JSP Scriptlet <% Code%> Insert the code of the service method. Equivalent XML expression is: Code JSP declaration <%! Code%> code is inserted into the servlet class (outside the service method). Equivalent XML expression is: Code Page Instruction <% @ Page Att = "VAL"%> Global Directive for the Servlet Engine. Equivalent XML expression is . The legitimate properties are as follows, with bold representation defaults: import = "package.class" contentty = "mime-type" isthreadsafe = "true | false" session = "true | false" buffer = "size kb | none" autoflush = "True | false" extends = "package.class" info = "message" errorpage = "url" iesrrorpage = "true | false" language = "java" include instruction <% @ include file = "URL"%> When JSP When converting into a servlet, a specified file on the local system should be included. Equivalent XML expression is: . Where the URL must be relative URL. Using JSP: Include Actions You can introduce files when requested (instead of JSP to servlet). JSP Note <% - Comment -%> Note; JSP is neglected when JSP is converted into servlet. If you want to embed the result html document, use a normal HTML annotation tag <- comment ->. JSP: Include action When the servlet is requested, the specified file is introduced. If you want to include a file while the page is converted, use the JSP Include instruction. Note: On some servers, the included file must be an HTML file or JSP file, which is determined by the server (usually determined according to the file extension).

JSP: UseBean action or ... find or instantiate a Java Bean. Possible properties include: id = "name" scope = "Page | Request | session | Application" class = "package.class" type = "package.class" beanname = "package.class" JSP: setProperty action Sets the properties of the bean. You can set a determined value or specify the attribute value from the request parameters. The legal properties include: name = "beanname" proty = "preordyname | *" param = "parametername" value = "val" jsp: getProperty action extract and output Bean's properties. JSP: Forward action turns the request to another page. JSP: Plugin action ... Generate Object or Embed tags based on the browser type to run Java Applet through Java Plugin. 11.3 About Template Text (Static HTML) Many times, a large part of the JSP page is composed of static HTML, which is also called "template text". Template text and normal HTML are almost identical, they all follow the same syntax rules, and template text is also sent directly to the client by servlet. In addition, template text can also be written in any existing page production tool. The only exception is that if "<%" is output, "<\%" should be written in the template text.

10.1 Session Status Overview The "stateless" feature of the HTTP protocol has brought a range of questions. Especially when shopping is online, the server can not successfully remember the previous business has become a serious problem. It makes it difficult for the application of "shopping basket" to achieve: When we add goods to the shopping basket, how can the server know what is the original in the basket? Even if the server saves context information, we still encounter problems in e-commerce applications. For example, when the user goes from the page selected by the product (supplied by ordinary servers), the server can remember what the user has bought? This issue generally has three solutions: cookie. With HTTP cookies to store information about shopping sessions, the subsequent connections can view the current session and extract complete information about the session from some places of the server. This is an excellent, and the most widely used method. However, even if servlet provides a high-level, easy to use the easy cookie interface, there are still some cumbersome details that require processing: Save the session ID from other cookies. Set a suitable invalidation time for cookies (for example, a session that interrupts more than 24 hours should be resended). Associate the session identifier and the information of the server side. (The actual saved information may be far more than the information saved to cookie, and sensitive information such as credit card should never be saved with cookies.) Rewriting the URL. You can attach the data of some identity sessions to each URL, and the server can associate the session identifier and the session data it saved. This is also a good method, and there is also the advantage when the browser does not support cookies or users have disabled cookies. However, most of the problems faced when using cookies also exist, that is, the server-side procedures should make a lot of simple but monotonous lengthy processing. In addition, you must also carefully ensure that the necessary information (including non-direct, such as a redirect URL given by Location) is guaranteed. If the user ends the session, the session information will be lost. Hidden form fields. The HTML form can contain the following input domain:

10.2 Session Status Tracking API Using Session Information in Servlet is quite simple, the main operations include: viewing the session objects associated with the current request, create a new session object when necessary, view information related to a session, in the session Save information in the object, and release the session object when the session is completed or aborted. 10.2.1 Viewing the currently requested session object View the currently requested session object is implemented by calling the GetSession method of httpservletRequest. If the getSession method returns null, you can create a new session object. More often, we automatically create a session object when there are no ready-made sessions, namely TRUE when there is no ready-made session. Therefore, the first step of accessing the current request session object is usually as follows: httpsession session = request.getSession (TRUE); 10.2.2 Viewing the information about the HTTPSession object HttpSession objects There is a servers, through the cookie or URL background The mechanism is automatically associated with the requesting sender. The session object provides a built-in data structure where any number of keys-value pairs can be saved in this structure. In the 2.1 or earlier version of the Servlet API, check the previously saved data is the GetValue ("Key") method. getValue Returns Object, so you have to convert it into a more specific data type. If the keys specified in the parameter do not exist, getValue returns NULL. API version 2.2 is recommended getAttribute instead getvalue, not only because getAttribute and setAttribute name more closely matches (and getvalue match is putvalue, rather than setvalue), but also because setAttribute allows the use of a subsidiary of HttpSessionBindingListener to monitor the value, and putvalue Can't. However, because there is only a few commercial servlet engines support 2.2, we still use GetValue in the examples. This is a very typical example, assuming ShoppingCart is a save purchased items of information such as: HttpSession session = request.getSession (true); ShoppingCart previousItems = (ShoppingCart) session.getvalue ( "previousItems"); if (previousItems =! NULL) {DOSMETHINGWITH (PREVIOSMS);} else {previousItems = new shoppingcart (...); DOSMETHINGELSEWITH (PREVIOSELSEWITH (PREVIOSEMS); The name of all attributes. GetValueSNames returns a string array. The API 2.2 is recommended to use GetAttributeNames, which is not only because of its name, but because it returns an enumeration, and other methods (such as HTTPSERVLETREQUEST's GetHeaders and getParameternames) are consistent.

Although developers are often the data saved to session objects, there are still other information. GetID: This method returns the unique identifier of the session. Sometimes the identity is used as a key-value pair, such as only one value is saved in the session, or saves the last session information. Isnew: Returns true if the customer (browser) has not bind to a session, often means that the session has just created, not a request from the client. For a session that has already existed, the return value is false. GetCreationTime: This method returns to establish a session time in millisecond meters, from 1970.01.01 (gmt). To get the time value for printout, the value can be passed to the Date constructor, or the settimeinmillis method of GregorianCalendar. GetLastAccesseedTime: This method returns to the customer's last time the request is measured in milliseconds, from 1970.01.01 (gmt). GetMaxInactiveInterval: Returns the maximum time interval in seconds, if the interval between the customer request does not exceed this value, the servlet engine will keep the session is valid. Negative numbers indicate that the session will never time out. 10.2.3 Save Data in the Session Object As described above, read the information stored in the session uses the getValue method (or, for the 2.2 version of the servlet specification, use GetAttribute). Save Data Use the PUTVALUE (or SetAttribute) method and specify the key and the corresponding value. Note PUTVALUE will replace any existing values. Sometimes this is exactly what we need (REFERRINGPAGE in the following example), but sometimes we need to extract the original value and expand it (as PreviousItems). The following sample code: HttpSession session = request.getSession (true); session.putvalue ( "referringPage", request.getHeader ( "Referer")); ShoppingCart previousItems = (ShoppingCart) session.getvalue ( "previousItems"); if (previousItems == null) {previousItems = new ShoppingCart (...);} String itemID = request.getParameter ( "itemID"); previousItems.addEntry (Catalog.getEntry (itemID)); session.putvalue ( "previousItems", previousItems) ; 10.3 Example: Display Session Information Below this example generates a web page and displays information about the current session in this page.

