Spring学习（三）——DI依赖注入及Bean的作用域

灰太狼 2022-12-31 07:26 108阅读 0赞

### 依赖注入 ###

*  构造器注入
 *  Set注入
 *   *  环境搭建
     *  八种方式注入
     *  测试
 *  拓展方式注入
 *   *  p命名空间注入
     *  c命名空间注入
 *  Bean的作用域
 *   *  1、单例模式（Spring默认机制）
     *  2、原型模式：每次从容器中get的时候，都会产生一个新对象
     *  3、其余的request、session、application只能在web中使用

# 构造器注入 #

之前的博客中的注入方式都为构造器注入

# Set注入 #

**依赖注入：set注入**

*  依赖：bean对象的创建依赖于容器
 *  注入：bean中的所有属性由容器注入
 *  ## 环境搭建 ##

创建一个复杂类型及测试用例  
![在这里插入图片描述][20201229092220629.png]

package com.my.pojo;
    
    public class Address {
        
        private String address;
    
        public String getAddress() {
        
            return address;
        }
    
        public void setAddress(String address) {
        
            this.address = address;
        }
    
        @Override
        public String toString() {
        
            return "Address{" +
                    "address='" + address + '\'' +
                    '}';
        }
    }
    
    
    
    package com.my.pojo;
    
    import java.util.*;
    
    
    public class Student {
        
    
        private String name;
        private Address address;
        private String[] books;
        private List<String> hobbies;
        private Map<String,String> card;
        private Set<String> games;
        private String wife;
        private Properties info; //配置类
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public Address getAddress() {
        
            return address;
        }
    
        public void setAddress(Address address) {
        
            this.address = address;
        }
    
        public String[] getBooks() {
        
            return books;
        }
    
        public void setBooks(String[] books) {
        
            this.books = books;
        }
    
        public List<String> getHobbies() {
        
            return hobbies;
        }
    
        public void setHobbies(List<String> hobbies) {
        
            this.hobbies = hobbies;
        }
    
        public Map<String, String> getCard() {
        
            return card;
        }
    
        public void setCard(Map<String, String> card) {
        
            this.card = card;
        }
    
        public Set<String> getGames() {
        
            return games;
        }
    
        public void setGames(Set<String> games) {
        
            this.games = games;
        }
    
        public String getWife() {
        
            return wife;
        }
    
        public void setWife(String wife) {
        
            this.wife = wife;
        }
    
        public Properties getInfo() {
        
            return info;
        }
    
        public void setInfo(Properties info) {
        
            this.info = info;
        }
    
        @Override
        public String toString() {
        
            return "Student{" +
                    "name='" + name + '\'' +
                    ", address=" + address +
                    ", books=" + Arrays.toString(books) +
                    ", hobbies=" + hobbies +
                    ", card=" + card +
                    ", games=" + games +
                    ", wife='" + wife + '\'' +
                    ", info=" + info +
                    '}';
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70]

在学生类的名字属性里面注入奥特曼，其他属性没有注入则打印出就为null  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 1][]

*  ## 八种方式注入 ##

<?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="address" class="com.my.pojo.Address">
            <property name="address" value="xian"/>
        </bean>
    
        <bean id="student" class="com.my.pojo.Student">
            
            <property name="name" value="奥特曼"/>
    
            
            <property name="address" ref="address"/>
            
    
            
            <property name="books">
                <array>
                    <value>红楼梦</value>
                    <value>三国</value>
                    <value>水浒</value>
                    <value>西游记</value>
                </array>
            </property>
    
            
            <property name="hobbies">
                <list>
                    <value>听歌</value>
                    <value>看电影</value>
                    <value>打篮球</value>
                </list>
            </property>
    
            
            <property name="card">
                <map>
                    <entry key="身份证" value="7758521461566"/>
                    <entry key="学生证" value="123456789"/>
                </map>
            </property>
    
            
            <property name="games">
                <set>
                    <value>王者荣耀</value>
                    <value>刺激战场</value>
                </set>
            </property>
    
            
            <property name="wife">
                <null/>
            </property>
    
            
            <property name="info">
                <props>
                    <prop key="学号">12345646</prop>
                    <prop key="班级">网络182</prop>
                </props>
            </property>
    
