In this post under JAXRS Client, I will show with simple example how to use the JAXRS Client API to make a GET request to REST api resource.
Below is the complete code of the example
Main Code
1 package defaultPackage;
2
3 import jakarta.ws.rs.client.Client;
4 import jakarta.ws.rs.client.ClientBuilder;
5 import jakarta.ws.rs.client.Invocation;
6 import jakarta.ws.rs.client.WebTarget;
7 import jakarta.ws.rs.core.Response;
8
9 public class Example1 {
10 public static void main(String[] args) {
11 Client client = ClientBuilder.newClient();
12 WebTarget webTarget = client.target("https://jsonplaceholder.typicode.com/users");
13 Invocation.Builder builder = webTarget.request();
14 Invocation invocation = builder.buildGet();
15 Response response = invocation.invoke();
16 if(response.getStatus() == 200) {
17 System.out.println("Successful");
18 String result = response.readEntity(String.class);
19 System.out.println(result);
20 } else {
21 System.out.println("Failed");
22 }
23 client.close();
24 }
25 }
In the above code, At line 11, we create an instance of “Client” interface taking the help of “ClientBuilder’s” static method “newClient”.
The “Client” interface is the main entry point to JAXRS Client API. Creating and destroying “Client” instance is very expensive and should be reused as much as possible.
At line 12, we use the “Client” instance to create an instance of “WebTarget” interface by calling the “target” method on the “Client” instance.
“WebTarget” instance represents the target to which we are making the request.
Now from the “WebTarget” instance we create an instance of “Invocation.Builder” class.
“Invocation.Builder” as the name represents is used to create an instance of “Invocation” class. This “Invocation.Builder” class follows the Builder pattern.
At line 13, we create an instance of “Invocation.Builder” class by calling “request” method on “WebTarget” instance.
At line 14, we get an instance of “Invocation” interface by calling “buildGet” method on the “Invocation.Builder” instance.
At line 14, we are saying create an instance of “Invocation” class which will handle sending GET request to the target url.
At line 15, we now actually send a GET request to the target url by calling “invoke” method on the “Invocation” instance.
This “invoke” method returns an instance of “Response” abstract class.
At line 16, we check the status of the response by calling “getStatus” method on the “Response” abstract class instance.
If successful, we read the data received from the response by calling “readEntity” method on “Response” abstract class instance. Refer to line 18.
Else we print “Failed” to the console.
At the end, at line 23, we close the “Client” instance. This is required and should not be skipped.
In this way, we can make REST API call using the JAXRS Client API.
Below is the output
Output
Successful
[
{
"id": 1,
"name": "Leanne Graham",
"username": "Bret",
"email": "Sincere@april.biz",
"address": {
"street": "Kulas Light",
"suite": "Apt. 556",
"city": "Gwenborough",
"zipcode": "92998-3874",
"geo": {
"lat": "-37.3159",
"lng": "81.1496"
}
},
"phone": "1-770-736-8031 x56442",
"website": "hildegard.org",
"company": {
"name": "Romaguera-Crona",
"catchPhrase": "Multi-layered client-server neural-net",
"bs": "harness real-time e-markets"
}
},
{
"id": 2,
"name": "Ervin Howell",
"username": "Antonette",
"email": "Shanna@melissa.tv",
"address": {
"street": "Victor Plains",
"suite": "Suite 879",
"city": "Wisokyburgh",
"zipcode": "90566-7771",
"geo": {
"lat": "-43.9509",
"lng": "-34.4618"
}
},
"phone": "010-692-6593 x09125",
"website": "anastasia.net",
"company": {
"name": "Deckow-Crist",
"catchPhrase": "Proactive didactic contingency",
