spring对象的获取及属性赋值方式

1、通过bean的id获取IOC容器中的对象

SpringDemoTest.java

import com.mashibing.bean.Person;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringDemoTest {
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("spring.xml");
        Person person =(Person) context.getBean("person");
        System.out.println(person);
    }
}

2、通过bean的类型获取对象

SpringDemoTest.java

import com.mashibing.bean.Person;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringDemoTest {
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("spring.xml");
        Person bean = context.getBean(Person.class);
        System.out.println(bean);
    }
}
注意：通过bean的类型在查找对象的时候，在配置文件中不能存在两个类型一致的bean对象，如果有的话，可以通过如下方法
SpringDemoTest.java

import com.mashibing.bean.Person;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringDemoTest {
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("spring.xml");
        Person person = context.getBean("person", Person.class);
        System.out.println(person);
    }
}

3、通过构造器给bean对象赋值

spring.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="person" class="com.mashibing.bean.Person">
        <property name="id" value="1"></property>
        <property name="name" value="单强"></property>
        <property name="age" value="32"></property>
        <property name="gender" value="男"></property>
    </bean>
    <!--给person类添加构造方法-->
    <bean id="person1" class="com.mashibing.bean.Person">
        <constructor-arg name="id" value="1"></constructor-arg>
        <constructor-arg name="name" value="qiangShan"></constructor-arg>
        <constructor-arg name="age" value="31"></constructor-arg>
        <constructor-arg name="gender" value="nan"></constructor-arg>
    </bean>
    <!--在使用构造器赋值的时候可以省略name属性，但是此时就要求必须严格按照构造器参数的顺序来填写了-->
    <bean id="person2" class="com.mashibing.bean.Person">
        <constructor-arg value="2"></constructor-arg>
        <constructor-arg value="yongfengQin"></constructor-arg>
        <constructor-arg value="51"></constructor-arg>
        <constructor-arg value="nv"></constructor-arg>
    </bean>
    <!--如果想不按照顺序来添加参数值，那么可以搭配index属性来使用-->
    <bean id="person3" class="com.mashibing.bean.Person">
        <constructor-arg value="wenyingJiang" index="1"></constructor-arg>
        <constructor-arg value="3" index="0"></constructor-arg>
        <constructor-arg value="nan" index="3"></constructor-arg>
        <constructor-arg value="30" index="2"></constructor-arg>
    </bean>
    <!--当有多个参数个数相同，不同类型的构造器的时候，可以通过type来强制类型-->
    <bean id="person4" class="com.mashibing.bean.Person">
        <constructor-arg value="5"></constructor-arg>
        <constructor-arg value="lisi"></constructor-arg>
        <constructor-arg value="20" type="java.lang.Integer"></constructor-arg>
    </bean>
    <!--如果不修改为integer类型，那么需要type跟index组合使用-->
    <bean id="person5" class="com.mashibing.bean.Person">
        <constructor-arg value="6"></constructor-arg>
        <constructor-arg value="lisi"></constructor-arg>
        <constructor-arg value="22" type="int" index="2"></constructor-arg>
    </bean>
</beans>

Person.java

package com.mashibing.bean;

public class Person {
    private int id;
    private String name;
    private Integer age;
    private String gender;

    public Person() {
    }

    public Person(int id, String name, Integer age, String gender) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
    }

    public Person(int id,String name,Integer age){
        this.id=id;
        this.name=name;
        this.age=age;
        System.out.println("age");
    }

    public Person(int id,String name,String gender){
        this.id=id;
        this.name=name;
        this.gender=gender;
        System.out.println("gender");
    }

    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 Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }
}

SpringDemoTest.java

import com.mashibing.bean.Person;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringDemoTest {
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("spring.xml");
        Person person = context.getBean("person1", Person.class);
        System.out.println(person);
        Person person2 = context.getBean("person2", Person.class);
        System.out.println(person2);
        Person person3 = context.getBean("person3", Person.class);
        System.out.println(person3);
        Person person4 = context.getBean("person4", Person.class);
        System.out.println(person4);
        Person person5 = context.getBean("person5", Person.class);
        System.out.println(person5);
    }
}

4、通过命名空间为bean赋值，简化配置文件中属性声明的写法

1、导入命名空间

<?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
">

2、添加配置

<bean id="person" class="com.mashibing.bean.Person" p:id="3" p:name="qiangShan" p:age="32" p:gender="nan"></bean>

5、为复杂类型进行赋值操作

在之前的测试代码中，我们都是给最基本的属性进行赋值操作，在正常的企业级开发中还会遇到给各种复杂类型赋值，如集合、数组、其他对象等。