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

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)

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
     
       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

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

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
     
       map = request.getParameterMap();		for (Map.Entry
      
        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)

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);	}}　

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

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.Driverurl=jdbc:mysql://localhost:3306/test?characterEncoding=utf-8username=rootpassword=123456

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;	}	}

　

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);	}}

　

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
     
       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;	}}
     

　　

     	不断汲取马克思主义的科学智慧和理论力量	
     
		
       		
      	    
      	
     
     
     
        用户名： 
      
      
    密码：  
      
      
      性别：男
            女：
      
      
      爱好：篮球
            足球
            排球
      
      
      
            
            
     
<%@ page language="java" contentType="text/html; charset=UTF-8"	pageEncoding="UTF-8"%>
     	
     
      <%=request.getAttribute("loginInfo")%>