本文介绍了一个图书管理系统的实现，包括增删改查功能，使用了自定义的BaseDao类进行数据库操作，实现了分页查询和条件筛选。
首先导入jar包
然后可以导入之前的mvc1和通用分页2的工具类：
BookDao类：
package dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;
import entity.Book;
import util.BaseDao;
import util.PageBean;
import util.StringUtils;
public class BookDao extends BaseDao<Book> {
public List<Book> list(Book book,PageBean pageBean) throws InstantiationException, IllegalAccessException, SQLException{
String sql = "select * from t_mvc_book where true ";
String bname = book.getBname();
int bid = book.getBid();
if(StringUtils.isNotBlank(bname)) {
sql += " and bname like '%"+bname+"%'";
}
if(bid != 0 ) {
sql += " and bid = "+bid;
}
return super.executeQuery(sql, Book.class, pageBean);
}
public int add(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException {
String sql = "insert into t_mvc_book values(?,?,?)";
return super.executeUpdate(sql, new String[] {"bid","bname","price"}, book);
}
public int edit(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException {
String sql = "update t_mvc_book set bname=?,price=? where bid=?";
return super.executeUpdate(sql, new String[] {"bname","price","bid"}, book);
}
public int del(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException {
String sql = "delete from t_mvc_book where bid = ?";
return super.executeUpdate(sql, new String[] {"bid"}, book);
}
public static void main(String[] args) {
BookDao bookDao = new BookDao();
Book book = new Book(141313, "xxx", 56f);
try {
bookDao.del(book);
} catch (IllegalArgumentException | IllegalAccessException | SQLException e) {
e.printStackTrace();
}
}
}
BaseDao类:(封装增删改)
package util;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import util.DBAccess;
import util.PageBean;
/**
* 通用分页查询（带条件查询）
*/
public class BaseDao<T> {
/**
*
* sql 由于不同的表查询语句不一样，所以靠子类写好来传递
* cls 需要返回不同的对象集合 查询的对象
* bean 可能要分页
* Exception
*/
public List<T> sqlBean (String sql,Class cls,PageBean bean) throws Exception{
List<T> list = new ArrayList<>();
Connection con = DBAccess.getConnection();
PreparedStatement ps = null;
ResultSet rs = null;
//决定是否分页：
if(bean != null && bean.isPagination()) {//判读条件
//分页
/**
* 1.分页是与分页助手类pagebean中的total有关，需要查询数据库得到total赋值给bean
* 2.查询出符合条件的某一页的数据
*/
String countsql = getCountsql(sql);
ps = con.prepareStatement(countsql);
rs = ps.executeQuery();
/**
* 符合条件的记录数
* select count(1) from (select * from t_mvc_book where bname like '%斗破%') t;
*/
if(rs.next()){
bean.setTotal(rs.getObject(1).toString());//查询多少条数据
}
/**
* 分页的查询语句
*select * from t_mvc_book where bname like '%斗破%' limit 起始下标（第几页）,变量（每页显示几条）
*/
String pagesql = getPagesql(sql, bean);
ps = con.prepareStatement(pagesql);
rs = ps.executeQuery();
}else {
//不分页
ps = con.prepareStatement(sql);
rs = ps.executeQuery();
}
T t = null;
while (rs.next()) {
/**
* 1. 实例化一个你要查询的对象 （比如book）
* 2. 通过对象的属性名去游标中取出属性值（通过反射来完成）
* 2.1 获取到类对象中的属性
* 2.2 给属性赋值
* 3. 已经赋值好的实例对象放入到list集合当中
*/
t = (T) cls.newInstance();//反射获取对象开始
Field [] fields = cls.getDeclaredFields();
for (Field f : fields) {
f.setAccessible(true);//打开权限
f.set(t, rs.getObject(f.getName()));
}
list.add(t);
}
DBAccess.close(con, ps, rs);
return list;
}
/**
*
* @param sql
* @param bean 获取查询的起始下标和变量
* @return
*/
private String getPagesql(String sql , PageBean bean) {
// TODO 分页查询语句
return sql + " limit " +bean.getStartIndex()+","+bean.getRows();
}
private String getCountsql(String sql) {
// TODO 用来查询对应条件有多少条数据
return "select count(1) from ("+sql+") t";
}
/**
* 封装增删改
* sql c传过来的查询语句
* t 实体类
* attrs 属性名数组
* Exception
*/
public int executeUpdate (String sql,T t,String [] attrs) throws Exception {
Connection con = DBAccess.getConnection();
PreparedStatement ps = con.prepareStatement(sql);
Field fields = null;
for (int i = 0; i < attrs.length; i++) {
/**
* 通过属性名以反射的方法获取到对应的值
* 比如 attrs[0] = bid fields.get(t)就是bid的值
*/
fields = t.getClass().getDeclaredField(attrs[i]);
fields.setAccessible(true);//打开权限
ps.setObject(i+1, fields.get(t));
}
return ps.executeUpdate();
}
}
增删改
package web;
import java.util.List;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.lww.framework.ActionSopport;
import com.lww.framework.ModelDriven;
import dao.BookDao;
import entity.Book;
import util.PageBean;
