- Spring Boot Tutorial
- Spring Boot - Home
- Spring Boot - Introduction
- Spring Boot - Quick Start
- Spring Boot - Bootstrapping
- Spring Boot - Tomcat Deployment
- Spring Boot - Build Systems
- Spring Boot - Code Structure
- Spring Beans & Dependency Injection
- Spring Boot - Runners
- Spring Boot - Application Properties
- Spring Boot - Logging
- Building RESTful Web Services
- Spring Boot - Exception Handling
- Spring Boot - Interceptor
- Spring Boot - Servlet Filter
- Spring Boot - Tomcat Port Number
- Spring Boot - Rest Template
- Spring Boot - File Handling
- Spring Boot - Service Components
- Spring Boot - Thymeleaf
- Consuming RESTful Web Services
- Spring Boot - CORS Support
- Spring Boot - Internationalization
- Spring Boot - Scheduling
- Spring Boot - Enabling HTTPS
- Spring Boot - Eureka Server
- Service Registration with Eureka
- Zuul Proxy Server and Routing
- Spring Cloud Configuration Server
- Spring Cloud Configuration Client
- Spring Boot - Actuator
- Spring Boot - Admin Server
- Spring Boot - Admin Client
- Spring Boot - Enabling Swagger2
- Spring Boot - Creating Docker Image
- Tracing Micro Service Logs
- Spring Boot - Flyway Database
- Spring Boot - Sending Email
- Spring Boot - Hystrix
- Spring Boot - Web Socket
- Spring Boot - Batch Service
- Spring Boot - Apache Kafka
- Spring Boot - Twilio
- Spring Boot - Unit Test Cases
- Rest Controller Unit Test
- Spring Boot - Database Handling
- Securing Web Applications
- Spring Boot - OAuth2 with JWT
- Spring Boot - Google Cloud Platform
- Spring Boot - Google OAuth2 Sign-In
- Spring Boot Resources
- Spring Boot - Quick Guide
- Spring Boot - Useful Resources
- Spring Boot - Discussion
Spring Boot - Servlet Filter
A filter is an object used to intercept the HTTP requests and responses of your application. By using filter, we can perform two operations at two instances −
- Before sending the request to the controller
- Before sending a response to the client.
The following code shows the sample code for a Servlet Filter implementation class with @Component annotation.
@Component public class SimpleFilter implements Filter { @Override public void destroy() {} @Override public void doFilter (ServletRequest request, ServletResponse response, FilterChain filterchain) throws IOException, ServletException {} @Override public void init(FilterConfig filterconfig) throws ServletException {} }
The following example shows the code for reading the remote host and remote address from the ServletRequest object before sending the request to the controller.
In doFilter() method, we have added the System.out.println statements to print the remote host and remote address.
package com.tutorialspoint.demo; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import org.springframework.stereotype.Component; @Component public class SimpleFilter implements Filter { @Override public void destroy() {} @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterchain) throws IOException, ServletException { System.out.println("Remote Host:"+request.getRemoteHost()); System.out.println("Remote Address:"+request.getRemoteAddr()); filterchain.doFilter(request, response); } @Override public void init(FilterConfig filterconfig) throws ServletException {} }
In the Spring Boot main application class file, we have added the simple REST endpoint that returns the “Hello World” string.
package com.tutorialspoint.demo; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @SpringBootApplication @RestController public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } @RequestMapping(value = "/") public String hello() { return "Hello World"; } }
The code for Maven build – pom.xml is given below −
<?xml version = "1.0" encoding = "UTF-8"?> <project xmlns = "http://maven.apache.org/POM/4.0.0" xmlns:xsi = " http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation = "http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.tutorialspoint</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>demo</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.8.RELEASE</version> <relativePath/> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
The code for Gradle Build – build.gradle is given below −
buildscript { ext { springBootVersion = '1.5.8.RELEASE' } repositories { mavenCentral() } dependencies { classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}") } } apply plugin: 'java' apply plugin: 'eclipse' apply plugin: 'org.springframework.boot' group = 'com.tutorialspoint' version = '0.0.1-SNAPSHOT' sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { compile('org.springframework.boot:spring-boot-starter-web') testCompile('org.springframework.boot:spring-boot-starter-test') }
You can create an executable JAR file, and run the Spring Boot application by using the Maven or Gradle commands shown below −
For Maven, use the command as shown below −
mvn clean install
After BUILD SUCCESS, you can find the JAR file under the target directory.
For Gradle, use the command as shown below −
gradle clean build
After BUILD SUCCESSFUL, you can find the JAR file under the build/libs directory.
Now, run the JAR file by using the following command
java –jar <JARFILE>
You can see the application has started on the Tomcat port 8080.
Now hit the URL http://localhost:8080/ and see the output Hello World. It should look as shown below −
Then, you can see the Remote host and Remote address on the console log as shown below −