package hall; import java.io. *; import javax.servlet *;. import javax.servlet.http *;. import java.net *;. import java.util *;. public class ShowSession extends HttpServlet {public void doGet ( HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {HttpSession session = request.getSession (true); response.setContentType ( "text / html"); PrintWriter out = response.getWriter (); String title = "Searching the Web"; String Heading; Integer AccessCount = new integer (0) ;; if (session.isnew ()) {heading = "welcome, newcomer";} else {heading = "welcome back"; Integer OldAccessCount = // In Servlet API 2.2 getAttribute used instead getvalue (Integer) session.getvalue ( "accessCount"); if (oldAccessCount = null!) {accessCount = new Integer (oldAccessCount.intvalue () 1);}} // 2.2 Servlet API used in putAttribute Session.putValue ("AccessCount"; Out.println (servletUtilities. Headwithtitle (Title) \n " "

heading " \N" "

information On your session: \ N " " \N " " \N" " \n "

"

\ N" " \N" " \n" "

Info Type	Value \ N " "
iD\N" "	" session.getid () "\N" "
CREATION TIME \ N" "	" New date (session.getcreationTime ()) "\N" "
TIME OF Last Access\ N" "	" New Date (session.getlastaccessedTime ()) "\N" "
Number of Previous Accesses\ N" "	" AccessCount "\N" " \N" "< / BODY> ");} public void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet (request, response);}} Cookie server is sent to the browser of a small volume of plain text information When the user visits the same web server, the browser will send them to the server. By letting the server reads the information you originally saved to the client, the website can provide the viewer to provide a series of convenience, such as the user identity in the online transaction process, and the security requirements are not high to avoid user repeated input name and password, portal The home page is customized, targetedly putting advertisements, and so on. The purpose of cookie is to bring convenience to users, bring value to the website. Although there are many mistakes, in fact, cookies will not cause serious security threats. Cookie will never be executed in any way, so there will be no virus or attack your system. In addition, since the browser is generally only allowed to store 300 cookies, each site stores up to 20 cookies, each cookie size is limited to 4 KB, so the cookie will not be full of your hard drive, and it will not be used as "refusal." Service "attack means. 9.2 SERVET Cookie API To send cookies to the client, servlet first creates one or more cookies (2.1) with the appropriate name and value, set various properties with cookie.setxxx ( Section 2.2), add the cookie to the response head (Section 2.3) via response.addcookie (cookie). To read from the client, servlet should call the request.getCookies (), and the getCookies () method returns an array of cookie objects. In most cases, you only need to use the individual elements of the array to find the cookie of the array, and then call the getValue method to get the value associated with the specified name, this part of this session will be discussed in Section 2.4. 9.2.1 Creating a cookie Call Cookie object constructor can create a cookie. The constructor of the cookie object has two string parameters: cookie name and cookie value. Names and values ​​cannot contain blank characters and the following characters: [] () =, "/? @:; 9.2.2 Read and set the cookie property Before adding the cookie to the response head to be sent, you can view or set the cookie Various properties. In summary These methods: getcomment / setcomment Get / set the cookie annotation. GetDomain / setdomain Get / set the cookie applicable domain. Generally, cookies only returns the identical server that is exactly the same as sending it. The method here can indicate that the browser returns the cookie to other servers in the same domain. Note that the domain must start with a point (for example, .sitename.com), non-national domain (such as .com, .edu, .gov) must contain two For a point, the country's domain (such as .com.cn, .edu.uk) must contain three points. GetMaxage / setMaxage Get / set the time before the cookie expires, in seconds. If this value is not set, Cookie is only It is valid within the current session, which is valid before the user closes the browser, and these cookies will not be saved to the disk. See below about longLivedCookie. GetName / SetName Get / set the name of the cookie. Essentially, the name and value are us Always care two parts. Because HTTPServletRequest's getCookies method returned to an array of cookie objects, it usually uses a loop to access this array to find a specific name, then check it with getValue. GetPath / setPath Get / setup cookies Applicable The path. If the path is not specified, the cookie will return all pages to the current page where the directory and its subdirectories. The method here can be used to set some more general conditions. For example, SomeCookie.setPath ("/"), At this point, all the pages on the server can receive the cookie. GetSecure / SetSecure Get / set a Boolean value, which represents whether cookies can only be sent by encrypted connections (ie, SSL). GetValue / setValue Gets / set the value of cookies As mentioned earlier, the names and values ​​are actually two aspects we have always cared. However, there are also some exceptions, such as using the name as a logical tag (that is, if the name exists, it means true. GetVersion / SetVersion Gets / Sets the protocol version of the cookies. The default version 0 (complies with the original Netscape specification); version 1 follows RFC 2109, but has not been widely supported. 