[大数据]自定义mvc增删改查应用

老规矩思维导图

?

?上图，之前的增删查改

上图，现在的增删查改?

优化后自定义mvc效果图,代码如下

?BookDao类

package com.lj.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;

import com.zking.entity.Book;
import com.zking.util.BaseDao;
import com.zking.util.DBAccess;
import com.zking.util.PageBean;
import com.zking.util.StringUtils;

public class BookDao extends BaseDao<Book>{
	/**
	 * 现状：增删改
	 * 	1.写sql
	 * 	2.建立链接
	 * 	3.预定义对象PreparedStatement
	 * 	4.设置参数
	 * 	5.执行sql
	 * 解决：
	 * 	
	 * @param book
	 * @throws Exception
	 */
//	public void add(Book book) throws Exception {
//		String sql  = "insert into t_mvc_book values(?,?,?)";
//		Connection con = DBAccess.getConnection();
//		PreparedStatement pst = con.prepareStatement(sql);
//		pst.setObject(1, book.getBid());
//		pst.setObject(2, book.getBname());
//		pst.setObject(3, book.getPrice());
//		pst.executeUpdate();
//	}
	public void add(Book book) throws Exception {
		String sql  = "insert into t_mvc_book values(?,?,?)";
		super.executeUpdate(sql, book, new String[] {"bid","bname","price"});
	}
	
	public void delete(Book book) throws Exception {
		String sql  = "delete from t_mvc_book where bid = ?";
		super.executeUpdate(sql, book, new String[] {"bid"});
	}
	
	public void edit(Book book) throws Exception {
		String sql  = "update t_mvc_book set bname = ?,price = ? where bid = ?";
		super.executeUpdate(sql, book, new String[] {"bname","price","bid"});
	}
	
	public List<Book> list(Book book,PageBean pageBean) throws Exception {
		String sql  = "select * from t_mvc_book where 1=1 ";
		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 static void main(String[] args) throws Exception {
		Book book = new Book();
		book.setBid(23224);
//		book.setBname("23225");
//		book.setPrice(23225f);
		BookDao bookDao = new BookDao();
//		bookDao.add(book);
//		bookDao.edit(book);
		bookDao.delete(book);
	}
}

Book类

package com.lj.entity;

public class Book {
	private int bid;
	private String bname;
	private float price;
	public int getBid() {
		return bid;
	}
	public void setBid(int bid) {
		this.bid = bid;
	}
	public String getBname() {
		return bname;
	}
	public void setBname(String bname) {
		this.bname = bname;
	}
	public float getPrice() {
		return price;
	}
	public void setPrice(float price) {
		this.price = price;
	}
	@Override
	public String toString() {
		return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
	}
	
}

PageTag类

package com.lj.tag;

import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;

import com.zking.util.PageBean;

public class PageTag extends BodyTagSupport{
	private PageBean pageBean;// 包含了所有分页相关的元素
	
	public PageBean getPageBean() {
		return pageBean;
	}

	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}

	@Override
	public int doStartTag() throws JspException {
//		没有标签体，要输出内容
		JspWriter out = pageContext.getOut();
		try {
			out.print(toHTML());
		} catch (IOException e) {
			e.printStackTrace();
		}
		return super.doStartTag();
	}

	private String toHTML() {
		StringBuffer sb = new StringBuffer();
//		隐藏的form表单---这个就是上一次请求下次重新发的奥义所在
//		上一次请求的URL
		sb.append("<form action='"+pageBean.getUrl()+"' id='pageBeanForm' method='post'>");
		sb.append("	<input type='hidden' name='page'>");
//		上一次请求的参数
		Map<String, String[]> paramMap = pageBean.getParamMap();
		if(paramMap != null && paramMap.size() > 0) {
			Set<Entry<String, String[]>> entrySet = paramMap.entrySet();
			for (Entry<String, String[]> entry : entrySet) {
//				参数名
				String key = entry.getKey();
//				参数值
				for (String value : entry.getValue()) {
//					上一次请求的参数，再一次组装成了新的Form表单
//					注意：page参数每次都会提交，我们需要避免
					if(!"page".equals(key)) {
						sb.append("	<input type='hidden' name='"+key+"' value='"+value+"' >");
					}
				}
			}
		}
		sb.append("</form>");
		
