在Spring Boot中使用拦截器&＃xff0c;可在以下情况下执行操作 -
例如&＃xff0c;使用拦截器在将请求发送到控制器之前添加请求标头&＃xff0c;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&＃xff0c;需要创建支持它的&＃64;Component类&＃xff0c;它应该实现HandlerInterceptor接口。 以下是在拦截器上工作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&＃xff0c;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 -
&＃64;Component
public class ProductServiceInterceptor implements HandlerInterceptor {&＃64;Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {return true;}&＃64;Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {}&＃64;Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) throws Exception {}
}
Java
必须使用WebMvcConfigurerAdapter向InterceptorRegistry注册此Interceptor&＃xff0c;如下所示 -
&＃64;Component
public class ProductServiceInterceptorAppConfig extends WebMvcConfigurerAdapter {&＃64;AutowiredProductServiceInterceptor productServiceInterceptor;&＃64;Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(productServiceInterceptor);}
}
Java
在下面给出的示例中&＃xff0c;将使用GET产品API&＃xff0c;该API提供的输出如下 - Interceptor类ProductServiceInterceptor.java的代码如下 -
package com.yiibai.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;&＃64;Component
public class ProductServiceInterceptor implements HandlerInterceptor {&＃64;Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("Pre Handle method is Calling");return true;}&＃64;Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("Post Handle method is Calling");}&＃64;Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) throws Exception {System.out.println("Request and Response is completed");}
}
Java
应用程序配置类文件的代码将拦截器注册到拦截器注册表,ProductServiceInterceptorAppConfig.java如下 -
package com.yiibai.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;&＃64;Component
public class ProductServiceInterceptorAppConfig extends WebMvcConfigurerAdapter {&＃64;AutowiredProductServiceInterceptor productServiceInterceptor;&＃64;Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(productServiceInterceptor);}
}
Java
控制器类文件ProductServiceController.java的代码如下 -
package com.yiibai.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.yiibai.demo.exception.ProductNotfoundException;
import com.yiibai.demo.model.Product;&＃64;RestController
public class ProductServiceController {private static Map productRepo &＃61; new HashMap<>(); static { Product honey &＃61; new Product();honey.setId("1");honey.setName("Honey");productRepo.put(honey.getId(), honey); Product almond &＃61; new Product();almond.setId("2");almond.setName("Almond");productRepo.put(almond.getId(), almond); }&＃64;RequestMapping(value &＃61; "/products")public ResponseEntity getProduct() {return new ResponseEntity<>(productRepo.values(), HttpStatus.OK);}
}
Java
POJO类Product.java 代码如下 -
package com.yiibai.demo.model;public class Product {private String id;private String name;public String getId() {return id;}public void setId(String id) {this.id &＃61; id;}public String getName() {return name;}public void setName(String name) {this.name &＃61; name;}
}
Java
Spring Boot应用程序类主要的文件DemoApplication.java 的代码如下 -
package com.yiibai.demo;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;&＃64;SpringBootApplication
public class DemoApplication {public static void main(String[] args) {SpringApplication.run(DemoApplication.class, args); }
}
Java
Maven build的代码 - pom.xml 如下所示 -
4.0.0com.yiibaidemo0.0.1-SNAPSHOTjardemoDemo project for Spring Bootorg.springframework.bootspring-boot-starter-parent1.5.8.RELEASE UTF-8UTF-81.8org.springframework.bootspring-boot-starter-weborg.springframework.bootspring-boot-starter-testtestorg.springframework.bootspring-boot-maven-plugin
XML
这里显示了Gradle构建文件&＃xff1a;build.gradle 的代码 -
buildscript {ext {springBootVersion &＃61; &＃39;1.5.8.RELEASE&＃39;}repositories {mavenCentral()}dependencies {classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")}
}
apply plugin: &＃39;java&＃39;
apply plugin: &＃39;eclipse&＃39;
apply plugin: &＃39;org.springframework.boot&＃39;
group &＃61; &＃39;com.yiibai&＃39;
version &＃61; &＃39;0.0.1-SNAPSHOT&＃39;
sourceCompatibility &＃61; 1.8repositories {mavenCentral()
}
dependencies {compile(&＃39;org.springframework.boot:spring-boot-starter-web&＃39;)testCompile(&＃39;org.springframework.boot:spring-boot-starter-test&＃39;)
}
Java
创建可执行的JAR文件&＃xff0c;并使用以下Maven或Gradle命令运行Spring Boot应用程序。 对于Maven&＃xff0c;使用如下所示的命令 -
在控制台上看到"BUILD SUCCESS"输出之后&＃xff0c;在target目录下找到JAR文件。对于Gradle&＃xff0c;使用如下所示的命令 -
在控制台上看到"BUILD SUCCESSFUL"之后&＃xff0c;在build/libs目录下找到JAR文件。使用以下命令运行JAR文件 -
现在&＃xff0c;应用程序已在Tomcat端口8080上启动&＃xff0c;如下所示 -
打开 POSTMAN 应用程序中的URL&＃xff0c;并输入&＃xff1a;http://localhost:8080/products&＃xff0c;看到输出如下 -
在控制台窗口中&＃xff0c;看到在拦截器中添加的System.out.println语句&＃xff0c;如下面给出的屏幕截图所示 -
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