java - 通过 android 模拟器发送 HTTP POST 请求不起作用

Question

我在我的本地机器上运行一个 tomcat servlet 和一个带有向 servlet 发出发布请求的应用程序的 Android 模拟器。 POST 的代码如下(没有异常(exception)等):

        String strUrl = "http://10.0.2.2:8080/DeviceDiscoveryServer/server/devices/";
        Device device = Device.getUniqueInstance();

        urlParameters += URLEncoder.encode("user", "UTF-8") + "=" + URLEncoder.encode(device.getUser(), "UTF-8");
        urlParameters += "&" + URLEncoder.encode("port", "UTF-8") + "=" + URLEncoder.encode(new Integer(Device.PORT).toString(), "UTF-8");
        urlParameters += "&" + URLEncoder.encode("address", "UTF-8") + "=" + URLEncoder.encode(device.getAddress().getHostAddress(), "UTF-8");

        URL url = new URL(strUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");

        OutputStreamWriter wr = new OutputStreamWriter(connection.getOutputStream());
        wr.write(urlParameters);
        wr.flush();
        wr.close();

无论何时执行此代码，都不会调用 servlet。但是，如果我将请求类型更改为“GET”并且不向输出流写入任何内容，则调用 servlet 并且一切正常。我只是没有正确地进行 POST 还是有其他错误？

Answer 1

试试下面的代码，可能对你有帮助

        try
{
    String argUrl = 
        "";

    String requestXml = "";
    URL url = new URL( argUrl );
    URLConnection con = url.openConnection();
    System.out.println("STRING" + requestXml);
    // specify that we will send output and accept input
    con.setDoInput(true);
    con.setDoOutput(true);

    con.setConnectTimeout( 20000 );  // long timeout, but not infinite
    con.setReadTimeout( 20000 );

    con.setUseCaches (false);
    con.setDefaultUseCaches (false);

    // tell the web server what we are sending
    con.setRequestProperty ( "Content-Type", "text/xml" );

    OutputStreamWriter writer = new OutputStreamWriter( con.getOutputStream() );
    writer.write( requestXml );
    writer.flush();
    writer.close();

    // reading the response
    InputStreamReader reader = new InputStreamReader( con.getInputStream() );

    StringBuilder buf = new StringBuilder();
    char[] cbuf = new char[ 2048 ];
    int num;

    while ( -1 != (num=reader.read( cbuf )))
    {
        buf.append( cbuf, 0, num );
    }

    String result = buf.toString();
    System.err.println( "\nResponse from server after POST:\n" + result );
}
catch( Throwable t )
{
    t.printStackTrace( System.out );
}