JavaWeb学习之HttpServletRequest

HttpServletRequest

在创建Servlet时会重写service()方法，或doGet()/doPost(),这些方法都有两个参数，一个是代表请求的request。一个是代表响应的response。

service方法中的request的类型是ServletRequest，而doGet/doPost方法中的request是HttpServletRequest，HttpServletRequest是ServletRequest的子接口。

request的运行流程

通过抓包工具抓取Http请求

由于request是代表请求，所以可以通过该对象分别获取Http请求的请求行，请求头，请求体。

通过request获得请求行

获取客户端的请求方式：String  getMethod()

获得请求的资源：String   getRequestURI()

                            StringBuffer  getRequestURL()  ---主机号+端口号

                            String  getContextPath()  ---web应用的名称

                            String  getQueryString()   ---get提交url地址后的参数字符串

                                   如：username=zhangsan&password=123

request获得客户端的一些信息

 request.getRemoteAddr()   ---获得访问的客户端的IP地址

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package com.oracle.demo01;
 
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class LineServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取请求方式
        String method = request.getMethod();
        System.out.println("请求方式：" + method);
        /// 获得请求资源的相关内容
        String requestURI = request.getRequestURI();//抓到什么就是什么
        StringBuffer requestURL = request.getRequestURL();// 加上主机号和端口号
        System.out.println(requestURI);
        System.out.println(requestURL);
 
        // 获取web应用的名称
        String contextPath = request.getContextPath();
        System.out.println("web应用的名称：" + contextPath);
        // 获取get方式提交的参数
        String param = request.getQueryString();
        System.out.println(param);
        // 获取客户端的IP地址
        String ip = request.getRemoteAddr();
        System.out.println("IP地址为：" + ip);
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

运行结果如下：

通过request获得请求头

long  getDateHeader(String name)

String  getHeader(String name)   --获取指定的头

Enumeration  getHeaderNames()   --获取所有的头

Enumeration  getHeaders(String name)

int  getIntHeader(String name)

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package com.oracle.demo01;
 
import java.io.IOException;
import java.util.Enumeration;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class HeaderServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取指定的头
        String header = request.getHeader("User-Agent");
        // 获得所有头的名称
        Enumeration<String> headerName = request.getHeaderNames();
        while (headerName.hasMoreElements()) {
            String headername = headerName.nextElement();
            String headervalue = request.getHeader(headername);
            System.out.println(headername + ":" + headervalue);
        }
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

运行结果如下：

referer头的作用：执行该此访问的来源做防盗链

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package com.oracle.demo01;
 
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class RefererServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 对请求的来源进行判断
        String header = request.getHeader("referer");
        if (header != null && header.startsWith("http://localhost:8080")) {
            response.setContentType("text/html;charset=UTF-8");
            response.getWriter().write("马克思主义");
        } else {
            response.getWriter().write("无耻之徒");
        }
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

通过request获得请求体

请求体中的内容是通过post提交的请求参数，格式是：

username=zhangsan&password=123&hobby=football&hobby=basketball

key----------------value

username          [zhangsan]

password           [123]

hobby                 [football,basketball]

获取请求的一些参数：

String getParameter(String name)

String[] getParameterValues(String name)

Enumeration  getParameterNames()

Map<String,String[]> getParameterMap()

注：如果是get请求方式请求参数，上述方法通过适用。

解决post提交方式的乱码问题：request.setCharacerEncoding("UTF-8");   该方式只用于post方式

解决get提交方式的乱码问题：parameter =new String(parameter.getbytes("iso8859-1"),"utf-8");  该方式既可以用于get,也可以用于post

