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Spring依赖注入的方式、类型、Bean的作用域、自动注入、在Spring配置文件中引入属性文件

1.Spring依赖注入的方式

通过set方法完成依赖注入
通过构造方法完成依赖注入

2.依赖注入的类型

基本数据类型和字符串使用value属性
如果是指向另一个对象的引入使用ref属性

User类

package com.alibaba.wlq.bean;

public class User {
	private String name;
	private Integer age;
	private String phone;
	private Student student;
	public Student getStudent() {
		return student;
	}
	public void setStudent(Student student) {
		this.student = student;
	}
	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 getPhone() {
		return phone;
	}
	public void setPhone(String phone) {
		this.phone = phone;
	}
	public User(String name, String phone) {
		super();
		this.name = name;
		this.phone = phone;
		System.out.println("调用两个参的构造函数");
	}
	public User(String name, Integer age, String phone) {
		super();
		this.name = name;
		this.age = age;
		this.phone = phone;
	}
	public User() {
		super();
		System.out.println("调用无参的构造函数");
	}
	
	@Override
	public String toString() {
		return "User [name=" + name + ", age=" + age + ", phone=" + phone + ", student=" + student + "]";
	}
	public void show() {
		System.out.println("调用了show方法");
	}
}

Student类

package com.alibaba.wlq.bean;

public class Student {
	private String address;
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	@Override
	public String toString() {
		return "Student [address=" + address + "]";
	}
}

配置文件

	<bean id="stu" class="com.alibaba.wlq.bean.Student">
		<property name="address" value="南京"></property>
	</bean>
	
	<bean id="user" class="com.alibaba.wlq.bean.User">
		<property name="name" value="刘亦菲"></property>
		<property name="age" value="18"></property>
		<property name="phone" value="10086"></property>
		<property name="student" ref="stu"></property>
	</bean>

测试类

package com.alibaba.wlq.test;
import org.omg.CORBA.portable.ApplicationException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.alibaba.wlq.bean.User;
public class Test {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ApplicationContext app = new ClassPathXmlApplicationContext("app.xml");
		User u = (User) app.getBean("user");
		u.show();
		System.out.println(u);
	}
}

如果类对象注入的属性类型为List类型

在User类中增加如下代码

private List<String> list;
	public List<String> getList() {
		return list;
	}
	public void setList(List<String> list) {
		this.list = list;
	}

配置文件中User类的配置改变

<bean id="user" class="com.alibaba.wlq.bean.User">
		<property name="name" value="刘亦菲"></property>
		<property name="age" value="18"></property>
		<property name="phone" value="10086"></property>
		<property name="student" ref="stu"></property>
		<property name="list">
			<list>
				<value>1</value>
				<value>2</value>
				<value>3</value>
				<value>4</value>
			</list>
		</property>
	</bean>

测试类中间部分

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ApplicationContext app = new ClassPathXmlApplicationContext("app.xml");
		User u = (User) app.getBean("user");
		List<String> list = u.getList();
		for (String string : list) {
			System.out.println(string);
		}
		u.show();
		System.out.println(u);
	}

打印结果

调用无参的构造函数
1
2
3
4
调用了show方法
User [name=刘亦菲, age=18, phone=10086, student=Student [address=南京]]

如果类对象注入的属性类型为Map类型

在User类中添加如下代码

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

配置文件

	<bean id="user" class="com.alibaba.wlq.bean.User">
		<property name="name" value="刘亦菲"></property>
		<property name="age" value="18"></property>
		<property name="phone" value="10086"></property>
		<property name="student" ref="stu"></property>
		<property name="list">
			<list>
				<value>1</value>
				<value>2</value>
				<value>3</value>
				<value>4</value>
			</list>
		</property>
		<property name="map">
			<map>
				<entry key="lyf" value="刘亦菲"></entry>
				<entry key="jsy" value="江疏影"></entry>
				<entry key="lye" value="林允儿"></entry>
			</map>	
		</property>
	</bean>

测试类

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ApplicationContext app = new ClassPathXmlApplicationContext("app.xml");
		User u = (User) app.getBean("user");
		List<String> list = u.getList();
		for (String string : list) {
			System.out.println(string);
		}
		Map<String, String> map = u.getMap();
		for (String k : map.keySet()) {
			System.out.println(k+"===="+map.get(k));
		}
		u.show();
		System.out.println(u);
	}

打印结果

调用无参的构造函数
1
2
3
4
lyf====刘亦菲
jsy====江疏影
lye====林允儿
调用了show方法
User [name=刘亦菲, age=18, phone=10086, student=Student [address=南京]]

3.Bean的作用域

Bean的作用域默认为单例模式

Strust2：该框架要求非单例

bean标签中有scope属性，不写默认为单例，scope属性表示Bean的作用域，非单例：scope="prototype"

4.自动注入

Service类

package com.alibaba.wlq.service;

import com.alibaba.wlq.bean.Product;

public class ProductService {
	private Product product;
	public void fun(){
		product.find();
	}
	public Product getProduct() {
		return product;
	}
	public void setProduct(Product product) {
		this.product = product;
	}
}

Product类

package com.alibaba.wlq.bean;

public class Product {
	private String name;
	private int num;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getNum() {
		return num;
	}
	public void setNum(int num) {
		this.num = num;
	}
	public void find() {
		System.out.println("======find=====");
	}
	@Override
	public String toString() {
		return "Product [name=" + name + ", num=" + num + "]";
	}
}

配置文件

<?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"
	default-autowire="byName">
	
	<bean id="pService" class="com.alibaba.wlq.service.ProductService" autowire="default">
	</bean>
	<bean id="product" class="com.alibaba.wlq.bean.Product">
		<property name="name" value="5700xt"></property>
		<property name="num" value="2"></property>
	</bean>
	
</beans>

测试代码

package com.alibaba.wlq.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.alibaba.wlq.bean.Product;
import com.alibaba.wlq.service.ProductService;

public class Test2 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ApplicationContext app = new ClassPathXmlApplicationContext("app2.xml");
		ProductService pService = (ProductService) app.getBean("pService");
		pService.fun();
		Product product = (Product) app.getBean("product");
		System.out.println(product);
	}

}

打印结果

======find=====
Product [name=5700xt, num=2]

5.在Spring配置文件中引入属性文件

在resources源文件夹下创建properties文件
```
p.name=3700x
p.num=99
```

在配置文件中引用properties文件

<context:property-placeholder location="classpath:my.properties"/>	
	<!-- 引入属性文件，如果要引入多个那就在后面加， -->
	<bean id="pService" class="com.alibaba.wlq.service.ProductService" autowire="default">
	</bean>
	<bean id="product" class="com.alibaba.wlq.bean.Product">
        <!--获取属性文件中的属性-->
		<property name="name" value="${p.name}"></property>
		<prope1rty name="num" value="${p.num}"></property>
	</bean>

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原文地址：https://www.cnblogs.com/wuliqqq/p/11477785.html