SpringBoot——纯注解配置的Spring

1.环境搭建

1.1.创建工程

拷贝ssm工程：

1.2.待改造的问题

我们发现，之所以我们现在离不开xml配置文件，是因为我们有一处很关键的配置，如果他要也能用注解配置，那么我们就可以脱离xml文件了：

1.2.1.jdbc配置

<context:property-placeholder location="classpath:db.properties"></context:property-placeholder>
    <!--数据源-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" 
          				  destroy-method="close">
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        <property name="driverClassName" value="${jdbc.driver}" />
        <property name="maxActive" value="10" />
        <property name="minIdle" value="5" />
    </bean>

1.2.2.mybatis配置

    <!--sqlSession工厂-->
    <bean id="sessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"></property>
        <property name="typeAliasesPackage" value="com.wt.pojo"></property>
    </bean>

    <!--配置MapperScan扫描mapper接口，并把生成的代理类交给spring去管理-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.wt.mapper"></property>
        <property name="sqlSessionFactoryBeanName" value="sessionFactoryBean"></property>
    </bean>

1.2.3.transactional配置

    <bean id="transactionManager" 
          class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    <!-- 开启spring对注解事务的支持 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

1.2.4.service配置

    <!--扫描service-->
    <context:component-scan base-package="com.wt.service"></context:component-scan>

1.2.5.springmvc配置

<!--配置springmvc要扫描的包-->
    <context:component-scan base-package="com.wt.controller,com.wt.exception"></context:component-scan>

    <!--开启注解驱动：配置handlerMapping和handlerAdapter-->
    <mvc:annotation-driven conversion-service="cs"></mvc:annotation-driven>

    <!--配置日期转换器-->
    <bean id="cs" class="org.springframework.context.support.ConversionServiceFactoryBean">
        <property name="converters">
            <set>
                <bean class="com.wt.converter.MyDateConverter"></bean>
            </set>
        </property>
    </bean>

    <!--配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

    <!--配置文件上传解析器-->
    <bean id="multipartResolver"
          class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="5242880" />
        <property name="defaultEncoding" value="UTF-8" />
    </bean>
    <!--资源映射器：直接放行无须dispatcherServlet去处理-->
    <mvc:resources location="/head/" mapping="/head/**"/>

    <!--配置拦截器-->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/account/**"/>
            <mvc:exclude-mapping path="/account/login"></mvc:exclude-mapping>
            <bean class="com.wt.interceptor.LoginInterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>

1.2.6.servlet配置

<!--配置监听器：监听tomcat启动,加载spring配置文件-->
<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext-*.xml</param-value>
</context-param>
<listener>
    <listener-class>
        org.springframework.web.context.ContextLoaderListener
    </listener-class>
</listener>

<!--前端控制器-->
<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>
<!--过滤器-->
<filter>
    <filter-name>CharacterEncodingFilter</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>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

2.新注解说明

2.1.@Configuration

作用：

用于指定当前类是一个spring配置类，可替换xml配置文件，作用和在spring的xml配置文件中的：<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{
}

2.2.@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：

<context:component-scan base-package="com.wt"/>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.wt")//等价于<context:component-scan>
public class SpringConfiguration{
}

2.3.@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;
}

2.4.@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

@Configuration
@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;
    }
}

2.5.@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.wt")
@Import({Configuration_Other.class})
public class SpringConfiguration {

}

@PropertySource("classpath:config.properties")
public class Configuration_Other {

}

3.Spring的纯注解配置

3.1.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;
    }
}

3.2.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.wt.pojo");
        return ssfb;
    }
    @Bean
    public MapperScannerConfigurer getMapperScannerConfigurer(){
        MapperScannerConfigurer msc=new MapperScannerConfigurer();
        msc.setBasePackage("com.wt.mapper");
        return msc;
    }
}

3.3.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;
    }
}

3.4.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.wt.service")
//等同于<tx:annotation-driven />，bean的名称默认取transactionManager
@EnableTransactionManagement
public class SpringConfig {
 
}

3.5.SpringMvcConfig

import com.wt.converter.MyDateConverter;
import com.wt.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.wt.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/");
    }
}

3.6.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 ServletConfig 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};
    }
}

3.7.删除xml配置文件

3.8.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>