自定义MVC--增删改查
2024-08-26 22:15:35
使用自定义mvc框架完成CRUD操作
1、通用分页的jar、自定义mvc框架、自定义标签
导入jar、导入之前写好的pageTag、自定义mvc.xml
1.1导入需要用到的jar包
1.2导入之前已写好的所有辅助类（可在前面写的mvc博客参考）
1.3优化BaseDao
package com.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.sun.corba.se.spi.legacy.connection.GetEndPointInfoAgainException;
import com.entity.Book; /**
* 代表你要对哪个实体类对应的表进行分页查询
* @author **
*
* @param <T>
*/
public class BaseDao<T> { /**
*
* @param sql 查询不同的实体类，对应的sql语句不同所以需要传递
* @param clz 生产出不同的实体类对应的实列，然后装进list容器中返回
* @param pageBean 决定是否分页
* @return
* @throws SQLException
* @throws IllegalAccessException
* @throws InstantiationException
*/
public List<T> executeQuery(String sql,Class clz,PageBean pageBean)throws SQLException, InstantiationException, IllegalAccessException {
Connection con = DBAccess.getConnection();
PreparedStatement ps =null;
ResultSet rs = null; if(pageBean!=null && pageBean.isPagination()) {
//需要分页
//计算总记录数
String consql= getCountsql(sql);
ps = con.prepareStatement(consql);
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;
while(rs.next()) {
/**
*1、实例化一个book对象(该对象为空)
*2、取book的所有属性，然后给器赋值
* 2.1获取所有属性对象
* 2.2给属性赋值
*3、赋值之后的book对象装进list容器中
*/
// list.add(new Book(rs.getInt("bid"), rs.getString("bname"), rs.getFloat("price"))); 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查询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()+"";
} /**
*
* @param sql
* @return
*/
private String getCountsql(String sql) { return "SELECT COUNT(1) FROM ("+sql+")t";
} /**
* 通用的增删改方法
* @param sql 决定增删改的一种
* @param attrs 决定？的位置 new String[]{"bid","bname","price"}
* @param t 要操作的实体类
* @return
* @throws SQLException
* @throws IllegalAccessException
* @throws IllegalArgumentException
* @throws SecurityException
* @throws NoSuchFieldException
*/
public int executeUpdate(String sql,String[] attrs,T t) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException{
Connection con = DBAccess.getConnection();
PreparedStatement ps = con.prepareStatement(sql);
// ps.setString(2, book.getBname());
// ps.setFloat(3, book.getPrice());
// ps.setInt(1, book.getBid()); 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(); return num;
} }
1.4配置mvc.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<config>
<!-- <action path="/addCal" type="com.yuan.web.AddCalAction">
<forward name="res" path="/res.jsp" redirect="false" />
</action>
<action path="/delCal" type="com.yuan.web.DelCalAction">
<forward name="res" path="/res.jsp" redirect="true"/>
</action> -->
<action path="/cal" type="com.yuan.web.CalAction">
<forward name="res" path="/res.jsp" redirect="false"/>
</action>
<action path="/book" type="com.yuan.web.BookAction">
<forward name="list" path="/bookList.jsp" redirect="false"/>
<forward name="edit" path="/bookEdit.jsp" redirect="false"/>
<!-- 增删改一定要用重定向，查询用转发， -->
<forward name="toList" path="/book.action?methodName=list"/>
</action>
</config>
注：在这里需要注意forward标签里面的redirect，当值为false时为重定向，为true或者不填则是转发，
配置的时候增删改一定要用重定向，查询用转发，否则会出现小bug！！！！
2、dao层 通用的增删改方法
2.1新建一个BookDao
package com.dao; import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List; import com.entity.Book;
import com.util.BaseDao;
import com.util.DBAccess;
import com.util.PageBean;
import com.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+"%'";//注意拼接的时候一定要记得在前面打一个空格
}
if(bid != 0) {
sql+= " AND bid ="+bid;
}
System.out.println(sql);
return super.executeQuery(sql, Book.class, pageBean);
} /**
* 修改方法
*/
public int edit (Book book) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException {
String sql="UPDATE t_mvc_book SET bname=?,price=? WHERE bid=?";
return super.executeUpdate(sql, new String[] {"bname","price","bid"}, book);
}
/**
* 新增方法
*/
public int add(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException {
String sql = "INSERT INTO t_mvc_book VALUES(?,?,?)";
System.out.println(sql);
return super.executeUpdate(sql, new String[] {"bid","bname","price"}, book);
} /**
* 删除方法
*/
public int del(Book book) throws SQLException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException {
String sql = "DELETE FROM t_mvc_book WHERE bid=?";
