Question

我在我的Android应用中使用NanoHTTPD作为网络服务器。

我将两个文件名从客户端浏览器传递给NanoHTTPD服务器，我希望一次下载这两个文件，但以下代码只下载file1，而不下载file2。

如何一次下载两个或多个文件？

public class MyWebServer extends NanoHTTPD
{

    private final String rootDir;

    public MyWebServer(int port, String rootDir)
    {
        super("192.168.1.4", port);
        this.rootDir = rootDir;
    }

    @Override
    public Response serve(IHTTPSession session)
    {       
        Map<String, String> parms = session.getParms();

        String filename1=GetFilename(parms);
        String filename2=GetFilename(parms);

        File file1 = new File(rootDir + filename1);
        File file2 = new File(rootDir + filename2);

        return downloadFile(file1);
        return downloadFile(file2);
    }


    private Response downloadFile(File file)
    {
        FileInputStream fis = null;
        try
        {
            fis = new FileInputStream(file);
        } catch (FileNotFoundException ex)
        {
            Logger.getLogger(MyWebServer.class.getName()).log(Level.SEVERE, null, ex);
        }
        return newFixedLengthResponse(Response.Status.OK, "application/octet-stream", fis, file.getTotalSpace());
    }



    @Override
    public Response newFixedLengthResponse(IStatus status, String mimeType, String message)
    {
        Response response = super.newFixedLengthResponse(status, mimeType, message);
        response.addHeader("Accept-Ranges", "bytes");
        return response;
    }


}

Answer 1

当您在MyWebServer构造函数中调用super(..)时，NanoHTTPD构造函数下面会创建一个异步任务。

public NanoHTTPD(String hostname, int port) {
        this.hostname = hostname;
        this.myPort = port;
        setTempFileManagerFactory(new DefaultTempFileManagerFactory());
        setAsyncRunner(new DefaultAsyncRunner());

        // creates a default handler that redirects to deprecated serve();
        this.httpHandler = new IHandler<IHTTPSession, Response>() {

            @Override
            public Response handle(IHTTPSession input) {
                return NanoHTTPD.this.serve(input);
            }
        };
    }

所以答案必须是每个操作都有一个downloadFile()。也就是说，您应该调用new MyWebServer()来启动每个下载任务。

@Override
    public Response serve(IHTTPSession session)
    {       
        Map<String, String> parms = session.getParms();

        String filename=GetFilename(parms);

        File file = new File(rootDir + filename);

        return downloadFile(file);
    }

修改

通过使用2个MyWebServer类实例，你可以收听2个参数中每个参数的客户端请求。（我没试过这个，但它必须工作，我建议你应该在客户端发送多个请求，在服务器端发送一个webserver实例）。

public class MyWebServer extends NanoHTTPD { private final String rootDir; private final int param_type = 1; //default 1 public MyWebServer(int port, String rootDir, int param) { super("192.168.1.4", port); this.rootDir = rootDir; this.param_type = param; } @Override public Response serve(IHTTPSession session) { Map<String, String> parms = session.getParms(); File file; if (param_type == 1){ String filename=parms.get("param1"); file = new File(rootDir + filename); }else if(param_type == 2){ String filename=parms.get("param2"); file = new File(rootDir + filename); } return downloadFile(file); } private Response downloadFile(File file) { FileInputStream fis = null; try { fis = new FileInputStream(file); } catch (FileNotFoundException ex) { Logger.getLogger(MyWebServer.class.getName()).log(Level.SEVERE, null, ex); } return newFixedLengthResponse(Response.Status.OK, "application/octet-stream", fis, file.getTotalSpace()); } @Override public Response newFixedLengthResponse(IStatus status, String mimeType, String message) { Response response = super.newFixedLengthResponse(status, mimeType, message); response.addHeader("Accept-Ranges", "bytes"); return response; } }

在MainActivity.java

@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); MyWebServer server1 = new MyWebServer(port, rootDir, 1); MyWebServer server2 = new MyWebServer(port, rootDir, 2); server1.start(); server2.start(); }

Answer 2

在Java中，如果希望函数返回多个值，则必须将这些值嵌入到返回的对象中。所以你需要定义一个类（例如：ReturnDownlowds），它可以有两个对象：

public class ReturnDownlowds {
    private File downloadFile1;
    private File downloadFile2;

//添加其他字段，构造函数和访问器

}

在您的Response服务器方法中，您需要调用此类的示例，如下所示：

return new ReturnDownlowds(downloadFile1, downloadFile2) ;

我希望这会有所帮助。

如何使用NanoHTTPD在Android中一次下载两个或多个文件？

2 个答案: