springboot攔截器解耦——自定義注解

什么是注解

@Target({ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) @Documented @Component public @interface Configuration {     @AliasFor(         annotation = Component.class    )     String value() default "";      boolean proxyBeanMethods() default true; }

• 創(chuàng)建注解的關(guān)鍵字是@interface
• 注解上也可以加注解
• 注解可以有屬性

• @Retention：保留期，聲明注解的存活時間
• RetentionPolicy.SOURCE：僅源代碼時保留，在編譯時會被丟棄忽略
• RetentionPolicy.CLASS：編譯為class時保留，但不會被加載到j(luò)vm中
• RetentionPolicy.RUNTIME：運行環(huán)境保留，會被加載到j(luò)vm中
• @Documented：保留本類中的注解并能夠被javadoc識別
• @Target：指定注解的添加位置（類/方法/變量等）
• ElementType.TYPE：類注解
• ElementType.FIELD：字段注解
• ElementType.METHOD：方法注解
• ElementType.PARAMETER：方法內(nèi)的參數(shù)注解
• ElementType.CONSTRUCTOR：構(gòu)造方法注解
• ElementType.LOCAL_VARIABLE：局部變量注解
• ElementType.ANNOTATION_TYPE：注解注解
• ElementType.PACKAGE：包注解
• ElementType.TYPE_PARAMETER
• ElementType.TYPE_USE
• @Inherited：注解是否能夠被子類繼承

創(chuàng)建springboot項目

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">     <modelVersion>4.0.0</modelVersion>     <groupId>io.github.syske</groupId>     <artifactId>custom-annotation-demo</artifactId>     <version>0.0.1-SNAPSHOT</version>     <name>custom-annotation-demo</name>     <description>Demo project for Spring Boot</description>      <properties>         <java.version>1.8</java.version>         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>         <spring-boot.version>2.3.0.RELEASE</spring-boot.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>             <exclusions>                 <exclusion>                     <groupId>org.junit.vintage</groupId>                     <artifactId>junit-vintage-engine</artifactId>                 </exclusion>             </exclusions>         </dependency>          <dependency>             <groupId>com.alibaba</groupId>             <artifactId>fastjson</artifactId>             <version>1.2.61</version>         </dependency>     </dependencies>      <dependencyManagement>         <dependencies>             <dependency>                 <groupId>org.springframework.boot</groupId>                 <artifactId>spring-boot-dependencies</artifactId>                 <version>${spring-boot.version}</version>                 <type>pom</type>                 <scope>import</scope>             </dependency>         </dependencies>     </dependencyManagement>      <build>         <plugins>             <plugin>                 <groupId>org.apache.maven.plugins</groupId>                 <artifactId>maven-compiler-plugin</artifactId>                 <configuration>                     <source>1.8</source>                     <target>1.8</target>                     <encoding>UTF-8</encoding>                 </configuration>             </plugin>             <plugin>                 <groupId>org.springframework.boot</groupId>                 <artifactId>spring-boot-maven-plugin</artifactId>             </plugin>         </plugins>     </build>  </project>

自定義注解

 import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target;  @Target(ElementType.METHOD) @Retention(RetentionPolicy.RUNTIME) public @interface CheckAuth { }

自定義注解應(yīng)用

 public class AuthenticationInterceptor implements HandlerInterceptor {     @Override     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {         if (handler instanceof HandlerMethod) {             HandlerMethod handlerMethod = (HandlerMethod) handler;             if (handlerMethod.hasMethodAnnotation(CheckAuth.class)) {                 System.out.println("有CheckAuth注解");                 String token = request.getParameter("token");                 if (!"ABCDEF12345".equals(token)) {                     throw new AuthException();                }            }        }         return true;    } }

  // 鑒權(quán)攔截器 registry.addInterceptor(new AuthenticationInterceptor()).addPathPatterns("/**");

• HandlerMethod：方法
• ResourceHttpRequestHandler：靜態(tài)資源

總結(jié)