resource-env-ref元素来指定对管理对象的servlet引用的声明，该对象与servlet环境中的资源相关联
<resource-env-ref>
<resource-env-ref-name>资源名</resource-env-ref-name>
<resource-env-ref-type>查找资源时返回的资源类名</resource-env-ref-type>
</resource-env-ref>
<resource-env-ref-name>：资源的名称 相对于java:comp/env >>context
<resource-env-ref-type>：当web应用查找该资源的时候，返回的Java类名的全称
建立步骤：
一.先在meta-inf目录下新建一个Context.xml文件配置如下：
<?xml version="1.0" encoding="UTF-8"?>
<Context>
<!--对于javax.sql.DataSource资源类型 Tomcat容器提供了默认factory org.apache.tomcat.dbcp.dbcp.BasicDataSourceFactory -->
<Resource name="jdbc/mssql" auth="Container"
type="javax.sql.DataSource" driverClassName="net.sourceforge.jtds.jdbc.Driver"
url="jdbc:jtds:sqlserver://127.0.0.1:1433;DatabaseName=spring3mvc"
username="sa" password="wlyoa_)*#!" >
</Resource>
<Resource name="bean/MyBeanFactory" auth="Container"
type="com.myapp.domain.MyBean" factory="org.apache.naming.factory.BeanFactory" projectName="我的测试项目">
</Resource>
</Context>
二.在web.xml中添加资源引用
<!--定义外部资源管理对象 在Web容器目录的conf\Catalina\localhost\工程名.xml文件中(可见示例文件：WebContext.xml) --> <resource-env-ref> <resource-env-ref-name>bean/MyBeanFactory</resource-env-ref-name> <resource-env-ref-type>com.myapp.domain.MyBean</resource-env-ref-type> </resource-env-ref> <resource-env-ref> <resource-env-ref-name>jdbc/mssql</resource-env-ref-name> <resource-env-ref-type>javax.sql.DataSource</resource-env-ref-type> </resource-env-ref>
三.在Servlet类中可通过如下方式查找或使用资源
package com.myapp.controller;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
import com.myapp.domain.MyBean;
/**
*
*/
public class MyFirstServlet extends HttpServlet {
private String servletInitParam="";
public MyFirstServlet() {
// TODO Auto-generated constructor stub
}
public void init(){
servletInitParam=this.getInitParameter("ServletInitParam");
}
public void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException, IOException {
testDataSourceJNDI();
testBeanSourceJNDI();
String parame1=getServletContext().getInitParameter("MyContextParam");
String projectName=getServletContext().getInitParameter("ProjectName");
System.out.println("上下文初始化参数1："+parame1);
System.out.println("上下文初始化参数2："+projectName);
PrintWriter writer=response.getWriter();
writer.println("<html><head> <meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" /><title>");
writer.println(projectName);
writer.println("</title></head>");
writer.println("<body>");
writer.println(servletInitParam+"："+servletInitParam+"<br/>");
writer.println("上下文初始化参数1："+parame1+"<br/>");
writer.println("上下文初始化参数2："+projectName+"<br/>");
writer.println("</body></html>");
}
public void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException, IOException {
doGet(request, response);
}
public void destroy() {
super.destroy();
System.out.println("我是destroy()方法！用来进行销毁实例的工作");
}
/**
* Java-Bean资源读取测试
*/
private void testBeanSourceJNDI()
{
try {
System.err.println("testBeanSourceJNDI");
Context context=new InitialContext();
Context envContext=(Context)context.lookup("java:/comp/env");
MyBean mBean=(MyBean)envContext.lookup("bean/MyBeanFactory");
System.out.println(mBean.getHello()+":"+mBean.getProjectName());
} catch (Exception e) {
// TODO: handle exception
}
}
/**
* DataSource资源测试
*/
private void testDataSourceJNDI()
{
try {
System.err.println("DataSourceJNDI");
Connection connection=null;
ResultSet result = null;
Statement stmt = null;
Context context=new InitialContext();
Context envContext=(Context)context.lookup("java:/comp/env");
DataSource dataSource=(DataSource)envContext.lookup("jdbc/mssql");
try {
connection=dataSource.getConnection();
stmt=connection.createStatement();
result=stmt.executeQuery("select * from Author");
while (result.next()) {
System.out.println(result.getString("name"));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally{
result.close();
stmt.close();
connection.close();
}
} catch (Exception e) {
// TODO: handle exception
}
}
}
package com.myapp.domain;
/**
*
*/
public class MyBean {
private String projectName;
private String hello="欢迎使用";
public String getProjectName() {
return projectName;
}
public void setProjectName(String projectName) {
this.projectName = projectName;
}
public String getHello() {
return hello;
}
public void setHello(String hello) {
this.hello = hello;
}
}