WEBVTT 1 00:00:00.613 --> 00:00:03.198 Hey, welcome back. 2 00:00:03.198 --> 00:00:05.863 This is part two on our discussion on Bean Scopes, 3 00:00:05.863 --> 00:00:10.030 so here we'll pick up with Session Scope and Request Scope. 4 00:00:12.624 --> 00:00:15.102 The next scope we have is Session Scope. 5 00:00:15.102 --> 00:00:16.834 Now, this scope is used when you need 6 00:00:16.834 --> 00:00:19.110 to keep track of a user's actions. 7 00:00:19.110 --> 00:00:20.740 So the bean is created once for 8 00:00:20.740 --> 00:00:23.991 the user's browser session, and it's unique for this user. 9 00:00:23.991 --> 00:00:25.569 Again, you want to keep track of 10 00:00:25.569 --> 00:00:27.777 a user's individual actions, so 11 00:00:27.777 --> 00:00:29.992 as an example, a shopping cart, 12 00:00:29.992 --> 00:00:32.524 online banking, or online exam, 13 00:00:32.524 --> 00:00:34.582 here you need to keep track of information 14 00:00:34.582 --> 00:00:37.385 for a given user; a specific user, 15 00:00:37.385 --> 00:00:40.537 not for everyone in the application. 16 00:00:40.537 --> 00:00:44.704 And that's a very practical use of the Session Scope. 17 00:00:45.678 --> 00:00:46.968 Alright, so let's take a look at 18 00:00:46.968 --> 00:00:49.867 a Session Scope code example, so again, 19 00:00:49.867 --> 00:00:51.816 we're gonna return to this form 20 00:00:51.816 --> 00:00:53.474 to interact with the bean, where we have 21 00:00:53.474 --> 00:00:56.340 a counter value and an increment button. 22 00:00:56.340 --> 00:00:58.334 So in the code here for this file: 23 00:00:58.334 --> 00:01:02.341 counter_one.xhtml, we display the counter value, 24 00:01:02.341 --> 00:01:04.382 and then move down to the form, 25 00:01:04.382 --> 00:01:06.270 and we simply have a command button 26 00:01:06.270 --> 00:01:08.119 with the value of Increment, and 27 00:01:08.119 --> 00:01:11.639 then the action here will say counterOne.increment. 28 00:01:11.639 --> 00:01:14.675 So we're gonna call a method on this CounterOne bean. 29 00:01:14.675 --> 00:01:16.081 Okay, so let's go ahead and look at 30 00:01:16.081 --> 00:01:18.128 the source code here for our bean. 31 00:01:18.128 --> 00:01:20.501 So, for our bean, to make use of Session Scope 32 00:01:20.501 --> 00:01:22.660 we add a special annotation on it, 33 00:01:22.660 --> 00:01:25.326 say @SessionScoped, and so here's 34 00:01:25.326 --> 00:01:29.301 our bean called CounterOne, so public class CounterOne. 35 00:01:29.301 --> 00:01:31.516 And we'll have our normal method for increment, 36 00:01:31.516 --> 00:01:33.423 which will simply increment the value 37 00:01:33.423 --> 00:01:35.381 of the counter by one, and will return 38 00:01:35.381 --> 00:01:38.380 the actual name of the page that we wanna show, CounterOne. 39 00:01:38.380 --> 00:01:40.336 So the key here is that annotation 40 00:01:40.336 --> 00:01:42.350 at the beginning: @SessionScoped, 41 00:01:42.350 --> 00:01:43.889 so this bean will be created once 42 00:01:43.889 --> 00:01:45.670 for the user's browser session, 43 00:01:45.670 --> 00:01:48.820 and it's unique for this given user. 44 00:01:48.820 --> 00:01:50.818 Alright, so let's go ahead and take a look at 45 00:01:50.818 --> 00:01:54.068 a code example using the Session Scope. 46 00:01:55.322 --> 00:01:56.749 Now, let's go ahead and take a look 47 00:01:56.749 --> 00:01:59.003 at the Session Scope demo, so again, 48 00:01:59.003 --> 00:02:00.864 moving back into Eclipse, making 49 00:02:00.864 --> 00:02:02.729 use of the same project as before, 50 00:02:02.729 --> 00:02:05.748 bean-demo, I move into the web content directory, 51 00:02:05.748 --> 00:02:09.915 and now I'll take a look at the file counter_one.xhtml. 