Spring Boot - 拦截器 Spring Boot - 异常处理 Spring Boot - Servlet过滤器 您可以在Spring Boot中使用Interceptor在以下情况下执行操作 在将请求发送到控制器之前 在将响应发送给客户端之前 例如,您可以使用拦截器在将请求发送到控制器之前添加请求标头,并在将响应发送到客户端之前添加响应标头。 要使用拦截器,您需要创建支持它的@Component类,它应该实现HandlerInterceptor接口。 以下是您在使用拦截器时应该了解的三种方法 preHandle()方法 - 用于在将请求发送到控制器之前执行操作。此方法应返回true以将响应返回给客户端。 postHandle()方法 - 用于在将响应发送到客户端之前执行操作。 afterCompletion()方法 - 用于在完成请求和响应后执行操作。 请注意以下代码以便更好地理解 @Component public class ProductServiceInterceptor implements HandlerInterceptor { @Override public boolean preHandle( HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { return true; } @Override public void postHandle( HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {} @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) throws Exception {} } 您必须注册该拦截器的InterceptorRegistry使用WebMvcConfigurerAdapter如下 @Component public class ProductServiceInterceptorAppConfig extends WebMvcConfigurerAdapter { @Autowired ProductServiceInterceptor productServiceInterceptor; @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(productServiceInterceptor); } } 在下面给出的示例中,我们将使用GET产品API,该API提供的输出如下 Interceptor类ProductServiceInterceptor.java的代码如下 package com.codingdict.demo.interceptor; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.stereotype.Component; import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView; @Component public class ProductServiceInterceptor implements HandlerInterceptor { @Override public boolean preHandle (HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println("Pre Handle method is Calling"); return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println("Post Handle method is Calling"); } @Override public void afterCompletion (HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) throws Exception { System.out.println("Request and Response is completed"); } } 应用程序配置类文件的代码将Interceptor注册到拦截器注册表 - ProductServiceInterceptorAppConfig.java如下 package com.codingdict.demo.interceptor; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import org.springframework.web.servlet.config.annotation.InterceptorRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter; @Component public class ProductServiceInterceptorAppConfig extends WebMvcConfigurerAdapter { @Autowired ProductServiceInterceptor productServiceInterceptor; @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(productServiceInterceptor); } } Controller类文件ProductServiceController.java的代码如下 package com.codingdict.demo.controller; import java.util.HashMap; import java.util.Map; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RestController; import com.codingdict.demo.exception.ProductNotfoundException; import com.codingdict.demo.model.Product; @RestController public class ProductServiceController { private static Map<String, Product> productRepo = new HashMap<>(); static { Product honey = new Product(); honey.setId("1"); honey.setName("Honey"); productRepo.put(honey.getId(), honey); Product almond = new Product(); almond.setId("2"); almond.setName("Almond"); productRepo.put(almond.getId(), almond); } @RequestMapping(value = "/products") public ResponseEntity<Object> getProduct() { return new ResponseEntity<>(productRepo.values(), HttpStatus.OK); } } Product.java的POJO类代码如下 package com.codingdict.demo.model; public class Product { private String id; private String name; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } 主要的Spring Boot应用程序类文件DemoApplication.java的代码如下 package com.codingdict.demo; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } } Maven build的代码 - pom.xml如下所示 <?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.codingdict</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> 这里显示了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.codingdict' 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') } 您可以创建可执行的JAR文件,并使用以下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 在“BUILD SUCCESS”之后,您可以在目标目录下找到JAR文件。 对于Gradle,使用如下所示的命令 gradle clean build 在“BUILD SUCCESSFUL”之后,您可以在build / libs目录下找到JAR文件。 您可以使用以下命令运行JAR文件 java –jar <JARFILE> 现在,应用程序已在Tomcat端口8080上启动,如下所示 现在点击POSTMAN应用程序中的以下URL,你可以看到输出如下 GET API:http://localhost:8080/ products 在控制台窗口中,您可以看到在Interceptor中添加的System.out.println语句,如下面给出的屏幕截图所示 Spring Boot - 异常处理 Spring Boot - Servlet过滤器