servlet学习笔记

乔兵

一、开发Servlet

public class TestServlet extends HttpServlet {

  public TestServlet() {
super();
  }

  /**
* Servlet销毁方法. <br>
*/
  public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
  }

  public void doDelete(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

  }

  public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {

response.setContentType("text/html");
request.setCharacterEncoding("GB18030");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print("       This is ");
out.print(this.getClass());
out.println(", using the GET method");

out.println("<br>");
String x = request.getParameter("x");
String y = request.getParameter("y");
out.println("x="+x);
out.println("<br>");
out.println("y="+y);
out.println("<br>");

out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
  }

  public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {

response.setContentType("text/html");
PrintWriter out = response.getWriter();
out
      .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print("       This is ");
out.print(this.getClass());
out.println(", using the POST method");

out.println("<br>");
String x = request.getParameter("x");
String y = request.getParameter("y");
out.println("x="+x);
out.println("<br>");
out.println("y="+y);
out.println("<br>");

out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
  }

  public void doPut(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {

  }

  public String getServletInfo() {
return "This is my default servlet created by Eclipse";
  }


  public void init() throws ServletException {

  }

}

2、配置Servlet
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
  xmlns="http://java.sun.com/xml/ns/j2ee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
  http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
      <description>This is the description of my J2EE component</description>
      <display-name>This is the display name of my J2EE component</display-name>
      <servlet-name>TestServlet</servlet-name>
      <servlet-class>test.TestServlet</servlet-class>
</servlet>

<servlet-mapping>
      <servlet-name>TestServlet</servlet-name>
      <url-pattern>/testServlet</url-pattern>
</servlet-mapping>

<welcome-file-list>
      <welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>

3、访问Servlet
部署web应用并启动Servlet容器Tomcat。然后分别用两种方式来访问Servlet

a、通过URL直接访问
http://localhost:8080/HelloApp/testServlet?x=11222&y=13123421
注意：第一参数x之前要用"?"号，其余参数之间用"&"符号。
显示效果：

b、通过一个JSP来访问
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%
String path = request.getContextPath();
%>
<html>
<body>
      test post Method<br>
      <form action="<%=path %>/testServlet" method="post">
      x:<input type="text" name="x"><br>
      y:<input type="text" name="y"><br>
      <input type="submit" value="submit">
      <input type="reset" value="reset">
      </form>

</body>
</html>

二、简单总结

HTTP请求有很多种，最常用的就是get和post。get请求的参数提交后会显示在url后面，而post请求不会。

get请求适合少量数据，post请求没有限制。
get请求参数会显示在rul后面，不安全。可以直接请求。
从安全角度考虑，应该使用post请求。

乔兵 · 乔兵

感谢楼主分享，我是来拿金币的{:soso_e102:}

暮雨 · 暮雨

servlet的功能不可知这些，servlet的功能主要是完成数据的接收和处理，然后再将数据传回jsp页面，你的这种只是完成了页面的输出。其实你的这种完全可以用jsp实现（毕竟jsp其实就是一个特殊的servlet，只是Tomcat会将你写的jsp文件组装成一个servlet进行执行），好了，我把自己以前写的一个servlet给你，让你看看，servlet的功能。

