Spring学习笔记（二）-阿里云开发者社区

自动装配

通过ByType

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:c="http://www.springframework.org/schema/c"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--
          自动装配
          byName 按照名字装配，要求bean的id于servcie中声明的对象一致
          byType 按照类型装配，要求容器中该类型只能有一个实例
       -->
    <bean id="userDAO4" class="cn.cqie.dao.impl.UserDAOImpl"></bean>
    <bean id="userService4" class="cn.cqie.service.impl.UserServiceImpl" autowire="byType"></bean>
</beans>

@Test
public void testAutowireByType(){
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("app5.xml");
    UserServiceImpl userService4 = (UserServiceImpl) applicationContext.getBean("userService4");
    userService4.save();
}

通过ByName

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:c="http://www.springframework.org/schema/c"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--
          自动装配
          byName 按照名字装配，要求bean的id于servcie中声明的对象一致
          byType 按照类型装配，要求容器中该类型只能有一个实例
       -->
    <bean id="userDAO" class="cn.cqie.dao.impl.UserDAOImpl"></bean>
    <bean id="userService4" class="cn.cqie.service.impl.UserServiceImpl" autowire="byName"></bean>
</beans>

@Test
public void testAutowireByName(){
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("app5.xml");
    UserServiceImpl userService4 = (UserServiceImpl) applicationContext.getBean("userService4");
    userService4.save();
}

FactoryBean

Spring 中有两种类型的Bean，一种是普通Bean，另一种是工厂Bean 即 FactoryBean。FactoryBean跟普通Bean不同，其返回的对象不是指定类的一个实例，而是该FactoryBean的getObject方法所返回的对象。创建出来的对象是否属于单例由isSingleton中的返回决定。

一般情况下，Spring通过反射机制利用的class属性指定实现类实例化Bean，在某些情况下，实例化Bean过程比较复杂，如果按照传统的方式，则需要在中提供大量的配置信息。配置方式的灵活性是受限的，这时采用编码的方式可能会得到一个简单的方案。Spring为此提供了一个org.springframework.bean.factory.FactoryBean的工厂类接口，用户可以通过实现该接口定制实例化Bean的逻辑。FactoryBean接口对于Spring框架来说占用重要的地位，Spring自身就提供了70多个FactoryBean的实现。它们隐藏了实例化一些复杂Bean的细节，给上层应用带来了便利。从Spring3.0开始，FactoryBean开始支持泛型，即接口声明改为FactoryBean的形式

以Bean结尾，表示它是一个Bean，不同于普通Bean的是：它是实现了FactoryBean接口的Bean，根据该Bean的ID从BeanFactory中获取的实际上是FactoryBean的getObject()返回的对象，而不是FactoryBean本身，如果要获取FactoryBean对象，请在id前面加一个&符号来获取。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:c="http://www.springframework.org/schema/c"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="userService" class="cn.cqie.util.UserServiceFactoryBean"/>
  <!--    这里的userService 是在cn.cqie.util.UserServiceFactoryBean 中的 getObject() 方法的返回值-->
</beans>

package cn.cqie.util;
import cn.cqie.dao.impl.UserDAOImpl;
import cn.cqie.service.UserService;
import cn.cqie.service.impl.UserServiceImpl;
import org.springframework.beans.factory.FactoryBean;
public class UserServiceFactoryBean implements FactoryBean<UserService> {
    /*
    通过FactoryBean返回指定类型的对象
     */
    @Override
    public UserService getObject() throws Exception {
        //编写复杂的组装逻辑
        UserServiceImpl userService = new UserServiceImpl();
        userService.setUserDAO(new UserDAOImpl());
        return userService;
    }
    @Override
    public Class<?> getObjectType() {
        //当前对象的类型
        return null;
    }
    @Override
    public boolean isSingleton() {
        //返回的对象是否为单例
        return false;
    }
}

@Test
public void testFactoryBean(){
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("app6.xml");
    UserServiceImpl userService = (UserServiceImpl) applicationContext.getBean("userService");
    userService.save();
}

Spring常用注解

可以通过注解可以在配置文件中少写一些内容

在配置文件中添加命名空间context，还需添加格式文件

xmlns:context="http://www.springframework.org/schema/context"
需要在xsi:schemaLocation中加入格式文件
http://www.springframework.org/schema/context  http://www.springframework.org/schema/context/spring-context.xsd

@Component 这是下面三个的老大

@Controller

@Service 在service的类上加

@Repository 在 dao 层 mapper 层加

注意：

1、需要注入的对象，在属性上添加注解@Autowire或者@Resource

2、所有bean的id默认为类名首字母小写。否则需要在注解中声明实例的id。

eg

MyBatis注解

mybatis的配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <typeAliases>
        <package name="cn.cqie.pojo"/>
    </typeAliases>
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/springmybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=utf8&amp;serverTimezone=Asia/Shanghai"/>
                <property name="username" value="root"/>
                <property name="password" value="tcx119"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
    <!--
    resource: xml所在的目录
        读取本地磁盘的xml 要用 url(file:///D:1.xml)
    -->
        <mapper resource="cn/cqie/mapper/ad.xml"/>
    </mappers>
</configuration>

