Java Http客户端通过POST上传文件

zzzyeukh  于 2023-02-02  发布在  Java
关注(0)|答案(6)|浏览(198)

我正在开发一个J2 ME客户机，它必须使用HTTP将文件上载到Servlet。
servlet部分使用Apache Commons FileUpload进行介绍

protected void doPost(HttpServletRequest request, HttpServletResponse response) 
{       

    ServletFileUpload upload = new ServletFileUpload();
    upload.setSizeMax(1000000);

    File fileItems = upload.parseRequest(request);

    // Process the uploaded items
    Iterator iter = fileItems.iterator();
    while (iter.hasNext()) {
        FileItem item = (FileItem) iter.next();
        File file = new File("\files\\"+item.getName());
        item.write(file);
    }
}

共享资源上传似乎只能上传多部分文件，但没有应用程序/octect流。
但是对于客户端，没有Multipart类，在本例中，也不可能使用任何HttpClient库。
另一种选择是使用HTTP Chunk上载，但是我还没有找到一个明确的例子来说明如何实现这一点，特别是在servlet端。
我的选择是：- 实现用于http块上载的servlet-实现用于http多部分创建的原始客户端
我不知道如何实现以上选项。有什么建议吗？

Java

6条答案

按热度按时间
w8biq8rn

w8biq8rn1#

通过HTTP发送文件应该使用multipart/form-data编码，servlet部分已经使用Apache Commons FileUpload来解析multipart/form-data请求，因此没有问题。
但是，您的客户端部分显然不太好，因为您似乎将文件内容原始写入请求主体。您需要确保您的客户端发送正确的multipart/form-data请求。具体如何操作取决于您用于发送HTTP请求的API。如果是普通的java.net.URLConnection，那么你可以在答案的底部找到一个具体的例子，如果你用Apache HttpComponents Client来做这个，那么这里有一个具体的例子，取自their documentation：

String url = "https://example.com";
File file = new File("/example.ext");

try (CloseableHttpClient client = HttpClients.createDefault()) {
    HttpPost post = new HttpPost(url);
    HttpEntity entity = MultipartEntityBuilder.create().addPart("file", new FileBody(file)).build();
    post.setEntity(entity);

    try (CloseableHttpResponse response = client.execute(post)) {
        // ...
    }
}

与具体问题无关，服务器端代码中存在一个错误：

File file = new File("\files\\"+item.getName());
item.write(file);

这可能会覆盖以前上传的同名文件，我建议使用File#createTempFile()。

String name = FilenameUtils.getBaseName(item.getName());
String ext = FilenameUtils.getExtension(item.getName());
File file = File.createTempFile(name + "_", "." + ext, new File("/files"));
item.write(file);
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bkhjykvo

bkhjykvo2#

以下代码可用于使用HTTP客户端4.x上传文件（以上答案使用MultipartEntity，该实体现已弃用）

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

String uploadFile(String url, File file) throws IOException
{
    HttpPost post = new HttpPost(url);
    post.setHeader("Accept", "application/json");
    _addAuthHeader(post);
    MultipartEntityBuilder builder = MultipartEntityBuilder.create();
    // fileParamName should be replaced with parameter name your REST API expect.
    builder.addPart("fileParamName", new FileBody(file));
    //builder.addPart("optionalParam", new StringBody("true", ContentType.create("text/plain", Consts.ASCII)));
    post.setEntity(builder.build());
    HttpResponse response = getClient().execute(post);;
    int httpStatus = response.getStatusLine().getStatusCode();
    String responseMsg = EntityUtils.toString(response.getEntity(), "UTF-8");

    // If the returned HTTP response code is not in 200 series then
    // throw the error
    if (httpStatus < 200 || httpStatus > 300) {
        throw new IOException("HTTP " + httpStatus + " - Error during upload of file: " + responseMsg);
    }

    return responseMsg;
}

您需要以下Apache库的最新版本：HTTP客户端、HTTP核心、HTTP MIME。
可以用HttpClients.createDefault()来替换getClient()。