package com.drp.web.fiscalcalculateperiod;
import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.drp.model.FiscalCalculatePeriod;
import com.drp.model.PageModel;
import com.drp.web.AbstractServlet;
@SuppressWarnings("serial")
public class FiscalCalculatePeriodServlet extends AbstractServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("GB18030");
String command = request.getParameter("command");
if("getFiscalCalculatePeriodList".equals(command)){
getFiscalCalculatePeriodList(request,response);
}else if("gotoAddFiscalCalculatePeriod".equals(command)){
gotoAddFiscalCalculatePeriod(request,response);
}else if("addFiscalCalculatePeriod".equals(command)){
addFiscalCalculatePeriod(request,response);
}else if("gotoModifyFiscalCalculatePeriod".equals(command)){
gotoModifyFiscalCalculatePeriod(request,response);
}else if("modifyFiscalCalculatePeriod".equals(command)){
modifyFiscalCalculaterPeriod(request,response);
}
}
private void modifyFiscalCalculaterPeriod(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
FiscalCalculatePeriod fiscalCalculatePeriod = new FiscalCalculatePeriod();
fiscalCalculatePeriod.setId(Integer.parseInt(request.getParameter("id")));
fiscalCalculatePeriod.setCalculateYear(Integer.parseInt(request.getParameter("fiscalYear")));
fiscalCalculatePeriod.setCalculateMonth(Integer.parseInt(request.getParameter("fiscalPeriod")));
try {
fiscalCalculatePeriod.setBeginDate(new SimpleDateFormat("yyyy-MM-dd").parse(request.getParameter("beginDate")));
fiscalCalculatePeriod.setEndDate(new SimpleDateFormat("yyyy-MM-dd").parse(request.getParameter("endDate")));
} catch (ParseException e) {
e.printStackTrace();
}
fiscalCalculatePeriod.setPeriodStatus(request.getParameter("periodSts")== null?"N":"Y");
FiscalCalculatePeriod fiscalCalculatePeriodResult = fiscalCalculatePeriodManager.modifyFiscalCalculatePeriod(fiscalCalculatePeriod);
if(fiscalCalculatePeriodResult != null){
request.setAttribute("fiscalCalculatePeriod", fiscalCalculatePeriodResult);
request.getRequestDispatcher("../basedata/fiscal_year_period_modify.jsp?modifyFiscalCalculatePeriod=success").forward(request, response);
}
}
private void gotoModifyFiscalCalculatePeriod(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String strId = request.getParameter("id");
if(strId != null && !strId.equals("")){
int id = Integer.parseInt(strId);
FiscalCalculatePeriod fiscalCalculatePeriod = fiscalCalculatePeriodManager.loadFiscalCalculatePeriodById(id);
if(fiscalCalculatePeriod != null){
request.setAttribute("fiscalCalculatePeriod", fiscalCalculatePeriod);
request.getRequestDispatcher("../basedata/fiscal_year_period_modify.jsp").forward(request, response);
}
}
}
private void getFiscalCalculatePeriodList(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
int pageNo = 1;
int pageSize = Integer.parseInt(this.getServletContext().getInitParameter("pageSize"));
String strPageNo = request.getParameter("pageNo");
if(strPageNo != null && !strPageNo.trim().equals("")){
pageNo = Integer.parseInt(strPageNo);
}
PageModel<FiscalCalculatePeriod> pageModel = fiscalCalculatePeriodManager.getFiscalCalculatePeriodList(pageNo, pageSize);
request.setAttribute("fiscalCalculatePeriodListPageModel", pageModel);
request.getRequestDispatcher("../basedata/fiscal_year_period_maint.jsp").forward(request, response);
}
private void addFiscalCalculatePeriod(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
FiscalCalculatePeriod fiscalCalculatePeriod = new FiscalCalculatePeriod();
fiscalCalculatePeriod.setCalculateYear(Integer.parseInt(request.getParameter("fiscalYear")));
fiscalCalculatePeriod.setCalculateMonth(Integer.parseInt(request.getParameter("fiscalPeriod")));
try {
fiscalCalculatePeriod.setBeginDate(new SimpleDateFormat("yyyy-MM-dd").parse(request.getParameter("beginDate")));
fiscalCalculatePeriod.setEndDate(new SimpleDateFormat("yyyy-MM-dd").parse(request.getParameter("endDate")));
} catch (ParseException e) {
e.printStackTrace();
}
fiscalCalculatePeriod.setPeriodStatus(request.getParameter("periodSts")== null?"N":"Y");
FiscalCalculatePeriod fiscalCalculatePeriodResult = fiscalCalculatePeriodManager.addFiscalCalculatePeriod(fiscalCalculatePeriod);
if(fiscalCalculatePeriodResult != null){
request.setAttribute("fiscalCalculatePeriod", fiscalCalculatePeriodResult);
request.getRequestDispatcher("../basedata/fiscal_year_period_add.jsp?addfiscalCalculatePeriod=success").forward(request, response);
}
}
private void gotoAddFiscalCalculatePeriod(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
request.getRequestDispatcher("../basedata/fiscal_year_period_add.jsp").forward(request, response);
}
}

复制代码

近夜之星 · 近夜之星

不错，学习了

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servlet学习笔记

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