Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 1 00:00:01,130 --> 00:00:02,590 In this video, we're going to cover 2 2 00:00:02,590 --> 00:00:04,833 Spring Inversion of Control. 3 3 00:00:07,410 --> 00:00:09,430 Now in the previous videos, we were working 4 4 00:00:09,430 --> 00:00:11,140 on our application. 5 5 00:00:11,140 --> 00:00:13,523 However, we didn't get it to a hundred percent 6 6 00:00:13,523 --> 00:00:16,910 because we didn't have the support for the configuration. 7 7 00:00:16,910 --> 00:00:19,850 And so we need to make use of an object factory 8 8 00:00:19,850 --> 00:00:22,433 to kind of help us out with this solution. 9 9 00:00:24,170 --> 00:00:26,050 And as I mentioned earlier, this is exactly 10 10 00:00:26,050 --> 00:00:27,820 what Spring comes into play. 11 11 00:00:27,820 --> 00:00:30,960 So Spring provides an object factory so we can have 12 12 00:00:30,960 --> 00:00:34,430 our application talk to Spring, say hey, give me an object. 13 13 00:00:34,430 --> 00:00:37,860 Based on a configuration file or annotation, 14 14 00:00:37,860 --> 00:00:40,840 Spring will give you the appropriate implementation. 15 15 00:00:40,840 --> 00:00:43,270 So then your app is configurable and will have 16 16 00:00:43,270 --> 00:00:46,650 full support for that based on our application requirements. 17 17 00:00:46,650 --> 00:00:47,950 So this looks pretty good. 18 18 00:00:49,590 --> 00:00:51,560 All right, so now we're into some real Spring stuff. 19 19 00:00:51,560 --> 00:00:54,430 So the Spring container, the primary functions 20 20 00:00:54,430 --> 00:00:57,750 of the Spring container is, one, create and manage objects, 21 21 00:00:57,750 --> 00:01:01,170 that's your inversion of control; and then two, 22 22 00:01:01,170 --> 00:01:03,900 inject object's dependencies, and that's what 23 23 00:01:03,900 --> 00:01:06,450 they call dependency injection. 24 24 00:01:06,450 --> 00:01:08,890 Now we'll actually cover all of this in the course. 25 25 00:01:08,890 --> 00:01:11,010 I'll start off with inversion of control, 26 26 00:01:11,010 --> 00:01:12,960 and then the following videos we'll actually get 27 27 00:01:12,960 --> 00:01:15,183 into dependency injection. 28 28 00:01:17,720 --> 00:01:20,430 There's three ways of configuring the Spring container. 29 29 00:01:20,430 --> 00:01:23,140 One is by using an XML configuration file, 30 30 00:01:23,140 --> 00:01:25,490 the other is using Java annotations. 31 31 00:01:25,490 --> 00:01:28,130 And then finally, you can make use of Java source code. 32 32 00:01:28,130 --> 00:01:30,540 And we'll actually cover all of these approaches 33 33 00:01:30,540 --> 00:01:33,220 or all of these techniques in this course. 34 34 00:01:33,220 --> 00:01:35,720 So let's talk about the XML configuration file. 35 35 00:01:35,720 --> 00:01:37,930 It's the original configuration file 36 36 00:01:37,930 --> 00:01:39,750 that was used when Spring was first released, 37 37 00:01:39,750 --> 00:01:42,160 so it's legacy, but we'll still cover it 38 38 00:01:42,160 --> 00:01:44,780 because most legacy apps still use this. 39 39 00:01:44,780 --> 00:01:47,880 So if you're joining a Spring team or you're joining 40 40 00:01:47,880 --> 00:01:50,503 a company that has existing Spring applications, 41 41 00:01:50,503 --> 00:01:54,730 it's a very high likelihood that their applications 42 42 00:01:54,730 --> 00:01:56,590 still use XML config files. 43 43 00:01:56,590 --> 00:01:58,410 So we'll start off with that. 44 44 00:01:58,410 --> 00:02:00,890 Also, Java annotation is kind of like the latest fad, 45 45 00:02:00,890 --> 00:02:03,290 the latest fashion, making annotations. 46 46 00:02:03,290 --> 00:02:05,910 And also, you can actually get rid of all config files 47 47 00:02:05,910 --> 00:02:07,210 and you can configure the container 48 48 00:02:07,210 --> 00:02:09,160 by using Java source code. 49 49 00:02:09,160 --> 00:02:12,160 But again, we're going to cover all of these techniques 50 50 00:02:12,160 --> 00:02:14,410 so you'll understand how each one of them works 51 51 00:02:14,410 --> 00:02:15,743 for your application. 52 52 00:02:18,090 --> 00:02:20,450 All right, so here's the Spring development process. 53 53 00:02:20,450 --> 00:02:21,870 And as you know, I luv to do lists, 54 54 00:02:21,870 --> 00:02:23,250 I luv step-by-step approaches. 55 55 00:02:23,250 --> 00:02:26,710 So the first step is configuring your Spring beans. 56 56 00:02:26,710 --> 00:02:29,940 The second step is creating a Spring container. 57 57 00:02:29,940 --> 00:02:31,840 And then the third step is retrieving 58 58 00:02:31,840 --> 00:02:33,730 the beans from the container. 59 59 00:02:33,730 --> 00:02:36,180 And we'll actually cover all of this step by step 60 60 00:02:36,180 --> 00:02:37,940 so you'll see how everything works, 61 61 00:02:37,940 --> 00:02:39,840 and we'll do all of this from scratch. 62 62 00:02:42,650 --> 00:02:44,040 All right, so let's start with step one, 63 63 00:02:44,040 --> 00:02:45,640 configuring your Spring beans. 