沃梦达 / 编程技术 / 编程语言 / Java开发 / 正文

Java基于JNDI 实现读写分离的示例代码

Java开发
2023-08-10

Java基于JNDI实现读写分离的示例代码 目录 一.JNDI数据源配置 二.JNDI数据源使用 三.web.xml配置 四.spring-servlet.xml配置 五.spring-db.xml配置 六.log4j.properties配置 七.相关路由数据源切换逻辑代码 八.搭建过程中遇到的问题和解决方案 一.JNDI数据源配置 在

目录
  • 一、JNDI数据源配置
  • 二、JNDI数据源使用
  • 三、web.xml配置
  • 四、spring-servlet.xml配置
  • 五、spring-db.xml配置
  • 六、log4j.properties配置
  • 七、相关路由数据源切换逻辑代码
  • 八、搭建过程中遇到的问题和解决方案

一、JNDI数据源配置

在Tomcat的conf目录下，context.xml在其中标签中添加如下JNDI配置：


<Resource name="dataSourceMaster" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
 auth="Container" type="javax.sql.DataSource" maxActive="100" maxIdle="30" maxWaitMillis="30000"
 username="root" password="root" driverClassName="com.mysql.jdbc.Driver"  url="jdbc:mysql://localhost:3306/user_master?useUnicode=true&amp;characterEncoding=utf-8"/>
<Resource name="dataSourceSlave" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
 auth="Container" type="javax.sql.DataSource" maxActive="100" maxIdle="30" maxWaitMillis="30000"
 username="root" password="root" driverClassName="com.mysql.jdbc.Driver"  url="jdbc:mysql://localhost:3306/user_slave?useUnicode=true&amp;characterEncoding=utf-8"/>

二、JNDI数据源使用

1、在普通web项目中

（1）在web.xml文件中添加如下配置（也可以不配置）：


<resource-ref>
 <res-ref-name>dataSourceMaster</res-ref-name>
 <res-type>javax.sql.DataSource</res-type>
 <res-auth>Container</res-auth>
</resource-ref>
<resource-ref>
 <res-ref-name>dataSourceSlave</res-ref-name>
 <res-type>javax.sql.DataSource</res-type>
 <res-auth>Container</res-auth>
</resource-ref>

三、web.xml配置


<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
 <display-name>Archetype Created Web Application</display-name>
 <context-param>
  <param-name>log4jConfigLocation</param-name>
  <param-value>classpath:log4j.properties</param-value>
 </context-param>
 <context-param>
  <param-name>log4jRefreshInterval</param-name>
  <param-value>60000</param-value>
 </context-param>
 <filter>
  <filter-name>CharacterEncodingFilter</filter-name>
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>
   <param-name>encoding</param-name>
   <param-value>utf-8</param-value>
  </init-param>
  <init-param>
   <param-name>forceEncoding</param-name>
   <param-value>true</param-value>
  </init-param>
 </filter>
 <filter-mapping>
  <filter-name>CharacterEncodingFilter</filter-name>
  <servlet-name>xiyun</servlet-name>
 </filter-mapping>
 <servlet>
  <servlet-name>xiyun</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <init-param>
   <param-name>contextConfigLocation</param-name>
   <param-value>        classpath:conf/spring/spring-servlet.xml      </param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
 </servlet>
 <servlet-mapping>
  <servlet-name>xiyun</servlet-name>
  <url-pattern>*.do</url-pattern>
 </servlet-mapping>
</web-app>

四、spring-servlet.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:context="http://www.springframework.org/schema/context"       xmlns:mvc="http://www.springframework.org/schema/mvc"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">    

 <context:component-scan base-package="com.xiaoxi"/>    

 <mvc:annotation-driven/>    

 <import resource="classpath:conf/spring/spring-db.xml"/>    

 <bean id="viewResolver"          class="org.springframework.web.servlet.view.InternalResourceViewResolver">
  <property name="prefix" value="/WEB-INF/freemarker/"/>
  <property name="suffix" value=".ftl"/>
  </bean>
 </beans>

五、spring-db.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"       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
 http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd" >    

 <!-- 主数据源配置 -->
 <bean id="dataSourceMaster" class="org.springframework.jndi.JndiObjectFactoryBean">
  <property name="jndiName" value="java:comp/env/dataSourceMaster"/>
 </bean>
 <!-- 从数据源配置 -->
 <bean id="dataSourceSlave" class="org.springframework.jndi.JndiObjectFactoryBean">
  <property name="jndiName" value="java:comp/env/dataSourceSlave"/>
 </bean>    

 <aop:aspectj-autoproxy proxy-target-class="true"/>    

    <context:annotation-config/>    

 <bean id="dynamicDataSource" class="com.xiaoxi.config.DynamicRoutingDataSource">
  <property name="targetDataSources">
   <map>
    <entry key="Master" value-ref="dataSourceMaster"/>
    <entry key="Slave" value-ref="dataSourceSlave"/>
   </map>
  </property>
  <property name="defaultTargetDataSource" value="dataSourceMaster"/>
 </bean>    

 <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
  <!-- 配置数据源 -->
  <property name="dataSource" ref="dynamicDataSource"/>
 </bean>    

 <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
  <!-- 映射数据源 -->
  <property name="dataSource" ref="dynamicDataSource"/>
  <!-- 映射mybatis核心配置文件 -->
  <property name="configLocation" value="classpath:conf/spring/mybatis-config.xml"/>
  <!-- 映射mapper文件 -->
  <property name="mapperLocations">
   <list>
    <value>classpath:conf/sqlMap/*.xml</value>
   </list>
  </property>
 </bean>    

 <!-- 获得sqlSession -->
 <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
  <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactory"/>
 </bean>    

 <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
  <!-- 这里的basePackage 指定了dao层接口路劲，这里的dao接口不用自己实现 -->
  <property name="basePackage" value="com.xiaoxi.dao" />
  <!-- 如果只有一个数据源的话可以不用指定，但是如果有多个数据源的话必须要指定 -->
  <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
  <!--直接指定了sqlsessionTemplate名称，这个和上面的其实是一样的 -->
  <property name="sqlSessionTemplateBeanName" value="sqlSession" />
 </bean>
</beans>

六、log4j.properties配置


log4j.rootLogger=DEBUG, CATALINA# Define all the appenders
log4j.appender.CATALINA=org.apache.log4j.RollingFileAppender
log4j.appender.CATALINA.File=${catalina.base}/logs/catalina.log
log4j.appender.CATALINA.Append=true
log4j.appender.CATALINA.MaxFileSize=10MB
log4j.appender.CATALINA.Encoding=UTF-8

# Roll-over the log once per day
log4j.appender.CATALINA.layout = org.apache.log4j.PatternLayout
log4j.appender.CATALINA.layout.ConversionPattern = %d [%t] %-5p %c- %m%n
log4j.appender.LOCALHOST=org.apache.log4j.RollingFileAppender
log4j.appender.LOCALHOST.File=${catalina.base}/logs/localhost.log
log4j.appender.LOCALHOST.MaxFileSize=10MB
log4j.appender.LOCALHOST.Append=true
log4j.appender.LOCALHOST.Encoding=UTF-8
log4j.appender.LOCALHOST.layout = org.apache.log4j.PatternLayout
log4j.appender.LOCALHOST.layout.ConversionPattern = %d [%t] %-5p %c- %m%n

log4j.appender.MANAGER=org.apache.log4j.RollingFileAppender
log4j.appender.MANAGER.File=${catalina.base}/logs/manager.log
log4j.appender.MANAGER.MaxFileSize=10MB
log4j.appender.MANAGER.Append=true
log4j.appender.MANAGER.Encoding=UTF-8
log4j.appender.MANAGER.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.MANAGER.layout = org.apache.log4j.PatternLayout
log4j.appender.MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%n

log4j.appender.HOST-MANAGER=org.apache.log4j.RollingFileAppender
log4j.appender.HOST-MANAGER.File=${catalina.base}/logs/host-manager.log
log4j.appender.HOST-MANAGER.MaxFileSize=10MB
log4j.appender.HOST-MANAGER.Append=true
log4j.appender.HOST-MANAGER.Encoding=UTF-8
log4j.appender.HOST-MANAGER.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.HOST-MANAGER.layout = org.apache.log4j.PatternLayout
log4j.appender.HOST-MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%n

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.Encoding=UTF-8
log4j.appender.CONSOLE.layout = org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern = %d [%t] %-5p %c- %m%n

# Configure which loggers log to which appenders
log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost]=INFO, LOCALHOST
log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager]= INFO, MANAGER
log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/host-manager]= INFO, HOST-MANAGER

七、相关路由数据源切换逻辑代码


package com.xiaoxi.config;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import java.util.Map;

public class DynamicRoutingDataSource extends AbstractRoutingDataSource {

    @Override
    public void setTargetDataSources(Map<Object, Object> targetDataSources) {
        super.setTargetDataSources(targetDataSources);
        super.afterPropertiesSet();
    }

    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDbType();
    }
}

package com.xiaoxi.config;

/**
 * 线程上下文 <br>
 * 用于保存线程本地变量DbType(用于切换数据源)
 * 如果是异步线程操作，需要用InheritableThreadLocal （需要保存父线程的变量）
 *
 * @see [相关类/方法](可选)
 * @since [产品/模块版本](可选)
 */
public class DataSourceContextHolder {

    private static final ThreadLocal<DbType> contextHolder = new ThreadLocal<>();

    public static ThreadLocal<DbType> getLocal() {
        return contextHolder;
    }

    private DataSourceContextHolder () {}

    public static String getDbType() {
        return contextHolder.get() == null ? DbType.MASTER.dbType : contextHolder.get().dbType;
    }

    public static void setDbType(DbType dbType) {
        contextHolder.set(dbType);
    }

    public static void clearDbType() {
        contextHolder.remove();
    }

    public enum DbType {

        MASTER("Master"),

        SLAVE("Slave");

        private String dbType;

