Add start of Java Web Build Examples page (#3274)

Simple hello-world projects using Spring Boot and Jetty. We can expand
it more in future

build.sc

@@ -1194,6 +1194,7 @@ object example extends MillScalaModule {
   object cross extends Cross[ExampleCrossModule](listIn(millSourcePath / "cross"))
   object misc extends Cross[ExampleCrossModule](listIn(millSourcePath / "misc"))
   object web extends Cross[ExampleCrossModule](listIn(millSourcePath / "web"))
+  object javaweb extends Cross[ExampleCrossModule](listIn(millSourcePath / "javaweb"))
 
   trait ExampleCrossModuleJava extends ExampleCrossModule {
 

docs/modules/ROOT/nav.adoc

@@ -16,6 +16,7 @@
 * xref:Java_Builtin_Commands.adoc[]
 * xref:Java_Build_Examples.adoc[]
 * xref:Java_Module_Config.adoc[]
+* xref:Java_Web_Build_Examples.adoc[]
 
 // This section is all about developing a deeper understanding of specific
 // topics in Mill. This is the opposite of `Quick Start` above: while we touch

docs/modules/ROOT/pages/Java_Web_Build_Examples.adoc

@@ -0,0 +1,18 @@
+= Web Build Examples
+
+This page contains examples of using Mill as a build tool for web-applications.
+It covers setting up a basic backend server with a variety of server frameworks
+
+== Jetty Hello World App
+
+include::example/javaweb/1-hello-jetty.adoc[]
+
+
+== Spring Boot Hello World App
+
+include::example/javaweb/2-hello-spring-boot.adoc[]
+
+== Spring Boot TodoMvc App
+
+include::example/javaweb/3-todo-spring-boot.adoc[]
+

example/javaweb/1-hello-jetty/build.sc

@@ -0,0 +1,28 @@
+import mill._, javalib._, publish._
+
+object hello extends RootModule with JavaModule {
+  def ivyDeps = Agg(
+    ivy"org.eclipse.jetty:jetty-server:9.4.43.v20210629",
+    ivy"javax.servlet:javax.servlet-api:4.0.1"
+  )
+
+  object test extends JavaModuleTests with TestModule.Junit4
+}
+
+// This example demonstrates how to set up a simple Jetty webserver,
+// able to handle a single HTTP request at `/` and reply with a single response.
+
+
+/** Usage
+
+> mill test
+...HelloJettyTest.testHelloJetty finished...
+
+> mill runBackground
+
+> curl http://localhost:8085
+...<h1>Hello, World!</h1>...
+
+> mill clean runBackground
+
+*/

example/javaweb/1-hello-jetty/resources/application.properties

@@ -0,0 +1 @@
+server.port=8084

example/javaweb/1-hello-jetty/src/HelloJetty.java

@@ -0,0 +1,24 @@
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.Request;
+import org.eclipse.jetty.server.handler.AbstractHandler;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+public class HelloJetty extends AbstractHandler {
+
+  public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException {
+    response.setContentType("text/html; charset=utf-8");
+    response.setStatus(HttpServletResponse.SC_OK);
+    baseRequest.setHandled(true);
+    response.getWriter().println("<h1>Hello, World!</h1>");
+  }
+
+  public static void main(String[] args) throws Exception {
+    Server server = new Server(8085);
+    server.setHandler(new HelloJetty());
+    server.start();
+    server.join();
+  }
+}

example/javaweb/1-hello-jetty/test/src/HelloJettyTest.java

@@ -0,0 +1,52 @@
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.server.handler.HandlerList;
+import org.eclipse.jetty.server.handler.HandlerWrapper;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+import static org.junit.Assert.assertEquals;
+
+public class HelloJettyTest {
+  private Server server;
+  private int port;
+
+  @Before
+  public void setUp() throws Exception {
+    server = new Server();
+    ServerConnector connector = new ServerConnector(server);
+    connector.setPort(0); // dynamically assign port
+    server.addConnector(connector);
+
+    HandlerList handlers = new HandlerList();
+    handlers.addHandler(new HelloJetty());
+    server.setHandler(handlers);
+
+    server.start();
+    port = connector.getLocalPort();
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    if (server != null) {
+      server.stop();
+    }
+  }
+
+  @Test
+  public void testHelloJetty() throws IOException {
+    URL url = new URL("http://localhost:" + port + "/");
+    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+
+    connection.setRequestMethod("GET");
+    connection.connect();
+
+    int responseCode = connection.getResponseCode();
+    assertEquals(HttpURLConnection.HTTP_OK, responseCode);
+  }
+}

