WEBVTT 00:00.050 --> 00:00.620 Hi everyone. 00:00.620 --> 00:01.250 Welcome back. 00:01.250 --> 00:04.580 In this lecture we will go and learn about the new HTTP client. 00:04.580 --> 00:06.230 That's part of modern Java. 00:06.260 --> 00:09.260 I'll start with some theory first and then we'll get to the coding part. 00:09.260 --> 00:13.790 The new HTTP client API got released in Java 11. 00:13.820 --> 00:21.320 The nicest thing about this particular HTTP client is that it has a support for HTTP two and websockets 00:21.350 --> 00:22.340 on top of it. 00:22.340 --> 00:28.820 This client also has the ability to build HTTP clients in synchronous and asynchronous mode. 00:28.820 --> 00:32.210 If you have questions on what does it mean, don't worry about it. 00:32.240 --> 00:34.940 We will be coding both of these types in action. 00:34.970 --> 00:36.260 That's all about the theory part. 00:36.290 --> 00:40.850 With this information, let's jump right in and start coding this HTTP two client. 00:40.850 --> 00:42.410 So I'm back in IntelliJ over here. 00:42.410 --> 00:45.680 So we have this J web server still up and running. 00:45.710 --> 00:50.990 If I go to the browser and then try to hit this endpoint like if I go to movies dot JSON, it still 00:50.990 --> 00:52.280 gives me this response. 00:52.280 --> 00:58.400 And then if I go to the movies by id JSON, this still responds with a valid movie JSON. 00:58.400 --> 01:03.180 So to test our HTTP client, we need to have this J web server up and running. 01:03.180 --> 01:04.500 So I'm back in IntelliJ here. 01:04.500 --> 01:06.840 So we are going to be working on the HTTP client. 01:06.870 --> 01:07.080 Right. 01:07.110 --> 01:13.080 So you will notice the HTTP package under the explorer jar latest Java features project. 01:13.110 --> 01:14.190 So let's go and open that. 01:14.190 --> 01:18.030 And then you will see a representation of our domain class named movie. 01:18.030 --> 01:22.500 So this is a representation of all the properties we have seen in the JSON response. 01:22.500 --> 01:28.620 So if you go to the browser again so the browser has or the JSON has the movie ID name, let's zoom 01:28.620 --> 01:29.310 in a little bit. 01:29.310 --> 01:33.360 So we have the movie ID name here cast and release date. 01:33.360 --> 01:36.510 So this is exactly what we have in this record class. 01:36.510 --> 01:40.890 So what we are going to do is we are going to be making a call to that service, and then we are going 01:40.890 --> 01:43.710 to be parsing the response and map it to this object. 01:43.740 --> 01:44.130 Okay. 01:44.160 --> 01:46.410 So let's go back to the HTTP client. 01:46.410 --> 01:49.140 In this case we have a class named movies client. 01:49.140 --> 01:54.600 So we are going to be working on building functions that's going to interact with these two services. 01:54.600 --> 01:58.260 So in order to save some time what I did was I have created these two constants. 01:58.260 --> 02:04.450 So the first one actually the URL that gives you all the ten movies, that is part of this JSON and 02:04.450 --> 02:07.240 this is the one which is movie id by URL. 02:07.240 --> 02:13.090 This actually calls this movie by id JSON, which actually returns just one single object. 02:13.120 --> 02:13.450 Okay. 02:13.480 --> 02:17.620 So now with this information, what we will do is as part of this lecture, we are going to build a 02:17.620 --> 02:21.430 HTTP client that's going to be interacting with this particular URL. 02:21.430 --> 02:25.000 So the very first thing here is that we are going to create a function which is going to be public. 02:25.000 --> 02:27.850 And this function is going to be returning a movie object. 02:27.880 --> 02:28.150 Okay. 02:28.180 --> 02:32.440 And then the movie function name is going to be get movie by ID. 02:32.650 --> 02:32.830 Okay. 02:32.860 --> 02:36.250 This function is not going to get any method parameters. 