.setString(1,Title);
    if(inputStream != null){
    // fetches input stream of the upload file for the blob column
 ps.setBlob(2, inputStream);
    } else{  pw.println(" blob data not available");  }
 ps.setString(3,Author);
 ps.setString(4, Pricef);



 // Sends the statement to the database server
 int row= ps.executeUpdate();
 if(row>0){
 pw.println("data inserted");

 }

  } catch (SQLException ex) {
         ex.getMessage();
      //  ex.printStackTrace();
      ex.printStackTrace(pw);
        pw.println("Connection not Established_1");
    } catch (ClassNotFoundException ex) {
        Logger.getLogger(insertbooks.class.getName()).log(Level.SEVERE, null, ex);
    } finally {
        if (conn != null) {
            // closes the database connection
            try {
                conn.close();
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
        }

        System.out.println("Successfully");
        // sets the message in request scope
      //  request.setAttribute("message", message);

        // forwards to the message page
       // getServletContext().getRequestDispatcher("/message.jsp").forward(request, response);
    }

pw.close();
}
}

这些是错误的：

java.sql.SQLException: No value specified for parameter 2
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1132)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1057)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeLargeUpdate(ClientPreparedStatement.java:1377)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdate(ClientPreparedStatement.java:1042)
at insertbooks.doPost(insertbooks.java:90)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)

Answer 1

您不应该将图像存储在数据库中，存储文件的最佳方法是将它们保存在服务器中并将文件名存储在数据库中。如果需要图像，请获取存储在数据库中的文件名，然后从服务器获取图像。
如果您确实需要将图像存储在数据库中，请尝试将所有代码放在if语句之后，询问if中的filePart是否为null，如下所示：

if (filePart != null) { System.out.println(filePart.getName()); System.out.println(filePart.getSize()); System.out.println(filePart.getContentType()); inputStream = filePart.getInputStream(); pw.println("Got photooo"); //PUT ALL THE CODE AFTER THIS IF STATEMENT HERE }

为什么图像未插入数据库

1 个答案: