servlet的ServletConfig ServletContext演示

import java.io.IOException;

import java.io.InputStream;

import java.util.Enumeration;

import javax.servlet.Servlet;

import javax.servlet.ServletConfig;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

public class HelloServlet implements Servlet {

@Override

public void destroy() {

// TODO Auto-generated method stub

System.out.println("destroy()");

}

@Override

public ServletConfig getServletConfig() {

// TODO Auto-generated method stub

System.out.println("getServletConfig()");

return null;

}

@Override

public String getServletInfo() {

// TODO Auto-generated method stub

System.out.println("getServletInfo()");

return null;

}

@Override

public void init(ServletConfig arg0) throws ServletException {

// TODO Auto-generated method stub

System.out.println("init(ServletConfig arg0)");

String servletName=arg0.getServletName();

System.out.println(servletName);

// 获取<servlet>的属性

System.out.println("获取<servlet>的属性user:"+arg0.getInitParameter("user"));

System.out.println("获取<servlet>的属性password："+arg0.getInitParameter("password"));

Enumeration<String> names= arg0.getInitParameterNames();

while(names.hasMoreElements()){

String name=names.nextElement();

String value=arg0.getInitParameter(name);

System.out.println(name+"="+value);

}

ServletContext srvContext=arg0.getServletContext();

// 获取应用的名称：

System.out.println("获取应用的名称："+srvContext.getServletContextName());

// 获取应用的路径。

System.out.println("获取应用的路径"+srvContext.getContextPath());

Enumeration con= srvContext.getAttributeNames();

while(con.hasMoreElements()){

Object name=con.nextElement();

System.out.println("getAttributeName:"+name);

}

// 获取<context-param>的属性 ，应用的全局属性。  相对于<servlet>里面的<init-param>是全局属性。

Enumeration<String> paraname=srvContext.getInitParameterNames();

while(paraname.hasMoreElements()){

String pname=paraname.nextElement();

String value=srvContext.getInitParameter(pname);

System.out.println("获取<context-param>的属性pname="+pname+" 获取<context-param>的属性value="+value);

}

String contextPath=srvContext.getContextPath();

System.out.println("contextPath:"+contextPath);

// getRealPath，获取文件的相对发布路径。

String realPath=srvContext.getRealPath("/hello.jsp");

System.out.println(realPath);

// F:\apache-tomcat-9\webapps\tomcatDemo2\hello.jsp 这个实际显示的PATH是，这个WEB应用发布时的PATH。

// 物理的原PATH为：D:\workspace\tomcatDemo2\WebContent\hello.jsp.

// 默认的Class path下，得到IS流

getIS("jdbc.properties");

// 使用ServletContext得到IS，必须要注意，这个PATH必须是对发布路径的路径。

contextGetIS(srvContext,"/WEB-INF/classes/jdbc.properties");

}

@Override

public void service(ServletRequest arg0, ServletResponse arg1)

throws ServletException, IOException {

System.out.println("service(ServletRequest arg0, ServletResponse arg1)");

// TODO Auto-generated method stub

}

public HelloServlet(){

System.out.println("HelloServlet()");

}

public InputStream getIS(String path){

InputStream is=this.getClass().getClassLoader().getResourceAsStream(path);

System.out.println(is);

return is;

}

public InputStream contextGetIS(ServletContext srvContext,String path){

InputStream is=srvContext.getResourceAsStream(path);

System.out.println("contextGetIS:"+is);

return is;

}

}