从Java客户端到Grails web应用程序的可恢复上传？

在谷歌搜索了将近两个工作日，并尝试了我在网上发现的几种不同的可能性之后，我在这里提出了这个问题，希望我能最终得到答案

首先，我想做的是： 我正在开发一个客户机和一个服务器应用程序，目的是在一台服务器上的多个客户机之间交换大量大型文件。客户端是在纯Java（JDK1.6）中开发的，而web应用程序是在Grails（2.0.0）中开发的

由于客户端的目的是允许用户交换大量的大文件（通常每个文件大约2GB），因此我必须以某种方式实现它，以便上传是可恢复的，即用户可以随时停止和恢复上传

以下是我迄今为止所做的： 实际上，我做到了我想做的事情，将大文件流式传输到服务器，同时仍然能够使用原始套接字暂停和恢复上传。我会向服务器发送一个常规请求（使用Apache的HttpClient库），让服务器向我发送一个免费使用的端口，然后在服务器上打开一个ServerSocket并从客户端连接到该特定的套接字

这就是问题所在： 事实上，这至少有两个问题：

我自己打开这些端口，所以我必须自己管理打开和使用的端口。这很容易出错

我实际上绕过了Grails管理大量（并发）连接的能力

最后，这里是我现在应该做的事情和问题： 由于我上面提到的问题是不可接受的，我现在应该使用Java的URLConnection/HttpURLConnection类，同时仍然坚持使用Grails

连接到服务器并发送简单的请求一点问题都没有，一切正常。当我尝试使用流（客户端中连接的OutputStream和服务器中请求的InputStream）时，问题就开始了。打开客户机的OutputStream并将数据写入其中非常简单。但对我来说，从请求的InputStream读取数据似乎是不可能的，因为该数据流似乎总是空的

示例代码 下面是服务器端（Groovy控制器）的一个示例：

正如我提到的，问题是，

request.inputStream

总是产生一个空的inputStream，因此我永远无法从中读取任何内容（当然）。但这正是我想要做的（这样我就可以将要上传到服务器的文件流化，从InputStream读取并保存到一个文件），这是相当令人失望的

我尝试了不同的HTTP方法，不同的数据有效负载，并且一遍又一遍地重新排列代码，但似乎无法解决问题

我希望找到什么 当然，我希望找到解决我问题的办法。任何东西都值得高度赞赏：提示、代码片段、库建议等等。也许我甚至都搞错了，需要走完全不同的方向

---

那么，我如何实现从Java客户机到Grails web应用程序的相当大（二进制）文件的可恢复文件上载，而不必手动打开服务器端的端口呢？

HTTP GET方法具有用于范围检索的特殊头文件：大多数下载程序都使用它从服务器进行可恢复下载

据我所知，在POST/PUT请求中使用此标题没有标准实践，但这取决于您，对吗？您可以制作非常标准的Grails控制器，它将接受标准的http上传，标题类似于

范围：bytes=500-999

。控制器应该把500个上传的字节从客户端放到文件中，从位置500开始

在这种情况下，您不需要打开任何套接字，也不需要制定自己的协议等

---

p.S.500字节只是一个例子，可能您使用的是更大的部件。

客户端Java编程：

    public class NonFormFileUploader {
    static final String UPLOAD_URL= "http://localhost:8080/v2/mobileApp/fileUploadForEOL";


    static final int BUFFER_SIZE = 4096;

    public static void main(String[] args) throws IOException {
        // takes file path from first program's argument
        String filePath = "G:/study/GettingStartedwithGrailsFinalInfoQ.pdf";
        File uploadFile = new File(filePath);

        System.out.println("File to upload: " + filePath);

        // creates a HTTP connection
        URL url = new URL(UPLOAD_URL);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setDoOutput(true);
        httpConn.setRequestMethod("POST");
        // sets file name as a HTTP header
        httpConn.setRequestProperty("fileName", uploadFile.getName());

        // opens output stream of the HTTP connection for writing data
        OutputStream outputStream = httpConn.getOutputStream();

        // Opens input stream of the file for reading data
        FileInputStream inputStream = new FileInputStream(uploadFile);

        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;

        while ((bytesRead = inputStream.read(buffer)) != -1) {
            System.out.println("bytesRead:"+bytesRead);
            outputStream.write(buffer, 0, bytesRead);
            outputStream.flush();
        }

        System.out.println("Data was written.");
        outputStream.flush();
        outputStream.close();
        inputStream.close();

        int responseCode = httpConn.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            // reads server's response
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    httpConn.getInputStream()));
            String response = reader.readLine();
            System.out.println("Server's response: " + response);
        } else {
            System.out.println("Server returned non-OK code: " + responseCode);
        }
    }
 }

服务器端Grails程序：

    public class NonFormFileUploader {
    static final String UPLOAD_URL= "http://localhost:8080/v2/mobileApp/fileUploadForEOL";


    static final int BUFFER_SIZE = 4096;

    public static void main(String[] args) throws IOException {
        // takes file path from first program's argument
        String filePath = "G:/study/GettingStartedwithGrailsFinalInfoQ.pdf";
        File uploadFile = new File(filePath);

        System.out.println("File to upload: " + filePath);

        // creates a HTTP connection
        URL url = new URL(UPLOAD_URL);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setDoOutput(true);
        httpConn.setRequestMethod("POST");
        // sets file name as a HTTP header
        httpConn.setRequestProperty("fileName", uploadFile.getName());

