Request需要掌握
Request对象
package com.kuang.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class RequestDemo01 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//查看request对象的方式
System.out.println(request.getContextPath()); //获得web项目路径
System.out.println(request.getRequestURI()); //请求的URL路径
//Remote 远程
System.out.println(request.getRemoteUser()); //获得远程的用户名
System.out.println(request.getRequestedSessionId()); //获得SessionId;
System.out.println(request.getServletPath()); //请求servlet的url
System.out.println(request.getLocalAddr()); //获得本地地址 防火墙
System.out.println(request.getLocalName()); //获得本地名字
System.out.println(request.getLocalPort()); //获得访问的端口号
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}
Request对象接收前端用户提交的参数
1.写前端注册页面
- 表单的提交方式 get/post
- 表单提交的位置 action:服务项目的路径/servlet对应的请求url
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>注册</title>
</head>
<body>
<%--
JSP的注释
--%>
<%--
Form表单
action:代表要提交的路径,表单要提交到哪里 ,可以提交到一个Servlet
//提交到Servlet需要,获取到Web项目的路径下的Servlet
method: 提交表单的方式
--%>
<h1>注册</h1>
<form action="${pageContext.request.contextPath}/r2" method="post">
<p>用户名:<input type="text" name="username"></p>
<p>密码:<input type="password" name="password"></p>
<p>
<input type="submit">
<input type="reset">
</p>
</form>
</body>
</html>
2.写处理前端提交信息的Servlet
- 接收前端传递的控件信息, request.getParameter(“控件的name‘);
package com.kuang.servlet;
import javax.print.attribute.HashPrintRequestAttributeSet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
//处理前端提交过来的数据
public class RequestDemo02 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//通过HttpServletRequest获取前端用户提交的信息
//req.getParameterValues(); 获得前端传递的控件信息,通过控件的name;但是可以接受多个参数的控件,比如(多选框....)
//req.getParameter(); 获得前端传递的控件信息,通过控件的name;
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");
String username = req.getParameter("username");
String password = req.getParameter("password");
//连接数据库,比较数据库中的信息是否匹配
if (username.equals("admin")&&password.equals("1234567")){
System.out.println("登录成功!"); //跳转到成功页面
}else {
System.out.println("登录失败!"); //提示重新注册
}
System.out.println(username);
System.out.println(password);
}
}
3.配置web.xml
- 配置对应的XML文件
<servlet>
<servlet-name>RequsetDemo02</servlet-name>
<servlet-class>com.kuang.servlet.RequestDemo02</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>RequsetDemo02</servlet-name>
<url-pattern>/r2</url-pattern>
</servlet-mapping>
4.提交测试
- 检查英文提交情况,服务器是否接收成功!
- 提交中文,看看乱码情况
- 设置编码统一,解决乱码问题;
Request实现请求转发
-
重定向:服务器告诉客户端你应该请求另外一个地址; (地址栏会变)
使用:resp.sendRedirect(“url”);
-
转发:服务器把这个请求转向另外一个Servlet去处理; (地址栏不会变)
使用:RequestDispatcher ,需要使用RequestDispatcher来进行处理,我们需要获得这个类
//参数就是他要转发到的页面
RequestDispatcher requestDispatcher = req.getRequestDispatcher("/success.jsp");
requestDispatcher.forward(req,resp);
servlet编写:
package com.kuang.servlet;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class FormServlet1 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//处理乱码
req.setCharacterEncoding("UTF-8");
//处理前端的请求
String username = req.getParameter("username");
String password = req.getParameter("password");
System.out.println("接收到的用户名:"+username+"\n密码:"+password+"\n爱好:");
String[] hobbies = req.getParameterValues("hobby");
for (String hobby : hobbies) {
System.out.println(hobby);
}
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
req.getRequestDispatcher("/success.jsp").forward(req,resp);
}
}
register.jsp编写:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>注册</title>
</head>
<body>
<h1>注册</h1>
<form action="${pageContext.request.contextPath}/register" method="post">
<p>
<%-- 控件必须有name属性,因为Servlet要通过name才能接收到用户输入的信息 --%>
用户名:<input type="text" name="username">
</p>
<p>
密码:<input type="password" name="password">
</p>
<p>
爱好 :
<input type="checkbox" name="hobby" value="girl">女孩
<input type="checkbox" name="hobby" value="code">代码
<input type="checkbox" name="hobby" value="movie">电影
<input type="checkbox" name="hobby" value="music">音乐
</p>
<p>
<input type="submit" value="提交">
<input type="reset" value="重置">
</p>
</form>
</body>
</html>
success编写:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>注册成功!</h1>
</body>
</html>
注意:
**转发和重定向的区别 (面试常见题:笔试)
重定向:服务器告诉客户端,你去请求另外一个地址;客户端行为
-
地址栏会变
-
不能携带参数
转发:服务器自己转发到服务器上的另一个请求; 服务器行为
- 地址栏不会变
- 可以携带参数**