0310 HttpServletRequest
回顾一下 servlet运行流程
通过request获得请求行
获得客户端的请求方式：String getMethod()
获得请求的资源:
获取请求地址uri: String getRequestURI()
获取请求地址url:StringBuffer getRequestURL()
获取去web应用名称:String getContextPath()
获取get请求提交的参数:String getQueryString()
获取客户端的IP地址:getRemoteAddr()
代码展示
register.jsp
<%@ 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>
<form action="/WEB04/LineServlet" method="get">
用户名：<input type="text" name="uname"><br>
密码：<input type="password" name="pwd"><br>
爱好：
足球：<input type="checkbox" name="hobby" value="zq">
篮球：<input type="checkbox" name="hobby" value="lq">
乒乓球：<input type="checkbox" name="hobby" value="ppq"><br>
<input type="submit" value="注册">
</form>
</body>
</html>
LineServlet
public class LineServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取哦请求方式
String method=request.getMethod();
System.out.println("请求方式"+method);
//获取请求地址uri
String uri=request.getRequestURI();
System.out.println("请求地址uri:"+uri);
//获取请求地址
StringBuffer url=request.getRequestURL();
System.out.println("请求地址url是："+url);
//获取去web应用名称
String name=request.getContextPath();
System.out.println("web应用名称是："+name);
//获取get请求提交的参数
String query=request.getQueryString();
System.out.println("get请求提交的参数"+query);
//获取客户端的IP地址
String ip=request.getRemoteAddr();
System.out.println("客户端IP地址是："+ip);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
如果jsp文件的提交方式改成post那么这个get请求提交参数就是null
通过request获得请求头
String getHeader();
referer头的作用：获取该访问的的来源
代码展示
public class HeadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取refer头
String refer=request.getHeader("referer");
System.out.println(refer);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
还是使用register.jsp的代码将action中的路径改成/WEB04/HeadServlet
referer头可以做一个防盗链的作用 就是可以判断这个访问来自哪里 如果不是我指定的访问路径 就不让他链接
代码展示
referer.jsp
<%@ 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>
<a href="/WEB04/RefererServlet">14天交易日A股暴跌30%</a>
</body>
</html>
public class RefererServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取referer头
String refer=request.getHeader("referer");
//解决响应乱码
response.setContentType("text/html;charset=utf-8");
if(refer.startsWith("http://localhost")){
response.getWriter().write("这是一跳爆炸新闻");
}else{
response.getWriter().write("到连着 可耻");
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
通过request获得请求体
获取请求体:
String getParameter(String key);
String[] getParameterValues(String name)
Map<String, String[]> getParameterMap()
解决post请求乱码
setCharacterEncoding("UTF-8") 指定码表
解决get 请求乱码
当客户端提交中文，那么先将数据提交，请求行会按照ISO8859-1码表进行解析 存到 request对象中 然后再传到服务器进行解析，因为服务器是utf-8码表所以解析不出来 ，所以就会响应给客户端一个乱码，这个解决这个乱码，我们可以再按照这个编码给他编译回去。
运用到
getbytes（“码表”）可以指定码表
new String（bytes,"码表"）也可以指定码表
例：new String(parameter.getbytes("iso8859-1"),"utf-8")
代码展示
register.jsp post请求
<%@ 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>
<form action="/WEB04/BodyServlet" method="post">
用户名：<input type="text" name="uname"><br>
密码：<input type="password" name="pwd"><br>
爱好：
足球：<input type="checkbox" name="hobby" value="zq">
篮球：<input type="checkbox" name="hobby" value="lq">
乒乓球：<input type="checkbox" name="hobby" value="ppq"><br>
<input type="submit" value="注册">
</form>
</body>
</html>
public class BodyServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//解决post请求乱码
request.setCharacterEncoding("UTF-8");
//获取请求体
String uname=request.getParameter("uname");
//解决get请求乱码
//uname=new String(uname.getBytes("ISO8859-1"),"UTF-8");
System.out.println("用户名"+uname);
String pwd=request.getParameter("pwd");
System.out.println("密码"+pwd);
String[] hobbys=request.getParameterValues("hobby");
for(String s:hobbys){
System.out.println(s);
}
//获取所有参数所在的map集合
Map<String, String[]> map=request.getParameterMap();
//获取所有key躲在的set集合
Set<String> keys=map.keySet();
for(String key:keys){
System.out.print(key+":");
String[] values=map.get(key);
for(String value:values){
System.out.print(value+" ");
}
System.out.println();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
register.jsp get请求 将register文件中的post改成get，将bodyservlet文件中的 将解决post乱码的代码行注释掉，将解决get乱码代码行放开
因为在上述代码中只解决了第一个name的乱码 并没有解决下边的那个map集合中的中文乱码。
request其他功能
request是一个域对象
request对象也是一个存储数据的区域对象、
setAttribute(String name,Object j)
getAttribute(String name)
removeAttribute(String name)
注意：request域的作用范围：一次请求中
request完成请求转发
getRequestDispatcher(String path)方法获得一个RequestDispatcher转发器对象，通过调用RequestDispatcher对象的forward(ServletRequest request, ServletResponse response)方法完成请求转发
代码展示
public class Servlet01 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//request域中存值
request.setAttribute("name", "张三");
//请求转发
//获取请求转发器调用转发方法
request.getRequestDispatcher("/Servlet02").forward(request, response);;
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
public class Servlet02 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
//取值
String name=(String)request.getAttribute("name");
response.getWriter().write("hello"+name);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
request域与ServletContext域的区别
request作用域是一次请求中，请求时创建，请求结束销毁
ServletContext作用域是整个项目文件，服务器开启状态部署文件时创建，服务器关闭销毁
重定向与请求转发区别
重定向是请求两次，地址栏改变，不能够传递数据，可以用于访问外部资源。
请求转发是请求一次，地址栏不改变，可以数据传递，只能访问内部资源
图解
