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;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

spring-p.xml

<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：

<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 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;
    }

    @Override
    public 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;
    }

    @Override
    public String toString() {
        return "MyDataSource2{" +
                "properties=" + properties +
                '}';
    }
}

spring-util.xml

<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.Driverprop>
        <prop key="url">jdbc:mysql://localhost:3306/springprop>
        <prop key="username">rootprop>
        <prop key="password">123456prop>
    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

<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：

    @Test
    public 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

<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.xsd
                           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">


    <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>