        DbType(String dbType) {
            this.dbType = dbType;
        }

        public String getDbType() {
            return dbType;
        }
    }
}

package com.xiaoxi.aop;

import com.xiaoxi.config.DataSourceContextHolder;
import org.apache.log4j.Logger;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

/**
 * 数据源切面，用于在执行sql前进行读写数据源切换 <br>
 * 〈功能详细描述〉
 *
 * @see [相关类/方法](可选)
 * @since [产品/模块版本](可选)
 */
@Aspect
@Order(-1)
@Component
public class DataSourceAop {

    private static Logger logger = Logger.getLogger(DataSourceAop.class);

    @Before("execution(* com.xiaoxi.dao..*.query*(..))")
    public void setReadDataSourceType() {
        DataSourceContextHolder.setDbType(DataSourceContextHolder.DbType.MASTER);
        logger.debug("[DataSourceAop] DataSource Covert To SLAVE");
    }

    @Before("execution(* com.xiaoxi.dao..*.insert*(..))" +
         "|| execution(* com.xiaoxi.dao..*.update*(..))" +
         "|| execution(* com.xiaoxi.dao..*.delete*(..))")
    public void setWriteDataSourceType() {
        DataSourceContextHolder.setDbType(DataSourceContextHolder.DbType.SLAVE);
        logger.debug("[DataSourceAop] DataSource Covert To MASTER");
    }

    /** ☆☆☆☆☆ 也可以获取参数中路由字段进行切换数据源 ☆☆☆☆☆ **/

    @Pointcut("execution(* com.xiaoxi.dao..*.*(..))")
    public void cutPoint() {}

    @Before(value="cutPoint()")
    public void setDynamicDataSource(JoinPoint point){
        String className = point.getTarget().getClass().getSimpleName();
        String methodName = point.getSignature().getName();
        String log = "[DataSourceAop] className:%s, methodName:%s";
        logger.debug(String.format(log, className, methodName));
    }
}

八、搭建过程中遇到的问题和解决方案

1、注入数据源dataSourceMaster和dataSourceSlave失败
spring 中jndiName配置的数据源名称和Tomcat配置文件中Resource name存在区别，并非一致,其中java:comp/env为环境，否则会报can not find jndi name …

2、Cannot create JDBC driver of class ‘' for connect URL ‘null'

3、The requested resource is not available（404）
分析了web.xml和servlet.xml发现配置无误，注解驱动和包扫描都配置，但仍然访问不了，后发现
项目启动过程中打印的日志存在问题，如下：
2019-12-17 16:20:41,767 [RMI TCP Connection(3)-127.0.0.1] INFO org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping- Mapped “{[/userInfo],methods=[GET]}” onto public java.lang.String com.xiaoxi.controller.UserInfoController.queryUserInfoById(java.lang.String)
通过分析发现这里的请求映射，通过controller的requestMapping映射到具体方法，却丢失了方法上的requestMapping路径，后发现方法RequestMapping写法如下：


@Controller
@RequestMapping("/userInfo")
public class UserInfoController {

    private static Logger logger =Logger.getLogger(UserInfoController.class);

    @Autowired
    private UserInfoService userInfoService;

    @ResponseBody
    @RequestMapping(name= "/queryUserInfoById", method = RequestMethod.GET)
    public String queryUserInfoById(@RequestParam("id") String id){
        logger.info("UserInfoController.queryUserInfoById.  id:{}" + id);
        UserInfo userInfo = userInfoService.queryUserInfoById(id);
        return JSON.toJSONString(userInfo);
    }
}

此处的RequestMapping属性name应该改为value，否则解析为空（可查看注解定义）

到此这篇关于Java基于JNDI 实现读写分离的示例代码的文章就介绍到这了,更多相关Java JNDI读写分离内容请搜索我们以前的文章或继续浏览下面的相关文章希望大家以后多多支持我们！

本文标题为：Java基于JNDI 实现读写分离的示例代码

上一篇： 使用JPA自定义VO接收返回结果集(unwrap)
下一篇： SpringBoot实现整合微信支付方法详解

基础教程推荐

学习HTML
学习jQuery
学习Laravel
学习CSS3
学习Vue.js
学习Bootstrap5
学习ThinkPHP
学习AJAX
猜你喜欢
最新文章
热门文章
编程基础
热门标签
网站首页 HTML/CSS 菜单 Layui Yii2