将文件从REST Web服务发送到客户端的正确方法是什么？ [英] what's the correct way to send a file from REST web service to client?

问题描述

我刚刚开始开发REST服务，但我遇到了一个困难的情况：从我的REST服务向我的客户端发送文件。到目前为止，我已经掌握了如何发送简单数据类型（字符串，整数等），但发送文件是另一回事，因为有太多的文件格式，我不知道我应该在哪里开始。我的REST服务是基于Java的，我使用的是Jersey，我使用JSON格式发送所有数据。

I've just started to develop REST services, but I've come across a difficult situation: sending files from my REST service to my client. So far I've gotten the hang of how to send simple data types (strings, integers, etc) but sending a file is a different matter since there are so many file formats that I don't know where I should even begin. My REST service is made on Java and I'm using Jersey, I'm sending all the data using the JSON format.

我读过有关base64编码的信息，有些是人们说这是一种很好的技术，其他人说这不是因为文件大小问题。什么是正确的方法？这就是我项目中的简单资源类的样子：

I've read about base64 encoding, some people say it's a good technique, others say it isn't because of file size issues. What is the correct way? This is how a simple resource class in my project is looking:

import java.sql.SQLException;
import java.util.List;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.UriInfo;

import com.mx.ipn.escom.testerRest.dao.TemaDao;
import com.mx.ipn.escom.testerRest.modelo.Tema;

@Path("/temas")
public class TemaResource {

    @GET
    @Produces({MediaType.APPLICATION_JSON})
    public List<Tema> getTemas() throws SQLException{

        TemaDao temaDao = new TemaDao();        
        List<Tema> temas=temaDao.getTemas();
        temaDao.terminarSesion();

        return temas;
    }
}

我猜测发送文件的代码会类似于：

I'm guessing the code for sending a file would be something like:

import java.sql.SQLException;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;

@Path("/resourceFiles")
public class FileResource {

    @GET
    @Produces({application/x-octet-stream})
    public File getFiles() throws SQLException{ //I'm not really sure what kind of data type I should return

        // Code for encoding the file or just send it in a data stream, I really don't know what should be done here

        return file;
    }
}

我应该使用哪种注释？我见过一些人推荐 @GET 使用 @Produces（{application / x-octet-stream}），这是正确的方法吗？我发送的文件是特定文件，因此客户端不需要浏览文件。任何人都可以指导我如何发送文件？我应该使用base64对其进行编码以将其作为JSON对象发送吗？或者不需要编码将其作为JSON对象发送？感谢您提供的任何帮助。

What kind of annotations should I use? I've seen some people recommend for a @GET using @Produces({application/x-octet-stream}), is that the correct way? The files I'm sending are specific ones so the client doesn't need to browse through the files. Can anyone guide me into how am I supposed to send the file? Should I encode it using base64 to send it as a JSON object? or the encoding isn't necessary to send it as a JSON object? Thanks for any help you may give.

推荐答案

我不建议在base64中编码二进制数据并将其包装在JSON中。它只会不必要地增加响应的大小并减慢速度。

I don't recommend encoding binary data in base64 and wrapping it in JSON. It will just needlessly increase the size of the response and slow things down.

只需使用GET和 application / octect-stream <提供文件数据/ code>使用 <$ c的工厂方法之一$ c> javax.ws.rs.core.Response （JAX-RS API的一部分，所以你没有锁定泽西岛）：

Simply serve your file data using GET and application/octect-streamusing one of the factory methods of javax.ws.rs.core.Response (part of the JAX-RS API, so you're not locked into Jersey):

@GET
@Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response getFile() {
  File file = ... // Initialize this to the File path you want to serve.
  return Response.ok(file, MediaType.APPLICATION_OCTET_STREAM)
      .header("Content-Disposition", "attachment; filename=\"" + file.getName() + "\"" ) //optional
      .build();
}

如果你没有实际的文件 object，但是 InputStream ， Response.ok（entity，mediaType） 也应该能够处理它。

If you don't have an actual File object, but an InputStream, Response.ok(entity, mediaType) should be able to handle that as well.

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