我有一个 JSP,我想在其中显示数据库中的车辆图像。我的实体类如下所示:
public class Vehicle implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id_vehicle")
private int idVehicle;
private String model;
private String manufacturer;
private byte[] image;
@Transient
private String encodedImage;
// Getters and setters
}
在 JSP 中显示所有图像的一种方法如下所示:
<c:forEach items="${vehicles}" var="v">
<img src="data:image/jpg;base64, <c:out value='${v.encodedImage}'/>"
width="214" height="138" />
</c:forEach>
这意味着,字节数组被编码为String
,并且所有内容都传递给新的List
:
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.codec.binary.Base64;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import ba.spiderweb.carshop.dao.VehicleDao;
import ba.spiderweb.carshop.entity.Vehicle;
import ba.spiderweb.carshop.util.PageConverter;
@Service
@Transactional
public class VehicleServiceImpl implements VehicleService {
@Autowired
private VehicleDao vehicleDao;
@Override
public List<Vehicle> findAll() {
List<Vehicle> finalList = new ArrayList<Vehicle>();
for (Vehicle v : vehicleDao.findAll()) {
v.setEncodedImage(new String(Base64.encodeBase64(v.getImage())));
finalList.add(v);
}
return finalList;
}
}
有没有更好的方法在 JSP 中显示多个图像,而不是之前将字节数组编码为 String
并重新创建新的List
车辆?可以直接在 JSP 中对字节数组进行编码吗?
最佳答案
创建一个将 url 映射到图像文件内容的 servlet。
html/jsp
<c:forEach items="${vehicles}" var="v">
<img src="images/${v.idVehicle}"
width="214" height="138" />
</c:forEach>
将调用网址 images/112
、/images/333
... 上的图像,其中这些数字是车辆 ID。
servlet 将使用此信息在数据库中查找车辆并提供其图像:
public class VehicleServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String path = req.getPathInfo();
//gets what comes after "/" (I've not tested it)
String strVehicleId = path.substring(path.indexOf('/'));
int vehicleId = Integer.parseInt(strVehicleId);
//finds the vehicle
Vehicle v = vehicleDao.findByPrimaryKey(vehicleId);
//sends the image
resp.setContentType("image/jpg");
BufferedOutputStream out = new BufferedOutputStream(resp.getOutputStream());
out.write(v.getImage());
out.close();
}
别忘了 map this servlet到 web.xml
配置文件上的“/images/”路径。
关于java - 在 JSP 中显示多个图像的最佳方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25915723/