1. 需求：用户信息的增删改查操作
2. 设计：
1. 技术选型：Servlet+JSP+MySQL+JDBCTempleat+Duird+BeanUtilS+tomcat
2. 数据库设计：
create database day17; -- 创建数据库
use day17; -- 使用数据库
create table user( -- 创建表
id int primary key auto_increment,
name varchar(20) not null,
gender varchar(5),
age int,
address varchar(32),
qq varchar(20),
email varchar(50)
);
3. 开发：
1. 环境搭建
1. 创建数据库环境
2. 创建项目，导入需要的jar包
2. 编码
4. 测试
5. 部署运维1.完成登录功能
2.完成增加功能
3.完成删除功能
4.完成修改功能
5.完成选中项删除功能
6.完成分页查询功能
7.完成复杂条件查询功能
1.简单增删改查（重要）
2.选中项删除（重要）
3.分页条件查询（重要）
列表查询功能的具体执行流程：servlet--------->service---->dao查询数据库
调整案例所需页面的样式以及内容
登录的时候要先校验验证码是否正确，正确再去校验账号密码，密码正确放入session中保存用户信息，需要注意的是用户验证成功后把登录信息存入session中。
request.setCharacterEncoding("utf-8");
//2.获取数据
//2.1获取用户填写验证码
String verifycode = request.getParameter("verifycode");
//3.验证码校验
HttpSession session = request.getSession();
String checkcode_server = (String) session.getAttribute("CHECKCODE_SERVER");
session.removeAttribute("CHECKCODE_SERVER");//确保验证码一次性
if(!checkcode_server.equalsIgnoreCase(verifycode)){
//验证码不正确
//提示信息
request.setAttribute("login_msg","验证码错误！");
//跳转登录页面
request.getRequestDispatcher("/login.jsp").forward(request,response);
return;
}
Map<String, String[]> map = request.getParameterMap();
//4.封装User对象
User user = new User();
try {
BeanUtils.populate(user,map);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//5.调用Service查询
UserService service = new UserServiceImpl();
User loginUser = service.login(user);
//6.判断是否登录成功
if(loginUser != null){
//登录成功
//将用户存入session
session.setAttribute("user",loginUser);
//跳转页面
response.sendRedirect(request.getContextPath()+"/index.jsp");
}else{
//登录失败
//提示信息
request.setAttribute("login_msg","用户名或密码错误！");
//跳转登录页面
request.getRequestDispatcher("/login.jsp").forward(request,response);
}添加页面，输入数据一定要有属性名称，提交form表单到后台，后台接收数据封装到user中，并编写sql语句
//1.设置编码
request.setCharacterEncoding("utf-8");
//2.获取参数
Map<String, String[]> map = request.getParameterMap();
//3.封装对象
User user = new User();
try {
BeanUtils.populate(user,map);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//4.调用Service保存
UserService service = new UserServiceImpl();
service.addUser(user);
//5.跳转到userListServlet
response.sendRedirect(request.getContextPath()+"/userListServlet");通过id删除数据，编写sql语句。
//1.获取id
String id = request.getParameter("id");
//2.调用service删除
UserService service = new UserServiceImpl();
service.deleteUser(id);
//3.跳转到查询所有Servlet
response.sendRedirect(request.getContextPath()+"/userListServlet");
首先要进行数据回显，然后提交修改后数据到后台，进行保存。
//1.获取id
String id = request.getParameter("id");
//2.调用Service查询
UserService service = new UserServiceImpl();
User user = service.findUserById(id);
//3.将user存入request
request.setAttribute("user",user);
//4.转发到update.jsp
request.getRequestDispatcher("/update.jsp").forward(request,response); //1.设置编码
request.setCharacterEncoding("utf-8");
//2.获取map
Map<String, String[]> map = request.getParameterMap();
//3.封装对象
User user = new User();
try {
BeanUtils.populate(user,map);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//4.调用Service修改
UserService service = new UserServiceImpl();
service.updateUser(user);
//5.跳转到查询所有Servlet
response.sendRedirect(request.getContextPath()+"/userListServlet");首先要获取选中条目的id，然后根据id进行删除。
//给删除选中按钮添加单击事件
document.getElementById("delSelected").onclick = function(){
if(confirm("您确定要删除选中条目吗？")){
var flag = false;
//判断是否有选中条目
var cbs = document.getElementsByName("uid");
for (var i = 0; i < cbs.length; i++) {
if(cbs[i].checked){
//有一个条目选中了
flag = true;
break;
}
}
if(flag){//有条目被选中
//表单提交
document.getElementById("form").submit();
}
} //1.获取所有id
String[] ids = request.getParameterValues("uid");
//2.调用service删除
UserService service = new UserServiceImpl();
service.delSelectedUser(ids);
//3.跳转查询所有Servlet
response.sendRedirect(request.getContextPath()+"/userListServlet");判断前台页面传到后台的数据是否为空。避免出现空指针异常。
前台页面需要把当前页与每页显示条数传入后台。
//1.获取参数
String currentPage = request.getParameter("currentPage");//当前页码
String rows = request.getParameter("rows");//每页显示条数
if(currentPage == null || "".equals(currentPage)){
currentPage = "1";
}
