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java - 不能转换为 java.sql.Blob

问题描述

小服务程序

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");

    }

道

public CandidatePojo insertdata(CandidatePojo pojo) throws SQLException { String sql = "INSERT INTO Candidateregist (firstname, lastname, gender,dob,email,experience,pwd,cpwd,address,mobile,resume) VALUES (?, ?, ? ,? , ? ,? ,? , ? ,? ,?, ?)"; 连接（）;

    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;
}

波乔

公共类候选人Pojo {

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 投射到我的编码中，请有人在此代码中找到什么错误..

在控制台中出现这样的错误

java.lang.ClassCastException：org.apache.catalina.core.ApplicationPart 在registration.servelt.RegistrationController.doGet(RegistrationController.Dao.CandidateRegistrationDao.insertdata(CandidateRegistrationDao.java:62) 处无法转换为java.sql.Blob。 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)

标签： java

解决方案

问题是您要通过直接转换直接将a 转换org.apache.catalina.core.ApplicationPart为 a Blob：

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

问题是Part不能以Blob这种方式将 a 强制转换为 a。

解决此问题的一种方法是将 the 转换Part为 anInputStream并将其转换为 a ，这是由SerialBlobbyte[]理解的，它可用作 Blob - 有点长的路线。

使用Commons IO。将以下内容添加到 pojo 以将 Part 转换为byte[]：

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

将以下内容添加到插入代码中：

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。

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