java - 使用 spring mvc 和 hibernate 在 jsp 上显示图像

Question

我在mysql数据库中有一个BLOB类型的图像，我想在jsp上显示该图像。我正在使用 Hibernate 和 Spring MVC。这是我的模型类:

@Repository
@Entity
@Table(name = "foto")
public class Image {

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "fk_id_users", nullable = false)
    private Users user;

    @Id
    @Column(name = "id_foto")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id_foto;

    @Column(name = "tipo")
    private String tipo;

    @Column(name = "size")
    private String size;

    @Column(name = "nome")
    private String nome;

    @Column(name = "image")
    private byte[] image;

    //Getters and Setters

这是我的 Controller :

@Controller
@SessionAttributes("UserSession")
public class LoginController {

    @Autowired
    private UsersService usersService;

    @RequestMapping(value = "loginUsers", method = RequestMethod.POST)
    public ModelAndView loginUsers(HttpServletRequest request,@RequestParam("username") String username,
            @RequestParam("password") String password) {

        Users user = usersService.loginUsers(username, password);

        if( user == null ) {
            ModelAndView MV = new ModelAndView("login");
            MV.addObject("erroreLogin", "username e/o password errati");
            return MV;
        } else if ( user.getAmministratore() == false ){
            request.getSession().setAttribute("UserSession",user);
            ModelAndView mav = new ModelAndView("homeUtente");
            mav.addObject("galleria", usersService.getAllFoto());
            return mav;
        } else {
            request.getSession().setAttribute("UserSession",user);
            ModelAndView mav = new ModelAndView("utenti");
            mav.addObject("lista", usersService.getAllUtenti());
            return mav;
        }
    }

    @RequestMapping(value = "logout", method = RequestMethod.GET)
    public ModelAndView logout(HttpServletRequest request) {
        request.getSession().invalidate(); //invalido i dati presenti in sessione
        return new ModelAndView("login");
    }

}

在我的jsp中，我使用它来显示图像列表中的图像，因为每个用户都有一个要显示的图库:

<img alt="Kangoo_image" src="data:image/jpeg;base64,${galleria.image}" />

当我尝试在 jsp 中显示它时。它显示一些二进制文件，例如 [B@59e73b47.我怎样才能在jsp中显示这里的图像？

Answer 1

要在 JSP 上显示图像而不存储到文件系统并链接到它，您必须对字节数组进行 Base64 编码。通过以下几行即可轻松完成

byte[] encodeBase64 = Base64.encodeBase64(usersService.getAllFoto());
String base64Encoded = new String(encodeBase64, "UTF-8");
mav.addObject("galleria", usersService.getAllFoto());

IOUtils 和 Base64 均来自 org.apache.commonsEndFragment