A Spring Boot application embeds a web server, and sometimes, we may want to discover the HTTP port at runtime.<\/p>\n
In this tutorial, we’ll address how to get the HTTP port programmatically in a Spring Boot application.<\/p>\n
2. Introduction<\/h2>\n<\/div>\n2.1. Our Spring Boot Application<\/h3>\n<\/div>\nWe’ll create a simple Spring Boot application example to quickly show the methods to discover the HTTP port at runtime:<\/p>\n
@SpringBootApplication\r\npublic class GetServerPortApplication {\r\n public static void main(String[] args) {\r\n SpringApplication.run(GetServerPortApplication.class, args);\r\n }\r\n}\r\n<\/code><\/pre>\n2.2. Two Scenarios of Setting the Port<\/h3>\n<\/div>\nUsually, the most straightforward way to configure the HTTP port<\/a> of a Spring Boot application is by defining the port in the configuration file application.properties<\/em> or application.yml<\/em>.<\/p>\nFor example, in the application.properties<\/em> file, we can set 7777<\/em> as the port our application is running on:<\/p>\nserver.port=7777\r\n<\/code><\/pre>\nAlternatively, instead of defining a fixed port, we can let the Spring Boot application run on a random port by setting “0<\/em>” as the value of the “server.port<\/em>” property<\/strong>:<\/p>\nserver.port=0\r\n<\/code><\/pre>\nNext, let’s go through the two scenarios and discuss different ways to get the port programmatically at runtime.<\/p>\n
In this tutorial, we’ll discover the server port in unit tests.<\/p>\n
3. Getting a Fixed Port at Runtime<\/h2>\n<\/div>\nLet’s create a properties file application-fixedport.properties<\/em> and define a fixed port 7777 <\/em>in it:<\/p>\nserver.port=7777<\/code><\/pre>\nNext, we’ll try to get the port in a unit test class:<\/p>\n
@RunWith(SpringRunner.class)\r\n@SpringBootTest(classes = GetServerPortApplication.class,\r\n webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)\r\n@ActiveProfiles(\"fixedport\")\r\npublic class GetServerFixedPortUnitTest {\r\n private final static int EXPECTED_PORT = 7777;\r\n ....\r\n}\r\n<\/code><\/pre>\nBefore we see the test methods, let’s take a quick look at the annotations of the test class:<\/p>\n
\n- @RunWith(SpringRunner.class)<\/em> – This will join the JUnit test with the Spring TestContext<\/em><\/li>\n
- @SpringBootTest( … SpringBootTest.WebEnvironment.DEFINED_PORT)<\/em> – In the SpringBootTest<\/em>, we’ll use the DEFINED_PORT<\/em> for the embedded web server<\/li>\n
- @ActiveProfiles(“fixedport”)<\/em> – With this annotation, we enabled the Spring profile<\/a> “fixedport<\/em>” so that our application-fixedport.properties<\/em> will be loaded<\/li>\n<\/ul>\n
3.1. Using the @Value(“${server.port}”)<\/em> Annotation<\/h3>\n<\/div>\nSince the application-fixedport.properties<\/em> file will be loaded, we can get the “server.port<\/em>” property using the @Value<\/em> annotation<\/a>:<\/p>\n@Value(\"${server.port}\")\r\nprivate int serverPort;\r\n@Test\r\npublic void givenFixedPortAsServerPort_whenReadServerPort_thenGetThePort() {\r\n assertEquals(EXPECTED_PORT, serverPort);\r\n}\r\n<\/code><\/pre>\n3.2. Using the ServerProperties<\/em> Class<\/h3>\n<\/div>\nServerProperties<\/a><\/em> holds the properties of the embedded web server, such as the port, the address, and the server header.<\/p>\nWe can inject a ServerProperties<\/em> component and get the port from it:<\/p>\n@Autowired\r\nprivate ServerProperties serverProperties;\r\n@Test\r\npublic void givenFixedPortAsServerPort_whenReadServerProps_thenGetThePort() {\r\n int port = serverProperties.getPort();\r\n \r\n assertEquals(EXPECTED_PORT, port);\r\n}<\/code><\/pre>\nSo far, we’ve learned two ways to get a fixed port at runtime. Next, let’s see how to discover the port in the random port scenario.<\/p>\n
4. Getting Random Port at Runtime<\/h2>\n<\/div>\nThis time, let’s create another properties file application-randomport.properties<\/em>:<\/p>\nserver.port=0<\/code><\/pre>\nAs the code above shows, we allow Spring Boot to choose a free port randomly when the web server starts.<\/p>\n
In the same vein, let’s create another unit test class:<\/p>\n
