Spring配置项<context:annotation-config/>解释说明

本文介绍Spring框架中&lt;context:annotation-config/&gt;的作用及其如何简化@Autowired等注解的配置过程。通常,为了使系统识别这些注解,需要手动声明对应的BeanPostProcessor。而&lt;context:annotation-config/&gt;可以自动完成这一过程。

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在基于主机方式配置Spring的配置文件中,你可能会见到<context:annotation-config/>这样一条配置,他的作用是式地向 Spring 容器注册

AutowiredAnnotationBeanPostProcessor、CommonAnnotationBeanPostProcessor、

PersistenceAnnotationBeanPostProcessor 以及 RequiredAnnotationBeanPostProcessor 这 4 个BeanPostProcessor。

注册这4个 BeanPostProcessor的作用,就是为了你的系统能够识别相应的注解。

例如:

如果你想使用@Autowired注解,那么就必须事先在 Spring 容器中声明 AutowiredAnnotationBeanPostProcessor Bean。传统声明方式如下:

 
  1. <bean class="org.springframework.beans.factory.annotation. AutowiredAnnotationBeanPostProcessor "/> 

如果想使用@ Resource 、@ PostConstruct、@ PreDestroy等注解就必须声明CommonAnnotationBeanPostProcessor

如果想使用@PersistenceContext注解,就必须声明PersistenceAnnotationBeanPostProcessor的Bean。

如果想使用 @Required的注解,就必须声明RequiredAnnotationBeanPostProcessor的Bean。同样,传统的声明方式如下:

 
  1. <bean class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor"/> 

一般来说,这些注解我们还是比较常用,尤其是Antowired的注解,在自动注入的时候更是经常使用,所以如果总是需要按照传统的方式一条一条配置显得有些繁琐和没有必要,于是spring给我们提供<context:annotation-config/>的简化配置方式,自动帮你完成声明。

   不过,呵呵,我们使用注解一般都会配置扫描包路径选项

 
  1. <context:component-scan base-package=”XX.XX”/> 

    该配置项其实也包含了自动注入上述processor的功能,因此当使用 <context:component-scan/> 后,就可以将 <context:annotation-config/> 移除了。

本文出自 “苦逼coder” 博客,请务必保留此出处http://mushiqianmeng.blog.51cto.com/3970029/723880

package com.ljy.test; import com.ljy.domain.Book; import com.ljy.service.BookService; import com.ljy.config.SpringConfig; // 正确导入配置类 import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.test.context.ContextConfiguration; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(classes = SpringConfig.class) public class BookServiceTest { @Autowired private BookService bookService; @Test public void testFindBookById() { Book book = bookService.findBookById(1); System.out.println("图书id: " + book.getId()); // 确保 Book 类有 getId() } }无法解析符号 'test'无法解析符号 'SpringJUnit4ClassRunner'无法解析符号 'ContextConfiguration'<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.ljy</groupId> <artifactId>ljy-book</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <properties> <spring.version>5.3.28</spring.version> <mybatis.version>3.5.7</mybatis.version> <mybatis-spring.version>2.0.6</mybatis-spring.version> <mysql-connector.version>8.0.33</mysql-connector.version> <druid.version>1.2.16</druid.version> <servlet.version>3.1.0</servlet.version> <!-- 切换回Java EE版本 --> <jsp.version>2.2.1-b03</jsp.version> <!-- 切换回Java EE版本 --> <jstl.version>1.2</jstl.version> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-framework-bom</artifactId> <version>${spring.version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <repositories> <repository> <id>aliyun-maven</id> <url>https://maven.aliyun.com/repository/central</url> <releases> <enabled>true</enabled> </releases> <snapshots> <enabled>false</enabled> </snapshots> </repository> <repository> <id>central</id> <url>https://repo.maven.apache.org/maven2</url> <releases> <enabled>true</enabled> </releases> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories> <dependencies> <!-- Spring Core --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> </dependency> <!-- MyBatis --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>${mybatis.version}</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> <version>${mybatis-spring.version}</version> </dependency> <!-- Database --> <dependency> <groupId>com.mysql</groupId> <artifactId>mysql-connector-j</artifactId> <version>${mysql-connector.version}</version> <scope>runtime</scope> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>${druid.version}</version> </dependency> <!-- Servlet/JSP --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>${servlet.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>jsp-api</artifactId> <version>${jsp.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>${jstl.version}</version> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.28</version> <scope>provided</scope> </dependency> <!-- JSON Processing --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.15.2</version> </dependency> <!-- Logging --> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.7.36</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.2.11</version> </dependency> <!-- Testing --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13.2</version> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.1</version> <configuration> <source>${maven.compiler.source}</source> <target>${maven.compiler.target}</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-resources-plugin</artifactId> <version>3.2.0</version> <configuration> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> </resource> </resources> </configuration> </plugin> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> <configuration> <port>8080</port> <path>/</path> </configuration> </plugin> </plugins> </build> </project>
05-15
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>ssm</display-name> <!-- 编码过滤器开始 --> <filter> <filter-name>charset</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> </filter> <filter-mapping> <filter-name>charset</filter-name> <!-- <url-pattern>*.action</url-pattern> --> <servlet-name>springmvc</servlet-name> </filter-mapping> <!-- 编码过滤器结束 --> <!-- 配置spring容器的监听器 开始 目地:在启用tomcat的时候加载 applicationContext.xml ApplicationContext context=new ClassPathXmlApplicationContext("classpath:applicationContext.xml') --> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <!-- 配置上下文的参数 contextConfigLocation 在org.springframework.web.context.ContextLoader里面--> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </context-param> <!-- 配置spring容器的监听器 结束--> <!-- 配置前端控制器开始 --> <servlet> <servlet-name>springmvc</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <!--配置contextConfigLocation --> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:springmvc.xml</param-value> </init-param> <!-- load-on-startup 1 代表当tomcat启动加web.xml里就创建 DispatcherServlet的对象 --> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>springmvc</servlet-name> <!-- *.action:所以的在xxxx.action结尾的请求都交给DispatcherServlet /* 所以的请求都交给DispacherServlet 包含静态文件的地址 js css png gif,使用此种方式可以实现 RESTful风格的url --> <url-pattern>*.html</url-pattern> </servlet-mapping> <!-- 配置前端控制器结束 --> <!--欢迎页面 当tomcat启动的时候 直接执行的页面--> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app> classpath填什么?
最新发布
08-08
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