这篇文章主要介绍“Java基于JNDI怎么实现读写分离”，在日常操作中，相信很多人在Java基于JNDI怎么实现读写分离问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”Java基于JNDI怎么实现读写分离”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
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&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&characterEncoding=utf-8"/>二、JNDI数据源使用
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/sqlMappublic 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;@Aspect@Order(-1)@Componentpublic 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"); } @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
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 …
Cannot create JDBC driver of class ‘' for connect URL ‘null'
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）
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