springboot2-request-logger - implemented spring filter

Author: bvn13

recursion-print/src/main/java/com/bvn13/example/recursion/print/RecursionPrint.java

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+package com.bvn13.example.recursion.print;
+
+/**
+ * @author bvn13
+ * @since 21.09.2019
+ */
+public class RecursionPrint {
+
+    public static void main(String... args) {
+
+        long n = 20;
+
+        boolean result = printIt(1, n);
+
+    }
+
+    private static boolean printIt(long x, long n) {
+        System.out.println(x);
+
+        return String.valueOf(x).equals(String.valueOf(n)) || printIt(x+1, n);
+    }
+
+}

springboot2-request-logger/.gitignore

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+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**
+!**/src/test/**
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/

springboot2-request-logger/README.md

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+# How to log every Request in SpringBoot
+
+## Prerequesites
+
+Imagine we have an web SpringBoot application containing a [Controller](./src/main/java/com/bvn13/example/springboot/springrequestlogger/controllers/FirstController.java).
+It returns a template [index](/src/main/resources/templates/index.html) containing two links: on [css file](./src/main/resources/static/test.css) and on [js file](./src/main/resources/static/test.js).
+
+So we want to log every request from client while opening `index.html`:
+1. `index.html`
+2. `test.css`
+3. `test.js`
+
+## Enabling logging
+
+We must set up the logging of our classes. Take a look at example of [logback-spring.xml](./src/main/resources/logback-spring.xml).
+
+## Build a Filter
+
+Every Spring Web application have a chain on different filters. Every request flows through this filter chain before getting a controller.
+
+So we can implement a [logging filter](./src/main/java/com/bvn13/example/springboot/springrequestlogger/filters/RequestLoggingFilter.java) and put it into Spring Filter Chain to achieve our goal.
+
+```java
+@Slf4j
+@Component
+public class RequestLoggingFilter extends OncePerRequestFilter {
+    @Override
+    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
+        log.debug(
+                String.format("FILTERED URL: %s", request.getRequestURI())
+        );
+
+        //continue filtering
+        filterChain.doFilter(request, response);
+    }
+}
+```
+
+Using `@Slf4j` annotation get us to decrease boilerplate code to have a logger in a class.
+
+We must annotate our class with `@Component` annotation to make SpringBoot to instantiate this class as spring bean in Singleton scope.
+
+Our class extends `OncePerRequestFilter` abstract class so every request goes through our filter only once.
+
+And we are able to log anything regarding the request inside `doFilterInternal` method.
+
+### Result
+
+You may run [testControllerLoggingWithFilter](./src/test/java/com/bvn13/example/springboot/springrequestlogger/SpringrequestloggerApplicationTests.java) to see the result
+
+```java
+    @Test(expected = HttpClientErrorException.NotFound.class)
+    public void testControllerLoggingWithFilter() {
+        restTemplate.getForObject("http://localhost:"+port+"/", String.class);
+        restTemplate.getForObject("http://localhost:"+port+"/test.js", String.class);
+        restTemplate.getForObject("http://localhost:"+port+"/test.css", String.class);
+        restTemplate.getForObject("http://localhost:"+port+"/does-not-exist.file", String.class);
+    }
+```
+
+![](./img/2019-09-29_21-09.png)
+
+So our goal is achieved. We can see all files we request and not existing file too.
+

springboot2-request-logger/build.gradle

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+plugins {
+    id 'org.springframework.boot' version '2.1.8.RELEASE'
+    id 'io.spring.dependency-management' version '1.0.8.RELEASE'
+    id 'java'
+}
+
+group = 'com.bvn13.example.springboot'
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = '1.8'
+
+
+configurations {
+    compileOnly {
+        extendsFrom annotationProcessor
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
+    implementation 'org.springframework.boot:spring-boot-starter-web'
+    compileOnly 'org.projectlombok:lombok'
+    annotationProcessor 'org.projectlombok:lombok'
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}

springboot2-request-logger/gradle/wrapper/gradle-wrapper.jar

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists