Add simple filters for a chain.doFilter() presentation (#18045)

* BAEL-6550 Add simple filter for chain.doFilter presentation

* BAEL-6550 Move code example to another module and rename test class

* BAEL-6550 Align code example with blog changes

* BAEL-6550 Fix filter chain example, improve test

Author: apelan

spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/chaindofilter/ChainDoFilterApplication.java

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

spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/chaindofilter/ChainDoFilterController.java

@@ -0,0 +1,19 @@
+package com.baeldung.chaindofilter;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/chain/do-filter")
+public class ChainDoFilterController {
+
+    public static final String RESPONSE_MESSAGE = "Chain doFilter test!";
+
+    @GetMapping
+    public ResponseEntity<String> chainDoFilter() {
+        return ResponseEntity.ok(RESPONSE_MESSAGE);
+    }
+
+}

spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/chaindofilter/FirstFilter.java

@@ -0,0 +1,27 @@
+package com.baeldung.chaindofilter;
+
+import java.io.IOException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Component;
+
+import jakarta.servlet.Filter;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
+
+@Order(1)
+@Component
+public class FirstFilter implements Filter {
+
+    private final Logger LOG = LoggerFactory.getLogger(FirstFilter.class);
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {
+        LOG.info("Processing the First Filter");
+        chain.doFilter(request, response);
+    }
+}

spring-boot-modules/spring-boot-basic-customization/src/main/java/com/baeldung/chaindofilter/SecondFilter.java

@@ -0,0 +1,27 @@
+package com.baeldung.chaindofilter;
+
+import java.io.IOException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.core.annotation.Order;
+import org.springframework.stereotype.Component;
+
+import jakarta.servlet.Filter;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
+
+@Order(2)
+@Component
+public class SecondFilter implements Filter {
+
+    private final Logger LOG = LoggerFactory.getLogger(SecondFilter.class);
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
+        LOG.info("Processing the Second Filter");
+        chain.doFilter(request, response);
+    }
+}

spring-boot-modules/spring-boot-basic-customization/src/test/java/com/baeldung/chaindofilter/ChainExampleFilterUnitTest.java

@@ -0,0 +1,28 @@
+package com.baeldung.chaindofilter;
+
+import static com.baeldung.chaindofilter.ChainDoFilterController.RESPONSE_MESSAGE;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.web.servlet.MockMvc;
+
+@SpringBootTest
+@AutoConfigureMockMvc
+public class ChainExampleFilterUnitTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Test
+    void givenHeaderInResponse_whenFilterDoChain_thenAssertHeaderPresent() throws Exception {
+        mockMvc.perform(get("/chain/do-filter"))
+            .andExpect(status().isOk())
+            .andExpect(jsonPath("$").value(RESPONSE_MESSAGE));
+    }
+
+}

spring-boot-modules/spring-boot-basic-customization/src/test/resources/logback-test.xml

@@ -1,6 +1,13 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <configuration>
-    <root level="info">
+    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
         <appender-ref ref="CONSOLE" />
     </root>
 </configuration>