Java方式配置Spring

概述

　　本文主要讲的是如何使用Java Bean来配置Spring，而不是用xml来配置Spring。

　　本文主要是代码，需要注意的都在注释里面。

　　代码打包下载地址(注：项目使用Maven构建)

---

Java配置Spring

 package com.wisely.highlight_spring4.ch1.javaconfig;

 /**
  * 最终被调用的类
  */
 public class FunctionService {
     public String sayHello(String word){
         return "Hello " + word +" !";
     }
 }

 package com.wisely.highlight_spring4.ch1.javaconfig;

 /**
  * 调用类
  */
 public class UseFunctionService {
     //这里也可以使用@Autowired将FunctionService的实体bean注入到UseFunctionService中,
     //让UseFunctionService具备将FunctionService的实体bean注入到UseFunctionService中的功能
     //@Autowired
     FunctionService functionService;

     public void setFunctionService(FunctionService functionService) {
         this.functionService = functionService;
     }

     public String SayHello(String word){
         return functionService.sayHello(word);
     }
 }

 package com.wisely.highlight_spring4.ch1.javaconfig;

 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;

 /**
  * 配置类，代替xml配置
  */
 //声明当前类是一个配置类
 @Configuration
 //自动扫描包名下所有使用@Service/@Component/@Repository和@Controller的类,并注册为Bean
 //@ComponentScan("com.wisely.highlight_spring4.ch1")
 public class JavaConfig {
     /**
      * 声明当前方法的返回值是一个bean,bean的名称是方法名
      * @return bean
      */
     @Bean
     public FunctionService functionService(){
         return new FunctionService();
     }

     @Bean
     public UseFunctionService useFunctionService(){
         UseFunctionService useFunctionService = new UseFunctionService();
         //注入FunctionService的时候直接调用functionService
         useFunctionService.setFunctionService(functionService()); //
         return useFunctionService;

     }
     /**
      * 也可以将bean作为方法参数传入,spring会自动注入
      */
 //    @Bean
 //    public UseFunctionService useFunctionService(FunctionService functionService){//4
 //        UseFunctionService useFunctionService = new UseFunctionService();
 //        useFunctionService.setFunctionService(functionService);
 //        return useFunctionService;
 //    }
 }

 package com.wisely.highlight_spring4.ch1.javaconfig;

 import org.springframework.context.annotation.AnnotationConfigApplicationContext;

 /**
  * 程序入口
  */
 public class Main {
     public static void main(String[] args) {
         //使用AnnotationConfigApplicationContext作为容器,
         //接受输入一个配置类作为参数
         AnnotationConfigApplicationContext context =
                 new AnnotationConfigApplicationContext(JavaConfig.class);
         //获得声明配置的UseFunctionService的Bean
         UseFunctionService useFunctionService = context.getBean(UseFunctionService.class);
         //调用输出方法
         System.out.println(useFunctionService.SayHello("java config"));
         context.close();
     }
 }

　　最终效果如下所示

Java配置AOP

 package com.wisely.highlight_spring4.ch1.aop;

 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;

 /**
  * 拦截规则的注解
  */
 @Target(ElementType.METHOD)
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
 public @interface Action {
     //注解参数
     String name();
 }

 package com.wisely.highlight_spring4.ch1.aop;

 import org.springframework.stereotype.Service;

 /**
  * 使用注解的被拦截类
  */
 @Service
 public class DemoAnnotationService {
     @Action(name="注解式拦截的add操作")
     public void add(){}
 }

 package com.wisely.highlight_spring4.ch1.aop;

 import org.springframework.stereotype.Service;

 /**
  * 使用方法规则被拦截类
  */
 @Service
 public class DemoMethodService {
     public void add(){}
 }

 package com.wisely.highlight_spring4.ch1.aop;

 import org.aspectj.lang.JoinPoint;
 import org.aspectj.lang.annotation.After;
 import org.aspectj.lang.annotation.Aspect;
 import org.aspectj.lang.annotation.Before;
 import org.aspectj.lang.annotation.Pointcut;
 import org.aspectj.lang.reflect.MethodSignature;
 import org.springframework.stereotype.Component;

 import java.lang.reflect.Method;

 /**
  * 配置切面
  */
 @Aspect //声明切面
 @Component //让切面成为spring容器管理的bean
 public class LogAspect {
     //声明切点,拦截Action
     @Pointcut("@annotation(com.wisely.highlight_spring4.ch1.aop.Action)")
     public void annotationPointCut() {
     }

     //声明建言,并使用@Pointcut定义的切点annotationPointCut()
     @After("annotationPointCut()")
     public void after(JoinPoint joinPoint) {
         MethodSignature signature = (MethodSignature) joinPoint.getSignature();
         Method method = signature.getMethod();
         Action action = method.getAnnotation(Action.class);
         //通过反射获可得注解上的name属性,然后做日志记录相关的操作
         System.out.println("注解式拦截 " + action.name());
     }

     //声明建言,直接使用拦截规则作为参数
     @Before("execution(* com.wisely.highlight_spring4.ch1.aop.DemoMethodService.*(..))")
     public void before(JoinPoint joinPoint) {
         MethodSignature signature = (MethodSignature) joinPoint.getSignature();
         Method method = signature.getMethod();
         System.out.println("方法规则式拦截," + method.getName());
     }
 }

 package com.wisely.highlight_spring4.ch1.aop;

 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.EnableAspectJAutoProxy;

 /**
  * Spring配置类,因为程序中使用了诸如@Service之类的配置,所以这里不用写其他配置
  * 只需要使用@ComponentScan扫描一下就可以了
  */
 @Configuration
 //扫描注解,注册bean
 @ComponentScan("com.wisely.highlight_spring4.ch1.aop")
 //开启spring对AspectJ的支持
 @EnableAspectJAutoProxy //
 public class AopConfig {

 }

 package com.wisely.highlight_spring4.ch1.aop;

 import org.springframework.context.annotation.AnnotationConfigApplicationContext;

 /**
  * 程序入口
  */
 public class Main {
     public static void main(String[] args) {
          AnnotationConfigApplicationContext context =
                     new AnnotationConfigApplicationContext(AopConfig.class);
          DemoAnnotationService demoAnnotationService = context.getBean(DemoAnnotationService.class);
          DemoMethodService demoMethodService = context.getBean(DemoMethodService.class);
          demoAnnotationService.add();
          demoMethodService.add();
          context.close();
     }
 }

　　最终效果如下所示