public class BookAction extends ActionSopport implements ModelDriven<Book>{
private Book book = new Book();
private BookDao bookDao = new BookDao();
public String list(HttpServletRequest req,HttpServletResponse resp) {
PageBean pageBean = new PageBean();
pageBean.setRequest(req);//把请求的地址、参数存到pageBean
try {
List<Book> list = this.bookDao.list(book, pageBean);
req.setAttribute("bookList", list);
req.setAttribute("pageBean", pageBean);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "list";
}
/**
* 跳 新增修改页面（同一个）
*/
public String preSave(HttpServletRequest req,HttpServletResponse resp) {
if(book.getBid() != 0) {//判断是否有值 有就是修改 没有就是新增
try {
//数据回显的数据 根据bid查到数据回显
Book b = this.bookDao.list(book, null).get(0);
req.setAttribute("book", b);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return "edit";
}
/**
* 新增 新增数据
*/
public String add(HttpServletRequest req,HttpServletResponse resp) {
try {
this.bookDao.add(book);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "toList";
}
/**
* 修改 修改数据
*/
public String edit(HttpServletRequest req,HttpServletResponse resp) {
try {
this.bookDao.edit(book);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "toList";
}
/**
* 删除 删除数据
*/
public String del(HttpServletRequest req,HttpServletResponse resp) {
try {
this.bookDao.del(book);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "toList";
}
@Override
public Book getModel() {
return book;
}
}
配置web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>songwanxi_mvc</display-name>
<!-- 防止中文乱码 -->
<filter>
<filter-name>encodingFiter</filter-name>
<filter-class>util.EncodingFiter</filter-class>
</filter>
<filter-mapping>
<filter-name>encodingFiter</filter-name>
<url-pattern>*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>dispatcherServlet</servlet-name>
<servlet-class>framework.DispatcherServlet</servlet-class>
<!-- 当有同名的xml文件时，可以采用 ，没有重名时就注销 使用默认的 -->
<!-- <init-param>
<param-name>mvcXmlLocation</param-name>
<param-value>/song.xml</param-value>
</init-param> -->
</servlet>
<servlet-mapping>
<servlet-name>dispatcherServlet</servlet-name>
<url-pattern>*.action</url-pattern>
</servlet-mapping>
</web-app>
配置mvc.xml
<?xml version="1.0" encoding="UTF-8"?>
<!--
config标签:可以包含0~N个action标签
-->
<config>
<!--
action标签:可以饱含0~N个forward标签
path:以/开头的字符串,并且值必须唯一 非空
type:字符串,非空
-->
<!-- * -->
<!--
forward标签:没有子标签;
name:字符串,同一action标签下的forward标签name值不能相同 ;
path:以/开头的字符串
redirect:只能是false|true,允许空,默认值为false
-->
<action path="/book" type="web.BookAction">
<forward name="list" path="/index.jsp" redirect="false" />
<!-- 修改新增同一个页面 -->
<forward name="edit" path="/indexEdit.jsp" redirect="false" />
<!-- 执行完新增修改删除后都要刷新数据 -->
<forward name="toList" path="/book.action?methodName=list" />
</action>
</config>
前台页面代码index.jsp：
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="/lww" prefix="w"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<h2>小说目录</h2>
<br>
<!-- 顶部查询表单 用来提交查询条件 -->
<form action="${pageContext.request.contextPath}/book.action?methodName=list"
method="post">
书名：<input type="text" name="bname"> <input type="submit"
value="确定">
</form>
<a href="${pageContext.request.contextPath}/book.action?methodName=preSave">新增</a>
<!-- 查询结果显示表 -->
<table border="1" width="100%">
<tr>
<td>编号</td>
<td>名称</td>
<td>价格</td>
<td>操作</td>
</tr>
<c:forEach items="${bookList }" var="b">
<tr>
<td>${b.bid }</td>
<td>${b.bname }</td>
<td>${b.price }</td>
<td><a href="${pageContext.request.contextPath}/book.action?methodName=preSave&&bid=${b.bid }">修改</a>
<a href="${pageContext.request.contextPath}/book.action?methodName=del&&bid=${b.bid }">删除</a>
</td>
</tr>
</c:forEach>
</table>
<!-- 底部分页显示 -->
<w:page pageBean="${pageBean}"></w:page>
</body>
</html>
增加修改页面：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/book.action?methodName=${book.bid == null ? 'add' : 'edit'}" method="post">
bid : <input type="text" value="${book.bid}" name="bid"><br>
bname : <input type="text" value="${book.bname}" name="bname"><br>
price : <input type="text" value="${book.price}" name="price"><br>
<input type="submit" value="提交">
</form>
</body>
</html>
测试结果如下:
目录：
增和修改:
删：
之前：
之后：
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