Java Servlet(四):Servlet接口service工作(ServletRequest,ServletResponse对象)(jdk7+tomcat7+eclipse)
本篇将会记录,Servlet接收客户端传递来的参数信息,并返回信息使用的对象,及这些对象的函数相关用法。
还是在java ee工程中进行操作,在WebContent目录下创建一个login.jsp文件,并修改文件内容为:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body> <form id="form1" method="POST" action="LoginServlet"> 用户名称:<input id="username" name="username" type="text" /> 用户 密码:<input id="password" name="password" type="password" /> <br/> <input name="checkBox" type="checkbox" value="000"/>000 <br/> <input name="checkBox" type="checkbox" value="001"/>001 <br/> <input name="checkBox" type="checkbox" value="002"/>002 <br/> <input name="checkBox" type="checkbox" value="003"/>003 <br/> <input type="submit" name="submit" value="submit"/> </form> </body> </html>
在src目录下创建一个LoginServlet类,并实现Servlet接口及实现其接口函数:
1 package com.dx.hello; 2 3 import java.io.IOException; 4 import java.util.*; 5 6 import javax.servlet.Servlet; 7 import javax.servlet.ServletConfig; 8 import javax.servlet.ServletException; 9 import javax.servlet.ServletRequest; 10 import javax.servlet.ServletResponse; 11 import javax.servlet.http.HttpServletRequest; 12 13 public class LoginServlet implements Servlet { 14 15 public LoginServlet() { 16 // TODO Auto-generated constructor stub 17 } 18 19 @Override 20 public void destroy() { 21 // TODO Auto-generated method stub 22 23 } 24 25 @Override 26 public ServletConfig getServletConfig() { 27 // TODO Auto-generated method stub 28 return null; 29 } 30 31 @Override 32 public String getServletInfo() { 33 // TODO Auto-generated method stub 34 return null; 35 } 36 37 @Override 38 public void init(ServletConfig arg0) throws ServletException { 39 // TODO Auto-generated method stub 40 41 } 42 43 @Override 44 public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException { 45 System.out.println("LoginService's service ... "); 46 // ServletRequest的getParameter(String argo) 47 String username = request.getParameter("username"); 48 String password = request.getParameter("password"); 49 System.out.println("username:" + username); 50 System.out.println("password:" + password); 51 52 // ServletRequest的getParameterNames() 53 Enumeration<String> names = request.getParameterNames(); 54 while (names.hasMoreElements()) { 55 String name = names.nextElement(); 56 System.out.println("--->" + name); 57 String value = request.getParameter(name); 58 System.out.println("--->" + value); 59 } 60 61 // ServletRequest的getParameterValues(String argo) 62 String[] checkboxs = request.getParameterValues("checkBox"); 63 for (String value : checkboxs) { 64 System.out.println("key:checkBox,value:" + value); 65 } 66 67 // ServletRequest的getParameterMap() 68 Map<String, String[]> map = request.getParameterMap(); 69 for (Map.Entry<String, String[]> item : map.entrySet()) { 70 System.out 71 .println("getParameterMap()---->key:" + item.getKey() + ",value:" + Arrays.asList(item.getValue())); 72 } 73 74 // 强制转化为 HttpServletRequest 75 HttpServletRequest httpRequest = (HttpServletRequest) request; 76 77 // 获取request URI 78 String requestURI = httpRequest.getRequestURI(); 79 System.out.println("HttpServletRequest的getRequestURI():"+requestURI); 80 81 // 获取request Method 82 String method = httpRequest.getMethod(); 83 System.out.println("HttpServletRequest的getMethod():"+method); 84 85 // 获取资源文件在服务器上的物理路径 86 String relaPath = httpRequest.getRealPath("/WEB-INF/classes/jdbc.properties"); 87 System.out.println("HttpServletRequest的getRealPath():"+relaPath); 88 89 // 获取请求过程中,通过uri传递的参数 90 String queryString = httpRequest.getQueryString(); 91 System.out.println("HttpServletRequest的getQueryString():"+queryString); 92 93 // 获取servlet配置路径 94 String servletPath = httpRequest.getServletPath(); 95 System.out.println("HttpServletRequest的getServletPath():"+servletPath); 96 97 // 获取servlet服務名稱。 98 String servletName = httpRequest.getServerName(); 99 System.out.println("HttpServletRequest的getServerName():"+servletName); 100 101 } 102 103 }
修改web.xml注册LoginServlet servlet:
1 <servlet> 2 <servlet-name>LoginServlet</servlet-name> 3 <servlet-class>com.dx.hello.LoginServlet</servlet-class> 4 </servlet> 5 <servlet-mapping> 6 <servlet-name>LoginServlet</servlet-name> 7 <url-pattern>/LoginServlet</url-pattern> 8 </servlet-mapping>
运行tomcat服务,在浏览器中输入http://localhost:8080/MyServlet001/login.jsp,填写表单信息提交,查看到console输出信息:
LoginService's service ...