        // opens output stream of the HTTP connection for writing data
        OutputStream outputStream = httpConn.getOutputStream();

        // Opens input stream of the file for reading data
        FileInputStream inputStream = new FileInputStream(uploadFile);

        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;

        while ((bytesRead = inputStream.read(buffer)) != -1) {
            System.out.println("bytesRead:"+bytesRead);
            outputStream.write(buffer, 0, bytesRead);
            outputStream.flush();
        }

        System.out.println("Data was written.");
        outputStream.flush();
        outputStream.close();
        inputStream.close();

        int responseCode = httpConn.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            // reads server's response
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    httpConn.getInputStream()));
            String response = reader.readLine();
            System.out.println("Server's response: " + response);
        } else {
            System.out.println("Server returned non-OK code: " + responseCode);
        }
    }
 }

控制器内部：

在服务类内部：

def fileUploadForEOL（请求）{
def状态=假；
整数代码=500
def map=[：]
试一试{
字符串文件名=request.getHeader（“文件名”）；
文件保存文件=新文件（保存目录+文件名）；
System.out.println（“==beginheaders===”）；
枚举名称=request.getHeaderNames（）；
while（names.hasMoreElements（））{
字符串headerName=names.nextElement（）；
System.out.println（headerName+“=”+request.getHeader（headerName））；
}
System.out.println（“=======结束头========\n”）；
//打开读取数据请求的输入流
InputStream InputStream=request.getInputStream（）；
//打开输出流以写入文件
FileOutputStream outputStream=新的FileOutputStream（保存文件）；
字节[]缓冲区=新字节[缓冲区大小]；
int bytesRead=inputStream.read（缓冲区）；
长计数=字节读取
while（字节读取！=-1）{
写入（缓冲区，0，字节读取）；
bytesRead=inputStream.read（缓冲区）；
计数+=字节读取
}
println“计数：”+计数
System.out.println（“数据接收”）；
outputStream.close（）；
inputStream.close（）；
System.out.println（“文件写入：”+saveFile.getAbsolutePath（））；
代码=200
}捕获（例外e）{
log（java.util.logging.Level.SEVERE，“fileUploadForEOL中的异常”，e）；
}最后{
地图
    public class NonFormFileUploader {
    static final String UPLOAD_URL= "http://localhost:8080/v2/mobileApp/fileUploadForEOL";


    static final int BUFFER_SIZE = 4096;

    public static void main(String[] args) throws IOException {
        // takes file path from first program's argument
        String filePath = "G:/study/GettingStartedwithGrailsFinalInfoQ.pdf";
        File uploadFile = new File(filePath);

        System.out.println("File to upload: " + filePath);

        // creates a HTTP connection
        URL url = new URL(UPLOAD_URL);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setDoOutput(true);
        httpConn.setRequestMethod("POST");
        // sets file name as a HTTP header
        httpConn.setRequestProperty("fileName", uploadFile.getName());

        // opens output stream of the HTTP connection for writing data
        OutputStream outputStream = httpConn.getOutputStream();

        // Opens input stream of the file for reading data
        FileInputStream inputStream = new FileInputStream(uploadFile);

        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;

        while ((bytesRead = inputStream.read(buffer)) != -1) {
            System.out.println("bytesRead:"+bytesRead);
            outputStream.write(buffer, 0, bytesRead);
            outputStream.flush();
        }

        System.out.println("Data was written.");
        outputStream.flush();
        outputStream.close();
        inputStream.close();

        int responseCode = httpConn.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            // reads server's response
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    httpConn.getInputStream()));
            String response = reader.readLine();
            System.out.println("Server's response: " + response);
        } else {
            System.out.println("Server returned non-OK code: " + responseCode);
        }
    }
 }

def fileUploadForEOL(){
    def result
    try{
        result = mobileAppService.fileUploadForEOL(request);
    }catch(Exception e){
        log.error "Exception in fileUploadForEOL service",e
    }
    render result as JSON
}

    def fileUploadForEOL(request){
    def status = false;
    int code = 500
    def map = [:]
    try{
    String fileName = request.getHeader("fileName");
    File saveFile = new File(SAVE_DIR + fileName);

    System.out.println("===== Begin headers =====");
    Enumeration<String> names = request.getHeaderNames();
    while (names.hasMoreElements()) {
        String headerName = names.nextElement();
        System.out.println(headerName + " = " + request.getHeader(headerName));        
    }
    System.out.println("===== End headers =====\n");

    // opens input stream of the request for reading data
    InputStream inputStream = request.getInputStream();

    // opens an output stream for writing file
    FileOutputStream outputStream = new FileOutputStream(saveFile);

    byte[] buffer = new byte[BUFFER_SIZE];
    int bytesRead = inputStream.read(buffer);

    long count =  bytesRead

    while(bytesRead != -1) {
        outputStream.write(buffer, 0, bytesRead);
      bytesRead = inputStream.read(buffer);
      count += bytesRead
    }
     println "count:"+count
    System.out.println("Data received.");
    outputStream.close();
    inputStream.close();

    System.out.println("File written to: " + saveFile.getAbsolutePath());

    code = 200

    }catch(Exception e){
        mLogger.log(java.util.logging.Level.SEVERE,"Exception in fileUploadForEOL",e);
    }finally{
        map <<["code":code]
    }
    return map
}