spring —— IoC 容器（一）

标签：user 容器 name spring age User IoC public String

IoC 不是一种技术，而是一种设计思想，旨在降低代码之间的耦合性。Spring 通过 IoC 容器管理所有 Java 对象的实例化和初始化，控制对象与对象之间的依赖关系。

一、基于 XML 管理 bean

（一）通过 XML 获取 bean

public class User {
    private String name;
    private int age;

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public User(){
       
    }

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

public class TestUser {
    @Test
    public void userTest(){
        ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        User user = (User) context.getBean("user");
        System.out.println(user);
    }
}

<?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="com.fourth.user.User">       
    </bean>
</beans>

（二）使用 property 注入属性

<?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="com.fourth.user.User">
        <property name="name" value="tom"></property>
        <property name="age" value="20"></property>
    </bean>
</beans>

此时在 TestUser 中获取bean，其实是通过无参构造和 set 方法注入。

（三）使用 constructor-arg 注入属性

<?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="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
    </bean>
</beans>

此时在 TestUser 中获取bean，其实是通过有参构造进行注入。

（四）注入对象类型属性

1、外部 bean 注入

package com.fourth.user;

public class Person {
    private String pid;

    public Person(){}

    public void setPid(String pid) {
        this.pid = pid;
    }

    public Person(String pid) {
        this.pid = pid;
    }
}

package com.fourth.user;

public class User {
    private String name;
    private int age;
    private Person person;

    public User(String name, int age, Person person) {
        this.name = name;
        this.age = age;
        this.person = person;
    }

    public void setName(String name) {
       this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public void setPerson(Person person) {
        this.person = person;
    }
}

<?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="person" class="com.fourth.user.Person">
        <property name="pid" value="10010"></property>
    </bean>

    <bean id="user" class="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="person" ref="person"></constructor-arg>
    </bean>
</beans>

外部 bean 注入对象类型属性，通过 ref 进行引入。

2、内部 bean 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="user" class="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="person">
            <bean id="person" class="com.fourth.user.Person">
                <property name="pid" value="10010"></property>
            </bean>
        </constructor-arg>
    </bean>
</beans>

3、级联属性注入

<?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="person" class="com.fourth.user.Person">
        <constructor-arg name="pid" value="tom"></constructor-arg>
    </bean>

    <bean id="user" class="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="person" ref="person"></constructor-arg>
        <property name="person.pid" value="jerry"></property>
    </bean>
</beans>

或者：

<?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="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="person" >
            <bean id="person" class="com.fourth.user.Person">
                <constructor-arg name="pid" value="tom"></constructor-arg>
            </bean>
        </constructor-arg>
        <property name="person.pid" value="jerry"></property>
    </bean>
</beans>

级联属性注入，首先通过外部 bean 或者内部 bean 进行引入，然后通过 value 更改对象内部的属性。

（五）注入数组类型属性

package com.fourth.user;

public class User {
    private String name;
    private int age;
    private String[] hobby;

    public User(String name, int age, String[] hobby) {
        this.name = name;
        this.age = age;
        this.hobby = hobby;
    }

    public User() {
        
    }

    public void setName(String name) {
       this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public void setHobby(String[] hobby) {
        this.hobby = hobby;
    }

    public String getName() {
        return name;
    }
    public int getAge() {
        return age;
    }
    public String[] getHobby() {
        return hobby;
    }
}

package com.fourth.test;

import com.fourth.user.User;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.Arrays;

public class TestUser {
    @Test
    public void userTest(){
        ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        User user = (User) context.getBean("user");
        System.out.println(Arrays.toString(user.getHobby()));
    }
}

<?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="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="hobby" >
            <array>
                <value>eating</value>
                <value>sleeping</value>
                <value>playing</value>
            </array>
        </constructor-arg>
    </bean>
</beans>

本案例中，hobby 是一个 String 类型数组，对其进行属性注入通过 array 标签进行。

（六）注入 list 类型属性

package com.fourth.user;

import java.util.List;

public class User {
    private String name;
    private int age;
    private List<Person> personList;

    public User(String name, int age, List<Person> personList) {
        this.name = name;
        this.age = age;
        this.personList = personList;
    }

    public User() {
        
    }

    public void setName(String name) {
       this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public void setPersonList(List<Person> personList) {
        this.personList = personList;
    }

    public String getName() {
        return name;
    }
    public int getAge() {
        return age;
    }
    public List<Person> getPersonList() {
        return personList;
    }
}

package com.fourth.user;

public class Person {

    private String pid;

    public Person(){}

    public void setPid(String pid) {
        this.pid = pid;
    }

    public Person(String pid) {

        this.pid = pid;
    }

    public String getPid() {
        return pid;
    }
}

package com.fourth.test;

import com.fourth.user.Person;
import com.fourth.user.User;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestUser {
    @Test
    public void userTest(){
        ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        User user = (User) context.getBean("user");
        for(Person person:user.getPersonList()){
            System.out.println(person.getPid());
        }
    }
}