//		分页条
		sb.append("<ul class='pagination justify-content-center'>");
		sb.append("	<li class='page-item "+(pageBean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
		sb.append("	href='javascript:gotoPage(1)'>首页</a></li>");
		sb.append("	<li class='page-item "+(pageBean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
		sb.append("	href='javascript:gotoPage("+pageBean.previousPage()+")'>&lt;</a></li>");// less than 小于号
//		sb.append("	<li class='page-item'><a class='page-link' href='#'>1</a></li>");
//		sb.append("	<li class='page-item'><a class='page-link' href='#'>2</a></li>");
		sb.append("	<li class='page-item active'><a class='page-link' href='#'>"+pageBean.getPage()+"</a></li>");
		sb.append("	<li class='page-item "+(pageBean.getPage() == pageBean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pageBean.nextPage()+")'>&gt;</a></li>");
		sb.append("	<li class='page-item "+(pageBean.getPage() == pageBean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pageBean.maxPage()+")'>尾页</a></li>");
		sb.append("	<li class='page-item go-input'><b>到第</b><input class='page-link'");
		sb.append("	type='text' id='skipPage' name='' /><b>页</b></li>");
		sb.append("	<li class='page-item go'><a class='page-link'");
		sb.append("	href='javascript:skipPage()'>确定</a></li>");
		sb.append("	<li class='page-item'><b>共"+pageBean.getTotal()+"条</b></li>");
		sb.append("</ul>");
		
//		分页执行的JS代码
		sb.append("<script type='text/javascript'>");
		sb.append("	function gotoPage(page) {");
		sb.append("		document.getElementById('pageBeanForm').page.value = page;");
		sb.append("		document.getElementById('pageBeanForm').submit();");
		sb.append("	}");
		sb.append("	function skipPage() {");
		sb.append("		var page = document.getElementById('skipPage').value;");
		sb.append("		if (!page || isNaN(page) || parseInt(page) < 1 || parseInt(page) > "+pageBean.maxPage()+") {");
		sb.append("			alert('请输入1~"+pageBean.maxPage()+"的数字');");
		sb.append("			return;");
		sb.append("		}");
		sb.append("		gotoPage(page);");
		sb.append("	}");
		sb.append("</script>");
		
		return sb.toString();
	}
}

BaseDao类

package com.lj.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 com.zking.entity.Book;
import com.zking.util.DBAccess;
import com.zking.util.PageBean;
import com.zking.util.StringUtils;

/**
 * 所有Dao层的父类
 * 	BookDao
 * 	UserDao
 * 	OrderDao
 * 	...
 * @author Administrator
 *
 * @param <T>
 */
public class BaseDao<T> {
	
	/**
	 * 通用的增删改
	 * @param sql	具体的增删改SQL
	 * @param t		具体要操作的表对应实体类
	 * @param attrs	具体操作表的某些字段对应的实体类属性
	 * @throws SQLException 
	 */
	public void executeUpdate(String sql, T t, String[] attrs) throws Exception {
//		attrs = new String[] {"bid","bname","price"};
//		?->bid;?->bname;?->price
		Connection con = DBAccess.getConnection();
		PreparedStatement pst = con.prepareStatement(sql);
//		pst.setObject(1, book.getBid());
//		pst.setObject(2, book.getBname());
//		pst.setObject(3, book.getPrice());
		for (int i = 0; i < attrs.length; i++) {
//			attrs[0]=bid;
			Field f = t.getClass().getDeclaredField(attrs[i]);
			f.setAccessible(true);
//			f.get(t);		bid.get(book)
			pst.setObject(i+1, f.get(t));
		}
		
		pst.executeUpdate();
	}
	
	/**
	 * 通用分页查询
	 * @param sql
	 * @param clz
	 * @return
	 * @throws Exception
	 */
	public List<T> executeQuery(String sql,Class<T> clz,PageBean pageBean) throws Exception{
		List<T> list = new ArrayList<T>();
		Connection con = DBAccess.getConnection();;
		PreparedStatement pst = null;
		ResultSet rs = null;
		
