Spring 之在Web專案中使用
Spring 在Web中的第一次應用
1、配置Web環境，或者下載有Web外掛的eclipse
2、建立Web專案，選擇Dynamic Web Project(動態Web專案，對應的靜態Web專案 Static Web Project)
3、匯入jar包
commons-logging-1.1.1.jar
servlet-api.jar
spring-beans-4.0.0.RELEASE.jar
spring-context-4.0.0.RELEASE.jar
spring-core-4.0.0.RELEASE.jar
spring-expression-4.0.0.RELEASE.jar
spring-web-4.0.0.RELEASE.jar
spring-webmvc-4.0.0.RELEASE.jar
4、建立bean
public class Data {
private String id;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
@Override
public String toString() {
return "Data [id=" + id + "]";
}
}5、建立Spring配置檔案
檔名：ApplicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
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">
<bean 6、IOC容器在非Web應用中的main方法中直接建立，而在Web應用中，應該在伺服器載入時就建立IOC容器
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
@WebListener
public class SpringServletContextListener implements ServletContextListener {
public SpringServletContextListener() {
}
public void contextInitialized(ServletContextEvent arg0) {
ServletContext sct = arg0.getServletContext();
String config = sct.getInitParameter("configLocation");
System.out.println(config);
ApplicationContext ctx = new ClassPathXmlApplicationContext(config);
sct.setAttribute("ApplicationContext", ctx);
}
public void contextDestroyed(ServletContextEvent arg0) {
}
}如上程式碼，實現ServletContextListener 介面，在contextInitialized中建立IOC容器，並儲存在ServletContext 中。
然後要在web.xml配置檔案中做如下配置：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!-- 配置Spring配置檔案的名稱和位置 -->
<context-param>
<param-name>configLocation</param-name>
<param-value>classpath:ApplicationContext.xml</param-value>
</context-param>
<!-- 啟動IOC容器的listener -->
<listener>
<listener-class>com.led.htkj.servlets.listener.SpringServletContextListener</listener-class>
</listener>
</web-app>7、編寫servlet
@WebServlet("/CollectingData")
public class CollectingData extends HttpServlet {
private static final long serialVersionUID = 1L;
public CollectingData() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext servletContext = getServletContext();
ApplicationContext ctx = (ApplicationContext) servletContext.getAttribute("ApplicationContext");
Data data = (Data) ctx.getBean(Data.class);
System.out.println(data.toString());;
}
}8、建立jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<a href = "CollectingData"> here</a>
</body>
</html>啟動後在頁面中點選here結果在控制檯輸出：
Data [id=1111111111]總結
錯誤1：class path resource [applicationContext.xml] cannot be opened because it does not exist
錯誤2：No qualifying bean of type [com.led.htkj.Data] is defined
都是因為：
`
<context-param>
<param-name>configLocation</param-name>
<param-value>classpath:ApplicationContext.xml</param-value>
</context-param>
中ApplicationContext.xml首字母A被小寫，報錯誤1，百度後在classpath後加了*，結果報錯誤2，最終發現原來是大字母被小寫，解決問題`