....\r\n@ActiveProfiles(\"randomport\")\r\npublic class GetServerRandomPortUnitTest {\r\n...\r\n}\r\n<\/code><\/pre>\nHere, we need to activate the “randomport<\/em>” Spring profile to load the corresponding properties file.<\/p>\nWe’ve learned two ways to discover a fixed port at runtime. However, they can’t help us to get the random port:<\/p>\n
@Value(\"${server.port}\")\r\nprivate int randomServerPort;\r\n@Test\r\npublic void given0AsServerPort_whenReadServerPort_thenGet0() {\r\n assertEquals(0, randomServerPort);\r\n}\r\n@Autowired\r\nprivate ServerProperties serverProperties;\r\n@Test\r\npublic void given0AsServerPort_whenReadServerProps_thenGet0() {\r\n int port = serverProperties.getPort();\r\n \r\n assertEquals(0, port);\r\n}\r\n<\/code><\/pre>\nAs the two test methods show, both @Value(“${server.port}”)<\/em> and serverProperties.getPort()<\/em> report “0” as the port.<\/strong> Clearly, it is not the correct port we are expecting.<\/p>\n4.1. Using ServletWebServerApplicationContext<\/em><\/h3>\n<\/div>\nSpring Boot starts a ServletWebServerApplicationContext<\/em><\/a> if the embedded web server starts.<\/p>\nTherefore, we can get the WebServer<\/a> <\/em> from the context object to obtain the server information or manipulate the server:<\/p>\n@Autowired\r\nprivate ServletWebServerApplicationContext webServerAppCtxt;\r\n@Test\r\npublic void given0AsServerPort_whenReadWebAppCtxt_thenGetThePort() {\r\n int port = webServerAppCtxt.getWebServer().getPort();\r\n \r\n assertTrue(port > 1023);\r\n}\r\n<\/code><\/pre>\nIn the test above, we check if the port is greater than 1023. This is because 0-1023 are system ports.<\/p>\n
4.2. Handling ServletWebServerInitializedEvent<\/em><\/h3>\n<\/div>\nA Spring application can publish various events<\/a>\u00a0and EventListeners<\/a><\/em> handle the events.<\/p>\nWhen the embedded web server has started, a ServletWebServerInitializedEvent<\/a>\u00a0<\/em>will be published. This event contains information about the webserver.<\/p>\nTherefore, we can create an EventListener\u00a0<\/em>to get the port from this event:<\/p>\n@Service\r\npublic class ServerPortService {\r\n private int port;\r\n public int getPort() {\r\n return port;\r\n }\r\n @EventListener\r\n public void onApplicationEvent(final ServletWebServerInitializedEvent event) {\r\n port = event.getWebServer().getPort();\r\n }\r\n}<\/code><\/pre>\nWe can inject the service component to our test class to get the random port quickly:<\/p>\n
@Autowired\r\nprivate ServerPortService serverPortService;\r\n@Test\r\npublic void given0AsServerPort_whenReadFromListener_thenGetThePort() {\r\n int port = serverPortService.getPort();\r\n \r\n assertTrue(port > 1023);\r\n}\r\n<\/code><\/pre>\n5. Conclusion<\/h2>\n<\/div>\nUsually, we configure the server port of a Spring Boot application in a properties file or YAML file, where we can set either a fixed or random port.<\/p>\n
In this article, we’ve discussed different approaches to obtain the fixed and random port at runtime.<\/p>\n
As always, the full source code of the article is available over on GitHub<\/a>.<\/p>\nThe post Get the Running Port in Spring Boot<\/a> first appeared on Baeldung<\/a>.<\/p>\n![\"\"](\"https:\/\/feeds.feedblitz.com\/~\/i\/636049846\/0\/baeldung\")
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<\/p>","protected":false},"excerpt":{"rendered":"Learn how to get the HTTP port programmatically in a Spring Boot application<\/p>\n
The post Get the Running Port in Spring Boot<\/a> first appeared on Baeldung<\/a>.<\/p>\n<\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/div>\n<\/div>","protected":false},"author":915,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"Get the Running Port in Spring Boot - ITTeacherITFreelance.hk","description":"Learn how to get the HTTP port programmatically in a Spring Boot application The post Get the Running Port in Spring Boot first appeared on Baeldung . &n"},"footnotes":""},"categories":[6],"tags":[],"_links":{"self":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/83807"}],"collection":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/users\/915"}],"replies":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/comments?post=83807"}],"version-history":[{"count":4,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/83807\/revisions"}],"predecessor-version":[{"id":85412,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/83807\/revisions\/85412"}],"wp:attachment":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/media?parent=83807"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/categories?post=83807"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/tags?post=83807"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
