Java 之Spring框架Bean

一、基本使用

1、Bean的基本配置

• id属性：定义bean的名字
• class属性：定义bean的类名称
• name属性：bean的别名配置，可以有逗号，分号，空格分隔
• scope属性：控制对象是否为单例
• autowire：自动装配

2、实例化Bean的三种方式

• 构造方法（常用）
• 静态工厂（了解）

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import dao.UserDao;

import service.impl.UserServiceImpl;

import bean.User;


@SuppressWarnings("unused")
public class Test3 {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext3.xml");
        UserDao userDao = (UserDao) context.getBean("userDao");
        userDao.save();
    }
}

<?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="userDao" class="factory.UserDaoFactory" factory-method="getUserDao"></bean>
</beans>

package factory;

import dao.UserDao;
import dao.impl.UserDaoImpl;

public class UserDaoFactory {
    
    public static UserDao getUserDao()
    {
        return new UserDaoImpl();
    }
}

• 实例工厂
• 使用factoryBean（实用）

UserDaoFactoryBean.java

package factory;

import org.springframework.beans.factory.FactoryBean;

import dao.UserDao;
import dao.impl.UserDaoImpl;

public class UserDaoFactoryBean implements FactoryBean<UserDao> {

    //创建对象的方法
    public UserDao getObject() throws Exception {

        return new UserDaoImpl();
    }

    public Class<?> getObjectType() {

        return UserDao.class;
    }

    public boolean isSingleton() {
        // TODO Auto-generated method stub
        return false;
    }
}

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import dao.UserDao;

import service.impl.UserServiceImpl;

import bean.User;


@SuppressWarnings("unused")
public class Test3 {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext3.xml");
        UserDao userDao = (UserDao) context.getBean("userDao");
        userDao.save();
    }
}

applicationContext3.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="userDao" class="factory.UserDaoFactoryBean"></bean>
</beans>

3、bean的生命周期

<?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="userDao" class="dao.impl.UserDaoImpl" init-method="init" destroy-method="destroy"></bean>
</beans>

package dao.impl;

import dao.UserDao;


public class UserDaoImpl implements UserDao {
    
    public void init() {
        System.out.println("init...");
    }
    public void save() {
        System.out.println("UserDaoImpl save...");
    }
    
    public void destroy() {
        System.out.println("destroy...");
    }
}

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import dao.UserDao;

import service.impl.UserServiceImpl;

import bean.User;


@SuppressWarnings("unused")
public class Test3 {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext3.xml");
        UserDao userDao = (UserDao) context.getBean("userDao");
        userDao.save();
        context.registerShutdownHook();
    }
}

spring的方式 - InitializingBean,DisposableBean接口

package service.impl;

import javax.annotation.Resource;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;

import service.UserService;
import dao.UserDao;

@SuppressWarnings("restriction")
@Service("userService")
public class UserServiceImpl implements UserService,InitializingBean,DisposableBean {
    
    @Resource(name = "userDao")
    private UserDao userDao;
    
    public void save() {
        userDao.save();
        System.out.println("UserServiceImpl save...");
    }

    public void afterPropertiesSet() throws Exception {
        System.out.println("afterPropertiesSet...");
    }

    public void destroy() throws Exception {
        System.out.println("destroy...");
    }

//    public void setUserDao(UserDao userDao) {
//        this.userDao = userDao;
//    }
    
}

4、依赖注入方式4种

a、setter注入

 

 b、构造器注入

 UserDaoImpl.java

package service.impl;

import service.UserService;
import dao.UserDao;

public class UserServiceImpl implements UserService {
    
    private UserDao userDao;
    
    //创建UserServiceImpl 的构造方法
    public UserServiceImpl(UserDao userDao1) {
        this.userDao = userDao1;
    }
    
    public void save() {
        userDao.save();
        System.out.println("UserServiceImpl save...");
    }
    
}

applicationContext4.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="userDao" class="dao.impl.UserDaoImpl"></bean>
    
    <bean id="userService" class="service.impl.UserServiceImpl">
        <!-- index：构造方法中的参数位置，ref：关联上面bean中的id -->
        <constructor-arg index="0" ref="userDao"></constructor-arg>
    </bean>
</beans>

运行代码

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import service.UserService;


public class Test4 {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext4.xml");
        UserService userService = (UserService) context.getBean("userService");
        userService.save();
    }

}

c、自动装配（autowire）

UserServiceImpl.java

package service.impl;

import service.UserService;
import dao.UserDao;

public class UserServiceImpl implements UserService {
    
    private UserDao userDao;
    
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    public void save() {
        userDao.save();
        System.out.println("UserServiceImpl save...");
    }
    
}

运行代码

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import service.UserService;


public class Test5 {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext5.xml");
        UserService userService = (UserService) context.getBean("userService");
        userService.save();
    }
}

applicationContext5.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 class="dao.impl.UserDaoImpl"></bean>
    <!--autowire属性：开启自动装配，通常使用按类型装配-->
    <bean id="userService" class="service.impl.UserServiceImpl" autowire="byType"></bean>
</beans>

 d、集合注入

User.java

package bean;

import java.util.Map;
import java.util.Set;

public class User {
    private int id;
    private String name;
    private Set<String> set;
    private Map<String, String> map;
    
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

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

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

    @Override
    public String toString() {
        return "User [id=" + id + ", map=" + map + ", name=" + name + ", set="
                + set + "]";
    }
    
}

运行代码

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import bean.User;


public class Test6 {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext6.xml");
        User user = (User) context.getBean("user");
        System.out.println(user);
    }

}

applicationContext6.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="user" class="bean.User">
        <property name="id" value="1"></property>
        <property name="name" value="yy"></property>
        <property name="set">
            <set>
                <value>11</value>
                <value>22</value>
                <value>33</value>
            </set>
        </property>
        <property name="map">
            <map>
                <entry key="key1" value="11"></entry>
                <entry key="key2" value="22"></entry>
            </map>
        </property>
    </bean>
    
</beans>