在mvc框架和前一次通用分页的基础上，我们可以完善一下，把它做成一个通用的增删改查
话不多说直接上代码：
先创建一个与数据库表名对应的实体类Book：
package com.entity;
public class Book {
private int bid;
private String bname;
private float price;
@Override
public String toString() {
return "Book [bid=" + bid + ", bname=" + bname + ", price=" + 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;
}
public Book(int bid, String bname, float price) {
super();
this.bid = bid;
this.bname = bname;
this.price = price;
}
public Book() {
super();
}
}
创建一个执行sql语句的BaseDao：
package com.dao;
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.util.DBAccess;
import com.util.PageBean;
/**
* T代表你要对哪个实体类对应表进行查询
*
* @author Administrator
*
* @param <T>
*/
public class BaseDao<T> {
/**
*
* @param sql 查询不同的实体类，那么对应的sql不同，所以需要传递
* @param clz 生产出不同的实体类对应的实例，然后装进list容器中返回
* @param pageBean 决定是否分页
* @return
* @throws Exception
*/
public List<T> executeQuery(String sql,Class clz,PageBean pageBean) throws Exception{
Connection con=DBAccess.getConnection();
PreparedStatement ps=null;
ResultSet rs=null;
if(pageBean!=null&&pageBean.isPagination()) {
//需要分页(算符合条件的总记录数)
String countSql=getCountSql(sql);
ps=con.prepareStatement(countSql);
rs=ps.executeQuery();
if(rs.next()) {
pageBean.setTotal(rs.getLong(1)+"");
}
//查询出符合条件的结果集
String pageSql=getpageSql(sql,pageBean);
ps=con.prepareStatement(pageSql);
rs=ps.executeQuery();
}else {
ps=con.prepareStatement(sql);
rs=ps.executeQuery();
}
List<T> list=new ArrayList<T>();
T t;
while(rs.next()) {
/**
* 1.实例化一个book对象（该对象是空的）
* 2.取book的所有的属性，然后给其赋值
* 2.1获取所有属性对象
* 2.2给属性对象赋值
* 3.赋完值的book对象装进list容器中
*/
t=(T)clz.newInstance();
Field[] fields=clz.getDeclaredFields();
for (Field field : fields) {
field.setAccessible(true);
field.set(t, rs.getObject(field.getName()));
}
list.add(t);
}
DBAccess.close(con, ps, rs);
return list;
}
/**
* 利用原生sql拼接出符合条件的结果集的sql
* @param sql
* @param pageBean
* @return
*/
private String getpageSql(String sql, PageBean pageBean) {
// TODO Auto-generated method stub
return sql+" limit "+pageBean.getStartIndex()+","+pageBean.getRows();
}
/**
* 获取符合条件的总记录数的sql
* @param sql
* @return
*/
private String getCountSql(String sql) {
return "SELECT COUNT(1)FROM ("+sql+")t";
}
/**
*
* @param sql 决定增删改的一种
* @param attrs 决定？位置 new String[]{"bid,"bname"}
* @param t 要操作的实体
* @return
* @throws Exception
* @throws NoSuchFieldException
*/
public int executeUpdate (String sql,String[] attrs,T t) throws NoSuchFieldException, Exception {
Connection con=DBAccess.getConnection();
PreparedStatement ps=con.prepareStatement(sql);
for(int i=1;i<=attrs.length;i++) {
Field f=t.getClass().getDeclaredField(attrs[i-1]);
f.setAccessible(true);
ps.setObject(i, f.get(t));
}
int num=ps.executeUpdate();
DBAccess.close(con, ps, null);
return num;
}
}
创建一个提供sql语句的BookDao:
package com.dao;
import java.util.List;
import com.entity.Book;
import com.util.BaseDao;
import com.util.PageBean;
import com.util.StringUtils;
public class BookDao extends BaseDao<Book> {
/**
* 查询所有
*
* @param book
* @param pageBean
* @return
* @throws Exception
*/
public List<Book> list(Book book, PageBean pageBean) throws Exception {
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);
}
/**
* 修改
*
* @param book
* @return
* @throws Exception
* @throws NoSuchFieldException
*/
public int upde(Book book) throws NoSuchFieldException, Exception {
String sql = "update t_mvc_book set bname=?,price=? where bid=?";
return super.executeUpdate(sql, new String[] { "bname", "price", "bid" }, book);
}
/**
* 新增
*
* @param book
* @return
* @throws Exception
* @throws NoSuchFieldException
*/
public int add(Book book) throws NoSuchFieldException, Exception {
String sql = "insert into t_mvc_book values(?,?,?)";
System.out.println(sql);
return super.executeUpdate(sql, new String[] { "bid", "bname", "price" }, book);
}
/**
* 删除
*
* @param book
* @return
* @throws Exception
* @throws NoSuchFieldException
*/
public int del(Book book) throws NoSuchFieldException, Exception {
String sql = "delete from t_mvc_book where bid=?";
return super.executeUpdate(sql, new String[] { "bid" }, book);
}
}
执行类BookAction：
package com.web;
import java.util.List;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.dao.BookDao;
import com.entity.Book;
import com.framework.ActionSupport;
import com.framework.ModelDrivern;
import com.util.PageBean;
public class BookAction extends ActionSupport implements ModelDrivern<Book> {