2.1. Our Spring Boot Application<\/h3>\n<\/div>\nWe’ll create a simple Spring Boot application example to quickly show the methods to discover the HTTP port at runtime:<\/p>\n
@SpringBootApplication\r\npublic class GetServerPortApplication {\r\n public static void main(String[] args) {\r\n SpringApplication.run(GetServerPortApplication.class, args);\r\n }\r\n}\r\n<\/code><\/pre>\n2.2. Two Scenarios of Setting the Port<\/h3>\n<\/div>\nUsually, the most straightforward way to configure the HTTP port<\/a> of a Spring Boot application is by defining the port in the configuration file application.properties<\/em> or application.yml<\/em>.<\/p>\nFor example, in the application.properties<\/em> file, we can set 7777<\/em> as the port our application is running on:<\/p>\nserver.port=7777\r\n<\/code><\/pre>\nAlternatively, instead of defining a fixed port, we can let the Spring Boot application run on a random port by setting “0<\/em>” as the value of the “server.port<\/em>” property<\/strong>:<\/p>\nserver.port=0\r\n<\/code><\/pre>\nNext, let’s go through the two scenarios and discuss different ways to get the port programmatically at runtime.<\/p>\n
In this tutorial, we’ll discover the server port in unit tests.<\/p>\n
3. Getting a Fixed Port at Runtime<\/h2>\n<\/div>\nLet’s create a properties file application-fixedport.properties<\/em> and define a fixed port 7777 <\/em>in it:<\/p>\nserver.port=7777<\/code><\/pre>\nNext, we’ll try to get the port in a unit test class:<\/p>\n
@RunWith(SpringRunner.class)\r\n@SpringBootTest(classes = GetServerPortApplication.class,\r\n webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)\r\n@ActiveProfiles(\"fixedport\")\r\npublic class GetServerFixedPortUnitTest {\r\n private final static int EXPECTED_PORT = 7777;\r\n ....\r\n}\r\n<\/code><\/pre>\nBefore we see the test methods, let’s take a quick look at the annotations of the test class:<\/p>\n
\n- @RunWith(SpringRunner.class)<\/em> – This will join the JUnit test with the Spring TestContext<\/em><\/li>\n
- @SpringBootTest( … SpringBootTest.WebEnvironment.DEFINED_PORT)<\/em> – In the SpringBootTest<\/em>, we’ll use the DEFINED_PORT<\/em> for the embedded web server<\/li>\n
- @ActiveProfiles(“fixedport”)<\/em> – With this annotation, we enabled the Spring profile<\/a> “fixedport<\/em>” so that our application-fixedport.properties<\/em> will be loaded<\/li>\n<\/ul>\n
3.1. Using the @Value(“${server.port}”)<\/em> Annotation<\/h3>\n<\/div>\nSince the application-fixedport.properties<\/em> file will be loaded, we can get the “server.port<\/em>” property using the @Value<\/em> annotation<\/a>:<\/p>\n@Value(\"${server.port}\")\r\nprivate int serverPort;\r\n@Test\r\npublic void givenFixedPortAsServerPort_whenReadServerPort_thenGetThePort() {\r\n assertEquals(EXPECTED_PORT, serverPort);\r\n}\r\n<\/code><\/pre>\n3.2. Using the ServerProperties<\/em> Class<\/h3>\n<\/div>\nServerProperties<\/a><\/em> holds the properties of the embedded web server, such as the port, the address, and the server header.<\/p>\nWe can inject a ServerProperties<\/em> component and get the port from it:<\/p>\n@Autowired\r\nprivate ServerProperties serverProperties;\r\n@Test\r\npublic void givenFixedPortAsServerPort_whenReadServerProps_thenGetThePort() {\r\n int port = serverProperties.getPort();\r\n \r\n assertEquals(EXPECTED_PORT, port);\r\n}<\/code><\/pre>\nSo far, we’ve learned two ways to get a fixed port at runtime. Next, let’s see how to discover the port in the random port scenario.<\/p>\n
4. Getting Random Port at Runtime<\/h2>\n<\/div>\nThis time, let’s create another properties file application-randomport.properties<\/em>:<\/p>\nserver.port=0<\/code><\/pre>\nAs the code above shows, we allow Spring Boot to choose a free port randomly when the web server starts.<\/p>\n
