此文為基礎回顧，估計是最後一次總結。

專案利用maven進行架構，其基本專案結構為：

其中pom.xml中的內容為：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion
 
>

    <groupId>com.mc.base.learn</groupId>
    <artifactId>spring</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>spring</name>
    <url>http://maven.apache.org</url>

    <properties>
 

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</
 
version>
            <scope>test</scope>
        </dependency>

        <!-- Spring核心依賴 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>4.2.6.RELEASE</version>
        </dependency>
        
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>4.2.6.RELEASE</version>
        </dependency>

        <!-- 提供了Spring上下文物件 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.2.6.RELEASE</version>
        </dependency>
        
    </dependencies>
</project>

專案基本結構完成

一、通過建構函式建立物件。

2.1 利用無參建構函式+setter方法注入值

最基本的物件建立方式，只需要有一個無參建構函式（類中沒有寫任何的建構函式，預設就是有一個建構函式，如果寫了任何一個建構函式，預設的無參建構函式就不會自動建立哦!!）和欄位的setter方法。

Person類：

package com.mc.base.learn.spring.bean;

public class Person {

    private String name;
    private Integer id;
    
    public String getName() {
        return name;
    }

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

    public Integer getId() {
        return id;
    }

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

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

}

XML配置：

<?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="com.mc.base.learn.spring.bean.Person" id="person">
        <property name="name" value="LiuChunfu"></property>
        <property name="id" value="125"></property>
    </bean>
    
</beans>

其本質為：

SpringContext利用無參的建構函式建立一個物件，然後利用setter方法賦值。所以如果無參建構函式不存在，Spring上下文建立物件的時候便會報錯。

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'person' defined in class path resource [applicationContext.xml]: Instantiation of bean failed; 
nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.mc.base.learn.spring.bean.Person]: No default constructor found; 
nested exception is java.lang.NoSuchMethodException: com.mc.base.learn.spring.bean.Person.<init>()
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1105)
　　。。。。。

2.2 利用有參建構函式直接注入

Person類：

package com.mc.base.learn.spring.bean;

public class Person {

    private String name;
    private Integer id;
    
    public Person(String name, Integer id) {
        super();
        this.name = name;
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Integer getId() {
        return id;
    }

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

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

}

XML配置：

<?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="com.mc.base.learn.spring.bean.Person" id="person">
        <constructor-arg name="id" value="123"></constructor-arg>
        <constructor-arg name="name" value="LiuChunfu"></constructor-arg>
    </bean>
    
</beans>

二、通過靜態方法建立物件。

package com.mc.base.learn.spring.factory;

import com.mc.base.learn.spring.bean.Person;

public class PersonStaticFactory {
    
    public static Person createPerson(){
        return new Person();
    }
    
    /**
     * 工廠方法帶有引數如何處理？
     * @Title: createPerson 
     * @Description: TODO(這裡用一句話描述這個方法的作用) 
     * @param  @param id
     * @param  @param name
     * @param  @return 
     * @return Person    返回型別 
     * @throws
     */
    public static Person createPerson(Integer id,String name){
        return new Person(name,id);
    }
}

    <!--靜態的工廠方法核心是class+factory-method -->
    <bean id="person" class="com.mc.base.learn.spring.factory.PersonStaticFactory" factory-method="createPerson"></bean>

三、通過工廠方法建立物件。

package com.mc.base.learn.spring.factory;

import com.mc.base.learn.spring.bean.Person;

public class PersonFactory {

    public Person createInstance() {
        return new Person();
    }
}

    <!-- 例項工程方法需要先建立工廠例項，然後在建立所需物件的時候，將其賦值為factory-bean -->
    <bean id="personFactory" class="com.mc.base.learn.spring.factory.PersonFactory"></bean>
    <bean id="person2" factory-bean="personFactory" factory-method="createInstance"></bean>