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package com.oracle.demo01;
 
import java.io.IOException;
import java.util.Map;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class RegisterServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取表单中的值
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println(username + ":" + password);
        System.out.println("!!!!!!!!!!!!!!!!!!!!!!");
        // 通过数组获取指定name值
        String[] sex = request.getParameterValues("sex");
        for (String str : sex) {
            System.out.println(str);
        }
        System.out.println("*******************");
        // 通过map获得所有的值
        Map<String, String[]> map = request.getParameterMap();
        for (Map.Entry<String, String[]> entry : map.entrySet()) {
            // 获得对应的name值
            System.out.println(entry.getKey());
            //获得value值
            for (String str1 : entry.getValue()) {
                System.out.println(str1);
            }
            System.out.println("---------------");
        }
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

request是一个域对象

request对象也是一个存储数据的区域对象，同response一样，也具有如下方法：

setAttribute(String name,Object obj)

getAttribute(String name)

removeAttribute(String name)

注：request域的作用范围：一次请求中

request完成请求转发

获得请求转发器----path是转发的地址

RequestDispatcher  getRequestDispatcher(String path)

通过转发器对象转发

requestDispatcher.forward(ServletRequest  request,ServletResponse  response)

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package com.oracle.demo02;
 
import java.io.IOException;
 
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class Servlet01 extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //将请求转发给servlet02
        RequestDispatcher dispatcher=request.getRequestDispatcher("/Servlet02");
        //向request中存储数据
        request.setAttribute("name", "zhangsan");
        //执行转发的方法
        dispatcher.forward(request, response);
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}　
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package com.oracle.demo02;
 
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class Servlet02 extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String value = (String) request.getAttribute("name");
        response.getWriter().write("hello lzz..." + value);
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

注：ServletContext域与Request域的生命周期比较

    ServletContext：创建：服务器启动

                               销毁：服务器关闭

                             域的作用范围：整个web应用

           Request：创建：访问时创建request

                            销毁：响应结束request销毁

                             域的作用范围：一次请求中

注：请求转发与重定向的区别

   1、重定向是两次请求，转发是一次请求

   2、重定向地址栏变化，转发的地址栏不变

   3、重定向可以访问外部网站，转发只能访问内部资源

注：客户端地址与服务器端地址的写法

    客户端地址：是客户端去访问服务器的地址，服务器外部的地址，特点：写上web应用的名称

    重定向 

    服务器端地址：服务器内部资源的跳转地址，特点：不需要写web应用的名称

    转发

 案例：做一个登陆注册功能

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package com.oracle.demo03;
 
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
 
public class DButil {
    private DButil() {
    }
 
    public static Connection getConn() {
        try {
            InputStream in = DButil.class.getClassLoader().getResourceAsStream("db.properties");
            Properties pro = new Properties();
            pro.load(in);
            String url = pro.getProperty("url");
            String username = pro.getProperty("username");
            String password = pro.getProperty("password");
            String driver = pro.getProperty("driver");
            Class.forName(driver);
            // 获得连接
            Connection conn = DriverManager.getConnection(url, username, password);
            return conn;
        } catch (Exception ex) {
            throw new RuntimeException(ex + "数据库连接失败");
        }
    }
 
    public static void close(Statement sta, Connection conn) {
        if (sta != null) {
            try {
                sta.close();
            } catch (SQLException ex) {
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException ex) {
            }
        }
    }
 
    public static void close(ResultSet rs, Statement sta, Connection conn) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException ex) {
            }
        }
        close(sta, conn);
    }
 
}
db.properties配置文件文件
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/test?characterEncoding=utf-8
username=root
password=123456
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package com.oracle.demo03;
 
public class Users {
    private String uid;
    private String username;
    private String password;
    private String sex;
    private String hobby;
     
    @Override
    public String toString() {
        return "Users [uid=" + uid + ", username=" + username + ", password=" + password + ", sex=" + sex + ", hobby="
                + hobby + "]";
    }
    public String getUid() {
        return uid;
    }
    public void setUid(String uid) {
        this.uid = uid;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public String getHobby() {
        return hobby;
    }
    public void setHobby(String hobby) {
        this.hobby = hobby;
    }
     
}

　

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package com.oracle.demo03;
 