In the same vein, let’s create another unit test class:<\/p>\n
....\r\n@ActiveProfiles(\"randomport\")\r\npublic class GetServerRandomPortUnitTest {\r\n...\r\n}\r\n<\/code><\/pre>\nHere, we need to activate the “randomport<\/em>” Spring profile to load the corresponding properties file.<\/p>\nWe’ve learned two ways to discover a fixed port at runtime. However, they can’t help us to get the random port:<\/p>\n
@Value(\"${server.port}\")\r\nprivate int randomServerPort;\r\n@Test\r\npublic void given0AsServerPort_whenReadServerPort_thenGet0() {\r\n assertEquals(0, randomServerPort);\r\n}\r\n@Autowired\r\nprivate ServerProperties serverProperties;\r\n@Test\r\npublic void given0AsServerPort_whenReadServerProps_thenGet0() {\r\n int port = serverProperties.getPort();\r\n \r\n assertEquals(0, port);\r\n}\r\n<\/code><\/pre>\nAs the two test methods show, both @Value(“${server.port}”)<\/em> and serverProperties.getPort()<\/em> report “0” as the port.<\/strong> Clearly, it is not the correct port we are expecting.<\/p>\n4.1. Using ServletWebServerApplicationContext<\/em><\/h3>\n<\/div>\nSpring Boot starts a ServletWebServerApplicationContext<\/em><\/a> if the embedded web server starts.<\/p>\nTherefore, we can get the WebServer<\/a> <\/em> from the context object to obtain the server information or manipulate the server:<\/p>\n@Autowired\r\nprivate ServletWebServerApplicationContext webServerAppCtxt;\r\n@Test\r\npublic void given0AsServerPort_whenReadWebAppCtxt_thenGetThePort() {\r\n int port = webServerAppCtxt.getWebServer().getPort();\r\n \r\n assertTrue(port > 1023);\r\n}\r\n<\/code><\/pre>\nIn the test above, we check if the port is greater than 1023. This is because 0-1023 are system ports.<\/p>\n
4.2. Handling ServletWebServerInitializedEvent<\/em><\/h3>\n<\/div>\nA Spring application can publish various events<\/a>\u00a0and EventListeners<\/a><\/em> handle the events.<\/p>\nWhen the embedded web server has started, a ServletWebServerInitializedEvent<\/a>\u00a0<\/em>will be published. This event contains information about the webserver.<\/p>\nTherefore, we can create an EventListener\u00a0<\/em>to get the port from this event:<\/p>\n@Service\r\npublic class ServerPortService {\r\n private int port;\r\n public int getPort() {\r\n return port;\r\n }\r\n @EventListener\r\n public void onApplicationEvent(final ServletWebServerInitializedEvent event) {\r\n port = event.getWebServer().getPort();\r\n }\r\n}<\/code><\/pre>\nWe can inject the service component to our test class to get the random port quickly:<\/p>\n
@Autowired\r\nprivate ServerPortService serverPortService;\r\n@Test\r\npublic void given0AsServerPort_whenReadFromListener_thenGetThePort() {\r\n int port = serverPortService.getPort();\r\n \r\n assertTrue(port > 1023);\r\n}\r\n<\/code><\/pre>\n5. Conclusion<\/h2>\n<\/div>\nUsually, we configure the server port of a Spring Boot application in a properties file or YAML file, where we can set either a fixed or random port.<\/p>\n
In this article, we’ve discussed different approaches to obtain the fixed and random port at runtime.<\/p>\n
As always, the full source code of the article is available over on GitHub<\/a>.<\/p>\nThe post Get the Running Port in Spring Boot<\/a> first appeared on Baeldung<\/a>.<\/p>\n<\/p>\n
<\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/div>\n\n\u7acb\u523b\u8a3b\u518a\u53ca\u5831\u540d\u96fb\u8166\u88dc\u7fd2\u8ab2\u7a0b\u5427!<\/figcaption><\/figure>\r\n<\/br>Find A Teacher Form:\r\n<\/br>https:\/\/docs.google.com\/forms\/d\/1vREBnX5n262umf4wU5U2pyTwvk9O-JrAgblA-wH9GFQ\/viewform?edit_requested=true#responses\r\n<\/br><\/br>Email:\r\n<\/br>public1989two@gmail.com
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<\/p>","protected":false},"excerpt":{"rendered":"Learn how to get the HTTP port programmatically in a Spring Boot application<\/p>\n