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p4tfgftt

p4tfgftt3#

请查找在Java中使用HttpClient的文件上载功能的示例。

package test;

import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.FileEntity;
import org.apache.http.impl.client.DefaultHttpClient;

public class fileUpload {
private static void executeRequest(HttpPost httpPost) {
    try {
        HttpClient client = new DefaultHttpClient();
        HttpResponse response = client.execute(httpPost);
        System.out.println("Response Code:  " + response.getStatusLine().getStatusCode());
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IllegalStateException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public void executeMultiPartRequest(String urlString, File file) throws IOException {
    HttpPost postRequest = new HttpPost(urlString);
    postRequest = addHeader(postRequest, "Access Token");
    try {
        postRequest.setEntity(new FileEntity(file));
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    executeRequest(postRequest);
}

private static HttpPost addHeader(HttpPost httpPost, String accessToken) {
    httpPost.addHeader("Accept", "application/json;odata=verbose");
    httpPost.setHeader("Authorization", "Bearer " + accessToken);
    return httpPost;
}

public static void main(String args[]) throws IOException {
    fileUpload fileUpload = new fileUpload();
    File file = new File("C:\\users\\bgulati\\Desktop\\test.docx");
    fileUpload.executeMultiPartRequest(
            "Here Goes the URL", file);

}
}
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tyu7yeag

tyu7yeag4#

古代的问题和最好的答案依赖于不正确的陈述。
通过HTTP发送文件应该使用multipart/form-data编码。
以OCTET-STREAM格式发送文件效率更高。
JDK 11+客户端代码：

HttpRequest request = HttpRequest.newBuilder()
    .uri(new URI("http://YOUR-SERVER:PORT/ENDPOINT"))
    .timeout(Duration.of(60, SECONDS))
    .POST(HttpRequest.BodyPublishers.ofInputStream(is))
    .build();

HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
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hts6caw3

hts6caw35#

感谢所有的代码我已经狙击...这里是一些回来。

Gradle

compile "org.apache.httpcomponents:httpclient:4.4"  
compile "org.apache.httpcomponents:httpmime:4.4"


import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.util.Map;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.entity.mime.content.StringBody;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class HttpClientUtils {

    public static String post(String postUrl, Map<String, String> params,
            Map<String, String> files) throws ClientProtocolException,
            IOException {
        CloseableHttpResponse response = null;
        InputStream is = null;
        String results = null;
        CloseableHttpClient httpclient = HttpClients.createDefault();

        try {

            HttpPost httppost = new HttpPost(postUrl);

            MultipartEntityBuilder builder = MultipartEntityBuilder.create();

            if (params != null) {
                for (String key : params.keySet()) {
                    StringBody value = new StringBody(params.get(key),
                            ContentType.TEXT_PLAIN);
                    builder.addPart(key, value);
                }
            }

            if (files != null && files.size() > 0) {
                for (String key : files.keySet()) {
                    String value = files.get(key);
                    FileBody body = new FileBody(new File(value));
                    builder.addPart(key, body);
                }
            }

            HttpEntity reqEntity = builder.build();
            httppost.setEntity(reqEntity);

            response = httpclient.execute(httppost);
            // assertEquals(200, response.getStatusLine().getStatusCode());

            HttpEntity entity = response.getEntity();
            if (entity != null) {
                is = entity.getContent();
                StringWriter writer = new StringWriter();
                IOUtils.copy(is, writer, "UTF-8");
                results = writer.toString();
            }

        } finally {
            try {
                if (is != null) {
                    is.close();
                }
            } catch (Throwable t) {
                // No-op
            }

            try {
                if (response != null) {
                    response.close();
                }
            } catch (Throwable t) {
                // No-op
            }

            httpclient.close();
        }

        return results;
    }

    public static String get(String getStr) throws IOException,
            ClientProtocolException {
        CloseableHttpResponse response = null;
        InputStream is = null;
        String results = null;
        CloseableHttpClient httpclient = HttpClients.createDefault();

        try {
            HttpGet httpGet = new HttpGet(getStr);
            response = httpclient.execute(httpGet);

            assertEquals(200, response.getStatusLine().getStatusCode());

            HttpEntity entity = response.getEntity();
            if (entity != null) {
                is = entity.getContent();
                StringWriter writer = new StringWriter();
                IOUtils.copy(is, writer, "UTF-8");
                results = writer.toString();
            }

        } finally {

            try {
                if (is != null) {
                    is.close();
                }
            } catch (Throwable t) {
                // No-op
            }

            try {
                if (response != null) {
                    response.close();
                }
            } catch (Throwable t) {
                // No-op
            }

            httpclient.close();
        }

        return results;
    }

}
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yqhsw0fo

yqhsw0fo6#

无需输入血淋淋的细节，您的代码看起来很好。
现在你需要服务器端，我推荐你使用Jakarta FileUpload，所以你不需要实现任何东西，只需要部署和配置。

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