javaEE：day6-requset和response用法、表单参数的接受、文件手动上传（简易版）

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通过`<%=request.getContextPath() %>` 可以将项目名写活，这样，即使项目名变了，仍可以运行。

request代码每一次请求的容器。浏览器每次请求都是一个新的request对象。因此放在request里面的属性`request.getAttribute()`是空的,上一个request放的属性`request.setAttribute()` 是上一个的。与这次无关。但如果是转发的时候，那么request对象是共享的。这种情况下，两次的request是同一个。这种情况下，里面的属性可以共用的。

setCharacterEncoding()和getCharacterEncoding()

`setCharacterEncoding()`只对post请求方式有效,因为它只设置请求体(正文)中内容的读取编码

如果不设置setCharacterEncoding()，那么默认的`request.getCharacterEncoding()`是iso8859-1 返回的是null

getContentType()

如果是get提交则返回null

如果是post方式提交则返回：application/x-www-form-urlencoded

通过getMethod()判断请求方式，同时演示GET方式下的中文乱码解决

tomcat直接用iso8859-1解码，属于解码错误，如果非要用这种方式传中文，那么先还原再编码：

name = new String(name.getBytes("iso8859-1"),"utf-8");

注意，在get方式下的中文乱码解决不可靠。–如果避不开，那么就明确告诉用户，要使用什么浏览器访问!因为有的浏览器支持，而有的浏览器不支持。以上例子就有ie不支持，360支持。

获取客户端的国际化信息—浏览器Internet选项中设置的语言环境—-request.getLocale()

local.getCountry()

local.getDisplayCountry()

local.getDisplayLanguage()

local.getDisplayName()

参数接受–表单参数接受

单个参数值

request.getParameter("name")；

多个参数值

方法1：

        String hoby[]=request.getParameterValues("hoby");//如果某个参数的值有好几个，用这个方法        if (hoby!=null) {            for (String str : hoby) {                out.print( "<br/>"+str);                System.out.println(str);            }        }

方法2：一次将所有表单参数封装到map中，然后通过操纵map拿值

        //演示getParameterMap()        Map<String, String[]> map = request.getParameterMap();        ////遍历出所有参数及值        Iterator<Entry<String, String[]>> it = map.entrySet().iterator();        while(it.hasNext()){            Entry<String, String[]> en = it.next();            String key = en.getKey();            String[] value = en.getValue();            out.println("参数名称:"+key);            for(String v:value){                out.print("参数值:"+v+"&nbsp;&nbsp;");            }        }

获取客户端的ip和端口号

        String ip= request.getRemoteHost();        int port = request.getRemotePort();        out.print("<br>"+ip+":"+port);

request.getQueryString()

request.getQueryString()是将get方式提交的请求地址？后面的都封装成一个字符串。

文件上传

简易版：手动处理文件上传

在<form>中加入属性：enctype="multipart/form-data" 这样拿到的就是多段字符串。而不是一个文件名。但是这种手动上传很麻烦，要自己去解析。我们在下一篇博客文章中使用阿帕奇公司-Commons-io.jar 和 Commos-fileupload.jar写好的去做文件上传

本文完整代码如下：

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>        <title>演示request和response用法</title>  </head>  <body>  <!--通过request.getContextPath()可以把项目根目录(项目名)写活  -->        <form action="<%=request.getContextPath() %>/requestDemo" method="post">            姓名:<input type="text" name="name" /><br/>            <input type="submit" value="提交"/>        </form>        <!-- 演示表单参数的接受 -->        <form action="<%=request.getContextPath() %>/param" method="post">            姓名:<input type="text" name="name" /><br/>            年龄:<input type="text" name="age" /><br/>            <input type="checkbox" name="hoby" value="music" />音乐&nbsp;&nbsp;            <input type="checkbox" name="hoby" value="tv" />电视&nbsp;&nbsp;            <input type="checkbox" name="hoby" value="game" />游戏<br/>            <input type="radio" name="sex" value="0" checked="checked" >男&nbsp;&nbsp;            <input type="radio" name="sex" value="1">女            <input type="submit" value="提交"/>        </form>        <!-- 演示文件上传 -->        <h2>文件上传手动版</h2>        <form action="<%=request.getContextPath() %>/upload1" method="post" enctype="multipart/form-data">             文件名:<input type="file" name="fileName">            <input type="submit" value="上传">        </form>        <!-- 上面这种手动上传 的方法不好。要自己解析，麻烦，我们用阿帕奇公司-Commons-io.jar 和 Commos-fileupload.jar写好的去做文件上传 -->  </body></html>