9.2.3 Setting Cookie cookies in your response head to join the set-cookie response head with the AddCookie method of HttpservletResponse. Here is an example: cookie usercookie = New cookie ("User", "UID1234"); response.addcookie (userCookie); 9.2.4 Read Save to the client to send cookies to the client, first create a cookie, Then send a SET-Cookie HTTP response head with AddCookie. These contents have been described above in Top 2.1. The getCookies method that calls HTTPSERVLETREQUEST when reading cookies from the client. This method returns an array of cookie objects corresponding to content in the HTTP request header. After getting this array, it is generally used to access the individual elements in the loop, call GetName to check the names of each cookie until the target cookie is found. Then, the GetValue is then called to this target cookie, and other processing is performed according to the result. The above processing process often encounters, and provides a getCookieValue method for the convenience meter. Just give the cookie object array, the cookie name, and defaults, the getCookieValue method returns a cookie value that matches the specified name. If you can't find the specified cookie, return the default value. 9.3 Several Cookie Tools Functions are several tool functions. Although these functions are simple, it is useful when dealing with cookies. 9.3.1 Getting a cookie value of the specified name This function is part of ServletUtilities.java. GetCookieValue sequentially accesses the various elements of the cookie object array via a loop, finds a cookie for specifying the name, if you find it, return the value of the cookie; otherwise, return the default value given in the parameter. GetCookieValue can simplify the extraction of the cookie value to a certain extent. public static String getCookievalue (Cookie [] cookies, String cookieName, String defaultvalue) {for (int i = 0; i package hall; import javax.servlet.http *;. public class LongLivedCookie extends Cookie {public static final int SECONDS_PER_YEAR = 60 * 60 * 24 * 365; public LongLivedCookie (String name, String value) {super (name, value); setMaxAge (Seconds_per_Year);}} 9.4. Instance: The custom search engine interface is also an example of a search engine interface, by modifying an example of the front HTTP status code. In this servlet, the user interface is dynamically generated instead of being provided by a static HTML file. In addition to reading form data and sending them to search engines, servlet is sent to the client. When the customer has access to the same form again, these cookies will be used to pre-fill the form, so that the form automatically displays the most recently used data. Searchenginesfrontend.java This servlet constructs a user interface that is primarily made by a form. When the first display, it is similar to the interface provided by the static HTML page. However, the value selected by the user will be saved to the cookie (this page sends the data to the CustomizeDsearchengines Servlet, which is set by the latter). When the user enters the same page in the future, even if the browser is started, the content is automatically filled in the previous search. Note that servlet uses servletutilities.java, where getCookieValue has been introduced, and HeadwithTitle is used to generate a part of the HTML page. In addition, here also used the LongliveCookie class that has been described above, and we use it to create a Cookie for a long waste term. package hall; import java.io. *; import javax.servlet *;. import javax.servlet.http *;. import java.net *;. public class SearchEnginesFrontEnd extends HttpServlet {public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {Cookie [] cookies = request.getCookies (); String searchString = ServletUtilities.getCookievalue (cookies, "searchString", "Java Programming"); String numResults = ServletUtilities.getCookievalue (cookies, "numResults", "10" ); String searchEngine = ServletUtilities.getCookievalue (cookies, "searchEngine", "google"); response.setContentType ( "text / html"); PrintWriter out = response.getWriter (); String title = "Searching the Web"; out .println (servletutilities.headwithtitle (title) \N " " Searching the Web \N " " \ N " " \N " " < Center> \N " " Search String: \ N " " \N " " Results to show per page: \n " " Text \ "name = \" NumResults\ "\N" "value =" NumResults "size = 3> \N" " \N" "Google | \N" " \N " " Infoseek | \N " " \n " " lycos | \N " " \N " " hotbot \ " " \n " " \n " " \ N " " \ N " " \N " " \N " " \n ");} private string checked (String name1, string name2) {if (name1.equals (name2)) Return (" checked ") , Else Return ("");}} CustomizedSearchengines.java SearchenginesFrontend Servlet sends data to the Customizedsearchengines Servlet. This example is similar to the example when introducing the HTTP status code in the previous example, in addition to constructing a targeted Search engine's URL and send a redirection