"bs": "synergize scalable supply-chains"
}
},
{
"id": 3,
"name": "Clementine Bauch",
"username": "Samantha",
"email": "Nathan@yesenia.net",
"address": {
"street": "Douglas Extension",
"suite": "Suite 847",
"city": "McKenziehaven",
"zipcode": "59590-4157",
"geo": {
"lat": "-68.6102",
"lng": "-47.0653"
}
},
"phone": "1-463-123-4447",
"website": "ramiro.info",
"company": {
"name": "Romaguera-Jacobson",
"catchPhrase": "Face to face bifurcated interface",
"bs": "e-enable strategic applications"
}
},
{
"id": 4,
"name": "Patricia Lebsack",
"username": "Karianne",
"email": "Julianne.OConner@kory.org",
"address": {
"street": "Hoeger Mall",
"suite": "Apt. 692",
"city": "South Elvis",
"zipcode": "53919-4257",
"geo": {
"lat": "29.4572",
"lng": "-164.2990"
}
},
"phone": "493-170-9623 x156",
"website": "kale.biz",
"company": {
"name": "Robel-Corkery",
"catchPhrase": "Multi-tiered zero tolerance productivity",
"bs": "transition cutting-edge web services"
}
},
{
"id": 5,
"name": "Chelsey Dietrich",
"username": "Kamren",
"email": "Lucio_Hettinger@annie.ca",
"address": {
"street": "Skiles Walks",
"suite": "Suite 351",
"city": "Roscoeview",
"zipcode": "33263",
"geo": {
"lat": "-31.8129",
"lng": "62.5342"
}
},
"phone": "(254)954-1289",
"website": "demarco.info",
"company": {
"name": "Keebler LLC",
"catchPhrase": "User-centric fault-tolerant solution",
"bs": "revolutionize end-to-end systems"
}
},
{
"id": 6,
"name": "Mrs. Dennis Schulist",
"username": "Leopoldo_Corkery",
"email": "Karley_Dach@jasper.info",
"address": {
"street": "Norberto Crossing",
"suite": "Apt. 950",
"city": "South Christy",
"zipcode": "23505-1337",
"geo": {
"lat": "-71.4197",
"lng": "71.7478"
}
},
"phone": "1-477-935-8478 x6430",
"website": "ola.org",
"company": {
"name": "Considine-Lockman",
"catchPhrase": "Synchronised bottom-line interface",
"bs": "e-enable innovative applications"
}
},
{
"id": 7,
"name": "Kurtis Weissnat",
"username": "Elwyn.Skiles",
"email": "Telly.Hoeger@billy.biz",
"address": {
"street": "Rex Trail",
"suite": "Suite 280",
"city": "Howemouth",
"zipcode": "58804-1099",
"geo": {
"lat": "24.8918",
"lng": "21.8984"
}
},
"phone": "210.067.6132",
"website": "elvis.io",
"company": {
"name": "Johns Group",
"catchPhrase": "Configurable multimedia task-force",
"bs": "generate enterprise e-tailers"
}
},
{
"id": 8,
"name": "Nicholas Runolfsdottir V",
"username": "Maxime_Nienow",
"email": "Sherwood@rosamond.me",
"address": {
"street": "Ellsworth Summit",
"suite": "Suite 729",
"city": "Aliyaview",
"zipcode": "45169",
"geo": {
"lat": "-14.3990",
"lng": "-120.7677"
}
},
"phone": "586.493.6943 x140",
"website": "jacynthe.com",
"company": {
"name": "Abernathy Group",
"catchPhrase": "Implemented secondary concept",
"bs": "e-enable extensible e-tailers"
}
},
{
"id": 9,
"name": "Glenna Reichert",
"username": "Delphine",
"email": "Chaim_McDermott@dana.io",
"address": {
"street": "Dayna Park",
"suite": "Suite 449",
"city": "Bartholomebury",
"zipcode": "76495-3109",
"geo": {
"lat": "24.6463",
"lng": "-168.8889"
}
},
"phone": "(775)976-6794 x41206",
"website": "conrad.com",
"company": {
"name": "Yost and Sons",
"catchPhrase": "Switchable contextually-based project",
"bs": "aggregate real-time technologies"
}
},
{
"id": 10,
"name": "Clementina DuBuque",
"username": "Moriah.Stanton",
"email": "Rey.Padberg@karina.biz",
"address": {
"street": "Kattie Turnpike",
"suite": "Suite 198",
"city": "Lebsackbury",
"zipcode": "31428-2261",
"geo": {
"lat": "-38.2386",
"lng": "57.2232"
}
},
"phone": "024-648-3804",
"website": "ambrose.net",
"company": {
"name": "Hoeger LLC",
"catchPhrase": "Centralized empowering task-force",
"bs": "target end-to-end models"
}
}
]