        </bean>
    
    </beans>

*  ## 测试 ##

import com.my.pojo.Student;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import java.util.Arrays;
    
    public class MyTest {
        
        public static void main(String[] args) {
        
            ApplicationContext context =  new ClassPathXmlApplicationContext("beans.xml");
            Student student = (Student) context.getBean("student");
    
            System.out.println(student.getName());
            System.out.println(student.getAddress());
            System.out.println(Arrays.toString(student.getBooks()));
            System.out.println(student.getHobbies());
            System.out.println(student.getCard());
            System.out.println(student.getGames());
            System.out.println(student.getWife());
            System.out.println(student.getInfo());
            System.out.println();
            System.out.println("====================================");
            System.out.println(student);
            
        }
    }
    
    
    奥特曼
    Address{
        address='xian'}
    [红楼梦, 三国, 水浒, 西游记]
    [听歌, 看电影, 打篮球]
    {
        身份证=7758521461566, 学生证=123456789}
    [王者荣耀, 刺激战场]
    null
    {
        学号=12345646, 班级=网络182}
    
    ====================================
    Student{
        name='奥特曼', address=Address{
        address='xian'}, books=[红楼梦, 三国, 水浒, 西游记], hobbies=[听歌, 看电影, 打篮球], card={
        身份证=7758521461566, 学生证=123456789}, games=[王者荣耀, 刺激战场], wife='null', info={
        学号=12345646, 班级=网络182}}

# 拓展方式注入 #

*  ## p命名空间注入 ##

![在这里插入图片描述][20201229100405523.png]  
p命名空间注入可以直接注入属性：property  
需要导入xml约束

**创建User实体类**

package com.my.pojo;
    
    public class User {
        
        private String name;
        private int age;
    
        public User() {
        
        }
    
        public User(String name, int age) {
        
            this.name = name;
            this.age = age;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public int getAge() {
        
            return age;
        }
    
        public void setAge(int age) {
        
            this.age = age;
        }
    
        @Override
        public String toString() {
        
            return "User{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 2]

<?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"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd">
    
    
        <bean id="user" class="com.my.pojo.User" p:name="hehe" p:age="123"/>
    
    </beans>

**测试**

@Test
        public void Test(){
        
            ApplicationContext context =  new ClassPathXmlApplicationContext("userBean.xml");
            User user =  context.getBean("user",User.class);
            System.out.println(user);
    
        }
    
    User{
        name='hehe', age=123}

*  ## c命名空间注入 ##

c命名空间注入 可以通过构造器注入：construct-arg  
需要导入xml约束  
![在这里插入图片描述][20201229101358775.png]  
使用的时候实体类的构造函数必须有参数  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 3]

<?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="user" class="com.my.pojo.User" p:name="hehe" p:age="123"/>
    
        
        <bean id="user2" class="com.my.pojo.User" c:name="lalala" c:age="7758521"/>
    
    </beans>

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 4]  
**测试**

@Test
        public void Test(){
        
            ApplicationContext context =  new ClassPathXmlApplicationContext("userBean.xml");
            User user =  context.getBean("user2",User.class);
            System.out.println(user);
        }
    
    
    User{
        name='lalala', age=7758521}

# Bean的作用域 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 5]

*  ## 1、单例模式（Spring默认机制） ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 6]

*  ## 2、原型模式：每次从容器中get的时候，都会产生一个新对象 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 7]

<bean id="user2" class="com.my.pojo.User" c:name="lalala" c:age="7758521" scope="prototype"/>
    
    
     @Test
        public void Test(){
        
            ApplicationContext context =  new ClassPathXmlApplicationContext("userBean.xml");
            User user =  context.getBean("user2",User.class);
            User user2 =  context.getBean("user2",User.class);
    
            System.out.println(user == user2);
        }
        
    false

*  ## 3、其余的request、session、application只能在web中使用 ##
 *  request在请求的作用域中
 *  session在一次会话的作用域中
 *  application是全局

[20201229092220629.png]: /images/20221120/c90093dd8d5745a7a4ba05c13e4e3b94.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20201229092942647.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ==,size_16,color_FFFFFF,t_70
[20201229100405523.png]: https://img-blog.csdnimg.cn/20201229100405523.png
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[20201229101358775.png]: https://img-blog.csdnimg.cn/20201229101358775.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20201229101740894.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoYXJfbQ==,size_16,color_FFFFFF,t_70
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