02:36.250 --> 02:37.810 It's going to be a simple function. 02:37.810 --> 02:41.320 But this function is going to interact with this particular URL. 02:41.320 --> 02:43.000 So what do we need here right now. 02:43.000 --> 02:44.290 So we need the client. 02:44.290 --> 02:48.220 And then we need the request object using which we can actually pass the URL. 02:48.220 --> 02:50.110 So very first thing is how do we build a client. 02:50.110 --> 02:52.780 So we can actually build a client as a class variable. 02:52.780 --> 02:55.390 So in this case we can call this one as HTTP client. 02:55.390 --> 02:57.970 So HTTP client is part of the Java dot. 02:57.970 --> 02:59.830 Net dot http package. 02:59.830 --> 03:03.610 And then let's name this one as client okay. 03:03.640 --> 03:09.180 And this client has a builder pattern using which we can build a HTTP client. 03:09.180 --> 03:12.090 So in this case so this is the builder right. 03:12.090 --> 03:17.160 And then let's set up a connection timeout just to show you what are the different options that we have. 03:17.160 --> 03:18.960 So in this case we press Dot here. 03:18.960 --> 03:21.540 It gives you all these different options we have. 03:21.570 --> 03:24.450 But in here I'm going to keep this example really simple. 03:24.450 --> 03:27.270 What I'm going to do I'm going to set up a connection timeout. 03:27.300 --> 03:31.050 So in this case it's going to be duration of seconds. 03:31.050 --> 03:33.270 And the number of seconds is going to be two seconds. 03:33.270 --> 03:36.570 So I'm setting up a connection timeout value to be two seconds. 03:36.570 --> 03:38.520 So using the client what can we do. 03:38.550 --> 03:42.090 Let's use this client over here and then press Dot over here. 03:42.120 --> 03:44.250 It's going to give you different options. 03:44.250 --> 03:48.030 So in this case you notice this send and send async. 03:48.030 --> 03:51.960 So send is basically the synchronous way of building the HTTP client. 03:51.960 --> 03:57.360 What does this mean is that when you make this call the calling thread will be blocked until the response 03:57.390 --> 03:58.740 is received from the service. 03:58.740 --> 04:01.260 And then we continue with the code execution. 04:01.260 --> 04:02.070 Send async. 04:02.100 --> 04:05.580 As you can see, the response is going to be of type completablefuture. 04:05.580 --> 04:08.800 So that's the asynchronous way of building a HTTP client. 04:08.800 --> 04:13.300 So we're going to start with a synchronous approach because that is very simple and straightforward. 04:13.300 --> 04:15.640 So we're going to be making a call to this one. 04:15.640 --> 04:19.270 And if you go to the function what it accepts is a HTTP request. 04:19.270 --> 04:23.320 So what we are going to build is we are going to build the HTTP request instance. 04:23.320 --> 04:26.260 And then we need to provide a body handler also. 04:26.290 --> 04:26.590 Okay. 04:26.620 --> 04:31.960 So now I'm going to create a function because we need a HTTP request for different URLs. 04:31.960 --> 04:38.800 So I'm going to create a generic function so that we can use it for both the movies by id URL and all 04:38.800 --> 04:39.520 movies URL. 04:39.550 --> 04:41.410 So I'm going to create a static function. 04:41.410 --> 04:44.800 It's going to be public static HTTP request. 04:44.800 --> 04:48.850 So that's a response or return type of this particular function. 04:48.880 --> 04:53.020 And then I'm going to give a name of this function as request builder okay. 04:53.050 --> 04:55.450 And this function is going to accept a URL. 04:55.480 --> 04:57.250 So in this case string URL. 04:57.280 --> 04:57.730 There you go. 04:57.760 --> 05:00.940 And then we are going to be calling the HTTP request. 05:00.940 --> 05:03.820 So this also have a builder pattern implemented. 05:03.820 --> 05:05.950 So HTTP request dot new builder. 