52 00:02:11.090 --> 00:02:13.006 So this is my example where I'll simply 53 00:02:13.006 --> 00:02:15.506 make use of the Session Scope. 54 00:02:16.946 --> 00:02:18.928 So on line 17, I simply display 55 00:02:18.928 --> 00:02:22.907 the value of the bean at that time, counterOne.value, 56 00:02:22.907 --> 00:02:25.490 on lines 21-24, I have the form 57 00:02:26.520 --> 00:02:28.900 for my increment button, and the action 58 00:02:28.900 --> 00:02:32.274 here is counterOne.increment, so we'll 59 00:02:32.274 --> 00:02:36.357 call the increment method on the CounterOne bean. 60 00:02:39.529 --> 00:02:40.727 Okay, so let's go ahead and look 61 00:02:40.727 --> 00:02:42.859 at the code here for the CounterOne bean. 62 00:02:42.859 --> 00:02:45.783 So, moving up here, CounterOne.java, 63 00:02:45.783 --> 00:02:49.365 let me expand the window here so we can see everything, 64 00:02:49.365 --> 00:02:52.305 and on lines six-eight, that's our Managedbean. 65 00:02:52.305 --> 00:02:54.452 Session Scope CounterOne. 66 00:02:54.452 --> 00:02:55.880 The important thing to notice here 67 00:02:55.880 --> 00:02:58.081 is in line seven, SessionScoped, so 68 00:02:58.081 --> 00:03:00.443 that means that this bean will be created, 69 00:03:00.443 --> 00:03:03.888 and it will be unique for a given user of our application. 70 00:03:03.888 --> 00:03:06.212 So each user will have their own bean 71 00:03:06.212 --> 00:03:09.212 that'll have their own counter value. 72 00:03:09.212 --> 00:03:11.785 On line 10 I set up the value=0, 73 00:03:11.785 --> 00:03:14.681 and lines 12-16 I have the increment method 74 00:03:14.681 --> 00:03:16.678 that we've seen before, so on line 13 75 00:03:16.678 --> 00:03:20.845 we say value++, we simply increment the value by one. 76 00:03:22.484 --> 00:03:25.060 Now let's go ahead and run the application. 77 00:03:25.060 --> 00:03:27.406 I'll move down to my form here, 78 00:03:27.406 --> 00:03:30.406 counter_one.xhtml, I'll right click, 79 00:03:31.827 --> 00:03:34.410 I'll say Run As, Run on Server. 80 00:03:39.793 --> 00:03:41.173 And this will run the application 81 00:03:41.173 --> 00:03:44.221 and it'll show us our Session Scope test page. 82 00:03:44.221 --> 00:03:48.057 Again, I'd like to go ahead and copy this URL, 83 00:03:48.057 --> 00:03:52.869 and I wanna open it up in one of our real browsers. 84 00:03:52.869 --> 00:03:57.036 So here I have Firefox on the left and Chrome on the right. 85 00:03:58.470 --> 00:04:02.637 I'll go ahead and paste the URL into the Firefox browser, 86 00:04:03.671 --> 00:04:05.117 and now I just do an increment, 87 00:04:05.117 --> 00:04:06.543 and so notice here it's incrementing, 88 00:04:06.543 --> 00:04:08.794 and it works out fine as desired. 89 00:04:08.794 --> 00:04:10.170 Now let me do a similar thing, 90 00:04:10.170 --> 00:04:13.670 dropping this URL into the Chrome browser, 91 00:04:17.136 --> 00:04:18.336 and I'll go through, and note here 92 00:04:18.336 --> 00:04:20.923 Counter value is zero, 93 00:04:20.923 --> 00:04:23.656 because this Chrome browser represents a new user, 94 00:04:23.656 --> 00:04:26.327 so each user, or in this case, each browser 95 00:04:26.327 --> 00:04:29.341 has its own Counter value, so we're 96 00:04:29.341 --> 00:04:32.696 using a different browser to simulate a different user, 97 00:04:32.696 --> 00:04:34.691 so it's almost like each user's in, 98 00:04:34.691 --> 00:04:37.129 is accessing our application, with 99 00:04:37.129 --> 00:04:38.884 their own shopping cart, and so they 100 00:04:38.884 --> 00:04:40.398 have their own unique value. 