Spring的纯注解配置

新注解说明

@Configuration

• 作用：用于指定当前类是一个spring配置列，可替换xml配置文件，作用和在spring的xml配置文件的：< beans></ beans>是一样的
• 示例代码

/**
 * spring的配置类
 */
@Configuration//等价于<beans>，当从一个类上加载到该注解时会创建spring容器
public class SpringConfiguration{
}

@ComponentScan

• 作用：
  用于指定spring在初始化容器时要扫描的包。作用和在spring的xml配置文件中的< contextLcomponent-scan base-package="com.by"/>是一样的
• 属性：
  basePackages:用于指定要扫描的包。和该注解中的value属性作用一样
  示例代码：

/**
 * spring的配置类
 */
@Configuration
@ComponentScan(basePackages = "com.by")//等价于<context:component-scan>
public class SpringConfiguration{
}

@Bean

• 作用：

  该注解只能写在方法上，表明使用此方法创建一个对象，并且放入spring容器。作用和在spring的xml配置文件中的：<bean/>是一样的。

• 属性：

  name：给当前@Bean注解方法创建的对象指定一个名称(即bean的id）。

• 示例代码

  public class Dog {
      private String nam;
      private Integer age;
  	//set get......
  }    

  @Bean
  public Dog dog(){
      Dog dog = new Dog();
      dog.setNam("二狗");
      dog.setAge(18);
      return dog;
  }

@PropertySource

• 作用：

  用于加载*.properties文件中的配置。作用和在spring的xml配置文件中的：<context:property-placeholder location="">是一样的。

• 属性：

  value\[\]：用于指定properties文件位置。如果是在类路径下，需要写上classpath:

• 示例代码

  #config.properties
  nam=二狗
  age=18

  @PropertySource("classpath:config.properties")
  public class SpringConfiguration {
  
      @Value("${nam}")
      private String nam;
      @Value("${age}")
      private Integer age;
  
      @Bean
      public Dog dog(){
          Dog dog = new Dog();
          dog.setNam(nam);
          dog.setAge(age);
          return dog;
      }
  }

@Import

• 作用：

  @Import注解是用来导入配置类或者一些需要前置加载的类。作用和在spring的xml配置文件中的：<import resource=""></import>是一样.

• 属性：

  value\[\]：用于指定其他配置类的字节码。

• 示例代码

  @Configuration
  @ComponentScan(basePackages = "com.by")
  @Import({Configuration_Other.class})
  public class SpringConfiguration {
  
  }
  
  @PropertySource("classpath:config.properties")
  public class Configuration_Other {
  
  }

Spring的纯注解配置

JdbcConfig

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.PropertySource;
import javax.sql.DataSource;
 
@PropertySource("classpath:db.properties")
public class JdbcConfig {
    @Value("${jdbc.driver}")
    private String driver;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String userName;
    @Value("${jdbc.password}")
    private String password;

    @Bean("dataSource")
    public DataSource getDatasource() {
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName(driver);
        ds.setUrl(url);
        ds.setUsername(userName);
        ds.setPassword(password);
        return ds;
    }
}

MybatisConfig

import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.context.annotation.Bean;
 
import javax.sql.DataSource;
 
public class MyBatisConfig {
    @Bean
    public SqlSessionFactoryBean getSqlSessionFactoryBean(
             DataSource dataSource){
        SqlSessionFactoryBean ssfb=new SqlSessionFactoryBean();
        ssfb.setDataSource(dataSource);
        ssfb.setTypeAliasesPackage("com.by.pojo");
        return ssfb;
    }
    @Bean
    public MapperScannerConfigurer getMapperScannerConfigurer(){
        MapperScannerConfigurer msc=new MapperScannerConfigurer();
        msc.setBasePackage("com.by.mapper");
        return msc;
    }
}

TxConfig

import org.springframework.context.annotation.Bean;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import javax.sql.DataSource;

public class TxConfig {

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource){
        DataSourceTransactionManager ds = new DataSourceTransactionManager();
        ds.setDataSource(dataSource);
        return ds;
    }
}

SpringConfig

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@Import({MyBatisConfig.class, JdbcConfig.class, TxConfig.class})
//等同<context:component-scan base-package="com.by"/>`
@ComponentScan(value = "com.by.service")
//等同于<tx:annotation-driven />，bean的名称默认取transactionManager
@EnableTransactionManagement
public class SpringConfig {
 
}

SpringMvcConfig

import com.by.converter.MyDateConverter;
import com.by.interceptor.LoginInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

@Configuration
//等同于<context:component-scan base-package="com.by.controller>
@ComponentScan("com.by.controller")
//等同于<mvc:annotation-driven></mvc:annotation-driven>
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer {

    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/pages/"); // 设置视图文件所在目录
        viewResolver.setSuffix(".jsp"); // 设置视图文件后缀名
        return viewResolver;
    }

    @Bean
    public CommonsMultipartResolver multipartResolver(){
        CommonsMultipartResolver commonsMultipartResolver=new CommonsMultipartResolver();
        return commonsMultipartResolver;
    }

    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(new MyDateConverter());
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginInterceptor()).addPathPatterns("/emp/**");
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/head/**").addResourceLocations("/head/");
    }
}

WebConfig

import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

import javax.servlet.Filter;

/**
 * 当类扩展了AbstractAnnotationConfigDispatcherServletlnitializer并将其部署到 Servlet容器时，
 * 容器会自动发现它，并用它来配置Servlet环境
 */
public class WebConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
    
    //加载Spring配置类
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }
    
    //加载SpringMVC配置类
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMvcConfig.class};
    }
    
    //设置SpringMVC请求地址拦截规则
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }
    
    //设置post请求中文乱码过滤器
    @Override
    protected Filter[] getServletFilters() {
        CharacterEncodingFilter filter = new CharacterEncodingFilter();
        filter.setEncoding("utf-8");
        return new Filter[]{filter};
    }
}

删除xml配置文件

修改web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <welcome-file-list>
        <welcome-file>login.jsp</welcome-file>
    </welcome-file-list>
</web-app>

最后测试