05:05.950 --> 05:10.680 And then you can actually pass the function or the type of HTTP call you want to make. 05:10.710 --> 05:14.580 So in this case it's going to be the get call and then dot build okay. 05:14.610 --> 05:15.780 But this is not enough right. 05:15.780 --> 05:18.780 We need to provide which URL we are going to be interacting with. 05:18.810 --> 05:20.910 So in this case it's going to be URI. 05:20.940 --> 05:23.190 So you can call URI create. 05:23.190 --> 05:25.650 And then we can provide the URL over here. 05:25.650 --> 05:31.200 So this is going to create a HTTP request for any kind of URL that you are going to be calling this 05:31.200 --> 05:31.890 function with. 05:31.890 --> 05:38.700 So in this case we can actually call request builder function and then pass the URL as movie by id url. 05:38.700 --> 05:42.360 So in this case this is going to give you a response as a request. 05:42.360 --> 05:44.910 So this is going to be request over here. 05:45.090 --> 05:45.840 There you go. 05:45.840 --> 05:49.260 And then we are going to be passing that to this one okay. 05:49.290 --> 05:51.930 And after that what is the response body handler. 05:51.930 --> 05:59.940 So if you take a look at HTTP response and then we can actually call dot body handlers. 06:00.420 --> 06:02.730 And then you can actually call off string. 06:02.730 --> 06:04.980 So I'm going to pass the response as a string. 06:05.010 --> 06:11.490 And then we can use some serialization and deserialization library to actually convert that to a movie 06:11.520 --> 06:12.120 object. 06:12.150 --> 06:13.170 Okay, there you go. 06:13.170 --> 06:14.670 And what this is going to return you. 06:14.670 --> 06:17.010 So this is going to return your HTTP response. 06:17.010 --> 06:20.940 So I'm going to name this one as where response equal to this one. 06:20.940 --> 06:25.890 And then I believe we need to add some kind of exception handler over here. 06:25.920 --> 06:30.480 There you go I'm going to have a generic exception block so that we don't have to deal with specific 06:30.480 --> 06:31.950 exceptions at the moment okay. 06:31.980 --> 06:35.430 And then I'm going to add an error to print the actual exception. 06:35.430 --> 06:38.730 But in reality if you are using a logging library you can use a logger. 06:38.760 --> 06:41.760 There are many options available to handle this one. 06:41.790 --> 06:47.040 Now the next option is I want to parse this response object, which is actually returning the response 06:47.040 --> 06:47.790 body as a string. 06:47.790 --> 06:48.240 Right. 06:48.240 --> 06:50.760 We want to convert that to a movie object. 06:50.760 --> 06:52.410 So how can we achieve that? 06:52.410 --> 06:57.180 There are many deserialization and serialization libraries available, but for this specific course 06:57.180 --> 06:59.190 I'm planning to use the Jackson mapper. 06:59.190 --> 07:03.330 So if you go to the build.gradle file over here you will notice this Jackson libraries. 07:03.330 --> 07:10.230 So this Jackson libraries has some API's or library code using which we can convert a string JSON into 07:10.230 --> 07:13.900 a Java object or a Java object to a string JSON. 07:13.900 --> 07:17.620 So in our case we want to convert a string JSON to a Java object. 07:17.620 --> 07:23.140 So I'm going to create an instance of object mapper so that we can use it across this specific class. 07:23.140 --> 07:27.790 So in here let's go ahead and create an object mapper instance private final. 07:27.790 --> 07:31.780 And then I'm going to give the object type as object object mapper over here. 07:31.780 --> 07:34.690 And then equal to new object mapper. 07:34.690 --> 07:39.850 And then we are going to be adding some modules because we are going to be dealing with the local data. 07:39.850 --> 07:44.350 So for the local date parsing and everything to work, what we need to do is we need to register a module. 