101 00:04:40.398 --> 00:04:42.128 And this is great, so this is primarily 102 00:04:42.128 --> 00:04:44.167 for using it with like a shopping cart, 103 00:04:44.167 --> 00:04:46.839 or an online test, or like online banking. 104 00:04:46.839 --> 00:04:48.242 You wanna make sure the user's actions 105 00:04:48.242 --> 00:04:50.825 are unique for that given user. 106 00:04:52.015 --> 00:04:53.130 Now let's take a look at our next 107 00:04:53.130 --> 00:04:55.468 example using a Request Scope. 108 00:04:55.468 --> 00:04:57.189 So with Request Scope, a new bean 109 00:04:57.189 --> 00:04:59.510 is created for every web request, 110 00:04:59.510 --> 00:05:01.884 so these beans are simply short-lived. 111 00:05:01.884 --> 00:05:04.523 It's commonly used for submitting form data, 112 00:05:04.523 --> 00:05:06.466 and it's really a one-time use, 113 00:05:06.466 --> 00:05:08.076 once you submit the data, it's 114 00:05:08.076 --> 00:05:10.425 used for that one request and then thrown away. 115 00:05:10.425 --> 00:05:13.040 They don't keep track of it over any period of time. 116 00:05:13.040 --> 00:05:15.130 An important thing to note here is that this is 117 00:05:15.130 --> 00:05:19.447 the default Scope for a bean if you don't specify it. 118 00:05:19.447 --> 00:05:21.757 Alright, so let's look at a code example here. 119 00:05:21.757 --> 00:05:24.029 We're gonna start off with our Counter value again, 120 00:05:24.029 --> 00:05:25.597 with our Increment button, and so 121 00:05:25.597 --> 00:05:28.717 on our code here for counter_three.xhtml, 122 00:05:28.717 --> 00:05:32.540 we have the command action: counterThree.increment. 123 00:05:32.540 --> 00:05:36.707 So it'll call the increment method on our counterThree bean. 124 00:05:40.541 --> 00:05:43.509 So here's the code example for this Request Scope. 125 00:05:43.509 --> 00:05:46.781 Here, a new bean's gonna be created for every request. 126 00:05:46.781 --> 00:05:49.572 So we have our bean called CounterThree, 127 00:05:49.572 --> 00:05:53.046 and then, note the new annotation here: @RequestScoped, 128 00:05:53.046 --> 00:05:54.522 so this basically says that this bean 129 00:05:54.522 --> 00:05:56.639 will only be used for this one web request, 130 00:05:56.639 --> 00:05:58.090 and then we'll throw it away. 131 00:05:58.090 --> 00:06:00.427 And again remember, this is the default scope 132 00:06:00.427 --> 00:06:03.427 if you don't explicitly specify one. 133 00:06:05.305 --> 00:06:07.322 Well, let's go ahead and look at a code demo 134 00:06:07.322 --> 00:06:10.072 here of using this Request Scope. 135 00:06:12.132 --> 00:06:14.223 Let's go ahead and move back into Eclipse, 136 00:06:14.223 --> 00:06:16.209 and let's take a look at this Request demo. 137 00:06:16.209 --> 00:06:17.902 So again, we're gonna use the same 138 00:06:17.902 --> 00:06:20.670 project as before: bean-demo. 139 00:06:20.670 --> 00:06:21.720 And I'm gonna look at this file 140 00:06:21.720 --> 00:06:25.150 here called counter_three.xhtml. 141 00:06:25.150 --> 00:06:26.720 So this is the file that we'll use 142 00:06:26.720 --> 00:06:28.970 for our Request Scope Test. 143 00:06:30.096 --> 00:06:32.156 So again, follow the similar format, 144 00:06:32.156 --> 00:06:36.729 on line 17 we simply display the value of the counter, 145 00:06:36.729 --> 00:06:39.396 lines 21-24 is our form, and our 146 00:06:40.295 --> 00:06:43.500 action is counterThree.increment, 147 00:06:43.500 --> 00:06:47.667 so we'll call the increment method on the CounterThree bean. 148 00:06:51.680 --> 00:06:53.699 Now let's go look at that CounterThree bean. 149 00:06:53.699 --> 00:06:57.449 So in my source directory, CounterThree.java, 150 00:06:58.503 --> 00:07:01.048 I'll expand the window here, 151 00:07:01.048 --> 00:07:03.716 lines six-eight is our class counter bean 152 00:07:03.716 --> 00:07:05.385 which is a ManagedBean. 