3. Spring

3.1 general

• IoC: control inversion, which reverses the right to create objects from new to spring.
• IoC core: manage the life cycle of objects and the relationship between objects (injection)

3.2 introduction case: basic case

• Objective: to write an introduction to spring IoC

• Steps:

  • Write the function implementation class and add it to the spring container: UserDao
  • Write configuration classes and scan the classes that need to be loaded
  • Test class

• Steps:

  • Function implementation class and add it to the spring container: UserDao

    package com.czxy.demo01.dao;
    
    import org.springframework.stereotype.Component;
    
    /**
     * @author Uncle Tong
     * @email liangtong@itcast.cn
     */
    @Component("userDao1")
    public class UserDao {
        public void selectAll() {
            System.out.println("userdao selectAll");
        }
    }
    
    

  • Write configuration classes and scan the classes that need to be loaded

    package com.czxy.demo01.config;
    
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    
    /**
     * @author Uncle Tong
     * @email liangtong@itcast.cn
     */
    @Configuration      //Configuration class
    @ComponentScan(basePackages = "com.czxy.demo01.dao")  //Scan the package of the class to be loaded
    public class SpringConfiguration {
    }
    
    

  • Test class

    package com.czxy.demo01;
    
    import com.czxy.demo01.config.SpringConfiguration;
    import com.czxy.demo01.dao.UserDao;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    /**
     * @author Uncle Tong
     * @email liangtong@itcast.cn
     */
    public class TestDemo01 {
        public static void main(String[] args) {
            // 1 obtain the factory by processing the notes
            ApplicationContext applicationContext = new AnnotationConfigApplicationContext(SpringConfiguration.class);
            // 2. Obtain mapper through the factory
            UserDao userDao =(UserDao) applicationContext.getBean("userDao1");
            // 3 call
            userDao.selectAll();
        }
    }
    
    

3.3 entry case: dependency injection

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• Steps:

  1. Write UserDao and use @ Component
  2. Write UserService and use @ Component
  3. Modify UserService, provide UserDao member variable, and use @ Resource to complete injection
  4. Write test classes and use @ componentscan (service, dao)
  5. Test class

• Steps:

1. Write UserDao and use @ Component

   package com.czxy.demo02.dao;
   
   import org.springframework.stereotype.Component;
   
   /**
    * @author Uncle Tong
    * @email liangtong@itcast.cn
    */
   @Component("userDao2")
   public class UserDao {
   
       public void selectAll() {
           System.out.println("dao : selectAll ");
       }
   }
   
   

2. Write UserService and use @ Component

3. Modify UserService, provide UserDao member variable, and use @ Resource to complete injection

   package com.czxy.demo02.service;
   
   import com.czxy.demo02.dao.UserDao;
   import org.springframework.stereotype.Component;
   
   import javax.annotation.Resource;
   
   /**
    * @author Uncle Tong
    * @email liangtong@itcast.cn
    */
   @Component("userService2")
   public class UserService {
   
       // Inject userDao1 into UserDao
       @Resource(name="userDao2")
       private UserDao userDao;
   
       public void selectAll() {
           // Call dao
           userDao.selectAll();
   
           System.out.println("service : selectAll ");
       }
   }
   
   

4. Write test classes and use @ componentscan (service, dao)

   package com.czxy.demo02.config;
   
   import org.springframework.context.annotation.ComponentScan;
   import org.springframework.context.annotation.Configuration;
   
   /**
    * @author Uncle Tong
    * @email liangtong@itcast.cn
    */
   @Configuration
   @ComponentScan(basePackages = {"com.czxy.demo02.dao","com.czxy.demo02.service"})
   public class Demo02Configuration {
   }
   
   

5. Test class

   package com.czxy.demo02;
   
   
   import com.czxy.demo02.config.Demo02Configuration;
   import com.czxy.demo02.dao.UserDao;
   import com.czxy.demo02.service.UserService;
   import org.springframework.context.ApplicationContext;
   import org.springframework.context.annotation.AnnotationConfigApplicationContext;
   