The post Get the Running Port in Spring Boot<\/a> first appeared on Baeldung<\/a>.<\/p>\n<\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/div>\n<\/div>","protected":false},"author":915,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"Get the Running Port in Spring Boot - ITTeacherITFreelance.hk","description":"Learn how to get the HTTP port programmatically in a Spring Boot application The post Get the Running Port in Spring Boot first appeared on Baeldung . &n"},"footnotes":""},"categories":[6],"tags":[],"_links":{"self":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/83807"}],"collection":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/users\/915"}],"replies":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/comments?post=83807"}],"version-history":[{"count":4,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/83807\/revisions"}],"predecessor-version":[{"id":85412,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/83807\/revisions\/85412"}],"wp:attachment":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/media?parent=83807"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/categories?post=83807"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/tags?post=83807"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
We’ll create a simple Spring Boot application example to quickly show the methods to discover the HTTP port at runtime:<\/p>\n
@SpringBootApplication\r\npublic class GetServerPortApplication {\r\n public static void main(String[] args) {\r\n SpringApplication.run(GetServerPortApplication.class, args);\r\n }\r\n}\r\n<\/code><\/pre>\n2.2. Two Scenarios of Setting the Port<\/h3>\n<\/div>\nUsually, the most straightforward way to configure the HTTP port<\/a> of a Spring Boot application is by defining the port in the configuration file application.properties<\/em> or application.yml<\/em>.<\/p>\nFor example, in the application.properties<\/em> file, we can set 7777<\/em> as the port our application is running on:<\/p>\nserver.port=7777\r\n<\/code><\/pre>\nAlternatively, instead of defining a fixed port, we can let the Spring Boot application run on a random port by setting “0<\/em>” as the value of the “server.port<\/em>” property<\/strong>:<\/p>\nserver.port=0\r\n<\/code><\/pre>\nNext, let’s go through the two scenarios and discuss different ways to get the port programmatically at runtime.<\/p>\n
In this tutorial, we’ll discover the server port in unit tests.<\/p>\n
3. Getting a Fixed Port at Runtime<\/h2>\n<\/div>\nLet’s create a properties file application-fixedport.properties<\/em> and define a fixed port 7777 <\/em>in it:<\/p>\nserver.port=7777<\/code><\/pre>\nNext, we’ll try to get the port in a unit test class:<\/p>\n
@RunWith(SpringRunner.class)\r\n@SpringBootTest(classes = GetServerPortApplication.class,\r\n webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)\r\n@ActiveProfiles(\"fixedport\")\r\npublic class GetServerFixedPortUnitTest {\r\n private final static int EXPECTED_PORT = 7777;\r\n ....\r\n}\r\n<\/code><\/pre>\nBefore we see the test methods, let’s take a quick look at the annotations of the test class:<\/p>\n
\n- @RunWith(SpringRunner.class)<\/em> – This will join the JUnit test with the Spring TestContext<\/em><\/li>\n
- @SpringBootTest( … SpringBootTest.WebEnvironment.DEFINED_PORT)<\/em> – In the SpringBootTest<\/em>, we’ll use the DEFINED_PORT<\/em> for the embedded web server<\/li>\n
- @ActiveProfiles(“fixedport”)<\/em> – With this annotation, we enabled the Spring profile<\/a> “fixedport<\/em>” so that our application-fixedport.properties<\/em> will be loaded<\/li>\n<\/ul>\n
3.1. Using the @Value(“${server.port}”)<\/em> Annotation<\/h3>\n<\/div>\nSince the application-fixedport.properties<\/em> file will be loaded, we can get the “server.port<\/em>” property using the @Value<\/em> annotation<\/a>:<\/p>\n@Value(\"${server.port}\")\r\nprivate int serverPort;\r\n@Test\r\npublic void givenFixedPortAsServerPort_whenReadServerPort_thenGetThePort() {\r\n assertEquals(EXPECTED_PORT, serverPort);\r\n}\r\n<\/code><\/pre>\n3.2. Using the ServerProperties<\/em> Class<\/h3>\n<\/div>\nServerProperties<\/a><\/em> holds the properties of the embedded web server, such as the port, the address, and the server header.<\/p>\nWe can inject a ServerProperties<\/em> component and get the port from it:<\/p>\n@Autowired\r\nprivate ServerProperties serverProperties;\r\n@Test\r\npublic void givenFixedPortAsServerPort_whenReadServerProps_thenGetThePort() {\r\n int port = serverProperties.getPort();\r\n \r\n assertEquals(EXPECTED_PORT, port);\r\n}<\/code><\/pre>\nSo far, we’ve learned two ways to get a fixed port at runtime. Next, let’s see how to discover the port in the random port scenario.<\/p>\n
