将文件从Java客户端上载到HTTP服务器
我想上传一些文件到HTTP服务器。基本上,我需要的是向服务器发送一个POST请求,其中包含一些参数和文件。我看过一些上传文件的例子,但没有找到如何传递额外的参数将文件从Java客户端上载到HTTP服务器,java,file-upload,urlconnection,Java,File Upload,Urlconnection,我想上传一些文件到HTTP服务器。基本上,我需要的是向服务器发送一个POST请求,其中包含一些参数和文件。我看过一些上传文件的例子,但没有找到如何传递额外的参数 最简单的免费解决方案是什么?有没有人有我可以学习的文件上传示例?我已经在谷歌上搜索了几个小时,但(也许这只是其中的一天)找不到我真正需要的东西。最好的解决方案是不涉及任何第三方类或库的解决方案。这可能取决于您的框架。(对于每一个问题都可能存在一个更简单的解决方案) 但要回答您的问题:对于此功能,有很多。查看如何使用apache comm
最简单的免费解决方案是什么?有没有人有我可以学习的文件上传示例?我已经在谷歌上搜索了几个小时,但(也许这只是其中的一天)找不到我真正需要的东西。最好的解决方案是不涉及任何第三方类或库的解决方案。这可能取决于您的框架。(对于每一个问题都可能存在一个更简单的解决方案) 但要回答您的问题:对于此功能,有很多。查看如何使用apache commons文件上载。通常用于触发HTTP请求。您通常也会对混合的帖子内容(二进制和字符数据)使用编码。单击该链接,它包含信息和如何组成
多部分/表单数据的示例。有关规范的详细信息,请参阅
以下是一个启动示例:
String url = "http://example.com/upload";
String charset = "UTF-8";
String param = "value";
File textFile = new File("/path/to/file.txt");
File binaryFile = new File("/path/to/file.bin");
String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.
String CRLF = "\r\n"; // Line separator required by multipart/form-data.
URLConnection connection = new URL(url).openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
try (
OutputStream output = connection.getOutputStream();
PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, charset), true);
) {
// Send normal param.
writer.append("--" + boundary).append(CRLF);
writer.append("Content-Disposition: form-data; name=\"param\"").append(CRLF);
writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF);
writer.append(CRLF).append(param).append(CRLF).flush();
// Send text file.
writer.append("--" + boundary).append(CRLF);
writer.append("Content-Disposition: form-data; name=\"textFile\"; filename=\"" + textFile.getName() + "\"").append(CRLF);
writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF); // Text file itself must be saved in this charset!
writer.append(CRLF).flush();
Files.copy(textFile.toPath(), output);
output.flush(); // Important before continuing with writer!
writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.
// Send binary file.
writer.append("--" + boundary).append(CRLF);
writer.append("Content-Disposition: form-data; name=\"binaryFile\"; filename=\"" + binaryFile.getName() + "\"").append(CRLF);
writer.append("Content-Type: " + URLConnection.guessContentTypeFromName(binaryFile.getName())).append(CRLF);
writer.append("Content-Transfer-Encoding: binary").append(CRLF);
writer.append(CRLF).flush();
Files.copy(binaryFile.toPath(), output);
output.flush(); // Important before continuing with writer!
writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.
// End of multipart/form-data.
writer.append("--" + boundary + "--").append(CRLF).flush();
}
// Request is lazily fired whenever you need to obtain information about response.
