Question

Servlet

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

    String firstname = request.getParameter("Firstname");
    String lastname = request.getParameter("Lastname");
    String gender = request.getParameter("gender");
    String dob = request.getParameter("dob");
    String email = request.getParameter("email");
    String experience =  request.getParameter("experience");
    String password = request.getParameter("pwd");
    String confirmpassword = request.getParameter("cpwd");
    String address = request.getParameter("address");
    String mobilenumber = request.getParameter("mobile");



    Part file = request.getPart("fileUpload");

    inputStream = file.getInputStream();

        CandidatePojo pojo = new CandidatePojo(firstname, lastname, gender,dob,email,experience,password,confirmpassword,address,mobilenumber,file);

        CandidateRegistrationDao dao = new CandidateRegistrationDao();

        try {
            pojo = dao.insertdata(pojo);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        response.sendRedirect("index.jsp");

    }

Dao

公共CandidatePojo insertdata（CandidatePojo pojo）引发SQLException { 字符串sql =“在候选注册表中插入（名字，姓氏，性别，dob，电子邮件，体验，pwd，cpwd，地址，移动电话，简历）值（？，？，？，？，？，？，？，？，？，？，？）“; connect（）;

    PreparedStatement statement = jdbcConnection.prepareStatement(sql);
    statement.setString(1, pojo.getFirstname());
    statement.setString(2, pojo.getLastname() );
    statement.setString(3, pojo.getGender());
    statement.setString(4, pojo.getDob());
    statement.setString(5, pojo.getEmail());
    statement.setString(6, pojo.getExperience());
    statement.setString(7, pojo.getPassword());
    statement.setString(8, pojo.getConfirmpassword());
    statement.setString(9, pojo.getAddress() );
    statement.setString(10, pojo.getMobilenumber());  


    statement.setBlob(11, (Blob) pojo.getFile());



    int rowsInserted = statement.executeUpdate();
    if (rowsInserted > 0) {
        System.out.println("A new record was inserted successfully!");
    }

    //boolean rowInserted = statement.executeUpdate() > 0;
    statement.close();
    disconnect();
    return pojo;
}

Pojo

公共类CandidatePojo {

private String firstname;
private String lastname;
private String gender;
private String dob;
private String email;
private String experience;
private String password;
private String confirmpassword;
private String address;
private String mobilenumber;
private Part file;


public CandidatePojo(String firstname, String lastname, String gender, String dob, String email, String experience,
        String password, String confirmpassword, String address, String mobilenumber,Part file) {
    this.firstname = firstname;
    this.lastname = lastname;
    this.gender = gender;
    this.dob = dob;
    this.email = email;
    this.experience = experience;
    this.password = password;
    this.confirmpassword = confirmpassword;
    this.address = address;
    this.mobilenumber = mobilenumber;
    this.file = file;

}

嗨...我无法将Blob转换为我的编码，请有人发现此代码中有什么错误。

在控制台中出现这样的错误

java.lang.ClassCastException：org.apache.catalina.core.ApplicationPart无法转换为java.sql.Blob 在registration.Dao.CandidateRegistrationDao.insertdata（CandidateRegistrationDao.java:62）在registration.servelt.RegistrationController.doGet（RegistrationController.java:75）在registration.servelt.RegistrationController.doPost（RegistrationController.java:48）在javax.servlet.http.HttpServlet.service（HttpServlet.java:660）在javax.servlet.http.HttpServlet.service（HttpServlet.java:741）

Answer 1

问题是您要通过直接投射直接将org.apache.catalina.core.ApplicationPart转换为Blob：

statement.setBlob(11, (Blob) pojo.getFile());

问题在于无法以这种方式将Part强制转换为Blob。

解决此问题的一种方法是将Part转换为InputStream并将其转换为byte[]，SerialBlob可以理解，即可用作Blob-距离很长。

使用Commons IO。将以下内容添加到pojo中，以将Part变成byte[]：

public byte[] getFileAsByteA() {
    try {
        return IOUtils.toByteArray(file.getInputStream());
    } catch (IOException ex) {
        return null;
    }
}

在插入代码中添加以下内容：

javax.sql.rowset.serial.SerialBlob sb = new SerialBlob(pojo.getFileAsByteA());
statement.setBlob(11, sb);

注意：代码只是拼凑在一起。

无法转换为java.sql.Blob

1 个答案: