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hello.java
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128 lines (114 loc) · 4.03 KB
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import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class hello extends HttpServlet {
/**
* Constructor of the object.
*/
public hello() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
/*
* 以Get方式访问页面时执行该函数 执行doGet前会先执行getLastModified,如果浏览器发现getLastModified返回数值
* 与上次访问返回数值相同，则认为该文档没有更新，浏览器执行缓存而不执行doGet 如果返回-1则认为是实时更新的，总是执行该函数
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.log("执行 doGet 方法...");
this.execute(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred 执行前不会执行getLastModified
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.log("执行 doPost 方法...");
this.execute(request, response);
}
/**
* 返回该Servlet生成文档的更新时间。对Get方法有效 返回的时间为相对于1970年1月1日08:00:00的毫秒数
* 如果返回-1表示实时更新。默认为-1
*/
@Override
public long getLastModified(HttpServletRequest request) {
this.log("执行 getLastModified 方法...");
return -1;
}
// 执行方法
private void execute(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");// 设置request和response编码，两个都要注意
request.setCharacterEncoding("UTF-8");
String requestURI = request.getRequestURI();// 访问Servlet的URI
String method = request.getMethod();// 访问Servlet的方式Get或Post
String param = request.getParameter("param");// 客户端提交的参数param值
response.setContentType("text/html");// 设置文档类型为HTML类型
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println("<meta http-equiv=\"content-type\" content=\"text/html; charset=UTF-8\">");
out.println("<HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.println(" 以" + method + " 方式访问该页面。提取的param参数为：" + param + "<br/>");
// input
out.println(" <form action='" + requestURI + "' method='get'>"
+ "<input type='text' name='param' value='param string'>"
+ "<input type='submit' value='以Get方式查询页面 '" + requestURI
+ "'>" + "</form>");
out.println(" <form action='" + requestURI + "' method='post'>"
+ "<input type='text' name='param' value='param string'>"
+ "<input type='submit' value='以Post方式查询页面 '" + requestURI
+ "'>" + "</form>");
// 由客户端浏览器读取该文档的更新时间
out.println(" <script>document.write('本页面的最后更新时间： '+document.lastModified);</script>");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException
* if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}