攻城师之路--复习java web之servlet

 1     @Override
 2     public void init(ServletConfig config) throws ServletException {
 3         String name = config.getInitParameter("shellway");
 4         System.out.println(name);
 5         //Enumeration相当于Iterator 它是Iterator的前身
 6          Enumeration<String> names = config.getInitParameterNames();
 7          while (names.hasMoreElements()) {
 8             String name2 = (String) names.nextElement();
 9             System.out.println(name2+":"+config.getInitParameter(name2));
10         }
11     }

1     public void doGet(HttpServletRequest request, HttpServletResponse response)
2             throws ServletException, IOException {
3         System.out.println(getServletConfig().getInitParameter("shellway"));
4         ServletContext sc = getServletContext();
5         System.out.println(sc.getInitParameter("XXX"));
6     }

 1 package com.shellway.servlet;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.ServletConfig;
 6 import javax.servlet.ServletContext;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 public class HelloServlet2 extends HttpServlet {
13     @Override
14     public void init() throws ServletException {
15         ServletContext  sc = getServletContext();
16         sc.setAttribute("times", 0);
17         System.out.println("已经初始化。。。");
18     }
19 
20     public void doGet(HttpServletRequest request, HttpServletResponse response)
21             throws ServletException, IOException {
22         ServletContext  sc = getServletContext();
23         int time=(Integer)sc.getAttribute("times");
24          time++;
25          sc.setAttribute("times", time);
26          System.out.println("被访问第："+time+"次");
27     }
28 
29     public void doPost(HttpServletRequest request, HttpServletResponse response)
30             throws ServletException, IOException {
31 
32         doGet(request, response);
33 
34     }
35 }

 1 package com.shellway.servlet;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.ServletContext;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 public class CountServlet extends HttpServlet {
13 
14     public void doGet(HttpServletRequest request, HttpServletResponse response)
15             throws ServletException, IOException {
16         ServletContext sc = getServletContext();
17         int time=(Integer)sc.getAttribute("times");
18          PrintWriter pw = response.getWriter();
19          pw.write("this site has been visit "+time+" times");
20 
21     }
22 
23     public void doPost(HttpServletRequest request, HttpServletResponse response)
24             throws ServletException, IOException {
25 
26         doGet(request, response);
27 
28     }
29 }

 1 package com.shellway.servletcontext;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.RequestDispatcher;
 6 import javax.servlet.ServletContext;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 public class CountForA_Z extends HttpServlet {
13 
14     public void doGet(HttpServletRequest request, HttpServletResponse response)
15             throws ServletException, IOException {
16         //拿到请求数据
17         String content = request.getParameter("content");
18         //减少工作量，把内容都转为大写
19         String upcontent = content.toUpperCase();
20         //为26个字母创建数组，每个字母对应一个数组位置，每个数组位置存放统计该字母的数量
21         int[] arr = new int[26];
22         for (int i = 0; i < upcontent.length(); i++) {
23             //charAt(int index)返回指定索引处的 char 值。索引范围为从 0 到 length()-1
24             char c = upcontent.charAt(i);
25             //isLetter()确定指定字符是否为字母。
26             if (Character.isLetter(c)) {  //等价于c>=‘A‘&&c<=‘Z‘
27                 arr[c-‘A‘]++;
28             }
29         }
30          ServletContext context = getServletContext();
31          context.setAttribute("arr", arr);
32          RequestDispatcher rd =context.getRequestDispatcher("/servlet/result");
33          rd.forward(request, response);
34     }
35 
36     public void doPost(HttpServletRequest request, HttpServletResponse response)
37             throws ServletException, IOException {
38 
39         doGet(request, response);
40 
41     }
42 }

 1 package com.shellway.servletcontext;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.ServletContext;
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 public class CountForResult extends HttpServlet {
13 
14     public void doGet(HttpServletRequest request, HttpServletResponse response)
15             throws ServletException, IOException {
16         ServletContext sc = getServletContext();
17         int []arr1 = (int[])sc.getAttribute("arr");
18         char c = 0 ;
19         response.setContentType("text/html;charset=utf-8");
20         PrintWriter pw =response.getWriter();
21         for (int i = 0; i < arr1.length; i++) {
22             c = (char) (i+‘A‘);
23             pw.write(c+"出现的次数为: "+arr1[i]+" 次"+"<br/>");
24         }
25     }
26 
27     public void doPost(HttpServletRequest request, HttpServletResponse response)
28             throws ServletException, IOException {
29 
30         doGet(request, response);
31 
32     }
33 }

 1 package com.shellway.io;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.FileNotFoundException;
 5 import java.io.FileReader;
 6 import java.io.IOException;
 7 
 8 public class ReadFile {
 9     public static void main(String[] args) throws Exception {
10         String fileName = "src/a1.txt";
11         readfile(fileName);
12         
13         String fileName2 = "WebRoot/a2.txt";
14         readfile(fileName2);
15         
16         String fileName3 = "a3.txt";
17         readfile(fileName3);
18     }
19 
20     private static void readfile(String fileName) throws FileNotFoundException,
21             IOException {
22         BufferedReader in = new BufferedReader(new FileReader(fileName));
23         String len;
24         while ((len = in.readLine())!=null) {
25             System.out.println(len);
26         }
27     }
28 }

 1 package com.shellway.io;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.FileNotFoundException;
 5 import java.io.FileReader;
 6 import java.io.IOException;
 7 
 8 import javax.servlet.ServletException;
 9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 
13 public class ReadFileServlet extends HttpServlet {
14 
15     public void doGet(HttpServletRequest request, HttpServletResponse response)
16             throws ServletException, IOException {
17         String fileName = "/a2.txt";//这里的/代表网站的根目录
18         String s = getServletContext().getRealPath(fileName);
19         //返回: D:\apache-tomcat-6.0.14\webapps\day03\a2.txt
20         System.out.println(s);
21         readfile(s);
22 
23         String fileName2 = "/a1.txt";//这里的/代表classpath根路径，即： /WEB-INF/classes
24         String s2 = ReadFileServlet.class.getResource(fileName2).getFile();
25         //返回: /D:/apache-tomcat-6.0.14/webapps/day03/WEB-INF/classes/a1.txt
26         System.out.println(s2);//
27         readfile(s2);
28     }
29 
30     private static void readfile(String fileName) throws FileNotFoundException,
31             IOException {
32         BufferedReader in = new BufferedReader(new FileReader(fileName));
33         String len;
34         while ((len = in.readLine()) != null) {
35             System.out.println(len);
36         }
37     }
38 
39     public void doPost(HttpServletRequest request, HttpServletResponse response)
40             throws ServletException, IOException {
41 
42         doGet(request, response);
43 
44     }
45 }