01上课笔记--SpringIOC

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wx5cee84fb43fbb 2023-01-09 17:07:51 博主文章分类：SpringBoot ©著作权

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IOC 依赖注入
有两种方式：基于xml和注解
xml又有构造器注入和set方法注入

SpringIOC

01上课笔记--SpringIOC_java

1.传统的new对象的方式

userDao.java

public interface UserDao {
    public void getUser();
}

userDaoImpl.java

import com.peach.hong2.dao.UserDao;

public class UserDaoImpl implements UserDao  {
    @Override
    public void getUser() {
        System.out.println("dao层服务被调用");
    }
}

userService.java

public interface UserService {
    public void getUser();
}

UserServieceImpl.java

import com.peach.hong2.dao.UserDao;
import com.peach.hong2.dao.impl.UserDaoImpl;
import com.peach.hong2.service.UserService;

public class UserServiceImpl implements UserService {

    private UserDao userDao = new UserDaoImpl();

    @Override
    public void getUser() {
        System.out.println("service层服务被调用");
        userDao.getUser();
    }
}

test下面的 hong2ApplicationTests.java

private UserService userService = new UserServiceImpl();
    @Test
    void testUser(){
        userService.getUser();
    }

方式一：xml配置类

@SpringBootTest
class Hong2ApplicationTests {
    //private UserService userService = new UserServiceImpl();
    private UserService userService ;

    @Test
    void testUser(){
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("bean.xml");
        userService = (UserService) applicationContext.getBean("userService");
        userService.getUser();
    }
}

01上课笔记--SpringIOC_System_02

1、通过构造器

UserServiceImpl.java

public class UserServiceImpl implements UserService {

//    private UserDao userDao = new UserDaoImpl();
    private UserDao userDao;

    //通过构造器
    public UserServiceImpl(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public void getUser() {
        System.out.println("service层服务被调用");
        userDao.getUser();
    }
}

bean.xml

<bean id="userService" class="com.peach.hong2.service.impl.UserServiceImpl">
    <constructor-arg name="userDao" ref="userDao"></constructor-arg>
</bean>
<bean id="userDao" class="com.peach.hong2.dao.impl.UserDaoImpl"></bean>

注意： bean 的id是自己起的，后面的class是实现类的路径。

01上课笔记--SpringIOC_xml_03

01上课笔记--SpringIOC_xml_04

2、通过set方法和property属性值的方式注入

userServiceImpl.java

public class UserServiceImpl implements UserService {

//    private UserDao userDao = new UserDaoImpl();
    private UserDao aaa;

    public void setAaa(UserDao hhh) {
        this.aaa = hhh;
    }

    @Override
    public void getUser() {
        System.out.println("service层服务被调用");
        aaa.getUser();
    }
}

bean.xml

<bean id="userService" class="com.peach.hong2.service.impl.UserServiceImpl">
<!--        <constructor-arg name="userDao" ref="userDao"></constructor-arg>-->
        <property name="aaa" ref="userDao"></property>
    </bean>

01上课笔记--SpringIOC_System_05

3、普通类型的注入

1. List

给list赋值，并且输出

UserDaoImpl.java

private List<String> list;

public void setList(List<String> list) {
    this.list = list;
}

@Override
public void getUser() {
    System.out.println("dao层服务被调用");
    for (String string:list) {
        System.out.println(string);
    }
}

bean.xml

<bean id="userDao" class="com.peach.hong2.dao.impl.UserDaoImpl">
    <property name="list" >
        <list>
            <value>list1</value>
            <value>list2</value>
            <value>list3</value>
        </list>
    </property>
</bean>

2.数组

给数组赋值，并且输出

UserDaoImpl.java

private String[] arr ;

    public void setArr(String[] arr) {
        this.arr = arr;
    }
    @Override
    public void getUser() {
        for (String s:arr) {
            System.out.println(s);
        }
    }

bean.xml

<bean id="userDao" class="com.peach.hong2.dao.impl.UserDaoImpl">
   <property name="arr">
       <array>
           <value>arr1</value>
           <value>arr2</value>
           <value>arr3</value>
       </array>
    </property>
</bean>

3. set与map

<property name="set">
    <set>
        <value>set1</value>
        <value>set2</value>
    </set>
</property>

<property name="map">
    <map>
        <entry key="1" value="map1"/>
        <entry key="2" value="map2"/>
    </map>
</property>

4、测试时在主程序里写的

// 获取容器
        ApplicationContext ac = new ClassPathXmlApplicationContext("springContext.xml");
        // 根据beanID获取对象
        // 调用前必须在springContext.xml中配置注解方式解析
        IUserClientService userClientService = (IUserClientService) ac.getBean("userService");
        userClientService.saveCustom();