username:111
password:2222
--->username
--->111
--->password
--->2222
--->checkBox
--->001
--->submit
--->submit
key:checkBox,value:001
key:checkBox,value:002
getParameterMap()---->key:username,value:[111]
getParameterMap()---->key:password,value:[2222]
getParameterMap()---->key:checkBox,value:[001, 002]
getParameterMap()---->key:submit,value:[submit]
HttpServletRequest的getRequestURI():/MyServlet001/LoginServlet
HttpServletRequest的getMethod():POST
HttpServletRequest的getRealPath():D:\java\workset\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\MyServlet001\WEB-INF\classes\jdbc.properties
HttpServletRequest的getQueryString():null
HttpServletRequest的getServletPath():/LoginServlet
HttpServletRequest的getServerName():localhost
代码示例已经完成,接下来进行分析service接收参数的原理及相关对象:
如何在Servlet中获取请求信息?
1、Servlet中的service()方法用于应答请求,每次请求都会调用service()方法。(service方法是服务器调用的)
@Override
public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException {。。。}
ServletRequest :封装了请求信息,可以从中获取到任何的请求信息;
ServletResponse :封装了响应信息,可以使用该接口的方法实现用户响应的信息。
这两个(ServletRequest 和ServletResponse )接口的实现都是服务器实现的,并在服务器调用service()方法时传入。
可以通过以下操作去查证下:
1 System.out.println(request); 2 //执行上边语句将会输出如下信息: 3 //org.apache.catalina.connector.RequestFacade@d952d1
而这个服务器可能是tomcat,也可能是其他servlet容器。
2、ServletRequest相关函数:
- ServletRequest的getParameter(String argo)
1 String username = request.getParameter("username"); 2 String password = request.getParameter("password"); 3 System.out.println("username:" + username); 4 System.out.println("password:" + password);
- ServletRequest的getParameterNames()
1 Enumeration<String> names = request.getParameterNames(); 2 while (names.hasMoreElements()) { 3 String name = names.nextElement(); 4 System.out.println("--->" + name); 5 String value = request.getParameter(name); 6 System.out.println("--->" + value); 7 }
- ServletRequest的getParameterValues(String argo)
1 String[] checkboxs = request.getParameterValues("checkBox"); 2 for (String value : checkboxs) { 3 System.out.println("key:checkBox,value:" + value); 4 }
- ServletRequest的getParameterMap()
1 Map<String, String[]> map = request.getParameterMap(); 2 for (Map.Entry<String, String[]> item : map.entrySet()) { 3 System.out 4 .println("getParameterMap()---->key:" + item.getKey() + ",value:" + Arrays.asList(item.getValue())); 5 }
- HttpServletRequest强制转化为 HttpServletRequest
1 HttpServletRequest httpRequest = (HttpServletRequest) request;
- HttpServletRequest 获取request URI
1 String requestURI = httpRequest.getRequestURI(); 2 System.out.println("HttpServletRequest的getRequestURI():"+requestURI);
- HttpServletRequest获取request Method
1 String method = httpRequest.getMethod(); 2 System.out.println("HttpServletRequest的getMethod():"+method);
- HttpServletRequest获取资源文件在服务器上的物理路径
1 String relaPath = httpRequest.getRealPath("/WEB-INF/classes/jdbc.properties"); 2 System.out.println("HttpServletRequest的getRealPath():"+relaPath);
- HttpServletRequest获取请求过程中,通过uri传递的参数
1 String queryString = httpRequest.getQueryString(); 2 System.out.println("HttpServletRequest的getQueryString():"+queryString);
- HttpServletRequest获取servlet配置路径
1 String servletPath = httpRequest.getServletPath(); 2 System.out.println("HttpServletRequest的getServletPath():"+servletPath);
- HttpServletRequest获取servlet服務名稱。
String servletName = httpRequest.getServerName();
System.out.println("HttpServletRequest的getServerName():"+servletName);
3.ServletResponse对象
封装了响应信息,如果需要给用户什么响应,具体可以使用该接口的方法实现。
- getWriter()方法:
可以返回一个PrintWriter对象,调用该对象的print()方法,将把print()中的参数直接打印到客户端浏览器上。
1 // 返回PrintWriter对象,如果想给用户什么响应,具体可以使用该接口的方法实现。 2 PrintWriter out = response.getWriter(); 3 out.println("hello");
setContentType(string arg0):
设置相应内容类型:
// 设置相应的内容类型 response.setContentType("miscrosoft/word");
内容类型可以参考:/tomcat/config/web.xml中设置信息。
可以通过response对象强制转化为:HttpServletResponse对象。
该对象比ServletResponse接口内容更多。
基础才是编程人员应该深入研究的问题,比如:
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2)mysql索引存储结构&如何调优/b-tree特点、计算复杂度及影响复杂度的因素。。。
3)JVM运行组成与原理及调优
4)Java类加载器运行原理
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6)Redis中hash一致性实现及与hash其他区别
7)Java多线程、线程池开发、管理Lock与Synchroined区别
8)Spring IOC/AOP 原理;加载过程的。。。
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