example/javaweb/2-hello-spring-boot/build.sc

@@ -0,0 +1,32 @@
+import mill._, javalib._, publish._
+
+object hello extends RootModule with JavaModule {
+  def ivyDeps = Agg(
+    ivy"org.springframework.boot:spring-boot-starter-web:2.5.6",
+    ivy"org.springframework.boot:spring-boot-starter-actuator:2.5.6"
+  )
+
+  object test extends JavaModuleTests with TestModule.Junit5 {
+    def ivyDeps = super.ivyDeps() ++ Agg(
+      ivy"org.springframework.boot:spring-boot-starter-test:2.5.6"
+    )
+  }
+}
+
+// This example demonstrates how to set up a simple Spring Boot webserver,
+// able to handle a single HTTP request at `/` and reply with a single response.
+
+
+/** Usage
+
+> mill test
+...com.example.HelloSpringBootTest#shouldReturnDefaultMessage() finished...
+
+> mill runBackground
+
+> curl http://localhost:8086
+...<h1>Hello, World!</h1>...
+
+> mill clean runBackground
+
+*/

example/javaweb/2-hello-spring-boot/resources/application.properties

@@ -0,0 +1 @@
+server.port=8086

example/javaweb/2-hello-spring-boot/src/HelloSpringBoot.java

@@ -0,0 +1,22 @@
+package com.example;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@SpringBootApplication
+public class HelloSpringBoot {
+
+  public static void main(String[] args) {
+    SpringApplication.run(HelloSpringBoot.class, args);
+  }
+
+  @RestController
+  class HelloController {
+    @GetMapping("/")
+    public String hello() {
+      return "<h1>Hello, World!</h1>";
+    }
+  }
+}

example/javaweb/2-hello-spring-boot/test/src/HelloSpringBootTest.java

@@ -0,0 +1,24 @@
+package com.example;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.web.server.LocalServerPort;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class HelloSpringBootTest {
+
+  @LocalServerPort
+  private int port;
+
+  @Autowired
+  private TestRestTemplate restTemplate;
+
+  @Test
+  public void shouldReturnDefaultMessage() {
+    String response = restTemplate.getForObject("http://localhost:" + port + "/", String.class);
+    assertEquals("<h1>Hello, World!</h1>", response);
+  }
+}

example/javaweb/3-todo-spring-boot/build.sc

@@ -0,0 +1,48 @@
+import mill._, javalib._, publish._
+
+object hello extends RootModule with JavaModule {
+  def ivyDeps = Agg(
+    ivy"org.springframework.boot:spring-boot-starter-data-jpa:2.5.4",
+    ivy"org.springframework.boot:spring-boot-starter-thymeleaf:2.5.4",
+    ivy"org.springframework.boot:spring-boot-starter-validation:2.5.4",
+    ivy"org.springframework.boot:spring-boot-starter-web:2.5.4",
+
+    ivy"javax.xml.bind:jaxb-api:2.3.1",
+
+    ivy"org.webjars:webjars-locator:0.41",
+    ivy"org.webjars.npm:todomvc-common:1.0.5",
+    ivy"org.webjars.npm:todomvc-app-css:2.4.1",
+
+    ivy"com.h2database:h2:2.3.230"
+  )
+
+  object test extends JavaModuleTests with TestModule.Junit5 {
+    def ivyDeps = super.ivyDeps() ++ Agg(
+      ivy"org.springframework.boot:spring-boot-starter-test:2.5.6"
+    )
+  }
+}
+
+// This is a larger example using Spring Boot, implementing the well known
+// https://todomvc.com/[TodoMVC] example app. Apart from running a webserver,
+// this example also demonstrates:
+//
+// * Serving HTML templates using Thymeleaf
+// * Serving static Javascript and CSS using Webjars
+// * Querying a SQL database using JPA and H2
+
+
+/** Usage
+
+> mill test
+...com.example.TodomvcApplicationTests#homePageLoads() finished...
+...com.example.TodomvcApplicationTests#addNewTodoItem() finished...
+
+> mill runBackground
+
+> curl http://localhost:8087
+...<h1>todos</h1>...
+
+> mill clean runBackground
+
+*/