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app version="3.0"     xmlns="http://java.sun.com/xml/ns/javaee"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee     http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">  <display-name></display-name>  <servlet>    <servlet-name>RequestDemo</servlet-name>    <servlet-class>cn.hncu.servlets.RequestDemo</servlet-class>    <init-param>        <param-name>name</param-name>        <param-value>Hello</param-value>    </init-param>  </servlet>  <servlet>    <servlet-name>ParamerServlet</servlet-name>    <servlet-class>cn.hncu.servlets.ParamerServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>UpFileServlet</servlet-name>    <servlet-class>cn.hncu.servlets.UpFileServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>RequestDemo</servlet-name>    <url-pattern>/requestDemo</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>ParamerServlet</servlet-name>    <url-pattern>/param</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>UpFileServlet</servlet-name>    <url-pattern>/upload1</url-pattern>  </servlet-mapping>      <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>

RequestDemo

package cn.hncu.servlets;import java.io.IOException;import java.io.PrintWriter;import java.util.Locale;import java.util.Random;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class RequestDemo extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doPost(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");        out.println("<HTML>");        out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");        out.println("  <BODY>");        out.print(request);        //每一次请求，request对象是新的，因此这里读取的属性是null，因为之前放进去的属性是属于另一个request对象        //如果是转发，那么request对象是共享的即是同一个，这种情况下，里面的属性可以共用        int num = new Random().nextInt(200);        if(request.getAttribute("name")==null){            System.out.println("放入:"+num);            request.setAttribute("name", num);        }        //setCharacterEncoding()只对post请求方式有效,因为它只设置请求体(正文)中内容的读取编码        //以下演示setCharacterEncoding()和getCharacterEncoding()        request.setCharacterEncoding("utf-8");        String character = request.getCharacterEncoding();//utf-8        //如果没有设置的话 默认的request.getCharacterEncoding()是iso8859-1 返回的是null//      String character = request.getCharacterEncoding();//null        System.out.println(character);        //以下演示getContentType()----如果是get提交则返回null，        //如果是post方式提交则返回：application/x-www-form-urlencoded        String contextType = request.getContentType();        System.out.println(contextType);//application/x-www-form-urlencoded        //下面演示通过getMethod()判断请求方式，同时演示GET方式下的中文乱码解决--        //注意，不可靠!!!--如果避不开，那么就明确告诉用户，要使用什么浏览器访问!        String name = request.getParameter("name");        if(request.getMethod().equals("GET")){            System.out.println("DOGET...");            name = new String(name.getBytes("iso8859-1"),"utf-8");            System.out.println(name);            out.print("<br/>name:"+name);        }        //获取客户端的国际化信息---浏览器Internet选项中设置的语言环境        Locale local = request.getLocale();        out.println("<br/>Country:"+local.getCountry());//Country:CN         out.println("<br/>DisplayCountry:"+local.getDisplayCountry());//DisplayCountry:中国         out.println("<br/>DisplayLanguage:"+local.getDisplayLanguage());//DisplayLanguage:中文         out.println("<br/>DisplayName:"+local.getDisplayName());//DisplayName:中文 (中国)         out.println("<br/>"+request.getAttribute("name"));        out.println("  </BODY>");        out.println("</HTML>");        out.flush();        out.close();    }}

ParamerServlet

package cn.hncu.servlets;import java.io.IOException;import java.io.PrintWriter;import java.util.Enumeration;import java.util.Iterator;import java.util.Map;import java.util.Map.Entry;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ParamerServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doPost(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        request.setCharacterEncoding("utf-8");        PrintWriter out = response.getWriter();        out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");        out.println("<HTML>");        out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");        out.println("  <BODY>");        String name = request.getParameter("name");//读取单个参数值        String age = request.getParameter("age");        out.println("name:"+name);        out.println("age:"+age);        String hoby[]=request.getParameterValues("hoby");//如果某个参数的值有好几个，用这个方法        if (hoby!=null) {            for (String str : hoby) {                out.print( "<br/>"+str);                System.out.println(str);            }        }        String sex = request.getParameter("sex");        if ("1".equals(sex)) {            out.print("<br/>女" );        }else{            out.print("<br/>男" );        }        System.out.println("sex="+sex);        //演示getParameterMap()        Map<String, String[]> map = request.getParameterMap();        ////遍历出所有参数及值        Iterator<Entry<String, String[]>> it = map.entrySet().iterator();        while(it.hasNext()){            Entry<String, String[]> en = it.next();            String key = en.getKey();            String[] value = en.getValue();            out.println("参数名称:"+key);            for(String v:value){                out.print("参数值:"+v+"&nbsp;&nbsp;");            }        }        ////获取客户端的ip和端口号        String ip= request.getRemoteHost();        int port = request.getRemotePort();        out.print("<br>"+ip+":"+port);        String queryStr= request.getQueryString();        out.println("queryStr:"+queryStr);        out.println("  </BODY>");        out.println("</HTML>");        out.flush();        out.close();    }}

UpFileServlet

package cn.hncu.servlets;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class UpFileServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doPost(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        request.setCharacterEncoding("utf-8");        InputStream in = request.getInputStream();        BufferedReader br = new BufferedReader(new InputStreamReader(in));        String line = null;        while((line=br.readLine())!=null){            System.out.println(line);        }    }}

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