使用 Thymeleaf 将文件上传到 @ModelAttribute

Question

如何使用 Thymeleaf 将文件上传到 @ModelAttribute？ 我正在做的事情是：

上传.html

<form method="POST" action="#" th:action="@{/sending}" th:object="${collage}" enctype="multipart/form-data" >
            <input type="file" th:field="*{picture}" />
            <input type="file" th:field="*{picture}"  />
            <input type="submit" value="upload" />
</form>

我的控制器：

@Controller
public class MainController {

@GetMapping(value = { "/" })
public String index(){
    return "upload";
}

@GetMapping("/collage")
public String paintPicture(Model model){        
    return "collage";
}

@PostMapping("/sending")
public String redirect(@ModelAttribute(value="collage") Collage collage, RedirectAttributes redirectAttr) {

        Collections.shuffle(Arrays.asList(collage.getCollage()));
        redirectAttr.addFlashAttribute("pictures",collage.getCollage());
        return "redirect:/collage"; 
}
}

拼贴类：

public class Collage {

private MultipartFile[] pictures;

public Collage(){}

public MultipartFile[] getCollage() {
    return pictures;
}

public void setCollage(MultipartFile[] pictures) {
    this.pictures = pictures;
}
}

我在控制台中得到：java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'collage' available as request attribute 和“/”页面上的文本：

Answer 1

一张图胜过1000字：

现在代码示例在实体内上传一个多部分文件数组：

<form action="#" th:action="@{/distribution/save}" class="form-horizontal"
                              role="form" method="post" th:object="${news}" enctype="multipart/form-data">

    <input type="hidden" name="id" value="id" th:field="*{id}"> <div class="form-group has-label"> <label for="inputTitle" th:text="#{news.title}">Título</label>
    <input type="text" class="form-control" id="inputTitle"  th:placeholder="#{news.title}" th:field="*{title}"></div>
    <input type="file" name = "multipartFilesDocument" value="multipartFilesDocument"  th:field="*{multipartFilesDocument}" multiple="multiple"/>
<button type="submit" class="btn btn-default"><span th:text="#{common.save}"></span></button>
</div>
</form>

控制器代码：

 @PostMapping("/save")
    public String saveMultiparthFile(Model model,@ModelAttribute NewsDTO eventDTO){

        eventDTO.getId();
        return getrDetail(model);
    }

实体代码：

public class NewsDTO {
private List<MultipartFile> multipartFilesDocument;
  public List<MultipartFile> getMultipartFilesDocument() {
        return multipartFilesDocument;
    }

    public void setMultipartFilesDocument(List<MultipartFile> multipartFilesDocument) {
        this.multipartFilesDocument = multipartFilesDocument;
    }
}

在这段代码中真的很重要enctype="multipart/form-data"和name = "multipartFilesDocument" value="multipartFilesDocument"在表单中

Answer 2

您可以应用此更改

1) 将@ModelAttibute 更改为@RequestParam

2) 使用 MultipartFile[] 作为参数并且只使用单个输入文件 html

//name of input html should be collage
@PostMapping("/sending")
public String redirect(@RequestParam("collage") MultipartFile[] files, RedirectAttributes redirectAttr) {

        Collections.shuffle(Arrays.asList(files));
        redirectAttr.addFlashAttribute("pictures",files);
        return "redirect:/collage"; 
}

和你的html页面

<form method="POST" th:action="@{/sending}" enctype="multipart/form-data" >
            <input type="file" name="collage" multiple="multiple"/>
            <input type="submit" value="upload" />
</form>