example/javaweb/3-todo-spring-boot/resources/application.properties

@@ -0,0 +1,2 @@
+spring.mvc.hiddenmethod.filter.enabled=true
+server.port=8087

example/javaweb/3-todo-spring-boot/resources/templates/fragments.html

@@ -0,0 +1,16 @@
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org" lang="en">
+<li th:fragment="todoItem(item)" th:classappend="${item.completed?'completed':''}">
+    <div class="view">
+        <form th:action="@{/{id}/toggle(id=${item.id})}" th:method="put">
+            <input class="toggle" type="checkbox"
+                   onchange="this.form.submit()"
+                   th:attrappend="checked=${item.completed?'true':null}">
+            <label th:text="${item.title}">Taste JavaScript</label>
+        </form>
+        <form th:action="@{/{id}(id=${item.id})}" th:method="delete">
+            <button class="destroy"></button>
+        </form>
+    </div>
+    <input class="edit" value="Create a TodoMVC template">
+</li>
+</html>

example/javaweb/3-todo-spring-boot/resources/templates/index.html

@@ -0,0 +1,84 @@
+<!doctype html>
+<html xmlns="http://www.w3.org/1999/xhtml"
+      xmlns:th="http://www.thymeleaf.org"
+      lang="en">
+<head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>Template • TodoMVC</title>
+    <link rel="stylesheet" th:href="@{/webjars/todomvc-common/base.css}">
+    <link rel="stylesheet" th:href="@{/webjars/todomvc-app-css/index.css}">
+</head>
+<body>
+<section class="todoapp">
+    <header class="header">
+        <h1>todos</h1>
+        <form th:action="@{/}" method="post" th:object="${item}">
+            <input class="new-todo" placeholder="What needs to be done?" autofocus
+                   th:field="*{title}">
+        </form>
+    </header>
+    <!-- This section should be hidden by default and shown when there are todos -->
+    <section class="main" th:if="${totalItemCount > 0}">
+        <form th:action="@{/toggle-all}" th:method="put">
+            <input id="toggle-all" class="toggle-all" type="checkbox"
+                   onclick="this.form.submit()">
+            <label for="toggle-all">Mark all as complete</label>
+        </form>
+        <ul class="todo-list" th:remove="all-but-first">
+            <li th:insert="fragments :: todoItem(${item})" th:each="item : ${todoItems}" th:remove="tag">
+            </li>
+            <!-- These are here just to show the structure of the list items -->
+            <!-- List items should get the class `editing` when editing and `completed` when marked as completed -->
+            <li class="completed">
+                <div class="view">
+                    <input class="toggle" type="checkbox" checked>
+                    <label>Taste JavaScript</label>
+                    <button class="destroy"></button>
+                </div>
+                <input class="edit" value="Create a TodoMVC template">
+            </li>
+            <li>
+                <div class="view">
+                    <input class="toggle" type="checkbox">
+                    <label>Buy a unicorn</label>
+                    <button class="destroy"></button>
+                </div>
+                <input class="edit" value="Rule the web">
+            </li>
+        </ul>
+    </section>
+    <!-- This footer should be hidden by default and shown when there are todos -->
+    <footer class="footer" th:if="${totalItemCount > 0}">
+        <th:block th:unless="${activeItemCount == 1}">
+            <span class="todo-count"><strong th:text="${activeItemCount}">0</strong> items left</span>
+        </th:block>
+        <th:block th:if="${activeItemCount == 1}">
+            <span class="todo-count"><strong>1</strong> item left</span>
+        </th:block>
+        <ul class="filters">
+            <li>
+                <a th:href="@{/}"
+                   th:classappend="${todoFilter.name() == 'ALL'?'selected':''}">All</a>
+            </li>
+            <li>
+                <a th:href="@{/active}"
+                   th:classappend="${todoFilter.name() == 'ACTIVE'?'selected':''}">Active</a>
+            </li>
+            <li>
+                <a th:href="@{/completed}"
+                   th:classappend="${todoFilter.name() == 'COMPLETED'?'selected':''}">Completed</a>
+            </li>
+        </ul>
+        <form th:action="@{/completed}" th:method="delete"
+              th:if="${completedItemCount > 0}">
+            <button class="clear-completed">Clear completed</button>
+        </form>
+    </footer>
+</section>
+<footer class="info">
+    <p>Double-click to edit a todo</p>
+</footer>
+<script th:src="@{/webjars/todomvc-common/base.js}"></script>
+</body>
+</html>

example/javaweb/3-todo-spring-boot/src/TodomvcApplication.java

@@ -0,0 +1,11 @@
+package com.example;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class TodomvcApplication {
+	public static void main(String[] args) {
+		SpringApplication.run(TodomvcApplication.class, args);
+	}
+}