JAX-RS @Path Expressions Example

@javax.ws.rs.Path annotation’s value is a URI path template relative to base URI. Its value defines the URI matching pattern for incoming HTTP requests.  The default value of the template parameter matches any text passed in but the template parameters can optionally specify a regular expression used to match their value and are not just limited to simple wildcard matching express.

Dependencies

See @Path annotation for details.

@Path with regular expression to match any digit

One can specify a template parameter within curly braces, for example @Path("{someParam}"). Here somParam is the template parameter and its value can be accessed using @PathParam annotation.

In the below example, @Path("{id: \\d+}"), contains a regular expression to match only digits.

RegularExpressionExamples:

package com.javarticles.rest;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;


@Path("regexExamples")
@Produces(MediaType.TEXT_PLAIN)
public class RegularExpressionExamples {

    @Path("{id: \\d+}")
    @GET
    public String findUserById(@PathParam("id") int userId) {
        return "Find users by id <" + userId + ">";
    }      
}

Enter http://localhost:8280/myapp/regexExamples/123 in browser.

Output:

Find users by id 

@Path with regular expression to match any String

If we want to find the user based on user’s name rather than ID, then we need to use a regular expression that can allow any character from a through z or A through Z, inclusive. For example, @Path("{name: [a-zA-Z]+}").
If we we want to include numeric as well then @Path("{name: [a-zA-Z0-9]+}")

RegularExpressionExamples:

package com.javarticles.rest;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;


@Path("regexExamples")
@Produces(MediaType.TEXT_PLAIN)
public class RegularExpressionExamples {

    @Path("{id: \\d+}")
    @GET
    public String findUserById(@PathParam("id") int userId) {
        return "Find users by id <" + userId + ">";
    } 
    
    @Path("{name: [a-zA-Z]+}")
    @GET
    public String findUserByName(@PathParam("name") String userName) {
        return "Find users by name <" + userName + ">";
    } 
    
    @Path("{name: [a-zA-Z0-9]+}")
    @GET
    public String findUserByNameIdMix(@PathParam("name") String userName) {
        return "Find users by name (mixed) <" + userName + ">";
    }     
}

Enter http://localhost:8280/myapp/regexExamples/John.

Output:

Find users by name 

Enter http://localhost:8280/myapp/regexExamples/John9.

Output:

Find users by name (mixed) 

@Path with multiple template expressions

Regular expressions are not limited in matching one segment of a URI. These template parameters can be embedded anywhere within an @Path declaration.
For example, @Path("{a: \\d+}-{b: \\d+}-{c: \\d+}") contains three segments.

RegularExpressionExamples:

package com.javarticles.rest;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;


@Path("regexExamples")
@Produces(MediaType.TEXT_PLAIN)
public class RegularExpressionExamples {

    @Path("{id: \\d+}")
    @GET
    public String findUserById(@PathParam("id") int userId) {
        return "Find users by id <" + userId + ">";
    } 
    
    @Path("{name: [a-zA-Z]+}")
    @GET
    public String findUserByName(@PathParam("name") String userName) {
        return "Find users by name <" + userName + ">";
    } 
    
    @Path("{name: [a-zA-Z0-9]+}")
    @GET
    public String findUserByNameIdMix(@PathParam("name") String userName) {
        return "Find users by name (mixed) <" + userName + ">";
    } 
    
    @Path("{a: \\d+}-{b: \\d+}-{c: \\d+}")
    @GET
    public String findUserByGroupId(@PathParam("a") int a, @PathParam("b") int b, @PathParam("c") int c) {
        return "Collective ID is " + a + "-" + b + "-" + c;
    } 
}

Enter http://localhost:8280/myapp/regexExamples/123-456-789 in browser.

Output:

Collective ID is 123-456-789

Download the source code

This was an example about using JAX-RS regular expressions in @Path.