sitelink1 http://www.java-forums.org/advanced-java...-ajax.html 
sitelink2  
sitelink3  
sitelink4 http://1 
extra_vars4 ko 
extra_vars5  
extra_vars6 sitelink1 

Question : flush data from servlet to jsp with ajax

I've a servlet that process a file and reports the number of line which has processed. In the other side, I have a JSP, wit a div. This jsp uses Ajax to call the servlet.

The intended result, is that Ajax receives all the out.print of the Servlet and with javascript update an html table in the jsp.

I've been able to update the table and all that, but only after the servlet finish, all the lines that is printing, are not received in the ajax (or printed in the page) until this servlet finishes.

I understand that Ajax can monitor the status of the servlet, and as I can see, it finishes when status is 4 (completed) and result is 200 (OK). I'm sending from the servlet the out.print("text"), but as I said, the jsp process it when both 4 state and 200 status are received, nothing is received while the servlet is processing.

Can you help me with this please?

These are some code snippets:
Ajax

Java Code:

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

var dinformacion = document.getElementById("informacion");

            var isIE;

            function XMLHttp(url) {

                return XMLHttp(url, null);

            }

            function XMLHttp(url, callback, callbackprocess) {

                var req = init();

                req.onreadystatechange = processRequest;

                function init() {

                    if (window.XMLHttpRequest) {

                        return new XMLHttpRequest();

                    } else {

                        if (window.ActiveXObject) {

                            isIE = true;

                            return new ActiveXObject("Microsoft.XMLHTTP");

                        }

                    }

                }

                function processRequest() {

                    //dinformacion.innerHTML = req.readyState + "/" + req.status;

                 

                    if ((req.readyState == 4) && (req.status == 200) && (callback)) {

                        var a = req;

                        callback(req.responseText);

                    }

                    else {

                        //HERE IT FAILS ALL THE TIME

                        callbackprocess(req.responseText);

                    }

                }

                this.doGet = function () {

                    req.open("GET", url, true);

                    req.send(null);

                };

                this.doPost = function (body) {

                    req.open("POST", url, true);

                    req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

                    req.send(body);

                };

            }

            function getElementY(element) {

                var targetTop = 0;

                if (element.offsetParent) {

                    while (element.offsetParent) {

                        targetTop += element.offsetTop;

                        element = element.offsetParent;

                    }

                } else {

                    if (element.y) {

                        targetTop += element.y;

                    }

                }

                return targetTop;

            }

 

 

         

            var req = new XMLHttp("../servlet/ConsultaServlet",onServerResponse,onServerProcess);

            req.doPost();

             

            function onServerResponse(responseXML){

                responseXML = trim(responseXML);

                alert(responseXML);

            }

            var dproc = document.getElementById("process");

             

            function onServerProcess(responseXML){

                responseXML = trim(responseXML);

                dproc.innerHTML = responseXML;

                 

            }

And my servlet snippet:

Java Code:

1

2

3

4

5

6

7

...

for(int i=1;i<20;i++){

                 

                out.print(i);

                out.flush();

            }  

...

 

 

 

 

Answer : Reply t flush data from servlet to jsp with ajax

I think you yourself gave the answer to it....
 

I understand that Ajax can monitor the status of the servlet, and as I can see, it finishes when status is 4 (completed) and result is 200 (OK). I'm sending from the servlet the out.print("text"), but as I said, the jsp process it when both 4 state and 200 status are received, nothing is received while the servlet is processing.

You don't receive the XmlHttpRequest object and so the responseText until the servlet you're calling via AJAX completes its execution! You might get a better view of it if u put a Thread.sleep(2000)....i.e., a delay of 2secs in your "for" loop
 

Java Code:

1

2

3

4

5

6

for(int i=1;i<20;i++){

                 

                out.print(i);

                out.flush();

                                Thread.sleep(2000);

            }

So, you cannot get any responseText while the servlet is processing. To achieve something like this, people tend to use a 'server push' method. You might like to see topics like 'Comet' also called Reverse Ajax, pushlets to get responses from the servlet to the client and u can use them your own way to achieve your goal!

good luck!! :)

 

 

 

번호 제목 글쓴이 날짜 조회 수
246 사용자 모듈 만들기 황제낙엽 2019.07.09 42086
245 User Agent 정보 모음 file 황제낙엽 2011.02.22 11346
244 페이지 스크롤 끝 확인 황제낙엽 2011.10.24 6816
243 숫자 여부와 자리수를 체크 하는 예제 황제낙엽 2009.01.12 5502
242 User Agent Parser들 황제낙엽 2017.11.20 5476
» 연속해서 스트림 받기 (flush data from servlet to jsp with ajax) 황제낙엽 2013.01.04 5098
240 ActiveX 설치 여부를 검사하는 스크립트 황제낙엽 2011.02.13 4440
239 [JavaScript Tutorials] Handling runtime errors in JavaScript using try/catch/finally (해석중) 황제낙엽 2009.04.08 3111
238 브라우저의 새로고침과 종료에 대한 이벤트 황제낙엽 2017.08.11 3100
237 오류:호출자(서버 응용 프로그램이 아닌 서버)가 사용될 수 없어서 사라졌습니다. file 황제낙엽 2012.03.14 2213
236 외부 라이브러리 (.js) 의 바람직하지 않은 동적 로딩 (eval함수 이용) 황제낙엽 2012.01.18 2157
235 object clone 황제낙엽 2011.07.08 2145
234 window.postMessage 이해하기 file 황제낙엽 2017.10.16 1904
233 window.postMessage() 황제낙엽 2020.07.29 1865
232 IE and Memory accumulation in Javascript (document.createElement()) file 황제낙엽 2011.11.24 1562
231 javascirpt IME-Mode 설정하기 황제낙엽 2010.08.17 1443
230 경과 시간 구하기 황제낙엽 2019.10.04 1442
229 부동소수점 (floating-point) file 황제낙엽 2018.03.26 1437
228 콜백지옥과 비동기제어 file 황제낙엽 2021.02.18 1305
227 중첩 함수, 함수 클로저 황제낙엽 2008.08.12 1233