JAVA HTTP 客户端和 Serlvlet

Question

我正在使用 Apache Tomcat，我想将数据发送到 http 服务器并从 HTTP 服务器（来自 servlet）获取响应。

问题：

当我使用HTTP客户端发送数据时，似乎没有传递数据（发送的参数没有被servlet显示）。当我通过 HTTP 浏览器 (Chrome) 进行模拟时，一切似乎都正常。

下面是我的 servlet 和我的 http 客户端的示例。

我的 HTTP Servlet：

public class MyServlet extends HttpServlet {
    public void doGet(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        PrintWriter out = res.getWriter();
        out.println("This ervlet requires POST but received GET");
        out.close();
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");

        PrintWriter out = response.getWriter();
        for (String name : request.getParameterMap().keySet()) {
            out.write("PARAMETER :" + name);
            out.write("\n");
        }

        for (Part name : request.getParts()) {
            out.write("MULTIPART PARAMETER :" + name.getName());
            out.write("\n");
        }

        String p1 = request.getParameter("input1");
        out.write("RECEIVED PARAMETER:" + p1);
        out.write("\n");

        out.close();
    }
}

我的 HTTP 客户端

/**
 * Example how to use multipart/form encoded POST request.
 */
public class ClientMultipartFormPost {

    public static void main(String[] args) throws Exception {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        try {
            HttpPost httppost = new HttpPost("http://example.com:8080" +
                    "/myservlet");

            FileBody bin = new FileBody(new File("file1.txt"));
            StringBody comment = new StringBody("A binary file of some kind", ContentType.TEXT_PLAIN);

            HttpEntity reqEntity = MultipartEntityBuilder.create()
                    .addPart("bin", bin)
                    .addPart("input1", comment)
                    .build();


            httppost.setEntity(reqEntity);

            System.out.println("executing request " + httppost.getRequestLine());
            CloseableHttpResponse response = httpclient.execute(httppost);
            try {
                System.out.println("----------------------------------------");
                System.out.println(response.getStatusLine());
                HttpEntity resEntity = response.getEntity();
                if (resEntity != null) {
                    PrintWriter sWriter = new PrintWriter(System.out);
                    IOUtils.copy(resEntity.getContent(), sWriter, "UTF-8");
                    sWriter.close();
                }
                EntityUtils.consume(resEntity);
            } finally {
                response.close();
            }
        } finally {
            httpclient.close();
        }
    }

}

输出：执行请求 POST

http://example.com:8080/myservletHTTP/1.1

---------------------------------------- HTTP/1.1 200 OK

接收参数：空

浏览器客户端（测试） 浏览器 POST 按预期工作：

<form name="input" action="http://example.com:8080/servlet" method="post">
<input type="text" name="input1">
<input type="submit" value="Submit">
</form>

输出：参数：输入1

收到的参数：AAAAAAAAA

更新： 浏览器代码：

Request URL:http://localhost:8080/servlet
Request Method:POST
Status Code:200 OK
Request Headersview parsed
POST /LyticsRemote/flexi HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Content-Length: 10
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Origin: null
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1700.102 Safari/537.36
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip,deflate,sdch
Accept-Language: cs,en-GB;q=0.8,en;q=0.6
Cookie: JSESSIONID=9BD73E186BC8A081AB87C8EF58483523
Form Dataview sourceview URL encoded
input1:aaa
Response Headersview source
Content-Length:41
Content-Type:text/html;charset=ISO-8859-1
Date:Fri, 31 Jan 2014 11:46:54 GMT
Server:Apache-Coyote/1.1

Answer 1

解决方案是在 servlet 中添加 getParameters 方法，因此最终代码为：

public class FlexiServlet extends HttpServlet {
    private FileItem fileItem;

    public void doGet(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        PrintWriter out = res.getWriter();
        out.println("This ervlet requires POST but received GET");
        out.close();
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");

        PrintWriter out = response.getWriter();
        boolean success = getParameters(request, out);
        out.write(" XXXXXXXXXXXXXXXXX" + success);
        out.write(" XXXXXXXXXXXXXXXXX" + fileItem);
        out.write("\n");
        for (String name : request.getParameterMap().keySet()) {
            out.write("PARAMETER :" + name);
            out.write("\n");
        }

        for (Part name : request.getParts()) {
            out.write("MULTIPART PARAMETER :" + name.getName());
            out.write("\n");
        }

        String p1 = request.getParameter("input1");
        out.write("RECEIVED PARAMETER:" + p1);
        out.write("\n");

        out.close();
    }

    public boolean getParameters(HttpServletRequest request, PrintWriter out) {
        List fileItemsList = null;
        try {
            if (ServletFileUpload.isMultipartContent(request)) {
                ServletFileUpload servletFileUpload = new ServletFileUpload(
                        new DiskFileItemFactory());
                try {
                    fileItemsList = servletFileUpload.parseRequest(request);
                } catch (FileUploadException ex) {
                }
                String optionalFileName = "";
                Iterator it = fileItemsList.iterator();
                while (it.hasNext()) {
                    FileItem fileItemTemp = (FileItem) it.next();
                    if (fileItemTemp.isFormField()) {
                        // for other form fields that are not multipart
                        // if (fileItemTemp.getFieldName().equals("commonName"))
                        // {
                        // commonName = fileItemTemp.getString();
                        // }
                        out.write("AAAAAAAAAAAA " + fileItemTemp.getFieldName());
                    } else {
                        if (fileItemTemp.getFieldName().equals("media_file")) {
                            fileItem = fileItemTemp;
                        }
                        out.write("BBBBBBBBBBBBBB " + fileItemTemp.getFieldName());

                    }
                }
            }
        } catch (Exception e) {
        }
        return true;
    }
}