Java基於JNDI 實現讀寫分離的示例代碼
一、JNDI數據源配置
在Tomcat的conf目錄下，context.xml在其中標簽中添加如下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數據源使用
1、在普通web項目中
（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" >
<!-- 主數據源配置 -->
<bean id="dataSourceMaster" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:comp/env/dataSourceMaster"/>
</bean>
<!-- 從數據源配置 -->
<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">
<!-- 配置數據源 -->
<property name="dataSource" ref="dynamicDataSource"/>
</bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 映射數據源 -->
<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>
<!-- 獲得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">
<!-- 這裡的basePackage 指定瞭dao層接口路勁，這裡的dao接口不用自己實現 -->
<property name="basePackage" value="com.xiaoxi.dao" />
<!-- 如果隻有一個數據源的話可以不用指定，但是如果有多個數據源的話必須要指定 -->
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
<!--直接指定瞭sqlsessionTemplate名稱，這個和上面的其實是一樣的 -->
<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、相關路由數據源切換邏輯代碼
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;
/**
* 線程上下文 <br>
* 用於保存線程本地變量DbType(用於切換數據源)
* 如果是異步線程操作，需要用InheritableThreadLocal （需要保存父線程的變量）
*
* @see [相關類/方法](可選)
* @since [產品/模塊版本](可選)
*/
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;
/**
* 數據源切面，用於在執行sql前進行讀寫數據源切換 <br>
* 〈功能詳細描述〉
*
* @see [相關類/方法](可選)
* @since [產品/模塊版本](可選)
*/
@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");
}
/** ☆☆☆☆☆ 也可以獲取參數中路由字段進行切換數據源 ☆☆☆☆☆ **/
@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、搭建過程中遇到的問題和解決方案
1、註入數據源dataSourceMaster和dataSourceSlave失敗
spring 中jndiName配置的數據源名稱和Tomcat配置文件中Resource name存在區別，並非一致,其中java:comp/env為環境，否則會報can not find jndi name …
2、Cannot create JDBC driver of class ‘’ for connect URL ‘null’
3、The requested resource is not available（404）
分析瞭web.xml和servlet.xml發現配置無誤，註解驅動和包掃描都配置，但仍然訪問不瞭，後發現
項目啟動過程中打印的日志存在問題，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)
通過分析發現這裡的請求映射，通過controller的requestMapping映射到具體方法，卻丟失瞭方法上的requestMapping路徑，後發現方法RequestMapping寫法如下：
@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);
}
}
此處的RequestMapping屬性name應該改為value，否則解析為空（可查看註解定義）
到此這篇關於Java基於JNDI 實現讀寫分離的示例代碼的文章就介紹到這瞭,更多相關Java JNDI讀寫分離內容請搜索WalkonNet以前的文章或繼續瀏覽下面的相關文章希望大傢以後多多支持WalkonNet！
推薦閱讀：
- log4j如何根據變量動態生成文件名
- Java開發之ssm三大框架整合
- Spring項目中使用Junit單元測試並配置數據源的操作
- SpringMVC註解的入門實例詳解
- 關於springmvc報錯404的問題