01上课笔记--SpringIOC_java_06

整体代码

目录结构
springContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="userService" class="com.peach.service.impl.IUserClientServiceImpl">
        <constructor-arg name="userClientDao" ref="userClientDao">
        </constructor-arg>

        <property name="list">
            <list>
                <value>list1</value>
                <value>list2</value>
                <value>list3</value>
            </list>
        </property>

        <property name="arr">
            <array>
                <value>arr1</value>
                <value>arr2</value>
                <value>arr3</value>
            </array>
        </property>

        <property name="set">
            <set>
                <value>set1</value>
                <value>set2</value>
            </set>
        </property>

        <property name="map">
            <map>
                <entry key="1" value="map1"/>
                <entry key="2" value="map2"/>
            </map>
        </property>


    </bean>

    <bean id="userClientDao" class="com.peach.dao.impl.IUserClientDaoImpl"/>

</beans>

dao层

IUserClientDao.java

public interface IUserClientDao {
    //保存客户信息
    void saveCustom();
}

IUserClientDaoImpl.java

public class IUserClientDaoImpl implements IUserClientDao {

    @Override
    public void saveCustom() {
        System.out.println("调用持久层");
    }
}

Service层

IUserClientService.java

public interface IUserClientService {
    //保存客户信息
    void saveCustom();
}

IUserClientServiceImpl.java

public class IUserClientServiceImpl implements IUserClientService {
    private IUserClientDao userClientDao;  //这个是通过构造器注入的

    private List<String> list;
    private String[] arr;
    private Set<String> set;
    private Map<String,String> map;

    //通过set和properties注入
    public void setList(List<String> list) {
        this.list = list;
    }

    public void setArr(String[] arr) {
        this.arr = arr;
    }

    public void setSet(Set<String> set) {
        this.set = set;
    }

    public void setMap(Map<String, String> map) {
        this.map = map;
    }

    public IUserClientServiceImpl(IUserClientDaoImpl userClientDao) {
        this.userClientDao = userClientDao;
    }

    private String name;

    @Override
    public void saveCustom() {
        System.out.println("业务层调用持久层"+name);
        userClientDao.saveCustom();
        for (String str: list
             ) {
            System.out.print(str+" ");
        }
        System.out.println();
        for (String str:arr
             ) {
            System.out.print(str+" ");
        }
        System.out.println();
        for (String str:set
        ) {
            System.out.print(str+" ");
        }

        System.out.println();
        //map比较特殊
        Iterator<Map.Entry<String,String>> entries = map.entrySet().iterator();
        while (entries.hasNext()){
            Map.Entry<String,String >entry = entries.next();
            String key = entry.getKey();
            String value = entry.getValue();
            System.out.println(key+":"+value);
        }
    }
}

方式二：注解方式

1.去掉bean.xml

删除bean.xml文件，删除ApplicationContext这两行代码

01上课笔记--SpringIOC_xml_07

IUserClientServiceImpl加注解 @Service； IUserClientDaoImpl 加注解 Repository

01上课笔记--SpringIOC_System_08

01上课笔记--SpringIOC_java_09

01上课笔记--SpringIOC_xml_10

2.@Component

@Component 相当于配置一个bean标签，出现的位置：类

属性值value，用于指定bean的id，如果不写该参数则它的默认值是当前类的短命首字母改小写。

衍生的三个注解（作用和component一模一样）

Controller：用于表现层注解
Service：用于业务层注解
Repository：用于持久层注解（Dao）

所以，把第一点中写的DaoImpl中的component替换为Repository，把ServiceImpl中的component换为Service

3. @Autowired

自动按照类型注入，不关心bean的id。

**注意：**一定不能出现二义性。也就是说如果有两个（如下图），则不能被识别。

01上课笔记--SpringIOC_System_11

01上课笔记--SpringIOC_xml_12

整体代码

目录结构
dao层 IUserClientDao.java

public interface IUserClientDao {
    //保存客户信息
    void saveCustom();
}

IUserClientDaoImpl

import com.peach.dao.IUserClientDao;
import org.springframework.stereotype.Repository;

@Repository("userClientDao")
public class IUserClientDaoImpl implements IUserClientDao {

    @Override
    public void saveCustom() {
        System.out.println("调用持久层");
    }
}

service层 IUserClientService.java

public interface IUserClientService {
    //保存客户信息
    void saveCustom();
}

IUserClientServiceImpl.java

@Service("userClientService")
public class IUserClientServiceImpl implements IUserClientService {

    /**
     * 这个是通过构造器注入的
     * */
    @Autowired
    @Qualifier("userClientDao")
//    @Resource(name = "userClientDao")
    private IUserClientDao userClientDao;
    @Value("peach")
    private String name;

    @Override
    public void saveCustom() {
        System.out.println(name);
        System.out.println("业务层调用持久层");
        userClientDao.saveCustom();
    }
}

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