		/*
		 * 是否需要分页？
		 * 	无需分页（项目中的下拉框，查询条件教员下拉框，无须分页）	
		 * 	必须分页（项目中列表类需求、订单列表、商品列表、学生列表...）
		 */
		if(pageBean != null && pageBean.isPagination()) {
//			必须分页（列表需求）
			String countSQL = getCountSQL(sql);
			pst = con.prepareStatement(countSQL);
			rs = pst.executeQuery();
			if(rs.next()) {
				pageBean.setTotal(String.valueOf(rs.getObject(1)));
			}
			
//			挪动到下面，是因为最后才处理返回的结果集
//			-- sql=SELECT * FROM t_mvc_book WHERE bname like '%圣墟%'
//			-- pageSql=sql limit (page-1)*rows,rows 	对应某一页的数据
//			-- countSql=select count(1) from (sql) t 	符合条件的总记录数
			String pageSQL = getPageSQL(sql,pageBean);//符合条件的某一页数据
			pst = con.prepareStatement(pageSQL);
			rs = pst.executeQuery();
		}else {
//			不分页（select需求）
			pst = con.prepareStatement(sql);//符合条件的所有数据
			rs = pst.executeQuery();
		}
		
		
		while (rs.next()) {
			T t = clz.newInstance();
			Field[] fields = clz.getDeclaredFields();
			for (Field f : fields) {
				f.setAccessible(true);
				f.set(t, rs.getObject(f.getName()));
			}
			list.add(t);
		}
		return list;
	}

	/**
	 * 将原生SQL转换成符合条件的总记录数countSQL
	 * @param sql
	 * @return
	 */
	private String getCountSQL(String sql) {
//		-- countSql=select count(1) from (sql) t 	符合条件的总记录数
		return "select count(1) from ("+sql+") t";
	}

	/**
	 * 将原生SQL转换成pageSQL
	 * @param sql
	 * @param pageBean
	 * @return
	 */
	private String getPageSQL(String sql,PageBean pageBean) {
//		(this.page - 1) * this.rows
//		pageSql=sql limit (page-1)*rows,rows
		return sql + " limit "+ pageBean.getStartIndex() +","+pageBean.getRows();
	}
}

BookAction类

package com.lj.web;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zking.dao.BookDao;
import com.zking.entity.Book;
import com.zking.framework.ActionSupport;
import com.zking.framework.ModelDriver;
import com.zking.util.PageBean;

public class BookAction extends ActionSupport implements ModelDriver<Book>{
	private Book book = new Book();
	private BookDao bookDao = new BookDao();
	@Override
	public Book getModel() {
		return book;
	}
	
	public String add(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bookDao.add(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	public String delete(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bookDao.delete(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	public String edit(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bookDao.edit(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	public String list(HttpServletRequest req, HttpServletResponse resp) {
		PageBean pageBean = new PageBean();
		pageBean.setRequest(req);
		try {
			List<Book> list = bookDao.list(book, pageBean);
			req.setAttribute("books", list);
			req.setAttribute("pageBean", pageBean);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "list";
	}
	
	public String toEdit(HttpServletRequest req, HttpServletResponse resp) {
//		濡傛灉璺宠浆鐨勬槸鏂板�炵晫闈㈡棤闇�鏌ヨ��锛屽�傛灉璺宠浆鐨勬槸淇�鏀圭晫闈�锛岄��瑕佹煡璇㈠綋鍓峛id瀵瑰簲鐨勬暟鎹�锛屽洖鏄惧埌鐣岄��
		if(book.getBid() != 0) {
			try {
//				bid=16
				List<Book> list = bookDao.list(book, null);
				req.setAttribute("b", list.get(0));
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return "toEdit";
	}

}