   /**
    * @author Uncle Tong
    * @email liangtong@itcast.cn
    */
   public class TestDemo02 {
       public static void main(String[] args) {
           // 1 obtain the factory by processing the notes
           ApplicationContext applicationContext = new AnnotationConfigApplicationContext(Demo02Configuration.class);
           // 2. Obtain mapper through the factory
           UserService userService = applicationContext.getBean("userService2", UserService.class);
           // 3 call
           userService.selectAll();
       }
   }
   
   

3.4 entry case: dependency injection interface

• step

  1. Write UserDao interface
  2. Write UserDao implementation class: UserDaoImpl
  3. Write UserService interface
  4. Write the UserServiceImpl implementation class and inject UserDao: UserServiceImpl
  5. Write configuration class
  6. Writing test classes

• step

  1. Write UserDao interface

     package com.czxy.demo03.dao;
     
     /**
      * @author Uncle Tong
      * @email liangtong@itcast.cn
      */
     public interface UserDao {
         public void selectAll() ;
     }
     
     

  2. Write UserDao implementation class: UserDaoImpl

     package com.czxy.demo03.dao.impl;
     
     import com.czxy.demo03.dao.UserDao;
     import org.springframework.stereotype.Component;
     
     /**
      * @author Uncle Tong
      * @email liangtong@itcast.cn
      */
     @Component("userDao3")
     public class UserDaoImpl implements UserDao {
         @Override
         public void selectAll() {
             System.out.println("userdao Interface: selectAll " );
         }
     }
     
     

  3. Write UserService interface

     package com.czxy.demo03.service;
     
     /**
      * @author Uncle Tong
      * @email liangtong@itcast.cn
      */
     public interface UserService {
         public void selectAll();
     }
     
     

  4. Write the UserServiceImpl implementation class and inject UserDao: UserServiceImpl

     package com.czxy.demo03.service.impl;
     
     import com.czxy.demo03.dao.UserDao;
     import com.czxy.demo03.service.UserService;
     import org.springframework.stereotype.Component;
     
     import javax.annotation.Resource;
     
     /**
      * @author Uncle Tong
      * @email liangtong@itcast.cn
      */
     @Component("userService3")
     public class UserServiceImpl implements UserService {
     
         @Resource(name="userDao3")
         private UserDao userDao;
         @Override
         public void selectAll() {
             userDao.selectAll();;
             System.out.println("userService3 : selectAll ");
         }
     }
     
     

  5. Write configuration class

     package com.czxy.demo03.config;
     
     import org.springframework.context.annotation.ComponentScan;
     import org.springframework.context.annotation.Configuration;
     
     /**
      * @author Uncle Tong
      * @email liangtong@itcast.cn
      */
     @Configuration
     @ComponentScan(basePackages = {"com.czxy.demo03.dao","com.czxy.demo03.service"})
     public class Demo03Configuration {
     }
     
     

  6. Write test classes and test with integrated JUnit

     package com.czxy.demo03;
     
     import com.czxy.demo03.config.Demo03Configuration;
     import com.czxy.demo03.service.UserService;
     import org.junit.Test;
     import org.junit.runner.RunWith;
     import org.springframework.test.context.ContextConfiguration;
     import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
     
     import javax.annotation.Resource;
     
     /**
      * @author Uncle Tong
      * @email liangtong@itcast.cn
      */
     @RunWith(SpringJUnit4ClassRunner.class)     //spring integrates Junit
     @ContextConfiguration(classes = Demo03Configuration.class)  //Load configuration class
     public class TestDemo03 {
     
         @Resource(name="userService3")
         private UserService userService;
     
         @Test
         public void testDemo03() {
             userService.selectAll();
         }
     }
     
     

     Summary: after Mybatis finishes learning, it immediately learns the most important framework. The spring framework is one of the most used frameworks in enterprises. Spring is a one-stop framework. The reason why it is called a one-stop framework is that spring can integrate other frameworks. So learning and mastering is very important. After typing the cases in the course, I tried to turn dao into Mybtis to query data. It was successful, but I felt that Mybatis was a little rusty before. I still need to strengthen it. A good memory is not as good as a bad pen.
     Another day closer to work