JavaWeb核心编程之(三)ServletContext配置

1 package com.xiaoan.test;
2
3 import java.io.IOException;
4 import java.io.InputStream;
5 import java.util.Enumeration;
6
7 import javax.servlet.Servlet;
8 import javax.servlet.ServletConfig;
9 import javax.servlet.ServletContext;
10 import javax.servlet.ServletException;
11 import javax.servlet.ServletRequest;
12 import javax.servlet.ServletResponse;
13
14 public class TestContext implements Servlet{
15
16 @Override
17 public void destroy() {
18 // TODO Auto-generated method stub
19
20 }
21
22 @Override
23 public ServletConfig getServletConfig() {
24 // TODO Auto-generated method stub
25 return null;
26 }
27
28 @Override
29 public String getServletInfo() {
30 // TODO Auto-generated method stub
31 return null;
32 }
33
34 @Override
35 public void init(ServletConfig arg0) throws ServletException {
36 ServletContext servletCOntext= arg0.getServletContext();
37 //通过key获得value
38 String username = servletContext.getInitParameter("username");
39 System.out.println("username: " + username);
40
41 //获得参数key列表
42 Enumeration keys = servletContext.getInitParameterNames();
43 while(keys.hasMoreElements()){
44 String key = keys.nextElement();
45 String val = servletContext.getInitParameter(key);
46 System.out.println("key: " + key + ", val: " + val);
47 }
48 //在WebContent下新建 test.txt文件
49 //获取当前web应用的某一个文件的真实路径(绝对路径)--是获取的服务器上的物理路径
50 String filePath1 = servletContext.getRealPath("/test.txt");
51 System.out.println(filePath1);
52
53 //获得当前web应用的名称
54 String webName = servletContext.getContextPath();
55 System.out.println("当前应用名为: " + webName);
56
//在src下(与包同级)创建testStream.txt文件, 作为流输入文件
57 //获得当前web应用的某一个文件对应的输入流
58 //第一种
59 try {
60 ClassLoader classLoader = servletContext.getClassLoader();
61 InputStream is = classLoader.getResourceAsStream("/testStream.txt");
62 System.out.println(is);
63 } catch (Exception e) {
64 // TODO Auto-generated catch block
65 e.printStackTrace();
66 }
67 //第二种
68 try {
69 InputStream is2 = servletContext.getResourceAsStream("/WEB-INF/classes/testStream.txt");
70 System.out.println(is2);
71 } catch (Exception e) {
72 // TODO Auto-generated catch block
73 e.printStackTrace();
74 }
75 }
76
77 @Override
78 public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {
79 // TODO Auto-generated method stub
80
81 }
82
83 }

1 xml version="1.0" encoding="UTF-8"?>
2 <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" id="WebApp_ID" version="3.0">
3 <display-name>testcontentdisplay-name>
4
5 <context-param>
6 <param-name>usernameparam-name>
7 <param-value>xiaoanparam-value>
8 context-param>
9
10 <context-param>
11 <param-name>passwordparam-name>
12 <param-value>123456param-value>
13 context-param>
14
15
16 <servlet>
17 <servlet-name>tcservlet-name>
18 <servlet-class>com.xiaoan.test.TestContextservlet-class>
19 servlet>
20 <servlet-mapping>
21 <servlet-name>tcservlet-name>
22 <url-pattern>/url-pattern>
23 servlet-mapping>
24 web-app>