response to the user, and send a cookies that saves user data. package hall; import java.io. *; import javax.servlet *;. import javax.servlet.http *;. import java.net *;. public class CustomizedSearchEngines extends HttpServlet {public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String searchString = request.getParameter ( "searchString"); Cookie searchStringCookie = new LongLivedCookie ( "searchString", searchString); response.addCookie (searchStringCookie); searchString = URLEncoder.encode (searchString); String numResults = request. getParameter ( "numResults"); Cookie numResultsCookie = new LongLivedCookie ( "numResults", numResults); response.addCookie (numResultsCookie); String searchEngine = request.getParameter ( "searchEngine"); Cookie searchEngineCookie = new LongLivedCookie ( "searchEngine", searchEngine ); Response.addcookie; searchspec [] commonspecs = searchspec.getCommonspecs (); for (int i = 0; i For example, several status code indicating "document location has changed" accompanied by a location head, and 401 (Unauthorized) status code must be accompanied by a WWW-Authenticate header. However, even when there is no special sense of state code, the specified response head is also useful. The response head can be used to complete: set cookies, specify the change date, indicating that the browser refreshes the new page according to the specified intervals, declares the length of the document to take advantage of lasting HTTP connection, ... and more many other tasks. Setting the most commonly used method of respondent is HTTPSERVLETRESPONSE's setHead, which has two parameters, indicating the name and value of the response head, respectively. Similar to setting status code, setting the response heads should be performed before sending any document content. The setDateHeader method and the setInTheadr method are specifically used to set the response to the date and integer value. The former avoids the trouble of converting Java time into a GMT time string, and the latter avoids the inclusion of integers into a string. HttpservletResponse also provides a number of simplicity methods for setting up common responses, as follows: setContentType: Sets the Content-Type header. Most servlets use this method. SetContentLength: Sets Content-Length Head. This function is useful for browsers that support persistent HTTP connections. AddCookie: Set a cookie (there is no setcookie method in the Servlet API, because response often contains multiple set-cookie headers). In addition, as described in the previous section, the SendRedirect method sets the local code 302 will also set the location header. 8.2 Common responses and its meaning about HTTP head detailed and complete descriptions, see http://www.w3.org/protocols/ specification. Respondent Description ALOW server supports which request methods (such as get, post, etc.). The encoding method of the Content-Encoding document. Only the content type specified by the Content-Type header can only be obtained after decoding. The use of GZIP compressed documents can significantly reduce the download time of the HTML document. Java's GzipOutPutStream can easily compress Gzip, but only IE 4 on the Netscape and Windows on UNIX, IE 5 supports it. Therefore, servlet should check if the browser supports Gzip by viewing an accept-encoding header ("Accept-encoding")), returning to the Gzip compressed HTML page for other browsers to return to the Gzip-compressed HTML page to support Gzip's browser page. Content-length represents the length of the content. This data is only required when the browser uses a persistent HTTP connection. If you want to use the advantage of a lasting connection, you can write the output document to ByteArrayoutputstram. After the completion is complete, then put this value into the Content-Length header, and finally send content by ByteaRrayStream.Writto (response.getputstream (). Content. Content. Content. Content. Content -Type indicates what MIME type later. Theservlet defaults to Text / Plain, but usually needs to be explicitly designated as Text / HTML. Since CONTENT-TYPE is often set, HTTPSERVLETRESPONSE provides a dedicated method setContentTyep. Date current GMT time. You can use SetDateHeader to set this head to avoid the trouble of conversion time format. When expires should think that the document has expired, no longer cache it? The last change time of the Last-Modified document. Customers can provide a date via the if-modified-since request header, which will be considered a condition GET, and only the change time is later than the document for the specified time, otherwise returns a 304 (Not Modified) state. Last-Modified can also be set with a SetDateHeader method. Location means where the customer should go to extract the document. Location is usually not directly set, but through HttpservletResponse's SendRedirect method, this method simultaneously sets the status code 302. Refresh means that the browser should refresh the document after the browser will refresh the document in seconds. In addition to refreshing the current document, you can let the browser read the specified page by SetHeader ("Refresh", "5; URL = http: // host / path"). Note that this feature is usually achieved by setting , automatic refresh or redirection Those HTML