<?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="person1" class="com.fourth.user.Person">
        <property name="pid" value="10011"></property>
    </bean>
    <bean id="person2" class="com.fourth.user.Person">
        <property name="pid" value="10086"></property>
    </bean>

    <bean id="user" class="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="personList" >
            <list>
                <ref bean="person1"></ref>
                <ref bean="person2"></ref>
            </list>
        </constructor-arg>
    </bean>
</beans>

（七）注入 map 类型属性

package com.fourth.user;

import java.util.Map;

public class User {
    private String name;
    private int age;
    private Map<String,Person> personMap;

    public User(String name, int age, Map<String,Person> personMap) {
        this.name = name;
        this.age = age;
        this.personMap = personMap;
    }

    public User() {
        
    }

    public void setName(String name) {
       this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public void setPersonMap(Map<String,Person> personMap) {
        this.personMap = personMap;
    }

    public String getName() {
        return name;
    }
    public int getAge() {
        return age;
    }
    public Map<String,Person> getPersonMap() {
        return personMap;
    }
}

package com.fourth.user;

public class Person {

    private String pid;

    public Person(){}

    public void setPid(String pid) {
        this.pid = pid;
    }

    public Person(String pid) {

        this.pid = pid;
    }

    public String getPid() {
        return pid;
    }
}

package com.fourth.test;

import com.fourth.user.User;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestUser {
    @Test
    public void userTest(){
        ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        User user = (User) context.getBean("user");
        for(String key:user.getPersonMap().keySet()){
            System.out.println(user.getPersonMap().get(key).getPid());
        }
    }
}

<?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="person1" class="com.fourth.user.Person">
        <property name="pid" value="10011"></property>
    </bean>
    <bean id="person2" class="com.fourth.user.Person">
        <property name="pid" value="10086"></property>
    </bean>

    <bean id="user" class="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="personMap" >
            <map>
                <entry>
                    <key>
                        <value>first</value>
                    </key>
                    <ref bean="person1"></ref>
                </entry>
                <entry>
                    <key>
                        <value>second</value>
                    </key>
                    <ref bean="person2"></ref>
                </entry>
            </map>
        </constructor-arg>
    </bean>
</beans>

（八）util 形式注入属性：对数组、list、map 的补充（1）

以 map 类型为例：

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

    <bean id="person1" class="com.fourth.user.Person">
        <property name="pid" value="10011"></property>
    </bean>
    <bean id="person2" class="com.fourth.user.Person">
        <property name="pid" value="10086"></property>
    </bean>

    <bean id="user" class="com.fourth.user.User">
        <constructor-arg name="name" value="tom"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="personMap" ref="map"></constructor-arg>
    </bean>

    <util:map id="map">
        <entry>
            <key>
                <value>first</value>
            </key>
            <ref bean="person1"></ref>
        </entry>
        <entry>
            <key>
                <value>second</value>
            </key>
            <ref bean="person2"></ref>
        </entry>
    </util:map>
    
</beans>

（九）p 命名空间注入属性：对数组、list、map 的补充（2）

同样以 map 类型为例：

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

    <bean id="person1" class="com.fourth.user.Person">
        <property name="pid" value="10011"></property>
    </bean>
    <bean id="person2" class="com.fourth.user.Person">
        <property name="pid" value="10086"></property>
    </bean>

    <bean id="user" class="com.fourth.user.User" p:name="tom" p:age="20" p:personMap-ref="map">
    </bean>

    <util:map id="map">
        <entry>
            <key>
                <value>first</value>
            </key>
            <ref bean="person1"></ref>
        </entry>
        <entry>
            <key>
                <value>second</value>
            </key>
            <ref bean="person2"></ref>
        </entry>
    </util:map>

</beans>

等于是不再用 property 或者 constructor-arg 注入属性，而是用 p 进行注入。

标签：user,容器,name,spring,age,User,IoC,public,String
From： https://blog.csdn.net/firstgrass/article/details/140599938