64 64 00:02:45,640 --> 00:02:46,887 So in this example, I'm going to make use 65 65 00:02:46,887 --> 00:02:49,540 of the XML configuration file. 66 66 00:02:49,540 --> 00:02:51,160 So here in the XML config file 67 67 00:02:51,160 --> 00:02:54,820 called applicationContext.xml, I have a bean. 68 68 00:02:54,820 --> 00:02:57,690 I give the actual bean id, myCoach, 69 69 00:02:57,690 --> 00:02:58,790 and then I give the class. 70 70 00:02:58,790 --> 00:03:02,140 And that's the fully qualified name of the Java class. 71 71 00:03:02,140 --> 00:03:05,980 So the id, that's simply the id that your Java application 72 72 00:03:05,980 --> 00:03:08,890 will use when they want to retrieve a beam 73 73 00:03:08,890 --> 00:03:10,910 from the Spring container. 74 74 00:03:10,910 --> 00:03:14,150 And again, class is the actual class or implementation 75 75 00:03:14,150 --> 00:03:16,543 that you'll have for your application. 76 76 00:03:21,630 --> 00:03:23,010 Okay, so let's move to step two. 77 77 00:03:23,010 --> 00:03:25,500 So step two is creating a Spring container. 78 78 00:03:25,500 --> 00:03:28,480 So in the Spring world, a Spring container is generally 79 79 00:03:28,480 --> 00:03:31,400 known as an ApplicationContext. 80 80 00:03:31,400 --> 00:03:33,600 So that's the term that you'll see a lot 81 81 00:03:33,600 --> 00:03:36,120 in Spring documentation and in Spring apps. 82 82 00:03:36,120 --> 00:03:38,870 So they have specialized implementations of it, 83 83 00:03:38,870 --> 00:03:41,300 one for reading XML from the class path, 84 84 00:03:41,300 --> 00:03:45,320 an AnnotationConfig, a WebApplicationContext and so on. 85 85 00:03:45,320 --> 00:03:48,073 And we'll take a look at all of these in this course. 86 86 00:03:51,420 --> 00:03:53,130 All righty, so creating the Spring container. 87 87 00:03:53,130 --> 00:03:55,620 So in this example, I'm going to read an XML file 88 88 00:03:55,620 --> 00:03:57,100 that's on my class path. 89 89 00:03:57,100 --> 00:04:01,670 So I make use of this ClassPathXmlApplicationContext. 90 90 00:04:01,670 --> 00:04:04,060 And I construct this object and I pass in 91 91 00:04:04,060 --> 00:04:06,900 the actual name of the configuration file 92 92 00:04:06,900 --> 00:04:08,030 that I'm using for Spring. 93 93 00:04:08,030 --> 00:04:09,420 So from step one, 94 94 00:04:09,420 --> 00:04:12,133 we had a file called applicationContext.xml. 95 95 00:04:14,070 --> 00:04:15,400 You can use any name that you want 96 96 00:04:15,400 --> 00:04:17,910 as long as you're consistent between step one and step two 97 97 00:04:17,910 --> 00:04:20,543 as far as reading that configuration file. 98 98 00:04:21,850 --> 00:04:24,150 All right, so we have this container create it. 99 99 00:04:24,150 --> 00:04:26,290 Now the next step is retrieving the beans 100 100 00:04:26,290 --> 00:04:27,400 from the container. 101 101 00:04:27,400 --> 00:04:29,780 So your application is simply going to talk 102 102 00:04:29,780 --> 00:04:32,240 to the Spring container and say hey, 103 103 00:04:32,240 --> 00:04:34,000 give me a coach object. 104 104 00:04:34,000 --> 00:04:36,690 And based on information in the configuration file, 105 105 00:04:36,690 --> 00:04:41,283 it'll give you an implementation of that given interface. 106 106 00:04:42,470 --> 00:04:44,240 So here's step three as far as code. 107 107 00:04:44,240 --> 00:04:47,320 So the previous line we already created our context, 108 108 00:04:47,320 --> 00:04:50,090 now we retrieve the bean from the container. 109 109 00:04:50,090 --> 00:04:53,920 So here I say context.getBean, 110 110 00:04:53,920 --> 00:04:56,493 and here I say myCoach comma Coach.class. 111 111 00:04:58,410 --> 00:05:01,290 So myCoach relates to the actual bean id 112 112 00:05:01,290 --> 00:05:03,820 to find in the configuration file. 113 113 00:05:03,820 --> 00:05:05,280 You have to make sure those match up 114 114 00:05:05,280 --> 00:05:07,090 with the exact same case. 115 115 00:05:07,090 --> 00:05:10,530 And then Coach.class, that's the name of the actual 116 116 00:05:10,530 --> 00:05:14,370 interface that BaseballCoach implements. 117 117 00:05:14,370 --> 00:05:17,742 So here, Coach.class is the interface, 118 118 00:05:17,742 --> 00:05:20,770 BaseballCoach is the actual implementation. 119 119 00:05:20,770 --> 00:05:21,850 And then you assign it. 120 120 00:05:21,850 --> 00:05:23,210 And that's basically what you have to do 121 121 00:05:23,210 --> 00:05:27,723 for retrieving a bean from a Spring container. 122 122 00:05:30,990 --> 00:05:33,150 All righty, so that's the coding here. 123 123 00:05:33,150 --> 00:05:35,930 In the next video, we're actually going to move into Eclipse. 124 124 00:05:35,930 --> 00:05:38,060 We'll get our hands dirty, and we'll actually write 125 125 00:05:38,060 --> 00:05:39,100 this code and we'll run it, 126 126 00:05:39,100 --> 00:05:41,490 and then we'll actually see it in action. 127 127 00:05:41,490 --> 00:05:42,953 So woohoo! 11247