[英]How to define getter and setter for an image in spring mvc
我正在尝试使用 spring mvc 将图像上传到 mysql 数据库。 我能够插入字符串和 integer 值,但是在上传图像时会抛出字段错误
代码:
dao.java 文件:
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import com.skillsoft.model.Book;
public class BookDao {
JdbcTemplate template;
public void setTemplate(JdbcTemplate template) {
this.template = template;
}
public List<Book> getExhibitionDetails() {
return template.query("select * from ExhibitionDetails", new RowMapper<Book>() {
public Book mapRow(ResultSet rs, int row) throws SQLException {
Book book = new Book();
book.setStudentId(rs.getInt(1));
book.setName(rs.getString(2));
book.setProjectName(rs.getString(3));
book.setPhoto(rs.getBytes(4));
return book;
}
});
}
public int save(Book p) {
String sql = "insert into ExhibitionDetails(StudentId, Name, ProjectName, Photo) values(" + p.getStudentId() + ",'"
+ p.getName() + "','" + p.getProjectName() + "','" + p.getPhoto() + "')" ;
return template.update(sql);
}
使用 p.getPhoto() 获取图像并将其插入数据库是否正确? 如果不是还有什么选择
Model class:
package com.skillsoft.model;
import java.util.List;
import org.springframework.web.multipart.MultipartFile;
public class Book {
private int studentId;
private String name;
private String projectName;
private byte[] photo;
public byte[] getPhoto() {
return photo;
}
public void setPhoto(byte[] photo) {
this.photo = photo;
}
public String getProjectName() {
return projectName;
}
public void setProjectName(String projectName) {
this.projectName = projectName;
}
public int getStudentId() {
return studentId;
}
public void setStudentId(int studentId) {
this.studentId = studentId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Controller:
导入 com.skillsoft.dao.BookDao; 导入 com.skillsoft.model.Book;
@Controller public class BookController {
@Autowired
BookDao bookdao;
@RequestMapping("/viewbook")
public String viewbook(Model m) {
List<Book> list = bookdao.getExhibitionDetails();
m.addAttribute("list", list);
return "viewbook";
}
@RequestMapping("/addform")
public String showform(Model m) {
m.addAttribute("command", new Book());
return "addform";
}
@RequestMapping(value = "/save", method = RequestMethod.POST)
public String save(@ModelAttribute("book") Book book) {
bookdao.save(book);
return "redirect:/viewbook";
}
Error:
Field error in object 'book' on field 'photo': rejected value [org.springframework.web.multipart.commons.CommonsMultipartFile@2e5c8975]; codes [typeMismatch.book.photo,typeMismatch.photo,typeMismatch.[B,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [book.photo,photo]; arguments []; default message [photo]]; default message [Failed to convert property value of type 'org.springframework.web.multipart.commons.CommonsMultipartFile' to required type 'byte[]' for property 'photo'; nested exception is java.lang.IllegalArgumentException: Cannot convert value of type 'org.springframework.web.multipart.commons.CommonsMultipartFile' to required type 'byte' for property 'photo[0]': PropertyEditor [org.springframework.beans.propertyeditors.CustomNumberEditor] returned inappropriate value of type 'org.springframework.web.multipart.commons.CommonsMultipartFile']]
谢谢。 从错误消息来看,您似乎正在将org.springframework.web.multipart.commons.CommonsMultipartFile
类型的变量传递给setPhoto()
,它需要byte[]
。 CommonsMultipartFile
有一个getBytes()
方法,因此您可以尝试调用它来获取 model 期望的字节数组。
关于我之前的评论:我的直觉是,将图像存储在关系数据库列中可能不是正确的设计选择。 如果您打算在 web 页面中显示这些图像,那么这几乎肯定不是正确的设计选择。 您可以考虑将上传的文件存储在文件系统(或 S3 等云服务)上,然后将路径或 URL 存储到 model 中的文件中。
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