从CAMEL

Question

作为Using Camel to stream output from a POST to a URL的后续内容，我需要使用CAMEL从HTTP POST请求流式传输到文件，而无需等待整个下载发生。我尝试了uri：stream uri：file和uri：bean组件，并且都无法逐字节地传输到文件，而是等待整个有效负载完成。我相信我必须做一些错误的配置，因为最终下载文件时，它不会完成（从servlet的输出判断）直到输出结束。这是一个问题，因为有效载荷很大。我相信我应该在从servlet完成刷新后立即看到文件中的输出，但这不是正在发生的事情。

这是路线：

<route>
    <from uri="file:inputsDir?fileName=input.json&amp;noop=true" />
    <log loggingLevel="INFO" message="${body}"/>
    <to uri="http://localhost:8080/ServingSource/FileServlet" />
    <to uri="bean:dloadBean?method=downloadFile" />
    <to uri="stream:out" />
</route>

这是一个名为：

的servlet

import java.io.IOException;
import java.io.StringWriter;
import java.nio.charset.StandardCharsets;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

import org.apache.commons.lang3.RandomStringUtils;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Servlet implementation class FileServlet
 */
@WebServlet("/FileServlet")
public class FileServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public FileServlet() {
        super();
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        ServletOutputStream out = response.getOutputStream();
        ObjectMapper mapper = new ObjectMapper();
        Staff input = mapper.readValue(request.getInputStream(), Staff.class);
        String prolog = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>";
        out.write(prolog.getBytes());
        String wrapperStart = "<wrapper>";
        out.write(wrapperStart.getBytes());
        JAXBContext jaxbContext = null;
        Marshaller jaxbMarshaller = null;
        try {
            jaxbContext = JAXBContext.newInstance(User.class);
            jaxbMarshaller = jaxbContext.createMarshaller();
        } catch (JAXBException e1) {
            e1.printStackTrace();
        }

        try {
            Random random = new Random();
            for (int i = 0; i < 10000000; i++) {
                int id = random.nextInt(300000000);
                User user = new User(id, input.getName() + "." + input.getSalary() + RandomStringUtils.randomAlphanumeric(10));
                jaxbMarshaller.setProperty("jaxb.fragment", Boolean.TRUE);
                StringWriter writer = new StringWriter();
                jaxbMarshaller.marshal(user, writer);
                String marshalled = writer.toString() + "\n";
                out.write(marshalled.getBytes(StandardCharsets.UTF_8));
                System.out.print("," + i);
                if (i % 60 == 0) {
                    System.out.println("");
                }
                    out.flush();
            }
        } catch (JAXBException e) {
            e.printStackTrace();
        }

        String wrapperEnd = "</wrapper>";
        out.write(wrapperEnd.getBytes());
        out.close();
    }

}

这是下载器bean：

package download;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class DownloaderBean {
    private static final int BUFFER_SIZE = 4096;

    public String downloadFile(InputStream inputStream) throws IOException {
        String fileName = "findAll.xml";

        String saveDir = "saveDir";
        String saveFilePath = saveDir + File.separator + fileName;

        FileOutputStream outputStream = new FileOutputStream(saveFilePath);

        int bytesRead = -1;
        byte[] buffer = new byte[BUFFER_SIZE];
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }

        outputStream.close();
        inputStream.close();

        return "File downloaded";
    }

}

Answer 1

为什么不使用camel-netty下载文件？它专门用于流。 http://camel.apache.org/netty-http.html