int responseCode = ((HttpURLConnection) connection).getResponseCode();
System.out.println(responseCode); // Should be 200
当您使用第三方库(如ApacheCommons)时,此代码就不那么冗长了
有些人错误地认为,Apache Commons只对服务器端感兴趣。您不能在客户端使用,也不需要它
另见
以下是您使用的方法(此解决方案适用于不介意使用第三方库的用户):
并在html中使用
和
,单击链接获取示例文件上载clint java with apache HttpComponents
public static String simSearchByImgURL(int catid ,String imgurl) throws IOException{
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String result =null;
try {
HttpPost httppost = new HttpPost("http://api0.visualsearchapi.com:8084/vsearchtech/api/v1.0/apisim_search");
StringBody catidBody = new StringBody(catid+"" , ContentType.TEXT_PLAIN);
StringBody keyBody = new StringBody(APPKEY , ContentType.TEXT_PLAIN);
StringBody langBody = new StringBody(LANG , ContentType.TEXT_PLAIN);
StringBody fmtBody = new StringBody(FMT , ContentType.TEXT_PLAIN);
StringBody imgurlBody = new StringBody(imgurl , ContentType.TEXT_PLAIN);
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.addPart("apikey", keyBody).addPart("catid", catidBody)
.addPart("lang", langBody)
.addPart("fmt", fmtBody)
.addPart("imgurl", imgurlBody);
HttpEntity reqEntity = builder.build();
httppost.setEntity(reqEntity);
response = httpClient.execute(httppost);
HttpEntity resEntity = response.getEntity();
if (resEntity != null) {
// result = ConvertStreamToString(resEntity.getContent(), "UTF-8");
String charset = "UTF-8";
String content=EntityUtils.toString(response.getEntity(), charset);
System.out.println(content);
}
EntityUtils.consume(resEntity);
}catch(Exception e){
e.printStackTrace();
}finally {
response.close();
httpClient.close();
}
return result;
}
和图书馆downalod链接
使用4.5.3.zip在我的代码中运行良好
还有我的工作代码
import java.io.File;
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
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;
import org.apache.http.util.EntityUtils;
public class ClientMultipartFormPost {
public static void main(String[] args) throws Exception {
CloseableHttpClient httpclient = HttpClients.createDefault();
try {
HttpPost httppost = new HttpPost("http://localhost:8080/MyWebSite1/UploadDownloadFileServlet");
FileBody bin = new FileBody(new File("E:\\meter.jpg"));
StringBody comment = new StringBody("A binary file of some kind", ContentType.TEXT_PLAIN);
HttpEntity reqEntity = MultipartEntityBuilder.create()
.addPart("bin", bin)
.addPart("comment", comment)
.build();
httppost.setEntity(reqEntity);
System.out.println("executing request " + httppost.getRequestLine());
CloseableHttpResponse response = httpclient.execute(httppost);
try {
System.out.println("----------------------------------------");
System.out.println(response.getStatusLine());
HttpEntity resEntity = response.getEntity();
if (resEntity != null) {
System.out.println("Response content length: " + resEntity.getContentLength());
}
EntityUtils.consume(resEntity);
} finally {
response.close();
}
} finally {
httpclient.close();
}
}
}
以下是如何使用Java 11的Java.net.http包实现这一点:
var fileA = new File("a.pdf");
var fileB = new File("b.pdf");
var mimeMultipartData = MimeMultipartData.newBuilder()
.withCharset(StandardCharsets.UTF_8)
.addFile("file1", fileA.toPath(), Files.probeContentType(fileA.toPath()))
.addFile("file2", fileB.toPath(), Files.probeContentType(fileB.toPath()))
.build();
var request = HttpRequest.newBuilder()
.header("Content-Type", mimeMultipartData.getContentType())
.POST(mimeMultipartData.getBodyPublisher())
.uri(URI.create("http://somehost/upload"))
.build();
var httpClient = HttpClient.newBuilder().build();
var response = httpClient.send(request, BodyHandlers.ofString());
使用以下MimeMultipartData:
public class MimeMultipartData {
public static class Builder {
private String boundary;
private Charset charset = StandardCharsets.UTF_8;
private List<MimedFile> files = new ArrayList<MimedFile>();
private Map<String, String> texts = new LinkedHashMap<>();
