Integrating Spring Boot with Minio for Direct File Upload Using Presigned Credentials

Spring Boot can be integrated with Minio to provide two file‑upload approaches: uploading through the backend (which allows centralized authentication, permission control, and additional processing) and uploading directly to Minio using a presigned credential generated by the backend.

Environment Preparation

A running Minio instance is required, e.g., http://mylocalhost:9001 .

Spring Boot Integration with Minio

1. Add Minio dependency

# pom.xml
<dependency>
    <groupId>io.minio</groupId>
    <artifactId>minio</artifactId>
    <version>7.1.0</version>
</dependency>

2. Configuration (application.yml)

# application.yml
minio:
  endpoint: http://mylocalhost:9001
  accessKey: minio
  secretKey: minio123
  bucket: demo

3. Property class

@Component
@ConfigurationProperties(prefix = "minio")
public class MinioProperties {
    private String endpoint;
    private String accessKey;
    private String secretKey;
    private String bucket;
    // getters and setters ...
}

4. Minio configuration bean

@Configuration
public class MinioConfig {
    @Bean
    public MinioClient minioClient(MinioProperties properties) {
        try {
            MinioClient.Builder builder = MinioClient.builder();
            builder.endpoint(properties.getEndpoint());
            if (StringUtils.hasLength(properties.getAccessKey()) && StringUtils.hasLength(properties.getSecretKey())) {
                builder.credentials(properties.getAccessKey(), properties.getSecretKey());
            }
            return builder.build();
        } catch (Exception e) {
            return null;
        }
    }
}

Presigned Upload Credential Endpoint

A POST endpoint /presign returns a map containing the fields required for a direct Minio upload.

@RequestMapping(value = "/presign", method = {RequestMethod.POST})
public Map
presign(@RequestBody PresignParam presignParam) {
    if (StringUtils.isEmpty(presignParam.getBucket())) {
        presignParam.setBucket("demo");
    }
    if (StringUtils.isEmpty(presignParam.getFilename())) {
        presignParam.setFilename(UUID.randomUUID().toString());
    }
    ZonedDateTime expirationDate = ZonedDateTime.now().plusMinutes(10);
    PostPolicy policy = new PostPolicy(presignParam.getBucket(), presignParam.getFilename(), expirationDate);
    try {
        Map
map = minioClient.presignedPostPolicy(policy);
        return map;
    } catch (MinioException | InvalidKeyException | IOException | NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return null;
}

The response includes fields such as bucket , x-amz-date , x-amz-signature , key , x-amz-algorithm , x-amz-credential , and policy .

Request Parameter Class

public class PresignParam {
    private String bucket;   // bucket name
    private String filename; // object name
    // getters and setters ...
}

Front‑End Upload Using the Credential

After obtaining the credential, the front‑end builds a FormData object and posts it directly to Minio.

uploadFile(file, policy) {
    console.log("准备上传文件：");
    console.log("file：" + file);
    console.log("policy：" + policy);
    var formData = new FormData();
    formData.append('file', file);
    formData.append('key', policy['key']);
    formData.append('x-amz-algorithm', policy['x-amz-algorithm']);
    formData.append('x-amz-credential', policy['x-amz-credential']);
    formData.append('x-amz-signature', policy['x-amz-signature']);
    formData.append('x-amz-date', policy['x-amz-date']);
    formData.append('policy', policy['policy']);
    return new Promise((resolve, reject) => {
        $.ajax({
            method: 'POST',
            url: 'http://mylocalhost:9001/' + policy['bucket'],
            data: formData,
            dataType: 'json',
            contentType: false,
            processData: false,
            xhr: function () {
                var xhr = $.ajaxSettings.xhr();
                if (xhr.upload) {
                    xhr.upload.addEventListener('progress', function (e) {
                        var percentage = parseInt(e.loaded / e.total * 100);
                        vm.uploadResult = percentage + "%" + "：" + policy['key'];
                    }, false);
                }
                return xhr;
            },
            success: function (result) {
                vm.uploadResult = '文件上传成功：' + policy['key'];
                resolve(result);
            },
            error: function (e) {
                reject();
            }
        });
    });
}

Chunked, Instant and Resumable Uploads

For large files, the article demonstrates splitting a file into 5 MB chunks, calculating an MD5 for each chunk (using SparkMD5), uploading each chunk with its own presigned credential, and finally merging the chunks on the server.