07:44.380 --> 07:47.890 So in this case we can do I believe we need to provide an instance variable name. 07:47.890 --> 07:48.490 There you go. 07:48.520 --> 07:50.740 And then we are going to call register module. 07:50.740 --> 07:54.490 So in the register module we're going to call new Java type module. 07:54.490 --> 07:57.910 And then we can configure the serialization feature. 07:57.910 --> 08:05.620 So serialization feature needs to be serialization feature and write data with timestamp or write dates 08:05.620 --> 08:07.270 as timestamp. 08:07.300 --> 08:09.880 And then I'm going to provide this flag value as false. 08:10.030 --> 08:10.480 There you go. 08:10.480 --> 08:16.680 So this is a configuration or a basic Jackson configuration that's needed for performing serialization 08:16.680 --> 08:18.660 and deserialization on the Java objects. 08:18.660 --> 08:20.700 In this case, we're going to use the object mapper. 08:20.700 --> 08:26.910 So in here what we can do is after this is done we can do object mapper dot read value. 08:26.940 --> 08:29.160 So in this case it's going to be read value. 08:29.160 --> 08:31.080 And then we're going to get the response body. 08:31.080 --> 08:32.460 So that's exactly what we need. 08:32.460 --> 08:34.650 So in this case response dot body. 08:34.650 --> 08:38.580 And then the value is going to be movie dot class okay. 08:38.580 --> 08:41.100 And then we'll go ahead and return this one. 08:41.250 --> 08:41.730 There you go. 08:41.730 --> 08:47.310 So this is going to take care of performing the string conversion to a movie object and then return 08:47.310 --> 08:47.910 that value. 08:47.910 --> 08:52.200 So just in case if you want to see what's happening in the loggers, what we can do is we can print 08:52.200 --> 08:53.550 the status code over here. 08:53.550 --> 08:57.600 So in this case and we can add the value as status code as. 08:57.630 --> 09:00.810 And then we can call response dot status code. 09:00.810 --> 09:03.000 So this should print the value in the console okay. 09:03.030 --> 09:08.460 So in the case of an error what we can do is we can throw a runtime exception, throw new runtime exception 09:08.460 --> 09:10.080 and then pass the exception into it. 09:10.260 --> 09:10.800 There you go. 09:10.800 --> 09:13.800 So we have successfully built our HTTP client. 09:13.830 --> 09:16.420 Now I'd like to give you a quick recap of what we did. 09:16.420 --> 09:20.770 So the very first thing that we did was we created an instance of the HTTP client. 09:20.770 --> 09:26.260 The way you do it is by calling this new Builder.build and then provide some additional properties to 09:26.260 --> 09:26.410 it. 09:26.410 --> 09:29.440 So this returns you an instance of HTTP client. 09:29.440 --> 09:35.260 So once that is done, what we have after that is the send function call or send function call. 09:35.260 --> 09:41.860 What this call accepts is it accepts a request which is of type HTTP request and then the response body 09:41.890 --> 09:42.400 handler. 09:42.400 --> 09:45.310 So and then what it returns is a HTTP response. 09:45.310 --> 09:49.990 So now from the response body we want to convert that to a movie object. 09:49.990 --> 09:52.120 That's exactly what we are doing over here. 09:52.120 --> 09:54.610 So we are doing that by using the object mapper. 09:54.640 --> 09:57.070 Object mapper is part of the Jackson Library. 09:57.070 --> 10:01.000 And we have created an instance of object mapper over here. 10:01.000 --> 10:03.610 So we have the client ready in the next lecture. 10:03.610 --> 10:08.800 What we'll do is we'll go ahead and test this one by writing a JUnit test case. 10:08.830 --> 10:12.520 I hope you all were able to follow along and create this HTTP client. 10:12.520 --> 10:15.010 In the next lecture we'll go ahead and test this one. 10:15.040 --> 10:16.420 This marks the end of this lecture. 10:16.420 --> 10:17.620 Thank you for watching.