一、Spring集成Web环境
Spring集成Web环境
- 1. 基本三层架构环境搭建
- 2. ApplicationContext应用上下文获取方式
-
- 2.1 ContextLoaderListener
- 2.1 对UserServlet的代码优化
- 3. Spring提供获取应用上下文的工具
1. 基本三层架构环境搭建
pom.xml：
<dependencies>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.12version>
<scope>testscope>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<version>5.1.32version>
dependency>
<dependency>
<groupId>c3p0groupId>
<artifactId>c3p0artifactId>
<version>0.9.1.2version>
dependency>
<dependency>
<groupId>com.alibabagroupId>
<artifactId>druidartifactId>
<version>1.1.10version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-contextartifactId>
<version>5.0.5.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-testartifactId>
<version>5.0.5.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-webartifactId>
<version>5.0.5.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-webmvcartifactId>
<version>5.0.5.RELEASEversion>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>javax.servlet-apiartifactId>
<version>3.0.1version>
<scope>providedscope>
dependency>
<dependency>
<groupId>javax.servlet.jspgroupId>
<artifactId>javax.servlet.jsp-apiartifactId>
<version>2.2.1version>
<scope>providedscope>
dependency>
<dependency>
<groupId>com.fasterxml.jackson.coregroupId>
<artifactId>jackson-coreartifactId>
<version>2.9.0version>
dependency>
<dependency>
<groupId>com.fasterxml.jackson.coregroupId>
<artifactId>jackson-annotationsartifactId>
<version>2.9.0version>
dependency>
<dependency>
<groupId>commons-fileuploadgroupId>
<artifactId>commons-fileuploadartifactId>
<version>1.3.1version>
dependency>
<dependency>
<groupId>commons-iogroupId>
<artifactId>commons-ioartifactId>
<version>2.3version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-jdbcartifactId>
<version>5.0.5.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-txartifactId>
<version>5.0.5.RELEASEversion>
dependency>
dependencies>
UserDaoImpl：
public class UserDaoImpl implements UserDao {
@Override
public void save() {
System.out.println("save running");
}
}
UserServiceImpl：
public class UserServiceImpl implements UserService {
private UserDao userDao;
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
@Override
public void save() {
userDao.save();
}
}
UserServlet：
public class UserServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = app.getBean(UserService.class);
userService.save();
}
}
2. ApplicationContext应用上下文获取方式
应用上下文对象通过new ClassPathXmlApplicationContext(“applicationContext.xml”)方式获取。
在Web项目中，可以使用ServletContextListener监听Web应用的启动，就可以在Web应用启动时，加载Spring的配置文件，创建应用上下文对象ApplicationContext，将其存储到最大域servletContext域中，这样就可以在任意位置从域中获得应用上下文ApplicationContext对象了。
2.1 ContextLoaderListener
Listener：
public class ContextLoaderListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent servletContextEvent) {
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
//将Spring的应用上下文对象存储到ServletContext域中
ServletContext servletContext = servletContextEvent.getServletContext();
servletContext.setAttribute("app",app);
System.out.println("Spring容器创建完毕......");
}
@Override
public void contextDestroyed(ServletContextEvent servletContextEvent) {
}
}
web.xml：
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<listener>
<listener-class>com.example.listener.ContextLoaderListenerlistener-class>
listener>
<servlet>
<servlet-name>UserServletservlet-name>
<servlet-class>com.example.web.UserServletservlet-class>
servlet>
<servlet-mapping>
<servlet-name>UserServletservlet-name>
<url-pattern>/userServleturl-pattern>
servlet-mapping>
web-app>
UserServlet：
public class UserServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
ServletContext servletContext = this.getServletContext();
ApplicationContext app = (ApplicationContext) servletContext.getAttribute("app");
UserService userService = app.getBean(UserService.class);
userService.save();
}
}
2.1 对UserServlet的代码优化
- web.xml中设置全局初始化参数：
<context-param>
<param-name>contextConfigLocationparam-name>
<param-value>applicationContext.xmlparam-value>
context-param>
自定义监听器ContextLoaderListener：
public class ContextLoaderListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent servletContextEvent) {
ServletContext servletContext = servletContextEvent.getServletContext();
//读取web.xml中的全局参数
String contextConfigLocation = servletContext.getInitParameter("contextConfigLocation");
ApplicationContext app = new ClassPathXmlApplicationContext(contextConfigLocation);
//将Spring的应用上下文对象存储到ServletContext域中
servletContext.setAttribute("app",app);
System.out.println("Spring容器创建完毕......");
}
@Override
public void contextDestroyed(ServletContextEvent servletContextEvent) {
}
}
UserServlet：
// ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
ServletContext servletContext = this.getServletContext();
- 自定义WebApplicationContextUtils：
public class WebApplicationContextUtils {
public static ApplicationContext getWebApplicationContext(ServletContext servletContext) {
return (ApplicationContext) servletContext.getAttribute("app");
}
}
UserServlet：
// ApplicationContext app = (ApplicationContext) servletContext.getAttribute("app");
ApplicationContext app = WebApplicationContextUtils.getWebApplicationContext(servletContext);
- 优化后的UserServlet：
public class UserServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
ServletContext servletContext = this.getServletContext();
// ApplicationContext app = (ApplicationContext) servletContext.getAttribute("app");
ApplicationContext app = WebApplicationContextUtils.getWebApplicationContext(servletContext);
UserService userService = app.getBean(UserService.class);
userService.save();
}
}
3. Spring提供获取应用上下文的工具
Spring提供了一个监听器ContextLoaderListener就是对上述功能的封装，该监听器内部加载Spring配置文件，创建应用上下文对象，并存储到ServletContext域中，提供了一个客户端工具WebApplicationContextUtils供使用者获得应用上下文对象。
所以我们做的只有两件事：
- 在web.xml中配置ContextLoaderListener监听器（导入spring-web坐标）
- 在WebApplicationContextUtils获得应用上下文对象ApplicationContext
web.xml：
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<context-param>
<param-name>contextConfigLocationparam-name>
<param-value>classpath:applicationContext.xmlparam-value>
context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListenerlistener-class>
listener>
<servlet>
<servlet-name>UserServletservlet-name>
<servlet-class>com.example.web.UserServletservlet-class>
servlet>
<servlet-mapping>
<servlet-name>UserServletservlet-name>
<url-pattern>/userServleturl-pattern>
servlet-mapping>
web-app>
UserServlet：
public class UserServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
ServletContext servletContext = this.getServletContext();
// ApplicationContext app = (ApplicationContext) servletContext.getAttribute("app");
// ApplicationContext app = WebApplicationContextUtils.getWebApplicationContext(servletContext);
WebApplicationContext app = WebApplicationContextUtils.getWebApplicationContext(servletContext);
UserService userService = app.getBean(UserService.class);
userService.save();
}
}