使用PropertyPlaceholderConfigurer读取配置以及配置数据库连接池

大大源码 • 2023年3月21日 pm9:57 • 未分类

一、介绍

1、在springboot项目中，都是将数据库连接池配置放在application.properties中，如果我们需要修改连接池配置，改完配置之后需要提交代码、打包、部署，这样就很麻烦，如果可以将连接池配置放在apollo、zookeeper、redis里是不是修改之后只需要重新部署就可以了，省去前两步；
2、案例中只是从Property配置文件中读取数据源配置。

PropertyPlaceholderConfigurer是干什么的？

PropertyPlaceholderConfigurer是spring的后置处理器，它的作用就是读取Property配置文件，将XML和java代码中有${key}占位符的替换掉，其中key的值就是Property中配置的key

二、案例

1、pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.1.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.cn.dl</groupId>
	<artifactId>springbootdemotest</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>
	<name>springbootdemotest</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
		</dependency>
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid</artifactId>
			<version>1.1.9</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.46</version>
		</dependency>
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>1.3.1</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>


</project>

2、TaskJobBean

package com.cn.dl.bean;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * Created by yanshao on 2018/12/11.
 */
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class TaskJobBean {
    //todo 实际开发还有很多属性!!!
    private String jobName;
    private String jobClassName;
    private String jobCron;
}

3、TaskJobMapper

package com.cn.dl.mapper;

import com.cn.dl.bean.TaskJobBean;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

/**
 * Created by yanshao on 2018/12/11.
 */
@Mapper
public interface TaskJobMapper {
    @Select("select job_name,job_class_name,job_cron from task_job_schedule")
    List<TaskJobBean> findAllTaskJob();
}

4、PropertyPlaceholderConfigurerCustomize

这个类是这个案例的重点，先从/config/springboot.properties读取配置，保存到PropertiesLoaderSupport类localProperties中

package com.cn.dl.config;

import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * 加载配置文件
 * Created by yanshao on 2018/12/11.
 */
@Component
public class PropertyPlaceholderConfigurerCustomize extends PropertyPlaceholderConfigurer {

    public PropertyPlaceholderConfigurerCustomize(){
        InputStream in =  PropertyPlaceholderConfigurerCustomize.class.getResourceAsStream("/config/springboot.properties");
        Properties properties = new Properties();
        try {
            properties.load(in);
            super.setProperties(properties);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

这段代码的作用相当于下面这段xml配置

<bean id= "placeholderConfigurer"
          class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" >
         <property name="location" >
             <value>classpath:/config/springboot.properties</value >
         </property>
</bean>

5、ReadApplicationContext：加载applicationContext-*.xml配置文件

package com.cn.dl.config;

import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.ImportResource;

/**
 * 加载applicationContext-*.xml配置文件
 * Created by yanshao on 2018/12/11.
 */
// TODO: 2018/12/11  @ImportResource不能单独使用
@SpringBootConfiguration // TODO: 2018/12/18 也可以用@Configuration
@ImportResource(locations = {"classpath*:applicationContext-*"})
public class ReadApplicationContext {
}

6、ServiceTest：验证PropertyPlaceholderConfigurerCustomize类是否成功加载到/config/springboot.properties配置文件

package com.cn.dl.service;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

/**
 * Created by yanshao on 2018/12/18.
 */
@Service
public class ServiceTest {
    //业务名称
    @Value("${serviceName}")
    private  String serviceName;
    //业务类型
    @Value("${serviceType}")
    private  String serviceType;

    public String getServiceName() {
        return serviceName;
    }

    public void setServiceName(String serviceName) {
        this.serviceName = serviceName;
    }

    public String getServiceType() {
        return serviceType;
    }

    public void setServiceType(String serviceType) {
        this.serviceType = serviceType;
    }

    @Override
    public String toString() {
        return "ServiceTest{" +
                "serviceName='" + serviceName + '\'' +
                ", serviceType='" + serviceType + '\'' +
                '}';
    }

}

7、ServiceController

package com.cn.dl.controller;

import com.cn.dl.mapper.TaskJobMapper;
import com.cn.dl.service.ServiceTest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * Created by yanshao on 2018/12/18.
 */
@RestController
@RequestMapping("/service")
public class ServiceController {

    @Autowired
    ServiceTest serviceTest;
    @Autowired
    TaskJobMapper taskJobMapper;

    @GetMapping("/test")
    public String serviceTest(){
        return serviceTest.toString();
    }
    @GetMapping("/job")
    public List findAll(){
        return taskJobMapper.findAllTaskJob();
    }

}

8、/config/springboot.properties内容

user.name=tiger
user.age=13
user.address=shanghai
serviceName=messageSystem
serviceType=save
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/tiger_base?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true&generateSimpleParameterMetadata=true
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.max-idle=10
spring.datasource.max-wait=60000
spring.datasource.min-idle=5
spring.datasource.initial-size=5
spring.datasource.validationQuery=select 'x'

9、applicationContext-dataSource.xml

注意：这块配置就是之前在application.properties中那些配置内容

<?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:tx="http://www.springframework.org/schema/tx"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       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/tx
           http://www.springframework.org/schema/tx/spring-tx.xsd
           http://www.springframework.org/schema/aop
           http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">

    <bean id="masterDatasource" class="com.alibaba.druid.pool.DruidDataSource"
          init-method="init" destroy-method="close" >
        <property name="dbType" value="mysql"/>
        <property name="url" value="${spring.datasource.url}"/>
        <property name="driverClassName" value="${spring.datasource.driver-class-name}"/>
        <property name="username" value="${spring.datasource.username}"/>
        <property name="password" value="${spring.datasource.password}"/>
        <property name="initialSize" value="${spring.datasource.initial-size}"/>
        <property name="maxWait" value="60000"/>
    </bean>

</beans>

三、测试

1、postMan调：127.0.0.1:8080/service/test

注意：看到messageSystem和save说明我们可以正常读取配置！

2、调127.0.0.1:8080/service/job

注意：表中有3条数据，调用接口返回下面3条数据，说明连接池配置成功

[
    {
        "jobName": "jobA",
        "jobClassName": "com.cn.dl.task.JobA",
        "jobCron": "0/5 * * * * ? *"
    },
    {
        "jobName": "jobB",
        "jobClassName": "com.cn.dl.task.JobB",
        "jobCron": "0 0 04 * * ? *"
    },
    {
        "jobName": "jobC",
        "jobClassName": "com.cn.dl.task.JobC",
        "jobCron": "0/30 * * * * ? *"
    }
]