如何使用JDK11java.net.http.HttpClient上传文件？

Question

最近遇到了JDK自带的java.net.http.HttpClient的一些问题 11.不知道怎么用文件上传。在 java.net.http.BodyPublishers 中找到了 ofInputStream()。我不知道我是否使用这种方法上传文件。下面是我写的例子。

    public HttpResponse<String> post(String url, Supplier<? extends InputStream> streamSupplier, String... headers) throws IOException, InterruptedException {
        HttpRequest.Builder builder = HttpRequest.newBuilder()
                .uri(URI.create(url))
                .headers(headers)
                .POST(null == streamSupplier ?
                        HttpRequest.BodyPublishers.noBody() : HttpRequest.BodyPublishers.ofInputStream(streamSupplier));
        HttpRequest request = builder.build();
        log.debug("Execute HttpClient Method:『{}』, Url:『{}』", request.method(), request.uri().toString());
        return client.send(request, HttpResponse.BodyHandlers.ofString());
    }

Answer 1

HttpRequest 类型提供工厂方法来创建请求发布者以处理正文类型，例如文件：

HttpRequest.BodyPublishers::ofFile(Path)

您可以更新您的方法：

public HttpResponse<String> post(String url, Path file, String... headers) throws IOException, InterruptedException {
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(url))
            .headers(headers)
            .POST(null == file ? HttpRequest.BodyPublishers.noBody() : 
                HttpRequest.BodyPublishers.ofFile(file))
            .build();

        log.debug("Execute HttpClient Method:『{}』, Url:『{}』", request.method(), 
            request.uri().toString());
        return client.send(request, HttpResponse.BodyHandlers.ofString());
}

Answer 2

java.net.http.HttpClient 处理通过 BodyPublisher 提供的字节作为原始 body 数据，没有任何解释。因此，无论您使用 HttpRequest.BodyPublishers::ofFile(Path) 还是 HttpRequest.BodyPublishers::ofByteArray(byte[]) 在语义上都是无关紧要的：变化只是如何获取将要传输的字节。在文件上传的情况下 - 您的服务器可能希望请求 body 以特定方式格式化。它还可能期望一些特定的 headers 与请求一起传输（例如 Content-Type 等）。 HttpClient 不会神奇地为您做到这一点。这是您需要在调用者级别实现的东西。

Answer 3

您可以通过以下方式使用方法：

public void uploadLocalFileToRemote(String notEncodedUrlStr, String remoteFilename, String localSourceDir, String localFilename) {
    
    Path sourcePath = Path.of(localSourceDir, localFilename);
    if(!sourcePath.toFile().canRead())
    {
        System.err.println("please check the local file existance/readability: " + sourcePath.toAbsolutePath());
        return;
    }
    
    FileInputStream ins = null;
    try {
        ins = new FileInputStream(sourcePath.toFile());//FileNotFoundException extends IOException
        BufferedInputStream buf_ins = new BufferedInputStream(ins);
        Supplier<? extends InputStream> streamSupplier = new Supplier<BufferedInputStream>() {
            @Override
            public BufferedInputStream get() {
                return buf_ins;
            }
        };
        
        //HttpResponse<String> response = post(notEncodedUrlStr, streamSupplier, 
        HttpResponse<String> response = post(notEncodedUrlStr, () -> buf_ins, 
                "User-Agent", "Java 11 HttpClient Bot", "Content-type", "application/octet-stream",
                "accept", "*/*", "fileName", remoteFilename);
        
        // print response:
        System.out.println(response.version().name() + " " + response.statusCode());
        // print response headers
        HttpHeaders headers = response.headers();
        headers.map().forEach((k, v) -> System.out.println(k + ":" + v));
        
        // print response body
        String body = response.body();
        System.out.println(body);
    } catch (IOException | InterruptedException e) {
        e.printStackTrace();
    }
}

另一个考虑因素是您的服务器端是如何实现的。这里假设服务器端将使用 http 1.1“分块”。并为 remoteFilename 配置目录。

如何使用JDK11java.net.http.HttpClient上传文件？

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