如何使用 HttpClient 将 XML 文件作为请求传递给我的 Servlet 之一？

Question

下面是我的代码，我在其中尝试生成一个 XML 文件，然后在生成 XML 后，我需要将此 XML 文件发送到我自己的一个 Servlet，该 Servlet 在我的机器上本地运行。我能够生成一个 XML 文件，但我不确定应该如何将该 XML 文件发送到我的一个 servlet，以便在 doGet 方法中，我可以解析该 XML 文件。

public static void main(String[] args) throws SAXException, XPathExpressionException, ParserConfigurationException, IOException,
    TransformerException {

String xml = generateXML();
send("http://localhost:8080/ServletExample/SampleServlet", xml);
}


/**
 * A simple method to generate an XML file
 *
 */  
public static String generateXML(String conn, String funcAddr) throws ParserConfigurationException, SAXException, IOException,
    XPathExpressionException, TransformerException {

DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();

// Some code here to make an XML file

String xmlString = sw.toString();

// print xml
System.out.println("Here's the xml:\n" + xmlString);

return xmlString;
}


/**
 * A simple method to send the XML to servlet class
 *
 */
public static void send(String urladdress, String file) throws MalformedURLException, IOException {
String charset = "UTF-8";
String s = URLEncoder.encode(file, charset);

// I am not sure what should I do here so that I can pass the 
//  above XML file that I made to my servlet class.

}

我的 servlet 在 8080 本地运行。下面是我的 servlet 类中的 sn-p-

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    BufferedReader reader = request.getReader();

    //Parse the XML file here?

    System.out.println(reader.readLine());

}

更新代码：-

我在新的dynamic web project 中创建了一个名为SampleServlet 的Servlet 类。我已经在调试模式下启动了服务器。下面是我的 Servlet 中的代码-

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    BufferedReader reader = request.getReader();
    System.out.println(reader.readLine());

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    BufferedReader b = new BufferedReader(request.getReader());  
    System.out.println(reader.readLine());

}

而我的web.xml文件是这样的-

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>ServletExample</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>SampleServlet</display-name>
    <servlet-name>SampleServlet</servlet-name>
    <servlet-class>com.servlet.example.SampleServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SampleServlet</servlet-name>
    <url-pattern>/SampleServlet</url-pattern>
  </servlet-mapping>
</web-app>

我在上述两种方法中都设置了断点。一旦我从浏览器中点击此网址-

http://localhost:8080/ServletExample/SampleServlet

我的断点总是在 doGet 方法中被命中。

现在我在 eclipse 中创建了一个新的 Java 项目，它是我的客户端，它将调用 servlet doPost 方法，因为我需要将 XML 文件作为请求传递给我的 servlet。

下面是我的代码-

public static void main(String[] args) {

    HttpPost post = new HttpPost("http://localhost:8080/ServletExample/SampleServlet");
    post.setHeader("Content-Type", "application/xml");
    post.setEntity(new StringEntity(generateNewXML()));
    HttpClient client = new DefaultHttpClient();
    HttpResponse response = client.execute(post);
}

但不知何故，一旦我将上面的主程序作为 Java 应用程序运行，它就不会命中我在 servlet 类中放置的断点。而且我不确定它为什么会发生，并且没有抛出异常。知道为什么会这样吗？

Answer 1

一切正常，我刚刚将您的代码复制到一个新项目中

public class SampleServlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doPost is called");
    }
}

并运行客户端：

public class PostClient {

    public static void main(String[] args) throws ClientProtocolException, IOException {
        HttpPost post = new HttpPost("http://localhost:8080/ServletExample/SampleServlet");
        post.setHeader("Content-Type", "application/xml");
        post.setEntity(new StringEntity("<xml></xml>"));
        HttpClient client = new DefaultHttpClient();
        HttpResponse response = client.execute(post);
    }

}

消息“doPost is called”已打印在 cosole 中，一切正常

Answer 2

要将某些内容发布到 servlet，使用 HTTP POST/doPost 是更好的选择。 GET/doGet 是获取资源。这是相同的相关代码：

Servlet doPost

public void doPost(HttpServletRequest req,  
                    HttpServletResponse res)  
      throws ServletException, IOException {  
      try {  
            BufferedReader b = new BufferedReader(req.getReader());  
            StringBuffer xmlBuffer = new StringBuffer();    
            String xmlString = "";          
            while((xmlString = b.readLine()) != null) {  
                   xmlBuffer.append(xmlString);  
            }  
            xmlString = xmlBuffer.toString();  
            if (workBuffer.length() > 0) {  
              System.out.println("Got XML: " + workString);  
            }      
            else {  
                 System.out.println("No XML document received");  
            }  
      }   

Http POST 客户端代码：

private void postMessage(TextMessage xmlMsg, String urlString)  
                throws Exception  
{  
  try  
  {  
    URL url = new URL(urlString);  
    URLConnection uc = url.openConnection();  
    HttpURLConnection conn = (HttpURLConnection) uc;  
    conn.setDoInput(true);  
    conn.setDoOutput(true);  
    conn.setRequestMethod("POST");  
    conn.setRequestProperty("Content-type", "text/xml");          
    PrintWriter pw = new PrintWriter(conn.getOutputStream());  
    pw.write(xmlMsg.getText());  
    pw.close();  
    BufferedInputStream bis = new BufferedInputStream(conn.getInputStream());  
    bis.close();  

  }  
  catch (Exception e)  
  {  
    e.printStackTrace();  
  }  
}   

Answer 3

如果不是“安全”的方法，你最好使用 POST 代替，然后你可以在 post 的 body 中发送 xml，如下：

HttpPost post = new HttpPost("http://localhost:8080/ServletExample/SampleServlet");
post.setHeader("Content-Type", "application/xml");
post.setEntity(new StringEntity(generateXML()));
HttpClient client = new DefaultHttpClient();
HttpResponse response = client.execute(post);

如果您更愿意使用 GET，一种方法是在查询字符串中编码 xml：

String xml = generateXML();
HttpGet get = new HttpGet("http://localhost:8080/ServletExample/SampleServlet?xml=" + URLEncoder.encode(xml, "UTF-8"));
HttpClient client = new DefaultHttpClient();
HttpResponse response = client.execute(get);

在 servlet 中解析 xml：

String xml = request.getParameter("xml");