过滤器是用于截获应用程序的 HTTP 请求和响应的对象。通过使用 filter,我们可以在两个实例上执行两个操作 -
下面的代码显示了带有@Component注释的 Servlet Filter 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 {}
}
下面的示例演示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,我们添加了 System.out.println 语句来打印远程主机和远程地址。
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,我们添加了返回“Hello World”字符串的简单 REST 端点。
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 build 的代码 – pom.xml 如下:
<?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>
Gradle Build – build.gradle 的代码如下
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')
}
您可以创建一个可执行的JAR文件,并使用如下所示的Maven或Gradle命令运行Spring Boot应用程序
对于 Maven,请使用如下所示的命令
mvn clean install
构建成功后,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
构建成功后,你可以在 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>
您可以看到应用程序已在 Tomcat 端口 8080 上启动。
现在点击 URL http://localhost:8080/ 并查看输出 Hello World.它应该如下所示
然后,您可以在控制台日志上看到远程主机和远程地址,如下所示