本文主要介绍使用Java Spring Boot上传文件(multipart和json)到服务器端,通过的DTO对象接收上传数据对象的方法,以及使用的示例代码。

一、第一种实现

1、接收上传form数据对象类(DTO)

public class FormWrapper {
    private MultipartFile image;
    private String title;
    private String description;
}

2、form表单html代码

<form method="POST" enctype="multipart/form-data" id="fileUploadForm" action="link">
<input type="text" name="title"/><br/>
<input type="text" name="description"/><br/><br/>
<input type="file" name="image"/><br/><br/>
<input type="submit" value="Submit" id="btnSubmit"/>
</form>

3、接收上传文件数据方法

@PostMapping("/api/upload/multi/model")
    public ResponseEntity<?> multiUploadFileModel(@ModelAttribute FormWrapper model) {
        try {
            saveUploadedFile(model.getImage());
            formRepo.save(mode.getTitle(),model.getDescription()); //Save as you want as per requirement 
        } catch (IOException e) {
            return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
        }
        return new ResponseEntity("Successfully uploaded!", HttpStatus.OK);
    }

4、保存上传文件

private void saveUploadedFile(MultipartFile file) throws IOException {
if (!file.isEmpty()) {
byte[] bytes = file.getBytes();
Path path = Paths.get(UPLOADED_FOLDER + file.getOriginalFilename());
Files.write(path, bytes);
}
}

二、第二种实现

1、后台controller代码

@RestController
public class FileUploadController {
@RequestMapping(value = "/upload", method = RequestMethod.POST, consumes = { "multipart/form-data" })
public void upload(@RequestPart("user") @Valid User user,
@RequestPart("file") @Valid @NotNull @NotBlank MultipartFile file) {
System.out.println(user);
System.out.println("Uploaded File: ");
System.out.println("Name : " + file.getName());
System.out.println("Type : " + file.getContentType());
System.out.println("Name : " + file.getOriginalFilename());
System.out.println("Size : " + file.getSize());
}
static class User {
@NotNull
String firstName;
@NotNull
String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Override
public String toString() {
return "User [firstName=" + firstName + ", lastName=" + lastName + "]";
}
}
}

2、html和js代码

<html>    
<head>
<script>
function onSubmit() {
var formData = new FormData();
formData.append("file", document.forms["userForm"].file.files[0]);
formData.append('user', new Blob([JSON.stringify({
"firstName": document.getElementById("firstName").value,
"lastName": document.getElementById("lastName").value
})], {
type: "application/json"
}));
var boundary = Math.random().toString().substr(2);
fetch('/upload', {
method: 'post',
body: formData
}).then(function (response) {
if (response.status !== 200) {
alert("There was an error!");
} else {
alert("Request successful");
}
}).catch(function (err) {
alert("There was an error!");
});;
}
</script>
</head>
<body>
<form name="userForm">
<label> File : </label>
<br/>
<input name="file" type="file">
<br/>
<label> First Name : </label>
<br/>
<input id="firstName" name="firstName" />
<br/>
<label> Last Name : </label>
<br/>
<input id="lastName" name="lastName" />
<br/>
<input type="button" value="Submit" id="submit" onclick="onSubmit(); return false;" />
</form>
</body>
</html>