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web.xml之资源管理对象配置 resource-env-ref

web.xmlresource-env-refservletjava 
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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;
}
}
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