private Book book = new Book();
private BookDao bookdao = new BookDao();
/**
* 分页查询
*
* @param request
* @param response
* @return
* @throws Exception
*/
public String list(HttpServletRequest request, HttpServletResponse response) throws Exception {
PageBean pageBean = new PageBean();
pageBean.setRequest(request);
List<Book> list = this.bookdao.list(book, pageBean);
request.setAttribute("booklist", list);
request.setAttribute("pagebean", pageBean);
return "list";
}
/**
*
* 跳转到增加或修改页面
*
* @param request
* @param response
* @return
* @throws Exception
*/
public String preSave(HttpServletRequest request, HttpServletResponse response) {
// bid的类型是int类型，而int类型的默认值是0，如果jsp未传递bid的参数值那么bid=0;
if (book.getBid() == 0) {
System.out.println("增加逻辑");
} else {
// 修改数据回显
Book b;
try {
b = this.bookdao.list(book, null).get(0);
request.setAttribute("book", b);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return "edit";
}
/**
* 新增
*
* @param request
* @param response
* @return
* @throws Exception
*/
public String add(HttpServletRequest request, HttpServletResponse response) throws Exception {
// 新增完了之后刷新页面
this.bookdao.add(book);
return "tolist";
}
/**
* 修改
*
* @param request
* @param response
* @return
* @throws Exception
*/
public String upde(HttpServletRequest request, HttpServletResponse response) throws Exception {
// 修改完了之后刷新页面
this.bookdao.upde(book);
return "tolist";
}
/**
* 删除
*
* @param request
* @param response
* @return
* @throws Exception
*/
public String del(HttpServletRequest request, HttpServletResponse response) throws Exception {
// 删除之后刷新页面
this.bookdao.del(book);
return "tolist";
}
@Override
public Book getModel() {
// TODO Auto-generated method stub
return book;
}
}
xml文件配置：
<?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>MVC</display-name> <servlet> <servlet-name>DispatcherServlet</servlet-name> <servlet-class>com.framework.DispatcherServlet</servlet-class> <init-param> <param-name>xmlPath</param-name> <param-value>/mvc.xml</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>DispatcherServlet</servlet-name> <url-pattern>*.action</url-pattern> </servlet-mapping> </web-app>
jsp主页面页面book.jsp：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@page isELIgnored="false" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="m" uri="/MyJSP"%>
<!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>
<c:if test="${empty booklist }">
<jsp:forward page="book.action?menthodName=list"></jsp:forward>
</c:if>
<form action="${pageContext.request.contextPath}/book.action?menthodName=list"
method="post">
书名：<input type="text" name="bname"> <input type="submit"
value="确定">
</form>
<a href="${pageContext.request.contextPath}/book.action?menthodName=preSave">新增</a>
<table border="1" width="100%">
<tr>
<td>编号</td>
<td>名称</td>
<td>价格</td>
<td>操作</td>
</tr>
<c:forEach items="${booklist }" var="b">
<tr>
<td>${b.bid }</td>
<td>${b.bname }</td>
<td>${b.price }</td>
<td><a href="${pageContext.request.contextPath}/book.action?menthodName=preSave&&bid=${b.bid}">修改</a>
</td>
<td><a href="${pageContext.request.contextPath}/book.action?menthodName=del&&bid=${b.bid}">删除</a>
</td>
</tr>
</c:forEach>
</table>
<m:page bean="${pagebean }"></m:page>
</body>
</html>
增，改通用的bookList.lsp页面：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@page isELIgnored="false"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@taglib prefix="m" uri="/MyJSP"%>
<!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>
<c:if test="${empty booklist }">
<jsp:forward page="book.action?menthodName=list"></jsp:forward>
</c:if>
<form
action="${pageContext.request.contextPath}/book.action?menthodName=list"
method="post">
书名：<input type="text" name="bname"> <input type="submit"
value="确定">
</form>
<a
href="${pageContext.request.contextPath}/book.action?menthodName=preSave">新增</a>
<table border="1" width="100%">
<tr>
<td>编号</td>
<td>名称</td>
<td>价格</td>
<td>操作</td>
</tr>
<c:forEach items="${booklist }" var="b">
<tr>
<td>${b.bid }</td>
<td>${b.bname }</td>
<td>${b.price }</td>
<td><a
href="${pageContext.request.contextPath}/book.action?menthodName=preSave&&bid=${b.bid}">修改</a>
</td>
<td><a
href="${pageContext.request.contextPath}/book.action?menthodName=del&&bid=${b.bid}">删除</a>
</td>
</tr>
</c:forEach>
</table>
<m:page bean="${pagebean }"></m:page>
</body>
</html>
效果如下：
原文地址：https://www.cnblogs.com/huxiaocong/p/11103306.html
时间： 2024-10-11 15:49:43