153 00:07:05.385 --> 00:07:07.419 Note: on line seven we have it listed 154 00:07:07.419 --> 00:07:10.629 as RequestScoped, so this bean will only be used 155 00:07:10.629 --> 00:07:13.043 for the current web request, and then thrown away, 156 00:07:13.043 --> 00:07:16.126 so it'll create a new one every time. 157 00:07:18.560 --> 00:07:21.523 So then we move down, say private value=0, 158 00:07:21.523 --> 00:07:24.184 we have our increment method, just like we've seen before, 159 00:07:24.184 --> 00:07:27.198 returns counter_three, and that's pretty much it. 160 00:07:27.198 --> 00:07:28.620 Now the important thing on line seven 161 00:07:28.620 --> 00:07:30.872 is that, if you don't specify a Scope, 162 00:07:30.872 --> 00:07:33.147 by default, it's Request Scope, 163 00:07:33.147 --> 00:07:34.679 so all of the examples that we've used 164 00:07:34.679 --> 00:07:37.463 in the previous videos, we didn't specify a Scope, 165 00:07:37.463 --> 00:07:39.779 so they all defaulted to Request Scope. 166 00:07:39.779 --> 00:07:43.946 So Request Scope is good for using one-time only form data. 167 00:07:47.337 --> 00:07:49.562 Alright, so let's go ahead and run the application. 168 00:07:49.562 --> 00:07:52.880 I'll choose the file counter_three.xhtml, 169 00:07:52.880 --> 00:07:55.781 I'll do a right click, I'll choose Run As, 170 00:07:55.781 --> 00:07:58.281 and I'll choose Run on Server. 171 00:08:03.456 --> 00:08:05.387 And this will fire it up, again we'll see 172 00:08:05.387 --> 00:08:07.339 our information here in the browser, 173 00:08:07.339 --> 00:08:09.256 I'll go ahead and copy this URL, 174 00:08:09.256 --> 00:08:11.861 just like I did before, now I'll 175 00:08:11.861 --> 00:08:16.028 move back to my regular browsers, Chrome and Firefox, 176 00:08:17.098 --> 00:08:18.835 and what I'll do here is I'll just drop 177 00:08:18.835 --> 00:08:21.430 in that URL, so I'll paste the URL into 178 00:08:21.430 --> 00:08:24.853 the Firefox browser, and then I'll just test it out, 179 00:08:24.853 --> 00:08:26.487 I'll hit Increment, and note here, 180 00:08:26.487 --> 00:08:27.769 what's really interesting here is 181 00:08:27.769 --> 00:08:30.178 that the Counter value stays at one, 182 00:08:30.178 --> 00:08:32.635 so it's doesn't keep track of the Counter Value 183 00:08:32.635 --> 00:08:35.171 over multiple web requests, so remember, 184 00:08:35.171 --> 00:08:37.981 the Request Scope, it's a one-time use only, 185 00:08:37.981 --> 00:08:40.616 they use it for one web request and throw it away, 186 00:08:40.616 --> 00:08:42.963 so effectively here, the bean is being thrown away 187 00:08:42.963 --> 00:08:44.889 and starting from scratch every time, 188 00:08:44.889 --> 00:08:47.703 so there's no history that's maintained, nothing per user, 189 00:08:47.703 --> 00:08:50.963 per application, it's simply per web request. 190 00:08:50.963 --> 00:08:53.390 So this is great for sending one-time form data, 191 00:08:53.390 --> 00:08:54.959 when you don't need to send any history. 192 00:08:54.959 --> 00:08:59.126 So most of your standard forms will be Request Scope. 193 00:09:02.914 --> 00:09:05.925 Well great, we can go ahead and wrap up this video. 194 00:09:05.925 --> 00:09:09.364 So in summary, we defined the Scopes for ManagedBeans, 195 00:09:09.364 --> 00:09:11.561 we also made use of the three most common 196 00:09:11.561 --> 00:09:16.320 Scopes: Application Scope, Session Scope, and Request Scope, 197 00:09:16.320 --> 00:09:19.605 and we followed each of them up with a real example. 198 00:09:19.605 --> 00:09:23.438 So this is some really good stuff, great work.