4. Getting Random Port at Runtime<\/h2>\n<\/div>\nThis time, let’s create another properties file application-randomport.properties<\/em>:<\/p>\nserver.port=0<\/code><\/pre>\nAs the code above shows, we allow Spring Boot to choose a free port randomly when the web server starts.<\/p>\n
In the same vein, let’s create another unit test class:<\/p>\n
....\r\n@ActiveProfiles(\"randomport\")\r\npublic class GetServerRandomPortUnitTest {\r\n...\r\n}\r\n<\/code><\/pre>\nHere, we need to activate the “randomport<\/em>” Spring profile to load the corresponding properties file.<\/p>\nWe’ve learned two ways to discover a fixed port at runtime. However, they can’t help us to get the random port:<\/p>\n
@Value(\"${server.port}\")\r\nprivate int randomServerPort;\r\n@Test\r\npublic void given0AsServerPort_whenReadServerPort_thenGet0() {\r\n assertEquals(0, randomServerPort);\r\n}\r\n@Autowired\r\nprivate ServerProperties serverProperties;\r\n@Test\r\npublic void given0AsServerPort_whenReadServerProps_thenGet0() {\r\n int port = serverProperties.getPort();\r\n \r\n assertEquals(0, port);\r\n}\r\n<\/code><\/pre>\nAs the two test methods show, both @Value(“${server.port}”)<\/em> and serverProperties.getPort()<\/em> report “0” as the port.<\/strong> Clearly, it is not the correct port we are expecting.<\/p>\n4.1. Using ServletWebServerApplicationContext<\/em><\/h3>\n<\/div>\nSpring Boot starts a ServletWebServerApplicationContext<\/em><\/a> if the embedded web server starts.<\/p>\nTherefore, we can get the WebServer<\/a> <\/em> from the context object to obtain the server information or manipulate the server:<\/p>\n@Autowired\r\nprivate ServletWebServerApplicationContext webServerAppCtxt;\r\n@Test\r\npublic void given0AsServerPort_whenReadWebAppCtxt_thenGetThePort() {\r\n int port = webServerAppCtxt.getWebServer().getPort();\r\n \r\n assertTrue(port > 1023);\r\n}\r\n<\/code><\/pre>\nIn the test above, we check if the port is greater than 1023. This is because 0-1023 are system ports.<\/p>\n
4.2. Handling ServletWebServerInitializedEvent<\/em><\/h3>\n<\/div>\nA Spring application can publish various events<\/a>\u00a0and EventListeners<\/a><\/em> handle the events.<\/p>\nWhen the embedded web server has started, a ServletWebServerInitializedEvent<\/a>\u00a0<\/em>will be published. This event contains information about the webserver.<\/p>\nTherefore, we can create an EventListener\u00a0<\/em>to get the port from this event:<\/p>\n@Service\r\npublic class ServerPortService {\r\n private int port;\r\n public int getPort() {\r\n return port;\r\n }\r\n @EventListener\r\n public void onApplicationEvent(final ServletWebServerInitializedEvent event) {\r\n port = event.getWebServer().getPort();\r\n }\r\n}<\/code><\/pre>\nWe can inject the service component to our test class to get the random port quickly:<\/p>\n
@Autowired\r\nprivate ServerPortService serverPortService;\r\n@Test\r\npublic void given0AsServerPort_whenReadFromListener_thenGetThePort() {\r\n int port = serverPortService.getPort();\r\n \r\n assertTrue(port > 1023);\r\n}\r\n<\/code><\/pre>\n5. Conclusion<\/h2>\n<\/div>\nUsually, we configure the server port of a Spring Boot application in a properties file or YAML file, where we can set either a fixed or random port.<\/p>\n
In this article, we’ve discussed different approaches to obtain the fixed and random port at runtime.<\/p>\n
As always, the full source code of the article is available over on GitHub<\/a>.<\/p>\nThe post Get the Running Port in Spring Boot<\/a> first appeared on Baeldung<\/a>.<\/p>\n<\/p>\n
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<\/p>","protected":false},"excerpt":{"rendered":"Learn how to get the HTTP port programmatically in a Spring Boot application<\/p>\n
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