Question

我正在开发一个J2ME客户端，它必须使用HTTP将文件上传到Servlet。

使用Apache Commons FileUpload

覆盖servlet部分

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);
    }
}

Commons Upload似乎只能上传多部分文件，但没有应用程序/ octect-stream。

但是对于客户端，没有Multipart类，在这种情况下，也不能使用任何HttpClient库。

其他选项可能是使用HTTP Chunk上传，但我还没有找到一个明确的例子，说明如何实现它，特别是在servlet端。

我的选择是： - 为http块上传实现servlet - 为http多部分创建实现原始客户端

我不知道如何实现上述选项。有什么建议吗？

Answer 1

通过HTTP发送文件应该使用multipart/form-data编码进行。您的servlet部分很好，因为它已使用Apache Commons FileUpload来解析multipart/form-data请求。

然而，您的客户端部分显然不合适，因为您似乎将文件内容原始写入请求正文。您需要确保客户端发送正确的multipart/form-data请求。具体操作方法取决于您用于发送HTTP请求的API。如果它是普通的java.net.URLConnection，那么你可以在this answer底部附近找到一个具体的例子。如果你正在使用Apache HttpComponents Client，那么这是一个具体的例子：

HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(url);

MultipartEntity entity = new MultipartEntity();
entity.addPart("file", new FileBody(file));
post.setEntity(entity);

HttpResponse response = client.execute(post);
// ...

对具体问题

无关，服务器端代码中存在错误：

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

这可能会覆盖任何以前上传的同名文件。我建议改为使用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);

Answer 2

以下代码可用于使用HTTP Client 4.x上传文件（以上答案使用现已弃用的MultipartEntity）

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;
}

您将需要以下Apache库的最新版本：httpclient，httpcore，httpmime。

getClient()可以替换为HttpClients.createDefault()。

Answer 3

感谢我已经狙击过的所有代码......这里有一些回复。

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;
    }

}

Answer 4

请找到使用Java中的HttpClient进行文件上传功能的示例工作示例。

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);

}
}

Answer 5

如果没有输入血腥的详细信息，您的代码就可以了。

现在你需要服务器端。我建议你使用雅加达FileUpload，所以你不必实现任何东西。只需部署和配置。

Java Http Client通过POST上传文件

5 个答案: