servlet的ServletConfig ServletContext示範

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);

// 擷取<servlet>的屬性

System.out.println("擷取<servlet>的屬性user:"+arg0.getInitParameter("user"));

System.out.println("擷取<servlet>的屬性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();

// 擷取應用的名稱：

System.out.println("擷取應用的名稱："+srvContext.getServletContextName());

// 擷取應用的路徑。

System.out.println("擷取應用的路徑"+srvContext.getContextPath());

Enumeration con= srvContext.getAttributeNames();

while(con.hasMoreElements()){

Object name=con.nextElement();

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

}

// 擷取<context-param>的屬性 ，應用的全局屬性。  相對于<servlet>裡面的<init-param>是全局屬性。

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

while(paraname.hasMoreElements()){

String pname=paraname.nextElement();

String value=srvContext.getInitParameter(pname);

System.out.println("擷取<context-param>的屬性pname="+pname+" 擷取<context-param>的屬性value="+value);

}

String contextPath=srvContext.getContextPath();

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

// getRealPath，擷取檔案的相對釋出路徑。

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

System.out.println(realPath);

// F:\apache-tomcat-9\webapps\tomcatDemo2\hello.jsp 這個實際顯示的PATH是，這個WEB應用釋出時的PATH。

// 實體的原PATH為：D:\workspace\tomcatDemo2\WebContent\hello.jsp.

// 預設的Class path下，得到IS流

getIS("jdbc.properties");

// 使用ServletContext得到IS，必須要注意，這個PATH必須是對釋出路徑的路徑。

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;

}

}