private Builder() {
this.boundary = new BigInteger(128, new Random()).toString();
}
public Builder withCharset(Charset charset) {
this.charset = charset;
return this;
}
public Builder withBoundary(String boundary) {
this.boundary = boundary;
return this;
}
public Builder addFile(String name, Path path, String mimeType) {
this.files.add(new MimedFile(name, path, mimeType));
return this;
}
public Builder addText(String name, String text) {
texts.put(name, text);
return this;
}
public MimeMultipartData build() throws IOException {
MimeMultipartData mimeMultipartData = new MimeMultipartData();
mimeMultipartData.boundary = boundary;
var newline = "\r\n".getBytes(charset);
var byteArrayOutputStream = new ByteArrayOutputStream();
for (var f : files) {
byteArrayOutputStream.write(("--" + boundary).getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(("Content-Disposition: form-data; name=\"" + f.name + "\"; filename=\"" + f.path.getFileName() + "\"").getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(("Content-Type: " + f.mimeType).getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(Files.readAllBytes(f.path));
byteArrayOutputStream.write(newline);
}
for (var entry: texts.entrySet()) {
byteArrayOutputStream.write(("--" + boundary).getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(("Content-Disposition: form-data; name=\"" + entry.getKey() + "\"").getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(entry.getValue().getBytes(charset));
byteArrayOutputStream.write(newline);
}
byteArrayOutputStream.write(("--" + boundary + "--").getBytes(charset));
mimeMultipartData.bodyPublisher = BodyPublishers.ofByteArray(byteArrayOutputStream.toByteArray());
return mimeMultipartData;
}
public class MimedFile {
public final String name;
public final Path path;
public final String mimeType;
public MimedFile(String name, Path path, String mimeType) {
this.name = name;
this.path = path;
this.mimeType = mimeType;
}
}
}
private String boundary;
private BodyPublisher bodyPublisher;
private MimeMultipartData() {
}
public static Builder newBuilder() {
return new Builder();
}
public BodyPublisher getBodyPublisher() throws IOException {
return bodyPublisher;
}
public String getContentType() {
return "multipart/form-data; boundary=" + boundary;
}
}
公共类MimeMultipartData{
公共静态类生成器{
私有字符串边界;
私有字符集Charset=StandardCharsets.UTF_8;
私有列表文件=新的ArrayList();
私有映射文本=新LinkedHashMap();
私人建筑商(){
this.boundary=new BigInteger(128,new Random()).toString();
}
带有字符集的公共生成器(字符集字符集){
this.charset=charset;
归还这个;
}
带边界的公共生成器(字符串边界){
this.boundary=边界;
归还这个;
}
公共生成器addFile(字符串名称、路径、字符串mimeType){
添加(新的mimefile(名称、路径、mimeType));
归还这个;
}
公共生成器addText(字符串名称、字符串文本){
文本。输入(名称、文本);
归还这个;
}
public MimeMultipartData build()引发IOException{
MimeMultipartData MimeMultipartData=新的MimeMultipartData();
mimeMultipartData.boundary=边界;
var newline=“\r\n”.getBytes(字符集);
var byteArrayOutputStream=新的byteArrayOutputStream();
for(var f:files){
byteArrayOutputStream.write(“-”+boundary.getBytes(charset));
byteArrayOutputStream.write(换行符);
byteArrayOutputStream.write((“内容处置:表单数据;名称=\”“+f.name+”\“文件名=\”“+f.path.getFileName()+”\).getBytes(字符集));
byteArrayOutputStream.write(换行符);
byteArrayOutputStream.write((“内容类型:+f.mimeType).getBytes(字符集));
byteArrayOutputStream.write(换行符);
byteArrayOutputStream.write(换行符);
byteArrayOutputStream.write(Files.readAllBytes(f.path));
byteArrayOutputStream.write(换行符);
}
for(变量条目:text.entrySet()){
byteArrayOutputStream.write(“-”+boundary.getBytes(charset));
byteArrayOutputStream.write(换行符);
byteArrayOutputStream.write((“内容处置:表单数据;名称=\”“+entry.getKey()+“\”).getBytes(字符集));
byteArrayOutputStream.write(换行符);
byteArrayOutputStream.write(换行符);
byteArrayOutputStream.write(entry.getValue().getBytes(charset));
byteArrayOutputStream.write(换行符);
}
byteArrayOutputStream.write((“-”+boundary+“-”).getBytes(字符集));
