/META-INF/context.xml

Tomcat下位于默认的webapps目录下的程序要使用dataSource,过去我都是直接修改%tomcat%/conf/server.xml中的<context>在这个标签下增加    <Resource name="jdbc/mysql" auth="Container" type="javax.sql.DataSource"/>
这样是可以达到了效果但是server.xml就被破坏了,如果一台机器上要使用多个tomcat服务器就会产生麻烦。

其实还可以写在web应用目录下面%myFirstWebApplicetion%/META-INF/context.xml中,如下:

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/">
    <Resource name="jdbc/mysql" auth="Container" type="javax.sql.DataSource"/>
    <ResourceParams name="jdbc/mysql">
        <parameter>
            <name>factory</name>
            <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
        </parameter>
        <parameter>
            <name>maxActive</name>
            <value>100</value>
        </parameter>
        <parameter>
            <name>maxIdle</name>
            <value>30</value>
        </parameter>
        <parameter>
            <name>maxWait</name>
            <value>10000</value>
        </parameter>
        <parameter>
            <name>username</name>
            <value>root</value>
        </parameter>
        <parameter>
            <name>password</name>
            <value></value>
        </parameter>
        <parameter>
            <name>driverClassName</name>
            <value>org.gjt.mm.mysql.Driver</value>
        </parameter>
        <parameter>
            <name>url</name>
            <value>jdbc:mysql://localhost:3306/my?autoReconnect=true&amp;useUnicode=true&amp;characterEncoding=gbk</value>
        </parameter>
    </ResourceParams>
</Context>

这样一样可以达到相同的效果。

1.创建项目 在IDEA中,创建一个名称为chapter10的Maven Web项目,如果默认创建的Maven项目中没有自动生成webapp文件夹,可以手工添加webapp目录,添加WEB-INF目录。 2.导入的依赖包括Spring核心包的依赖、Spring MVC。 <?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> <groupId>com.itheima</groupId> <artifactId>chapter10</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>1.7</maven.compiler.source> <maven.compiler.target>1.7</maven.compiler.target> </properties> <dependencies> <!--Spring 核心类--> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>5.2.8.RELEASE</version> </dependency> <!--Spring MVC--> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.2.8.RELEASE</version> </dependency> <!-- servlet --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope> </dependency> <!--JSP--> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>jsp-api</artifactId> <version>2.1</version> <scope>provided</scope> </dependency> </dependencies> <!--构建--> <build> <!--设置插件--> <plugins> <!--具体的插件配置--> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <configuration> <port>8080</port> <path>/chapter10</path> </configuration> </plugin> </plugins> </build> </project> 3.web.xml文件中配置前端控制器 <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <!-- 配置 Spring MVC 的前端控制器 --> <servlet> <servlet-name>DispatcherServlet</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <!-- 配置初始化参数,用于读取 Spring MVC 的配置文件 --> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:spring-mvc.xml</param-value> </init-param> <!-- 应用加载时创建--> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>DispatcherServlet</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app> 4.创建Spring MVC的配置文件spring-mvc.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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"> <!-- 配置 Spring MVC 要扫描的包 --> <context:component-scan base-package="com.itheima.controller"/> <!-- 配置视图解析器 --> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/pages/"/> <property name="suffix" value=".jsp"/> </bean> </beans> 5.创建处理器 在com.itheima.controller包中创建处理器FirstController类,用于处理客户端的请求并指定响应时转跳的页面。 package com.itheima.controller; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; //设置当前类为处理器类 @Controller public class FirstController { //设定当前方法的访问映射地址 @RequestMapping("/firstController") //设置当前方法返回值类型为 String,用于指定请求完成后跳转的页面 public String sayHello() { System.out.println("访问到 FirstController!"); //设定具体跳转的页面 return "success"; } } 6.创建视图(View)页面 在项目的Web-INF文件夹下创建名称为pages的文件夹,并在pages文件夹下创建名称为success的jsp文件,用于对客户端请求进行处理后的视图展示。 <html> <body> <h2>Spring MVC FirstController!</h2> </body> </html> 7.启动项目,测试应用 idea社区版需要自己安装Tomcat插件,选择File菜单下的Settings,选择Plugins添加smart tomcat。帮我把代码总结一下,并步骤完成并取得结果
05-17
/KuCun2/src/main/webapp/WEB-INF/web.xml<?xml version="1.0" encoding="UTF-8" standalone="no"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="3.1" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"> <context-param> <param-name>metadata-complete</param-name> <param-value>true</param-value> </context-param> <servlet> <servlet-name>exampleServlet</servlet-name> <servlet-class>com.example.ExampleServlet</servlet-class> </servlet> <servlet> <description>generated-servlet</description> <servlet-name>KuCun2 Servlet</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:KuCun2-web-context.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet> <description>generated-resources-servlet</description> <servlet-name>Resource Servlet</servlet-name> <servlet-class> org.springframework.js.resource.ResourceServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>exampleServlet</servlet-name> <url-pattern>/example</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>Resource Servlet</servlet-name> <url-pattern>/resources/*</url-pattern> </servlet-mapping> <listener> <listener-class> org.springframework.web.context.ContextLoaderListener </listener-class> </listener> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </context-param> </web-app> 2025-06-20 14:01:51.793 INFO 17004 --- [ main] com.kucun.DemoApplication : Started DemoApplication in 6.862 seconds (JVM running for 16.997) 2025-06-20 14:01:51.803 ERROR 17004 --- [ main] o.a.c.c.C.[.[localhost].[/KuCun2] : 异常将上下文初始化事件发送到类的侦听器实例.[org.springframework.web.context.ContextLoaderListener] java.lang.IllegalStateException: Cannot initialize context because there is already a root application context present - check whether you have multiple ContextLoader* definitions in your web.xml! at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:263) ~[spring-web-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:103) ~[spring-web-5.2.15.RELEASE.jar:5.2.15.RELEASE] at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4678) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5139) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:717) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:690) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1133) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1866) [catalina.jar:9.0.37] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_331] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_331] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) [tomcat-util.jar:9.0.37] at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:112) [na:1.8.0_331] at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1045) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:429) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1576) [catalina.jar:9.0.37] at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:309) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:423) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:366) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:936) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) [catalina.jar:9.0.37] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) [catalina.jar:9.0.37] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_331] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) [tomcat-util.jar:9.0.37] at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:134) [na:1.8.0_331] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930) [catalina.jar:9.0.37] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) [catalina.jar:9.0.37] at org.apache.catalina.startup.Catalina.start(Catalina.java:738) [catalina.jar:9.0.37] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_331] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_331] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_331] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_331] at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:342) [bootstrap.jar:9.0.37] at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:473) [bootstrap.jar:9.0.37] 2025-06-20 14:01:51.803 ERROR 17004 --- [ main] o.apache.catalina.core.StandardContext : 一个或多个listeners启动失败,更多详细信息查看对应的容器日志文件 2025-06-20 14:01:51.804 ERROR 17004 --- [ main] o.apache.catalina.core.StandardContext : 由于之前的错误,Context[/KuCun
06-21
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