request对象的类是HttpServletRequest，提供了很多有实用价值的方法
request的常见方法
-
request.getRequestURL()：浏览器发出请求时的完整URL -
request.getRequestURI()：浏览器发出请求的资源名部分 -
request.getQueryString()：请求行中的参数部分 -
request.getRemoteAddr()：浏览器所处于的客户机的IP地址 -
request.getRemoteHost()：浏览器所处于的客户机的主机名 -
request.getRemotePort()：浏览器所处于的客户机使用的网络端 -
request.getLocalAddr()：服务器的IP地址 -
request.getLocalName()：服务器的主机名 -
request.getMethod：得到客户机请求方式，Get或者是Post
- 重写LoginServlet
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String name = req.getParameter("name");
String password = req.getParameter("password");
System.out.println("浏览器发出请求时的完整URL" + req.getRequestURL());
System.out.println("浏览器发出请求的资源名部分" + req.getRequestURI());
System.out.println("请求行中的参数部分" + req.getQueryString());
System.out.println("浏览器所处于的客户机的IP地址" + req.getRemoteAddr());
System.out.println("浏览器所处于的客户机的主机名" + req.getRemoteHost());
System.out.println("浏览器所处于的客户机使用的网络端" + req.getRemotePort());
System.out.println("服务器的IP地址" + req.getLocalAddr());
System.out.println("服务器的主机名" + req.getLocalName());
System.out.println("得到客户机请求方式，Get或者是Post" + req.getMethod());
String html = null;
if ("admin".equals(name) && "123".equals(password)) {
html = "<div style='color:green'>登录成功</div>";
} else {
html = "<div style='color:red'>登录失败</div>";
}
resp.setContentType("text/html; charset=UTF-8");
resp.getWriter().println(html);
}
}
-
测试结果如下
image.png
获取参数
-
request.getParameter()：获取单值得参数 -
request.getParameterValues()：获取多值参数 -
request.getParameterMap()：遍历所有的参数，并返回Map类型 - 准备一个注册页面
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>注册页面</title>
</head>
<body>
<form action="register" method="get">
账号：<input type="text" name="name"> <br>
爱好：LOL<input type="checkbox" name="hobits" value="lol">
DOTA<input type="checkbox" name="hobits" value="dota"> <br>
<input type="submit" value="注册">
</form>
</body>
</html>
- 准备一个RegisterServlet
import java.io.IOException;
import java.util.Arrays;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class RegisterServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("获取单值参数name:" + request.getParameter("name"));
String[] hobits = request.getParameterValues("hobits");
System.out.println("获取具有多值的参数hobits:" + Arrays.asList(hobits));
System.out.println("通过 getParameterMap 遍历所有的参数: ");
Map<String, String[]> parameters = request.getParameterMap();
Set<String> paramNames = parameters.keySet();
for (String param : paramNames) {
String[] value = parameters.get(param);
System.out.println(param + ":" + Arrays.asList(value));
}
}
}
- 修改一下web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<servlet>
<servlet-name>HelloServlet</servlet-name>
<servlet-class>HelloServlet</servlet-class>
<load-on-startup>10</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>HelloServlet</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>RegisterServlet</servlet-name>
<servlet-class>RegisterServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>RegisterServlet</servlet-name>
<url-pattern>/register</url-pattern>
</servlet-mapping>
</web-app>
-
测试的效果
image.png
获取头信息
-
request.getHeader()：获取浏览器传递过来的头信息 -
request.getHeaderNames()：获取浏览器所有的头信息名称 - 修改HelloServlet，如下
import java.io.IOException;
import java.util.Date;
import java.util.Enumeration;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloServlet extends HttpServlet {
@Override
public void init(ServletConfig config) throws ServletException {
System.out.println("init of Hello Servlet");
}
public void doGet(HttpServletRequest request, HttpServletResponse responce) {
Enumeration<String> headerNames = request.getHeaderNames();
while (headerNames.hasMoreElements()) {
String header = headerNames.nextElement();
String value = request.getHeader(header);
System.out.printf("%s\t%s%n", header, value);
}
try {
responce.getWriter().println("<h1>Hello Servlet!</h1>");
responce.getWriter().println(new Date().toLocaleString());
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
-
运行效果
image.png
服务端传参
- setAttribute和getAttribute可以用来在进行服务端跳转的时候，在不同的Servlet之间进行数据共享
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