Chunked Upload Example (Vue.js)

sliceEvent() {
    var file = this.file;
    var chunkSize = 5 * 1024 * 1024; // 5 MB
    var totalChunk = Math.ceil(file.size / chunkSize);
    var chunks = [];
    for (var i = 0; i < totalChunk; i++) {
        var start = i * chunkSize;
        var end = Math.min(file.size, start + chunkSize);
        var blob = file.slice(start, end);
        chunks.push(blob);
    }
    this.sliceUploadResult = Array(totalChunk).fill(0);
    var index = 0;
    while (index < totalChunk) {
        var params = { bucket: "slice", filename: index + "寂寞的季节.mp4" };
        var policyPromise = this.requestPolicy(params);
        ((idx) => {
            var fileChunk = chunks[idx];
            policyPromise.then((result) => {
                var filename = result['key'];
                vm.uploadFile(fileChunk, result).then(() => {
                    vm.sliceUploadResult[idx] = '分片文件上传成功：' + filename;
                });
            });
        })(index);
        index++;
    }
}

Merge Chunks

@GetMapping("/compose")
public void merge() {
    List
sources = new ArrayList<>();
    sources.add(ComposeSource.builder().bucket("slice").object("0寂寞的季节.mp4").build());
    sources.add(ComposeSource.builder().bucket("slice").object("1寂寞的季节.mp4").build());
    sources.add(ComposeSource.builder().bucket("slice").object("2寂寞的季节.mp4").build());
    ComposeObjectArgs args = ComposeObjectArgs.builder()
        .bucket("demo")
        .object("寂寞的季节.mp4")
        .sources(sources)
        .build();
    try {
        minioClient.composeObject(args);
    } catch (MinioException | InvalidKeyException | IOException | NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
}

Complete Front‑End Example (HTML + Vue.js + jQuery)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Minio Test</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.7.14/vue.js"></script>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.4/jquery.js"></script>
    <script src="https://cdn.bootcdn.net/ajax/libs/spark-md5/3.0.2/spark-md5.min.js"></script>
</head>
<body>
<div id="app">
    <h1>{{title}}</h1>
    <form @submit.prevent="getPolicyForm">
        <label>桶名<input type="text" v-model="policyParams.bucket"></label><br>
        <label>文件名<input type="text" v-model="policyParams.filename"></label><br>
        <button type="submit">获取上传凭证</button>
    </form>
    <form @submit.prevent="uploadFileForm" v-show="policy != null">
        <label>文件<input type="file" @change="fileChange"></label><br>
        <button type="submit" v-show="file != null">上传文件</button>
    </form>
    <div v-show="file != null">
        <button @click="sliceEvent">测试文件分片上传</button>
        <button @click="sliceComposeEvent">分片文件合并</button>
    </div>
    <p>{{uploadResult}}</p>
    <ul>
        <li v-for="(item, index) in sliceUploadResult" :key="index">{{item}}</li>
    </ul>
</div>
<script>
var vm = new Vue({
    el: "#app",
    data() {
        return {
            title: "Minio测试",
            policyParams: { bucket: null, filename: null },
            policy: null,
            file: null,
            uploadResult: null,
            sliceUploadResult: null,
            sliceCount: 0
        };
    },
    methods: {
        getPolicyForm() {
            this.policyParams.bucket = "demo";
            this.policyParams.filename = "寂寞的季节.mp4";
            this.requestPolicy(this.policyParams);
        },
        requestPolicy(params) {
            return new Promise((resolve, reject) => {
                $.ajax({
                    type: "POST",
                    url: "http://localhost:8888/presign",
                    contentType: "application/json",
                    data: JSON.stringify(params),
                    success: (result) => { vm.policy = result; resolve(result); },
                    error: () => reject()
                });
            });
        },
        fileChange(event) { this.file = event.target.files[0]; },
        uploadFileForm() { this.uploadFile(this.file, this.policy); },
        // uploadFile implementation as shown earlier …
        sliceEvent() { /* chunked upload implementation as shown earlier */ },
        sliceComposeEvent() { /* merge request implementation */ }
    }
});
</script>
</body>
</html>

The article concludes with a reminder that the content is intended for technical discussion and not for advertising.