有时候没有数据库的情况下，要保存用户写的东西咋办呢。肯定就 用json或者txt来存了，为了好读取。一般都是json.。
环境的话，就配置好tomcat【 apache-tomcat-9.0.19】装好 jdk【1.8】就可以跑起来了！
demo ROOT目录文件 ¥ http://download.lllomh.com/cliect/#/product/J417136921386528
demo ROOT目录文件 c https://download.csdn.net/download/lllomh/11222951
那么最常用的就是 FileWriter 文件类来用：
try {
// 打开一个写文件器，构造函数中的第二个参数true表示以追加形式写文件
java.io.FileWriter writer = new java.io.FileWriter(filename, true);
String xconent = "{" +conent+"}," ;
writer.write(xconent);
writer.close();
} catch (java.io.IOException e) {
e.printStackTrace();
} finally {
}注册页面使用 表单提交内容：
test.jsp
后面拿到值 a.jsp中
String name=request.getParameter("usename");
String password=request.getParameter("ps");
String email=request.getParameter("email");
String phone=request.getParameter("phone");这里最注意的就是 json格式拼接有点绕手，
conent = ""name""+":" + """+name+"""+","+""password""+":" + """+password+"""+","+""email""+":" + """+email+"""+","+""phone""+":" + """+phone+"""+",";必须是要 json 格式，为了引号。生成的文件：
文件目录：
下面是完整代码：
test.jsp:
<%@ page contentType="text/html;charset=utf-8" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>test5</title>
</head>
<body>
<h1>用户注册</h1>
<form name="form1" action="a.jsp" method="post">
<table>
<tr>
<td>用户名：</td>
<td><input type="text" name="usename" size="20"></td>
</tr>
<tr>
<td>密码：</td>>
<td><input type="password" name="ps" size="20"></input></td>>
</tr>
<tr>
<td>email:</td>>
<td><input type="text" autocomplete="false" name="email" size="20"></input></td>>
</tr>
<tr>
<td>电话：</td>
<td><input type="text" name="phone" size="20"></input></td>
</tr>
<tr>
<td align="right"><input type="submit" value="提交" ></td>
<td align="center"><input type="reset" value="重置"></td>
</tr>
</table>
</form>a.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String filename = "moParam.json";
String path=request.getRealPath("");
filename = path+"\"+ filename ;
String conent ="";
java.io.File f = new java.io.File(filename);
//if(!f.exists()) { f.createNewFile(); }
%>
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.0//EN" "http://www.wapforum.org/DTD/xhtml-mobile10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="application/xhtml+xml; charset=utf-8"/>
<meta http-equiv="Cache-control" content="no-cache" />
<title>生成json lllomh</title>
</head>
<body>
<%
java.text.SimpleDateFormat sdfLongTimePlusMill = new java.text.SimpleDateFormat("yyyyMMddHHmmssSSSS");
java.sql.Date date = new java.sql.Date(new java.util.Date().getTime());
String nowDate = sdfLongTimePlusMill.format(date);
%>
=================================<%=nowDate %> ==========================================<br/>
<%
String sesstionStr = session.getId();
java.util.Enumeration e1 = request.getParameterNames();
while(e1.hasMoreElements()){
String paramName = (String)e1.nextElement();
String paramValue = (String)request.getParameter(paramName);
// 处理参数名paramName与参数值paramValue
conent = conent+"\r\n"+sesstionStr+":"+paramName+" = "+paramValue+"\r\n" ;
}
%>
Header<br/>
<%
//获取请求头信息
java.util.Enumeration e2 = request.getHeaderNames();
while (e2.hasMoreElements()) {
String name = (String)e2.nextElement();
String value = request.getHeader(name);
conent = conent+"
"+sesstionStr+":"+name + "=" + value+"
" ;
}
%>
文件会自动追加内容json,操作完后下载:
<a href="/moParam.json" title="" >下载文件</a>电脑访问,右键文件另存为.
</body>
</html>
<%
String name=request.getParameter("usename");
String password=request.getParameter("ps");
String email=request.getParameter("email");
String phone=request.getParameter("phone");
conent = ""name""+":" + """+name+"""+","+""password""+":" + """+password+"""+","+""email""+":" + """+email+"""+","+""phone""+":" + """+phone+"""+",";
%>
<%
try {
// 打开一个写文件器，构造函数中的第二个参数true表示以追加形式写文件
java.io.FileWriter writer = new java.io.FileWriter(filename, true);
String xconent = "{" +conent+"}," ;
writer.write(xconent);
writer.close();
} catch (java.io.IOException e) {
e.printStackTrace();
} finally {
}
%>如果在实践的过程中遇到什么问题,也可以在评论中或者邮件问我