feature: enable virtual threads, migrate RestTemplate to RestClient, remove stray root properties file

src/main/java/hello/Application.java

@@ -2,7 +2,7 @@
 
 import java.util.Arrays;
 import java.util.List;
-import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import hello.model.Customer;
 import hello.model.Quote;
@@ -14,8 +14,8 @@
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.context.ApplicationContext;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.web.client.RestClient;
 import org.springframework.web.client.RestClientException;
-import org.springframework.web.client.RestTemplate;
 
 @SpringBootApplication
 public class Application implements CommandLineRunner {
@@ -42,7 +42,7 @@ public static void main(String[] args) {
     JdbcTemplate jdbcTemplate;
 
     @Autowired
-    RestTemplate restTemplate;
+    RestClient restClient;
 
     @Override
     public void run(String... args) throws Exception {
@@ -54,10 +54,9 @@ public void run(String... args) throws Exception {
         jdbcTemplate.execute("CREATE TABLE customers(id SERIAL, first_name VARCHAR(255), last_name VARCHAR(255))");
 
         // Split up the array of whole names into an array of first/last names
-        List<Object[]> splitUpNames = Arrays.asList("John Woo", "Jeff Dean", "Josh Bloch", "Josh Long")
-                .stream()
-                .map(name -> name.split(" "))
-                .collect(Collectors.toList());
+        List<Object[]> splitUpNames = Stream.of("John Woo", "Jeff Dean", "Josh Bloch", "Josh Long")
+                .<Object[]>map(name -> name.split(" "))
+                .toList();
 
         // Use a Java 8 stream to print out each tuple of the list
         splitUpNames.forEach(name -> log.info(String.format("Inserting customer record for %s %s", name[0], name[1])));
@@ -80,7 +79,10 @@ public void run(String... args) throws Exception {
      */
     private void logRandomQuote() {
         try {
-            Quote quote = restTemplate.getForObject(QUOTE_URL, Quote.class);
+            Quote quote = restClient.get()
+                    .uri(QUOTE_URL)
+                    .retrieve()
+                    .body(Quote.class);
             log.info(String.valueOf(quote));
         } catch (RestClientException e) {
             log.warn("Could not fetch a quote from {}: {}", QUOTE_URL, e.getMessage());

src/main/java/hello/config/RestClientConfig.java

@@ -0,0 +1,14 @@
+package hello.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestClient;
+
+@Configuration
+public class RestClientConfig {
+
+    @Bean
+    public RestClient restClient(RestClient.Builder builder) {
+        return builder.build();
+    }
+}

src/main/resources/application.properties

@@ -0,0 +1,4 @@
+# Serve each request on a virtual thread (Java 21 + Spring Boot 3.2+).
+spring.threads.virtual.enabled=true
+
+#server.port = 8081