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 涵盖 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，但不能上传 application/octect-stream。
但是对于客户端来说，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 块上传，但我还没有找到如何实现的明确示例，特别是在 servlet 方面。
我的选择是： - 实现一个用于http块上传的servlet - 实现用于 http 多部分创建的原始客户端
我不知道如何实现上述选项。 有什么建议吗？
通过 HTTP 发送文件应该使用
multipart/form-datamultipart/form-datarequest.getPart()但是，您的客户端部分不正确，因为您似乎将原始文件内容写入请求正文。您需要确保您的客户发送正确的
multipart/form-datajava.net.URLConnectionString 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，您的服务器端代码中有一个错误：
File file = new File("\files\\"+item.getName());
item.write(file);
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);
以下代码可用于使用 HTTP Client 4.x 上传文件（以上答案使用 MultipartEntity，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;
}
您将需要以下 Apache 库的最新版本：httpclient、httpcore、httpmime。
getClient()HttpClients.createDefault()请查找在 Java 中使用 HttpClient 的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);
}
}
古老的问题和最佳答案依赖于错误的陈述。
通过 HTTP 发送文件应该使用多部分/表单数据编码。
以 OCTET-STREAM 形式发送文件效率更高。
JDK11+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());
感谢我截取的所有代码...这是一些回来的代码。
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;
}
}
无需输入血腥细节，您的代码看起来就很好。
现在您需要服务器端。我建议您使用 Jakarta FileUpload，这样您就不必执行任何操作。只需部署和配置即可。