spring命名空间注入和XML自动装配、引入外部配置文件

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p命名空间注入

作用：简化配置。

使用p命名空间注入的前提条件包括两个：
● 第一：在XML头部信息中添加p命名空间的配置信息：xmlns:p=“http://www.springframework.org/schema/p”
● 第二：p命名空间注入是基于setter方法的，所以需要对应的属性提供setter方法。

Customer.java

package com.w.spring6.bean;public class Customer {private String name;private int age;public void setName(String name) {this.name = name;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Customer{" +"name='" + name + '\'' +", age=" + age +'}';}
}

spring-p.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" 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="customerBean" class="com.w.spring6.bean.Customer" p:name="zhangsan" p:age="20"/></beans>

测试程序：

@Test
public void testP(){ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-p.xml");Customer customerBean = applicationContext.getBean("customerBean", Customer.class);System.out.println(customerBean);
}

运行结果：

util命名空间注入

使用util命名空间可以让配置复用。
使用util命名空间的前提是：在spring配置文件头部添加配置信息。如下：

<?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:util="http://www.springframework.org/schema/util"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">

MyDataSource1.java

package com.w.spring6.jdbc;import java.util.Properties;public class MyDataSource1 {private Properties properties;public void setProperties(Properties properties) {this.properties = properties;}@Overridepublic String toString() {return "MyDataSource1{" +"properties=" + properties +'}';}
}

MyDataSource2.java

package com.w.spring6.jdbc;import java.util.Properties;public class MyDataSource2 {private Properties properties;public void setProperties(Properties properties) {this.properties = properties;}@Overridepublic String toString() {return "MyDataSource2{" +"properties=" + properties +'}';}
}

spring-util.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" xmlns:util="http://www.springframework.org/schema/util"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/util https://www.springframework.org/schema/util/spring-util.xsd"><util:properties id="prop"><prop key="driver">com.mysql.cj.jdbc.Driver</prop><prop key="url">jdbc:mysql://localhost:3306/spring</prop><prop key="username">root</prop><prop key="password">123456</prop></util:properties><bean id="dataSource1" class="com.w.spring6.jdbc.MyDataSource1"><property name="properties" ref="prop"/></bean><bean id="dataSource2" class="com.w.spring6.jdbc.MyDataSource2"><property name="properties" ref="prop"/></bean></beans>

测试程序:

@Test
public void testUtil(){ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-util.xml");MyDataSource1 dataSource1 = applicationContext.getBean("dataSource1", MyDataSource1.class);System.out.println(dataSource1);MyDataSource2 dataSource2 = applicationContext.getBean("dataSource2", MyDataSource2.class);System.out.println(dataSource2);
}

基于XML的自动装配

Spring还可以完成自动化的注入，自动化注入又被称为自动装配。它可以根据名字进行自动装配，也可以根据类型进行自动装配。

根据名称自动装配

UserDao.java

package com.w.spring6.dao;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;public class UserDao {private static final Logger logger= LoggerFactory.getLogger(UserDao.class);public void insert(){//System.out.println("数据库正在保存信息");logger.info("数据库正在保存信息");}}

VipDao.java

package com.w.spring6.dao;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;public class VipDao {private static final Logger logger= LoggerFactory.getLogger(VipDao.class);public void insert(){logger.info("数据库正在保存vip信息");}
}

UserService.java

package com.w.spring6.service;import com.w.spring6.dao.UserDao;
import com.w.spring6.dao.VipDao;public class UserService {private UserDao userDao;private VipDao vipDao;//    public void setAbc(VipDao vipDao){
//        this.vipDao=vipDao;
//    }public void setVipDao(VipDao vipDao){this.vipDao=vipDao;}//set注入的话，必须提供一个set方法//spring容器会调用这个set方法，来给userDao赋值
/*    //自己写的不符合javabean规范public void setMySQLUserDao(UserDao xyz){this.userDao=xyz;}*///idea自动生成的符合javabean规范public void setUserDao(UserDao userDao) {this.userDao = userDao;}public void saveUser(){userDao.insert();vipDao.insert();}
}

spring-autowire.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="userService" class="com.w.spring6.service.UserService" autowire="byName"/><bean id="userDao" class="com.w.spring6.dao.UserDao"/><bean id="vipDao" class="com.w.spring6.dao.VipDao"/></beans>

测试程序：

    @Testpublic void testAutowireByName(){ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-autowire.xml");UserService userService = applicationContext.getBean("userService", UserService.class);userService.saveUser();}

运行结果：

Spring引入外部属性配置文件

在类路径下新建jdbc.properties文件，并配置信息

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/spring
username=root
password=123456

在spring配置文件中引入context命名空间，配置使用jdbc.properties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"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!--
引入外部的properties文件
第一步：引入context命名空间
第二步：使用标签location属性来指定属性配置文件的路径--><context:property-placeholder location="jdbc.properties"/><bean id="dataSource" class="com.w.spring6.jdbc.MyDataSource"><property name="driver" value="${jdbc.driverClass}"></property><property name="url" value="${jdbc.url}"></property><property name="username" value="${jdbc.username}"></property><property name="password" value="${jdbc.password}"></property></bean></beans>