Student.java
package com.mjrg.bean;public class Student { private String id;
private String pic;
private String username;
public Student() {
} public Student(String id, String username) {
this.id = id;
this.username = username;
} public String getId() {
return id;
} public String getPic() {
return pic;
} public String getusername() {
return username;
} public void setId(String id) {
this.id = id;
} public void setPic(String pic) {
this.pic = pic;
} public void setusername(String username) {
this.username = username;
}}
SaveStudentInfo.javapackage com.mjrg.bean;import java.util.ArrayList;
import java.util.List;import com.mjrg.bean.Student;public class SaveStudentInfo {
private List<Student> lst=new ArrayList<Student>();
public void add(Student stu) {
lst.add(stu);
System.out.println(lst.size()+".......................");
} public void delete() { } public void update() { } public void find() { }
public List<Student> findAll()
{
return lst;
}
}add.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page import="com.mjrg.bean.Student" %>
<%
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>
<base href="<%=basePath%>">
<title>My JSP 'add.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
--> </head>
<body>
<%
String id=request.getParameter("id");
String username=request.getParameter("username");
%>
<jsp:useBean id="stus" class="com.mjrg.bean.SaveStudentInfo" scope="session"></jsp:useBean>
<jsp:setProperty property="*" name="stus"/>
<jsp:useBean id="stu" class="com.mjrg.bean.Student" scope="session"></jsp:useBean>
<jsp:setProperty property="*" name="stu"/>
<form action="add.jsp" method="post" enctype="application/x-www-form-urlencoded">
学号:<input type="text" name="id"/><br/>
姓名:<input type="text" name="username"/><br/>
照片:<input type="file" name="pic"/><br/>
<input type="radio" name="sex" value="男" CHECKED/>男
<input type="radio" name="sex" value="女"/>女
<input type="submit" name="ok" value="添加"/><br/>
<input type="reset" value="重置"/><br/>
</form>
<% List<Student> lst=null; stu.setId(id);
stu.setusername(username);
stus.add(stu);
lst=stus.findAll();
%>
<%
Iterator it=lst.iterator();
while(it.hasNext()){
Student s=(Student)it.next();
out.print(s.getusername()+"......"+s.getId()+"<br/>");
}
%> </body>
</html>
运行后为什么添加数据会重复?javajsp
package com.mjrg.bean;public class Student { private String id;
private String pic;
private String username;
public Student() {
} public Student(String id, String username) {
this.id = id;
this.username = username;
} public String getId() {
return id;
} public String getPic() {
return pic;
} public String getusername() {
return username;
} public void setId(String id) {
this.id = id;
} public void setPic(String pic) {
this.pic = pic;
} public void setusername(String username) {
this.username = username;
}}
SaveStudentInfo.javapackage com.mjrg.bean;import java.util.ArrayList;
import java.util.List;import com.mjrg.bean.Student;public class SaveStudentInfo {
private List<Student> lst=new ArrayList<Student>();
public void add(Student stu) {
lst.add(stu);
System.out.println(lst.size()+".......................");
} public void delete() { } public void update() { } public void find() { }
public List<Student> findAll()
{
return lst;
}
}add.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page import="com.mjrg.bean.Student" %>
<%
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>
<base href="<%=basePath%>">
<title>My JSP 'add.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
--> </head>
<body>
<%
String id=request.getParameter("id");
String username=request.getParameter("username");
%>
<jsp:useBean id="stus" class="com.mjrg.bean.SaveStudentInfo" scope="session"></jsp:useBean>
<jsp:setProperty property="*" name="stus"/>
<jsp:useBean id="stu" class="com.mjrg.bean.Student" scope="session"></jsp:useBean>
<jsp:setProperty property="*" name="stu"/>
<form action="add.jsp" method="post" enctype="application/x-www-form-urlencoded">
学号:<input type="text" name="id"/><br/>
姓名:<input type="text" name="username"/><br/>
照片:<input type="file" name="pic"/><br/>
<input type="radio" name="sex" value="男" CHECKED/>男
<input type="radio" name="sex" value="女"/>女
<input type="submit" name="ok" value="添加"/><br/>
<input type="reset" value="重置"/><br/>
</form>
<% List<Student> lst=null; stu.setId(id);
stu.setusername(username);
stus.add(stu);
lst=stus.findAll();
%>
<%
Iterator it=lst.iterator();
while(it.hasNext()){
Student s=(Student)it.next();
out.print(s.getusername()+"......"+s.getId()+"<br/>");
}
%> </body>
</html>
运行后为什么添加数据会重复?javajsp
点击一次add显示了两个人?