如何將響應從另一個Servlet發送回Servlet

Question

我已經在不同的Web服務器上編寫了兩個servlet。 使用Java中的URL對象從Servlet1（Server1）發送請求。 並成功調用了Servlet2（server2）。 但是我也需要將響應從Servlet2發送回Servlet1 ...我該如何實現。 請幫我。

UPDATE

這是測試代碼。

Servlet1：

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("Inside MyServlet.");
    String urlParameters = "param1=a&param2=b&param3=c";
    byte[] postData       = urlParameters.getBytes( StandardCharsets.UTF_8 );
    int    postDataLength = postData.length;
    String requestURL = "http://localhost:8080/Application2/Servlet2";
    URL url = new URL( requestURL );
    HttpURLConnection conn= (HttpURLConnection) url.openConnection();
    conn.setDoOutput( true );
    conn.setInstanceFollowRedirects( false );
    conn.setRequestMethod( "POST" );
    conn.setRequestProperty( "Content-Type","application/x-www-form-urlencoded");
    conn.setRequestProperty( "charset", "UTF-8");
    conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
    conn.setUseCaches( false );
    ObjectOutputStream out = new ObjectOutputStream(conn.getOutputStream());
    out.write( postData );
    conn.connect();
 }

Servlet2：

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println("Inside CallToAuthorize.Getting Access Token.");
    //do something here and send the response back to Servlet1.
    //Primarily i will be sending String back to Servlet1 for its request.
 }

Answer 1

您的Servlet2，即Request-Receiver，應正常運行：

• 獲取請求參數
• 跟他們做點什么
• 產生回應
• 把它退回

一個基本的例子：

public class Servlet2 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/plain; charset=UTF-8");
        response.getWriter().append("That is my response");
    }

}

您的客戶（請求發送者）應處理響應：

int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
    System.out.println("SUCCESS");
}
else {
    System.out.println("Response Code: " +  responseCode);
}

// may be get the headers
Map<String, List<String>> headers = connection.getHeaderFields();
// do something with them

// read the response body (text, html, json,..)
// do something usefull
BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));
String line;

while ((line = reader.readLine()) != null) {
    System.out.println(line);
}