writers that cannot use CGI or servlet are important. However, for servlet, it is more convenient to set the Refresh header. Note that refresh is "refreshing this page after n seconds or access the specified page" instead of "refreshing this page or accesses the specified page every N-second". Therefore, continuous refresh requirements send a Refresh header each time, while sending 204 status code, preventing browsers from continuing to refresh, whether using the refresh head or . Note that the Refresh head is not part of the HTTP 1.1 formal specification, but an extension, but Netscape and IE support it. Server server name. Servlet generally does not set this value, but is set by the web server yourself. Set-cookie settings and page associated cookies. Servlet should not use Response.setHeader ("SET-Cookie", ...), but should use the dedicated method provided by HTTPSERVLETRESPONSE. See the discussion on cookie settings below. WWW-AUTHENTICATE CEO should provide what type of authorization information in the Authorization header? This head is required in the response containing the 401 (Unauthorized) status line. For example, Response.setHeader ("WWW-Authenticate", "Basic Realm = \" Executives\ "). Note that servlet does not perform this process, but allows the Mechanism of the web server to control the access (for example, .htaccess) of the password protection page (for example,. 8.3 Example: Automatic refresh page below when the content change is used to calculate a large number. Because the calculation is very large (for example, 500) may take a lot of time, the servlet will immediately return the result that has been found and continues to calculate in the background. The background is calculated using a lower priority thread to avoid excessive performance of the Web server. If the calculation has not been completed, the servlet will continue to request new content after a few seconds by sending a refresh header. Note that in addition to the use of the HTTP response head, this example also shows the other two very valuable functions of the servlet. First, it indicates that the servlet can handle multiple concurrent connections, each has its own thread. Servlet maintains a VECTOR table for existing prime calculations, and matchs all of these requests by looking at the number of number of numbers (lengths of the pop-up list) and the number of numbers (lengths of each prime) Synchronize to this list. Second, this example is proved that the status information between the request in the servlet is very easy. Maintaining status information is a very troublesome thing in traditional CGI programming. Since the status information is maintained, the browser can access the ongoing calculation process when refreshing the page, and also allows the servlet to save a list of recent request results, when a new request specifies the same parameters as the recently requested parameters Return the result immediately. Primenumbers.java Note that the servlet is used to servletUtilities.java given earlier. Also use: Primelist.java, used to create a VECTOR of a prime number in the background thread; Primes.java, used to randomly generate large numbers of the Biginteger type, check whether they are prone. (This is slightly removed from Primelist.java and Primes. Java. ) Package hall; import java.io. *; import javax.servlet *;. Import javax.servlet.http *;. Import java.util *;. Public class PrimeNumbers extends HttpServlet {private static Vector primeListVector = new Vector (); private static int maxPrimeLists = 30; public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {int numPrimes = ServletUtilities.getIntParameter (request, "numPrimes", 50); int numDigits = ServletUtilities.getIntParameter (request, "numDigits" , 120); primeList primeList = findPrimeList (primeListVector, numPrimes, numDigits); if (primeList == null) {primeList = new primeList (numPrimes, numDigits, true); synchronized (primeListVector) {if (primeListVector.size ()> = maxPrimeLists) primeListVector.removeElementAt (0); primeListVector.addElement (primeList);}} Vector currentPrimes = primeList.getPrimes (); int numCurrentPrimes = currentPrimes.size (); int numPrimesRemaining = (numPrimes - numCurrentPrimes); boolean isLastResult = (numPrimesRemaining == 0); if (isLastResult!) {response.setHeader ( "Refresh", "5");} response.setContentType ( "text / html"); PrintWriter OUT = response.Getwriter (); string title = "Some" Numdigits "-digit prime number"; outputln (servletutilities.headwithtitle (title) \n " " " Title " \N" "< H3> Primes Found with " Numdigits " or more Digits: " NumcurrentPrimes " "" f (islastResult) OUT.PRINTLN (" done search. "); Else Out.println (" STILL LOOKING FOR" NUMPRIMESREMAING "More ... ); Out.Println (" "); for (INT i = 0; i " currentprimes.elementat (i));} out.println (""); Out.println (" < / Html> ");} public void dopost (httpservletRequest request, httpservletResponse response) throws servletexception, ooException {dogt (request, response);} // checks if there is a similar type request (already completed, or being calculated). // The existence is returned to the existing result instead of the new background thread. private PrimeList findPrimeList (Vector primeListVector, int numPrimes, int numDigits) {synchronized (primeListVector) {for (int i = 0; i