JavaWeb基础(学习笔记)（二）

1.创建JSP页面

首先，在创建之前必须要做的事，更改编码。

在jsp页面中输出数组中的元素案例，使用for循环和Arrays.toString()方法
介绍两种导包方式：

1.<%@ page language="java" import = "java.util.Arrays" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

2.<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import = "java.util.Arrays" %>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import = "java.util.Arrays" %>





<%
	int[] arr = new int[]{1,2,3,4};
%>


Java和jsp混合使用
	
	
<%
	for(int i=0;i


<%=Arrays.toString(arr) %>

2.Java代码和html标签混合使用

java和html混合使用的小案例

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@ page import="java.util.*" %>
    <%@ page import="java.util.Map.*" %>





<%
ArrayList list = new ArrayList();
list.add("玩具");
list.add("文具");
list.add("书籍");
HashMap map = new HashMap<>();
map.put(1, "玩具");
map.put(2, "文具");
map.put(3, "书籍");
%>




	<%
		for(int i=0;i
	
	<%} %>

	

		
编号
		
类型
	

		
<%=i+1 %>
		
<%=list.get(i) %>
	


<%
	Set> e = map.entrySet();
	Iterator> it = e.iterator();
%>


	<%
		while(it.hasNext()){
			Entry key =it.next();
	%>
	<%=key.getValue() %>
	<%
		}
	%>



<%
	Set key = map.keySet();
	for(Integer k:key){	
%>
<%=map.get(k) %>
<%
	}
%>

3.实现用户的登录功能

注意：每次在jsp文件中写代码前更改编码

<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
%>

登录：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>







<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
%>


	用户名：

	密码：

	
	篮球
	足球
	棒球
	

	

登录成功的判断：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>







<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
%>
<%
	//从index.jps页面传递来的数据， 使用request来获取
	String name = request.getParameter("name");
	String password = request.getParameter("password");
	//设置登录名是张三，密码是9999，如果输入正确跳转到welcom.jsp页面，如果输入不正确，跳转到原来的页面
	if("张三".equals(name) && "9999".equals(password)){
		/*
			response是客户端行为，是客户端（浏览器行为）来发起跳转请求
			request是服务端行为，是由服务器内部进行跳转，如果服务器跳转了的地址 浏览器不知道，所以浏览器就停留在上一个地址
		*/
		//response.sendRedirect("welcom.jsp?name="+name);
		request.getRequestDispatcher("welcom.jsp").forward(request, response);
		//注意：服务器跳转的是相对路径
	}else{
		response.sendRedirect("index.jsp");
	}
%>

注意：用//response.sendRedirect(“welcom.jsp?name=”+name);
request.getRequestDispatcher(“welcom.jsp”).forward(request, response);跳转页面的区别；
在地址栏中：
response跳转
http://localhost:8080/web02/welcome.jsp?cu_name=???
request跳转
http://localhost:8080/web02/login1.jsp?cu_name=张三&cu_phone=9999

登陆成功后跳转的welcome.jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>







<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
%>
<%
	String name = request.getParameter("name");
%>
你好！<%=name %>

4.连接MySQL，进行用户的登录注册功能

登录页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>











用户名或密码错误
<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
	String err = request.getParameter("err");
	//如果err传回来的值是1，则输出错误提示
	if("1".equals(err)){
		out.println("");
	}
	
%>
	
	

		用户名：

		密码：

		没有账户嘛？
	

登录验证：
java连接数据库的代码

<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.SQLException"%>
<%@page import="java.sql.DriverManager"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
	String cu_name = request.getParameter("cu_name");
	String cu_phone = request.getParameter("cu_phone");
	Connection conn = null;
	try{
		Class.forName("com.mysql.jdbc.Driver");
		String url="jdbc:mysql://localhost:3306/ishopn?characterEncoding=utf8";
		String user="root";
		String password="123456";
		conn = DriverManager.getConnection(url, user, password);
		
		//sql的查询语句
		String sql = "select count(*) from customer where cu_name=? and cu_phone=?";
		PreparedStatement ps = conn.prepareStatement(sql);
		ps.setString(1,cu_name);
		ps.setString(2,cu_phone);
		ResultSet rs = ps.executeQuery();
		rs.next();
		int c = rs.getInt(1);
		if(c>0){
			//如果查到的值大于0则，登录成功，跳转到welcome.jsp页面
			request.getRequestDispatcher("welcome.jsp").forward(request, response);
		}else{
			//如果失败就跳转回登录页面输出提示
			response.sendRedirect("/web03_0904/index.jsp?err=1");
		}
		
	}catch (Exception e) {
		e.printStackTrace();	
	}finally{
		if(conn!=null){
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
%>

登陆成功跳转到welcome.jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>







<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
%>
<%
	String cu_name = request.getParameter("cu_name");
%>
你好！<%=cu_name %>

注册页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>








	<%
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");
	%>
	
	

		用户名：

		密码：

		性别：男
		女

		家庭地址：

		已经有账户!
	
	

表单验证 所有的不能为空 用户名不能少于3个字符 密码不能少于4个字符
js代码：

// 1 获取元素
var inputs=document.getElementsByTagName("input");
var cu_name=document.getElementsByName("cu_name")[0];
var cu_phone=document.getElementsByName("cu_phone")[0];
// 2 操作元素
function check(){
	//1为空判断
	for(var i=0;i

注册成功判断代码，注册成功后写入数据库中

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@page import="java.sql.*"%>
<%@page import="java.util.UUID"%>
<%
//修改字符集
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
//获取表单中的五个属性
String cu_id=UUID.randomUUID().toString();
String cu_name=request.getParameter("cu_name");
String cu_phone=request.getParameter("cu_phone");
String cu_gender=request.getParameter("cu_gender");
String cu_address=request.getParameter("cu_address");

//java连接数据库操作
Connection conn = null;

try{
Class.forName("com.mysql.jdbc.Driver");	
String url="jdbc:mysql://localhost:3306/ishopn?characterEncoding=utf8";
String user="root";
String password="123456";
conn = DriverManager.getConnection(url, user, password);
String sql = "insert into customer (cu_id,cu_name,cu_phone,cu_gender,cu_address) values (?,?,?,?,?)";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, cu_id);
ps.setString(2, cu_name);
ps.setString(3, cu_phone);
ps.setInt(4, new Integer(cu_gender));
ps.setString(5, cu_address);
int line = ps.executeUpdate();
//写入成功就跳转到welcome.jsp页面，失败就回到登录页面
if(line>0){
	response.sendRedirect("/web03_0904/welcome.jsp?cu_name="+cu_name);
}else{
	response.sendRedirect("/web03_0904/index.jsp?err=2");
}

}catch(Exception e){
	e.printStackTrace();
}finally{
	if(conn!=null){
		try{
			conn.close();
		}catch(Exception e){
			e.printStackTrace();
		}
		
	}
}
%>