if(rows == null || "".equals(rows)){
rows = "5";
}
//获取条件查询参数
Map<String, String[]> condition = request.getParameterMap();
//2.调用service查询
UserService service = new UserServiceImpl();
PageBean<User> pb = service.findUserByPage(currentPage,rows,condition);
System.out.println(pb);
//3.将PageBean存入request
request.setAttribute("pb",pb);
request.setAttribute("condition",condition);//将查询条件存入request
//4.转发到list.jsp
request.getRequestDispatcher("/list.jsp").forward(request,response);
} //1.获取参数
String currentPage = request.getParameter("currentPage");//当前页码
String rows = request.getParameter("rows");//每页显示条数
if(currentPage == null || "".equals(currentPage)){
currentPage = "1";
}
if(rows == null || "".equals(rows)){
rows = "5";
}
//获取条件查询参数
Map<String, String[]> condition = request.getParameterMap();
//2.调用service查询
UserService service = new UserServiceImpl();
PageBean<User> pb = service.findUserByPage(currentPage,rows,condition);
System.out.println(pb);
//3.将PageBean存入request
request.setAttribute("pb",pb);
request.setAttribute("condition",condition);//将查询条件存入request
//4.转发到list.jsp
request.getRequestDispatcher("/list.jsp").forward(request,response);
} <nav aria-label="Page navigation">
<ul class="pagination">
<c:if test="${pb.currentPage == 1}">
<li class="disabled">
</c:if>
<c:if test="${pb.currentPage != 1}">
<li>
</c:if>
<a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${pb.currentPage - 1}&rows=5&name=${condition.name[0]}&address=${condition.address[0]}&email=${condition.email[0]}" aria-label="Previous">
<span aria-hidden="true">«</span>
</a>
</li>
<c:forEach begin="1" end="${pb.totalPage}" var="i" >
<c:if test="${pb.currentPage == i}">
<li class="active"><a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${i}&rows=5&name=${condition.name[0]}&address=${condition.address[0]}&email=${condition.email[0]}">${i}</a></li>
</c:if>
<c:if test="${pb.currentPage != i}">
<li><a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${i}&rows=5&name=${condition.name[0]}&address=${condition.address[0]}&email=${condition.email[0]}">${i}</a></li>
</c:if>
</c:forEach>
<li>
<a href="${pageContext.request.contextPath}/findUserByPageServlet?currentPage=${pb.currentPage + 1}&rows=5&name=${condition.name[0]}&address=${condition.address[0]}&email=${condition.email[0]}" aria-label="Next">
<span aria-hidden="true">»</span>
</a>
</li>
<span style="font-size: 25px;margin-left: 5px;">
共${pb.totalCount}条记录，共${pb.totalPage}页
</span>把查询条件发送到后台，后台根据条件进行查询
//获取条件查询参数
Map<String, String[]> condition = request.getParameterMap();
//2.调用service查询
UserService service = new UserServiceImpl();
PageBean<User> pb = service.findUserByPage(currentPage,rows,condition);
//1.定义模板初始化sql
String sql = "select count(*) from user where 1 = 1 ";
StringBuilder sb = new StringBuilder(sql);
//2.遍历map
Set<String> keySet = condition.keySet();
//定义参数的集合
List<Object> params = new ArrayList<Object>();
for (String key : keySet) {
//排除分页条件参数
if("currentPage".equals(key) || "rows".equals(key)){
continue;
}
//获取value
String value = condition.get(key)[0];
//判断value是否有值
if(value != null && !"".equals(value)){
//有值
sb.append(" and "+key+" like ? ");
params.add("%"+value+"%");//？条件的值
}
}
System.out.println(sb.toString());
System.out.println(params);
return template.queryForObject(sb.toString(),Integer.class,params.toArray());String sql = "select * from user where 1 = 1 ";
StringBuilder sb = new StringBuilder(sql);
//2.遍历map
Set<String> keySet = condition.keySet();
//定义参数的集合
List<Object> params = new ArrayList<Object>();
for (String key : keySet) {
//排除分页条件参数
if("currentPage".equals(key) || "rows".equals(key)){
continue;
}
//获取value
String value = condition.get(key)[0];
//判断value是否有值
if(value != null && !"".equals(value)){
//有值
sb.append(" and "+key+" like ? ");
params.add("%"+value+"%");//？条件的值
}
}
//添加分页查询
sb.append(" limit ?,? ");
//添加分页查询参数值
params.add(start);
params.add(rows);
sql = sb.toString();
System.out.println(sql);
System.out.println(params);
return template.query(sql,new BeanPropertyRowMapper<User>(User.class),params.toArray());