写SQL语句的xml文件

<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.cqie.mapper.UserMapper">
    <select id="selectAll" resultType="User">
        select
        <include refid="BASE_COL_LIST"></include>
        from user
    </select>
    <sql id="BASE_COL_LIST">
        uname,pwd,hobby
    </sql>
</mapper>

注解

注意：在使用注解时要重新关联

package cn.cqie.mapper;
import cn.cqie.pojo.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import java.util.List;
public interface UserMapper {
    @Select("select * from user")
    List<User> selectAll();
    @Insert("insert into user values(#{uname},#{pwd},#{hobby})")
    int save(User user1);
}

package cn.cqie.test;
import cn.cqie.mapper.UserMapper;
import cn.cqie.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import java.io.IOException;
import java.util.List;
public class testApp {
    @Test
    public void testSelectAll() throws IOException {
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        //插入一条内容
        User user = new User("yhl", "dasd", "ai");
        int save = mapper.save(user);
        //这里一定要写，不然 在本地数据库中是没有的
        sqlSession.commit();
        List<User> users = mapper.selectAll();
        System.out.println(users);
    }
}

mybaties逆向工程

插件

时区：  serverTimezone=Asia/Shanghai

特别注意

若mysql的版本在8以及以上一定要写上时区

Spring与MyBatis集成

Spring+Mybatis

1、添加依赖

关于Mybatis依赖

关于Spring的依赖

关于Mybatis和Spring关联的依赖

其他依赖

<!-- mybatis -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.38</version>
    </dependency>
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.1.23</version>
    </dependency>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.4.6</version>
    </dependency>
    <!-- spring -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>4.3.18.RELEASE</version>
    </dependency>
    <!-- 对于持久层框架的支持 -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-orm</artifactId>
      <version>4.3.18.RELEASE</version>
    </dependency>
    <!-- mybatis和Spring关联的jar -->
    <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis-spring -->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.6</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>

2、逆向生成Mybatis代码 or 手写

3、Spring的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx.xsd">
<!--(扫描要被Spring管理的实例)    如果不想在xml文件中配置bean，
        我们可以给我们的类加上spring组件注解，只需再配置下spring的扫描器就可以实现bean的自动载入。-->
    <context:component-scan base-package="cn.cqie"/>
<!--    生成数据库连接池对象-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="url"
                  value="jdbc:mysql://localhost:3306/springmybatis?characterEncoding=utf8&amp; serverTimezone=Asia/Shanghai"/>
        <property name="username" value="root"/>
        <property name="password" value="tcx119"/>
    </bean>
<!--    生成SqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="typeAliasesPackage" value="cq.cqie.pojo"/>
    </bean>
<!--    扫描所有dao-->
<!--    通过下面的配置扫描cn.cqie.dao,将所有dao接口对应dao.xml生成对应的实例-->
    <bean id="mapperScanner" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
        <property name="basePackage" value="cn.cqie.dao"/>
    </bean>
</beans>

4、生成代码

UserServiceImpl

package cn.cqie.service.impl;
import cn.cqie.dao.UserDao;
import cn.cqie.pojo.User;
import cn.cqie.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
    @Resource
    private UserDao userDao;
    @Override
    public List<User> findAll() {
        return userDao.selectByExample(null);
    }
}

UserServlet

package cn.cqie.controller;
import cn.cqie.pojo.User;
import cn.cqie.service.impl.UserServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;
@WebServlet("/userServlet")
public class UserServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("app.xml");
        UserServiceImpl userServiceImpl = (UserServiceImpl) applicationContext.getBean("userServiceImpl");
        List<User> all = userServiceImpl.findAll();
        req.setAttribute("all",all);
        req.getRequestDispatcher("list.jsp").forward(req,resp);
    }
}

list.jsp

<%--
  Created by IntelliJ IDEA.
  User: admin
  Date: 2021/11/12
  Time: 18:17
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <table>
        <c:forEach items="${requestScope.all}" var="all">
            <tr>
                <td>${all.uname}</td>
            </tr>
        </c:forEach>
    </table>
</body>
</html>

以下需要注意

**若要使用@ WebServlet 注解需要添加依赖**

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
  </dependency>

**JSTL与EL需要导入的依赖**

<!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>jstl</artifactId>
  <version>1.2</version>
</dependency>
  <dependency>
  <groupId>taglibs</groupId>
  <artifactId>standard</artifactId>
  <version>1.1.2</version>
</dependency>
  <!-- https://mvnrepository.com/artifact/javax.el/javax.el-api -->
  <dependency>
      <groupId>javax.el</groupId>
      <artifactId>javax.el-api</artifactId>
      <version>3.0.1-b06</version>
  </dependency>

Spring学习笔记（二）