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
 
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class LoginServlet extends HttpServlet {
    @Override
    public void init() throws ServletException {
        int count = 0;
        ServletContext context = getServletContext();
        context.setAttribute("count", count);
    }
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1、获取用户名和密码
        String user = request.getParameter("username");
        String pwd = request.getParameter("password");
        System.out.println(user + "..." + pwd);
        // 2、从数据库验证用户名和密码是否正确
        try {
            Connection conn = DButil.getConn();
            String sql = "select * from users where username=?and pwd=?";
            PreparedStatement pst = conn.prepareStatement(sql);
            pst.setString(1, user);
            pst.setString(2, pwd);
            ResultSet rs = pst.executeQuery();
            if (rs.next()) {
                ServletContext context = getServletContext();
                Integer count = (Integer) context.getAttribute("count");
                count++;
                System.out.println(rs.getInt("id") + " " + rs.getString("username") + " " + rs.getString("pwd"));
                response.getWriter().write(rs.getInt("id") + " " + rs.getString("username") + " " + rs.getString("pwd")
                        + "you are success login person" + " " + count);
                context.setAttribute("count", count);
            } else {
                request.setAttribute("loginInfo", "用户名密码或错误");
                request.getRequestDispatcher("/login.jsp").forward(request, response);
            }
            DButil.close(rs, pst, conn);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
 
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

　

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package com.oracle.demo03;
 
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Map;
import java.util.UUID;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.apache.commons.beanutils.BeanUtils;
 
public class RegisteServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1、获取数据
        Map<String, String[]> properties = request.getParameterMap();
        Users user = new Users();
        // 2、将数据封装到JavaBean
        // 使用BeanUtil进行自动映射封装
        // 工作原理：将map中的数据根据key与实体中的属性的对应关系封装
        // 只要key的名字与实体中的属性名字一样，就自动封装到实体中
        // 需要导两个包
        try {
            BeanUtils.populate(user, properties);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        //手动封装一个uid--uuid---随机不重复的字符串32位，但实际的Java代码生成了36位
        user.setUid(UUID.randomUUID().toString());
        System.out.println(user.toString());
        //调用业务方法
        int row=regist(user);
        //跳转登陆页面
        if(row>0){
            response.sendRedirect(request.getContextPath()+"/login.html");
        }else{
            response.getWriter().write("注册失败，请重新注册");
            response.sendRedirect(request.getContextPath()+"/regist.html");
 
        }
    }
 
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
    public int regist(Users user){
        int row=0;
        Connection conn=DButil.getConn();
        String sql="insert into users values(?,?,?,?,?)";
        try{
            PreparedStatement pst=conn.prepareStatement(sql);
            pst.setString(1, user.getUid());
            pst.setString(2, user.getUsername());
            pst.setString(3, user.getPassword());
            pst.setString(4, user.getSex());
            pst.setString(5, user.getHobby());
            row=pst.executeUpdate();
            DButil.close(pst, conn);
        }catch(SQLException e){
            e.printStackTrace();
        }
        return row;
    }
}

　　

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<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <a href="/web07/RefererServlet">不断汲取马克思主义的科学智慧和理论力量</a>
    <form action="/web07/HeaderServlet" method="post">
        <input type="text" name="username">
        <input type="password"name="password">
        <input type="submit" value="提交">
    </form>
</body>
</html>
 
 
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/web07/RegisteServlet" method="post">
  用户名： <input type="text" name="username"><br>
    密码：  <input type="password" name="password"><br>
      性别：男<input type="radio" name="sex" value="nan">
      女：<input type="radio" name="sex" value="nv"><br>
      爱好：篮球<input type="checkbox" name="hobby" value="basketballl">
      足球<input type="checkbox" name="hobby" value="footballl">
      排球<input type="checkbox" name="hobby" value="volleyballl"><br>
      <input type="submit"  value="注册">
      <input type="reset"  value="重置">
       
</form>
</body>
</html>
 
<%@ 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=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <div><%=request.getAttribute("loginInfo")%></div>
 
    <form action="/web07/HeaderServlet" method="post">
        <input type="text" name="username"> <input type="password"
            name="password"> <input type="submit" value="提交">
    </form>
</body>
</html>

　　

posted @   低调的小孩儿  阅读(1920)  评论(0)  编辑  收藏  举报
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