插件准备： maven helper 解决包冲突必备神器。
目标：将原始项目的spring 版本4.3.22.RELEASE，升级为springboot 的2.3.5.RELEASE版本，步骤如下：

加入springboot包，并且改war包为jar包

    <packaging>jar</packaging>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <!-- Import dependency management from Spring Boot -->
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${version.springboot}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
   <!--spring boot-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
同步springframework版本号，也就是移除掉springframework系列包中指定的version，spring的版本会自动和dependencyManagement的spring版本一致
创建启动类，把原来的xml的配置文件包含进去
@SpringBootApplication(exclude = {RedisRepositoriesAutoConfiguration.class, DataSourceAutoConfiguration.class, RedisAutoConfiguration.class, KafkaAutoConfiguration.class, MongoDataAutoConfiguration.class, MongoRepositoriesAutoConfiguration.class})
@ImportResource(locations = {"/spring/applicationContext.xml"})
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(CustNotifyApplication .class, args);
增加springboot打包插件
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.demo.manage.Application</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
原先的disconf是xml方式配置的，看得不舒服，索性干掉了下面的xml配置：
<?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:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans.xsd
                        http://www.springframework.org/schema/aop
                        http://www.springframework.org/schema/aop/spring-aop.xsd">
 <aop:aspectj-autoproxy proxy-target-class="true" />
 <!-- disconf配置 -->
 <bean id="disconfMgrBean" class="com.baidu.disconf.client.DisconfMgrBean"
     destroy-method="destroy">
     <property name="scanPackage" value="com.demo.manage" />
 </bean>
 <bean id="disconfMgrBean2" class="com.baidu.disconf.client.DisconfMgrBeanSecond"
     init-method="init" destroy-method="destroy">
 </bean>
 <bean id="configproperties_no_reloadable_disconf"
     class="com.baidu.disconf.client.addons.properties.ReloadablePropertiesFactoryBean">
     <property name="locations">
             <value>redis.properties</value>
             <value>dubbo.properties</value>
             <value>kafka.properties</value>
             <value>kafka.consumer.config.properties</value>
             <value>db.properties</value>
         </list>
     </property>
 </bean>
 <bean id="hostBindProperties" class="com.demo.common.util.PropertiesFactoryBean">
     <property name="fileLists">
             <value>config/host-bind.properties</value>
         </list>
     </property>
 </bean>
 <!-- 使用托管方式的disconf配置(无代码侵入, 配置更改不会自动reload) -->
 <bean id="propertyConfigurerForNoReload"
     class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
     <property name="ignoreResourceNotFound" value="false" />
     <property name="ignoreUnresolvablePlaceholders" value="false" />
     <property name="propertiesArray">
             <ref bean="configproperties_no_reloadable_disconf" />
             <ref bean="hostBindProperties" />
         </list>
     </property>
 </bean>
</beans>
在application.yaml中加入disconf配置：
server:
  port: 8080
  shutdown: graceful
spring:
  application:
    name: demo-server
  profiles:
    active: ${profile.active}
  main:
    allow-bean-definition-overriding: true
  jackson:
    time-zone: GMT+8
dubbo:
  protocol:
    host: 127.0.0.1
# disconf config
disconf:
  scanPackage: com.demo.manage
  version: ${disconf.version}
  env: ${disconf.env}
  conf_server_host: ${disconf.server.host}
  files: redis.properties,dubbo.properties,kafka.properties,kafka.consumer.config.properties,db.properties
  app: demo-server
  debug: false
  enable:
    remote:
      conf: true
  conf_server_url_retry_times: 3
  conf_server_url_retry_sleep_seconds: 5
  user_define_download_dir: /app/spring-boot/demo-server/disconf
  enable_local_download_dir_in_class_path: false
在pom中加入了springboot的disconf启动包
        <dependency>
            <groupId>com.fcbox</groupId>
            <artifactId>spring-boot-starter-disconf</artifactId>
            <version>2.0.0</version>
        </dependency>
修改环境变量配置命名规范。
将pom中的profiles.activation修改为profile.active
logback文件按照配置环境区分配置:
    <springProfile name="dev,local,per,pet,uat,uat1,uat2,uat3,uat4,uat5,uat6,uat7">
        <root level="INFO">
            <appender-ref ref="CONSOLE"/>
            <appender-ref ref="notify_log"/>
            <appender-ref ref="error_log"/>
        </root>
    </springProfile>
    <springProfile name="prd,stg">
        <root level="INFO">
            <appender-ref ref="notify_log"/>
            <appender-ref ref="error_log"/>
        </root>
    </springProfile>
第三方sdk包中使用classpath读取不到配置文件，可以使用绝对路径加载，如：
 <bean id="personalPaymentService" class="com.demo.payment.client.impl.PersonalPaymentServiceImpl" >
     <property name="configPath" value="file:/app/spring-boot/demo-server/disconf/payment_common.properties" />
 </bean>
包冲突问题
jackson版本冲突，报错信息：Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/datatype/jsr310/ser/ZoneIdSerializer。直接升级到最高版本2.12.0，然后干掉版本不一致的jackson包,涉及的jackson包为：
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.12.0</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.12.0</version>
            <exclusions>
                <exclusion>
                    <artifactId>jackson-core</artifactId>
                    <groupId>com.fasterxml.jackson.core</groupId>
                </exclusion>
                <exclusion>
                    <artifactId>jackson-annotations</artifactId>
                    <groupId>com.fasterxml.jackson.core</groupId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.12.0</version>
        </dependency>
log4j包缺失报错 java.lang.ClassNotFoundException: org.apache.log4j.Logger。dubbo使用了 log4j所以需要引入log4j包：
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>log4j-over-slf4j</artifactId>
            <version>1.7.30</version>
        </dependency>
jedis包冲突 java.lang.ClassNotFoundException: redis.clients.jedis.util.Pool 排除掉jedis低版本包
Redis配置读取本地文件，需要改为Spring-map加载
<bean id="mallResourcePropertySource"
     class="org.springframework.core.io.support.ResourcePropertySource">
   <constructor-arg name="name" value="mall-redis-conf.properties"/>
   <constructor-arg name="resource"
                value="classpath:mall-redis-conf.properties"/>
</bean>
上面代码改为
<bean id="resourcePropertySource"
     class="org.springframework.core.env.PropertiesPropertySource">
   <constructor-arg name="name" value="mall-redis-conf.properties"/>
   <constructor-arg name="source">
         <entry key="spring.redis.cluster.max-redirects" value="${spring.redis.cluster.max-redirects}" />
         <entry key="spring.redis.cluster.nodes" value="${spring.redis.cluster.nodes}"/>
   </constructor-arg>
</bean>