java 将 byte[] 转换为图像并在 jsp 上显示
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Convert byte[] to image and display on jsp
提问by MJM
I'm trying to display an uploaded picture (which is now a byte array) on a jsp page. Now, the byte[] column exists in the database and has to be converted to an image.
我正在尝试在 jsp 页面上显示上传的图片（现在是一个字节数组）。现在，byte[] 列存在于数据库中，必须转换为图像。
This is what I've been trying:
这是我一直在尝试的：
Part of the table on jsp page:
jsp页面上的部分表格：
<c:forEach var="user" items="${userList}">
<tr>
<td>${user.fileName}</td>
<td>
<img src="data:image/jpg;base64,${user.imageFile}" alt="No image">
</td>
Part of the controller that takes an array of bytes from a MultipartFile object:
从 MultipartFile 对象中获取字节数组的控制器的一部分：
@RequestMapping(value = "/register", method = RequestMethod.POST)
public ModelAndView userRegister(@ModelAttribute("user") @Valid User user, BindingResult result, ModelMap model, @RequestParam("fileData") MultipartFile fileData) throws Exception {
if (!fileData.isEmpty() && fileData != null) {
byte[] bytes = fileData.getBytes();
user.setFileName(fileData.getOriginalFilename());
user.setImageFile(bytes);
}
}
If any additional information is needed, please let me know. Thanks.
如果需要任何其他信息，请告诉我。谢谢。
回答by Master Slave
You can add a tranisent base64imageFileproperty to your User. It will hold the base64 encoded string of the image, which you can access in your jsp like
您可以将瞬态base64imageFile属性添加到您的User. 它将保存图像的 base64 编码字符串，您可以在 jsp 中访问它，例如
<img alt="img" src="data:image/jpeg;base64,${user.base64imageFile}"/>
And in your method you should do the encoding, somethig like
在您的方法中，您应该进行编码，例如
@RequestMapping(value = "/register", method = RequestMethod.POST)
public ModelAndView userRegister(@ModelAttribute("user") @Valid User user, BindingResult result, ModelMap model, @RequestParam("fileData") MultipartFile fileData) throws Exception {
if (!fileData.isEmpty() && fileData != null) {
byte[] bytes = fileData.getBytes();
user.setFileName(fileData.getOriginalFilename());
user.setImageFile(bytes);
byte[] encodeBase64 = Base64.encodeBase64(bytes);
String base64Encoded = new String(encodeBase64, "UTF-8");
user.setBase64image(base64encoded);
}
}
IOUtilsand Base64are a handy util classes from org.apache.commons, shouldn't have a problem finding
IOUtils并且Base64是来自 的一个方便的 util 类org.apache.commons，查找应该没有问题
