过滤器是一个对象,用于拦截应用程序的HTTP请求和响应。通过使用过滤器,无涯教程可以在两个实例上执行两个操作-
以下代码显示了带有@Component批注的Servlet过滤器实现类的示例代码。
@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 {} }
以下示例显示了用于在将请求发送到控制器之前从ServletRequest对象读取远程主机和远程地址的代码。
在doFilter()方法中,添加了System.out.println语句以打印远程主机和远程地址。
package com.learnfk.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 {} }
在Spring Boot主应用程序类文件中,无涯教程添加了简单的REST端点,该端点返回" Hello World"字符串。
package com.learnfk.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"; } }
Maven构建的代码- pom.xml 在下面给出-
<?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.learnfk</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>
下面给出了Gradle Build – build.gradle的代码-
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.learnfk' 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') }
您可以创建一个可执行的JAR文件,并使用下面显示的Maven或Gradle命令运行Spring Boot应用程序-
对于Maven,使用如下所示的命令-
mvn clean install
创建成功后,您可以在目标目录下找到JAR文件。
对于Gradle,请使用如下所示的命令-
gradle clean build
创建成功后,您可以在build/libs目录下找到JAR文件。
现在,使用以下命令运行JAR文件
java –jar <JARFILE>
您可以在Tomcat端口8080上看到该应用程序已启动。
现在点击URL http:// localhost:8080/并查看输出Hello World。它看起来应该如下图所示-
然后,您可以在控制台日志中看到"Remote Host"和"Remote Address",如下所示:
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