Servlet中的service方法
Servlet中的service方法用于应答浏览器请求，每次请求都会调用该方法。
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
}
}ServletResponse：封装了响应信息，用于响应用户请求。
这两个接口都是服务器给予实现的，并在服务器调用service方法时传入。
1.ServletRequest：
1.1 获取请求参数：
1.1.1 String getParameter(String name); 根据名字获取值
html:
login.html
loginServlet
com.sa.servlet.LoginServlet
loginServlet
/login
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
String login=request.getParameter("login");
String password=request.getParameter("password");
System.out.println("login:"+login);
System.out.println("password:"+password);
}
login:admin
password:123 1.1.2 Map
key:参数名,value:参数值，String[] 类型
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
Map map=request.getParameterMap();
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + Arrays.toString(map.get(key)));
}
}
key= login and value= [admin]
key= password and value= [123]
key= interesting and value= [Party, Shopping] 1.1.3 Enumeration
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
//Map request.getParameterMap();
//Enumeration request.getParameterNames();
//String[] request.getParameterValues(arg0);
Enumeration enums=request.getParameterNames();
while(enums.hasMoreElements()){
String name=enums.nextElement();
String[] value=request.getParameterValues(name);
System.out.println("name:"+name+",value:"+Arrays.toString(value));
}
name:login,value:[admin]
name:password,value:[123]
name:interesting,value:[Playing, Party]1.1.4 String[] getParameterValues(String name);根据名字获取值数组，例如checkbox
html：
login.html
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
String login=request.getParameter("login");
String password=request.getParameter("password");
String[] interesting=request.getParameterValues("interesting");
System.out.println("login:"+login);
System.out.println("password:"+password);
System.out.println("interesting:"+Arrays.toString(interesting));
}
1.2 获取请求的URI：
HttpServletRequest是ServletRequest的子接口，针对于HTTP请求所定义，里面有
大量获取HTTP信息的方法。
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
HttpServletRequest httpServletRequest=(HttpServletRequest) request;
String uri=httpServletRequest.getRequestURI();
System.out.println("uri:"+uri);
}
uri:/MyLab2/login 1.3 获取请求方式：
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
HttpServletRequest httpServletRequest=(HttpServletRequest) request;
String method=httpServletRequest.getMethod();
System.out.println("method:"+method);
}
method:POST2. ServletReponse：
2.1 getWriter（）：
返回PrintWriter对象，调用该对象的print()方法，把print()中参数打印在网页上。
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
PrintWriter writer=response.getWriter();
writer.println("hello world");
}
2.2 setContentType（）：
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("application/msword");
PrintWriter writer=response.getWriter();
writer.println("hello world");
}
2.3 void sendRedirect（String location）：
请求的重定向。（此方法为HttpServletResponse中定义）
在web.xml文件中设置两个WEB应用的初始化参数：user,password.
定义一个login.html,里边定义两个请求字段：user,password,发送请求到loginServlet.
在loginServlet中，获取请求的user,password,比较其和web.xml文件中的初始化参数是否一致，
若一致，则响应: hello,xxx；若不一致，则响应: sorry ,xxx;
html:
login.html
user
sasa
password
123
loginServlet
com.sa.servlet.LoginServlet
loginServlet
/login
package com.sa.servlet;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.Map;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet implements Servlet {
public LoginServlet(){
}
@Override
public void destroy() {
// TODO Auto-generated method stub
}
@Override
public ServletConfig getServletConfig() {
// TODO Auto-generated method stub
return null;
}
@Override
public String getServletInfo() {
// TODO Auto-generated method stub
return null;
}
@Override
public void init(ServletConfig arg0) throws ServletException {
// TODO Auto-generated method stub
}
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
String user=request.getParameter("login");
String password=request.getParameter("password");
ServletContext servletContext=request.getServletContext();
String user2=servletContext.getInitParameter("user");
String password2=servletContext.getInitParameter("password");
//HttpServletResponse httpServletResponse=(HttpServletResponse) response;
PrintWriter writer=response.getWriter();
if(user.equals(user2)&&password.equals(password2)){
writer.println("hello,"+user);
}else{
writer.println("sorry,"+user);
}
}
}
