Question

我最近添加了一个名为“GetAveGoogleChart.Java”的servlet，它将通过hibernate从MySQLDB中获取值。

公共类GetAveGoogleChart扩展了HttpServlet {

/**
 * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
 * methods.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("application/json");
    response.setContentType("text/html;charset=UTF-8");

    String applicationName = request.getParameter("appName");
    String transactionName = request.getParameter("tranName");
    TransactionAO myAO = new TransactionAO();
    Iterator<Transactionentry> transactionEntries= myDAO.getTransactions(applicationName, transactionName).listIterator();
    //System.out.println("Entries size = " + transactionEntries.size());

    SimpleDateFormat sdf = new SimpleDateFormat("YYYY-MM-dd'T'HH:mm:ss");
     SimpleDateFormat sdf1 = new SimpleDateFormat("YYYY,MM,dd,HH,mm,ss");

    JSONObject rootNode = new JSONObject();

    JSONArray colsArray = new JSONArray();
    JSONObject col1Object = new JSONObject();
    col1Object.put("id", "TestDate");
    col1Object.put("label", "TestDate");
    col1Object.put("type", "datetime");
    col1Object.put("p", new JSONArray());


    JSONObject col2Object = new JSONObject();
    col2Object.put("id", "Utils");
    col2Object.put("label", "CPU Average (in %)");
    col2Object.put("type", "number");
    col2Object.put("p", new JSONArray());

    colsArray.put(col1Object);
    colsArray.put(col2Object);

    JSONArray rowsArray = new JSONArray();
     while(transactionEntries.hasNext()){
        Transactionentry te=transactionEntries.next();

        Date entryDate = te.getTranendtime();
        double value = te.getAvecpu().doubleValue();
        JSONObject rowObject = new JSONObject();

        JSONArray cArray = new JSONArray();
        JSONObject myDateObject = new JSONObject();
        myDateObject.put("v", "Date("+sdf1.format(entryDate)+")");
        JSONObject valueObject = new JSONObject();
        valueObject.put("v", value);
        cArray.put(myDateObject);
        cArray.put(valueObject);

        rowObject.put("c", cArray);
        rowsArray.put(rowObject);
    }

     //JSONObject colsObject = new JSONObject();
     //colsObject.put("cols", colsArray);
     //JSONObject rowsObject = new JSONObject();
     //rowsObject.put("rows", rowsArray);
    rootNode.put("cols", colsArray);
    rootNode.put("rows", rowsArray);

    PrintWriter out = response.getWriter();
    // Assuming your json object is **jsonObject**, perform the following, it will return your json object  
    out.print(rootNode);
    out.flush();

}

// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
 * Handles the HTTP <code>GET</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);
}

/**
 * Handles the HTTP <code>POST</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);
}

/**
 * Returns a short description of the servlet.
 *
 * @return a String containing servlet description
 */
@Override
public String getServletInfo() {
    return "Short description";
}// </editor-fold>

}

当我点击带有网址

的网页时

http://localhost:8080/sample/GetAveGoogleChart?tranName=Login&appName=SVA%20-%20And

我收到的回复是

Servlet GetAveGoogleChart at / sample

我没有得到任何其他有效的JSON响应。

请帮我解决问题。

提前致谢。

Answer 1

在上面的代码中，您有：

response.setContentType("application/json");
response.setContentType("text/html;charset=UTF-8");

如果删除第二个response.setContentType（）调用，这可能会有所帮助：）

Servlet以HTML而不是JSON的形式返回响应

1 个答案: