session [：previous_url]和request.env [“ HTTP_REFERER”]有什么区别？
我收到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;
}
}
而
library(dplyr)
df %>%
group_by(location) %>%
filter(row_number() %in% 1:5)
request.env给了我立即被调用的最后一个，而session给了倒数第二个URL。有人可以帮忙吗？我是这个领域的新手。