Spring MultipartFile验证和转换
我目前有一个采用MultipartFile的Spring MVC控制器
@RequestMapping(method = RequestMethod.POST)public String doUpload(@RequestParam("file") final MultipartFile file) {
/* ... */
}
该文件包含csv数据,每行将使用该数据创建域对象列表。可以了
我已经为行数据编写了一个转换器:
class MyObjectConverter implements org.springframework...Converter<String[], MyObject> { /* ... */
}
还有一个文件验证器
class UploadFileValidator implements org.springframework.validation.Validator { /* ... */
}
我有一个表格可以上传:
<form method="post" action="<@spring.url '/upload'/>"
enctype="multipart/form-data">
<input id="upload" type="file" name="file"/>
<input type="submit" id="uploadButton"/>
</form
但是我真正想做的是将它们捆绑在一起,以便我的控制器可以使用类似
@RequestMapping(method = RequestMethod.POST)public String doUpload(
@Valid final List<MyObject> objList,
final BindingResult result) { ...}
我知道Spring MVC框架支持转换器和验证器,但是我无法理解如何使它们协同工作。
回答:
首先,我将MultipartFile包装在一个表单支持对象中:
public class UploadBackingForm { private MultipartFile multipartFile;
/* ... getter/setter */
}
然后我将其绑定到表单:
<form method="post" enctype="multipart/form-data"><@spring.bind "backingform.*"/>
<tr>
<td><@spring.formInput 'backingform.multipartFile' '' 'file' /></td>
<td> <button type="submit">Upload</button> </td>
</tr>
</form>
在控制器中,我分配一个验证器:
@InitBinderpublic void initBinder(final DataBinder binder) {
binder.setValidator(new UploadValidator());
}
这是验证者:
public class UploadValidator implements Validator { private final Converter<String[], MyObject> converter
= new MyObjectConverter();
@Override
public boolean supports(final Class<?> clazz) {
return UploadBackingForm.class.equals(clazz);
}
@Override
public void validate(final Object target, final Errors errors) {
final UploadBackingForm backingForm = (UploadBackingForm) target;
final MultipartFile multipartFile = backingForm.getMultipartFile();
final List<String[]> uploadData = /* parse file */
for (final String[] uploadDataRow : uploadData){
try {
converter.convert(uploadDataRow);
} catch (IllegalArgumentException e) {
errors.rejectValue("multipartFile", "line.invalid", ...);
}
}
}
}
验证器使用Converter将行项目转换为MyObj。
现在,doPost方法如下所示:
@RequestMapping(method = RequestMethod.POST)public String doUpload(
@Valid @ModelAttribute("backingform") UploadBackingForm backingForm,
final BindingResult result,
final HttpSession session) throws IOException {
final UploadConverter converter = new UploadConverter();
final List<MyObj> imports =
converter.convert(backingForm.getMultipartFile().getInputStream());
}
UploadConverter与UploadValidator大致相同:
public class UploadConverter implements Converter<InputStream, List<MyObject>> { private final Converter<String[], MyObject> converter = new MyObjectConverter();
@Override
public List<MyObject> convert(final InputStream source) {
final List<String[]> detailLines = /* ... getDetailLines */
final List<MyObject> importList =
new ArrayList<MyObject>(detailLines.size());
for (final String[] row : detailLines) {
importList.add(converter.convert(row));
}
return importList;
}
}
唯一的问题是验证和转换过程几乎是同一回事。幸运的是,上传文件不会很大,因此重复工作并不是大问题。
以上是 Spring MultipartFile验证和转换 的全部内容, 来源链接: utcz.com/qa/399186.html