mimeMultipartData.bodyPublisher=bodyPublisher.of字节数组(byteArrayOutputStream.toByteArray());
返回mimultipartdata;
}
公共类模拟文件{
公共最终字符串名;
公共最终路径;
公共最终字符串mimeType;
公共mimefile(字符串名称、路径、字符串mimeType){
this.name=名称;
this.path=path;
this.mimeType=mimeType;
}
}
}
私有字符串边界;
私人实体出版商;
私有MimeMultipartData(){
}
公共静态生成器newBuilder(){
返回新的生成器();
}
public BodyPublisher getBodyPublisher()引发IOException{
返回bodyPublisher;
}
公共字符串getContentType(){
返回“多部分/表单数据;边界=”+边界;
}
}
谢谢,我试试看。问题是关于这一行:writer.println(paramToSend);我不应该使用编码器来编码这个值吗?还是按原样发送?不,它是多部分/表单数据
,而不是应用程序/x-www-form-urlencoded
。但是,您希望指定使用的字符集。我已经相应地更新了答案。我刚刚尝试过。有点问题:(另一端的PHP脚本将整个内容视为post参数
var fileA = new File("a.pdf");
var fileB = new File("b.pdf");
var mimeMultipartData = MimeMultipartData.newBuilder()
.withCharset(StandardCharsets.UTF_8)
.addFile("file1", fileA.toPath(), Files.probeContentType(fileA.toPath()))
.addFile("file2", fileB.toPath(), Files.probeContentType(fileB.toPath()))
.build();
var request = HttpRequest.newBuilder()
.header("Content-Type", mimeMultipartData.getContentType())
.POST(mimeMultipartData.getBodyPublisher())
.uri(URI.create("http://somehost/upload"))
.build();
var httpClient = HttpClient.newBuilder().build();
var response = httpClient.send(request, BodyHandlers.ofString());
public class MimeMultipartData {
public static class Builder {
private String boundary;
private Charset charset = StandardCharsets.UTF_8;
private List<MimedFile> files = new ArrayList<MimedFile>();
private Map<String, String> texts = new LinkedHashMap<>();
private Builder() {
this.boundary = new BigInteger(128, new Random()).toString();
}
public Builder withCharset(Charset charset) {
this.charset = charset;
return this;
}
public Builder withBoundary(String boundary) {
this.boundary = boundary;
return this;
}
public Builder addFile(String name, Path path, String mimeType) {
this.files.add(new MimedFile(name, path, mimeType));
return this;
}
public Builder addText(String name, String text) {
texts.put(name, text);
return this;
}
public MimeMultipartData build() throws IOException {
MimeMultipartData mimeMultipartData = new MimeMultipartData();
mimeMultipartData.boundary = boundary;
var newline = "\r\n".getBytes(charset);
var byteArrayOutputStream = new ByteArrayOutputStream();
for (var f : files) {
byteArrayOutputStream.write(("--" + boundary).getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(("Content-Disposition: form-data; name=\"" + f.name + "\"; filename=\"" + f.path.getFileName() + "\"").getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(("Content-Type: " + f.mimeType).getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(Files.readAllBytes(f.path));
byteArrayOutputStream.write(newline);
}
for (var entry: texts.entrySet()) {
byteArrayOutputStream.write(("--" + boundary).getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(("Content-Disposition: form-data; name=\"" + entry.getKey() + "\"").getBytes(charset));
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(newline);
byteArrayOutputStream.write(entry.getValue().getBytes(charset));
byteArrayOutputStream.write(newline);
}
byteArrayOutputStream.write(("--" + boundary + "--").getBytes(charset));
mimeMultipartData.bodyPublisher = BodyPublishers.ofByteArray(byteArrayOutputStream.toByteArray());
return mimeMultipartData;
}
public class MimedFile {
public final String name;
public final Path path;
public final String mimeType;
public MimedFile(String name, Path path, String mimeType) {
this.name = name;
this.path = path;
this.mimeType = mimeType;
}
}
}
private String boundary;
private BodyPublisher bodyPublisher;
private MimeMultipartData() {
}
public static Builder newBuilder() {
return new Builder();
}
public BodyPublisher getBodyPublisher() throws IOException {
return bodyPublisher;
}
public String getContentType() {
return "multipart/form-data; boundary=" + boundary;
}
}