return super.executeUpdate(sql, new String[] {"bid"}, book);
} }
2.2新建一个与数据库数据匹配的实体类Book
package com.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 + "]";
}
}
3、web层
3.1新建BookAction 继承上次写的优化后的子控制器并且实现（implement）ModelDrivern模型驱动接口
package com.yuan.web; import java.sql.SQLException;
import java.util.List; import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; import com.dao.BookDao;
import com.entity.Book;
import com.util.PageBean;
import com.yuan.framework.ActionSupport;
import com.yuan.framework.ModelDrivern; /**
* 分页查询
* @author **
*
*/
public class BookAction extends ActionSupport implements ModelDrivern<Book> { private Book book = new Book();
private BookDao bookDao = new BookDao(); public String list(HttpServletRequest req, HttpServletResponse resp) {
PageBean bean = new PageBean();
bean.setRequest(req);
try {
List<Book> list = this.bookDao.list(book, bean);
req.setAttribute("booklist", list);
req.setAttribute("pageBean", bean);
} catch (InstantiationException | IllegalAccessException | SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} return "list";
} /**
* 跳转到增加或者修改页面
* @param req
* @param resp
* @return
*/
public String preSave(HttpServletRequest req, HttpServletResponse resp) {
//bid的类型是int类型 int类型的默认值是0，如果jsp未传递bid的参数值，那么bid=0；跳转新增，否则跳转修改。
if(book.getBid() == 0) {
System.out.println("增加....");
}else {
//修改数据后回显
try {
Book b = this.bookDao.list(book, null).get(0);
req.setAttribute("book", b);
} catch (InstantiationException | IllegalAccessException | SQLException e) {
e.printStackTrace();
}
} return "edit";
} /**
* 新增
* @param req
* @param resp
* @return
*/
public String add(HttpServletRequest req, HttpServletResponse resp) {
try {
this.bookDao.add(book);
} catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException | SecurityException
| SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//新增完之后需要刷新页面
return "toList";
}
/**
* 修改
* @param req
* @param resp
* @return
*/
public String edit(HttpServletRequest req, HttpServletResponse resp) {
try {
this.bookDao.edit(book);
} catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException | SecurityException
| SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//修改之后需要刷新页面
return "toList";
} /**
* 删除
* @param req
* @param resp
* @return
*/
public String del(HttpServletRequest req, HttpServletResponse resp) {
try {
this.bookDao.del(book);
} catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException | SecurityException
| SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//删除之后需要刷新页面
return "toList";
} @Override
public Book getModel() {
// TODO Auto-generated method stub
return book;
} }
4、jsp页面
4.1数据展示首页booklist
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page isELIgnored="false"%>
<%@taglib prefix="z" uri="/yuan" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!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>
<%-- <c:if test="${empty bookList }">
<jsp:forward page="bookServlet.action"></jsp:forward>
</c:if> --%>
<h2>小说目录</h2>
<br>
<form action="${pageContext.request.contextPath}/book.action?methodName=list"
method="post">
书名：<input type="text" name="bname"> <input type="submit"
value="确定">
<input type="hidden" name="pagination" value="false">
<input type="hidden" name="rows" value="20">
</form>
<a href="${pageContext.request.contextPath}/book.action?methodName=preSave">新增</a>
<table border="1" width="100%">
<tr>
<td>编号</td>
<td>名称</td>
<td>价格</td>
<td>操作</td>
</tr>
<c:forEach items="${booklist }" var="s">
<tr>
<td>${s.bid }</td>
<td>${s.bname }</td>
<td>${s.price}</td>
<td>
<a href="${pageContext.request.contextPath}/book.action?methodName=preSave&&bid=${s.bid }">修改</a>
<a href="${pageContext.request.contextPath}/book.action?methodName=del&&bid=${s.bid }">删除</a>
</td>
</tr>
</c:forEach>
</table>
<z:Page pageBean="${pageBean }"></z:Page> </body>
</html>
4.2新增和修改的页面
因为我们在web层做了判断，判别出是新增还是修改，所以不需要担心只有一个界面的问题
<%@ 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="${pageContext.request.contextPath}/book.action" method="post">
<input type="hidden" name="methodName" value="${book.bname==null ? 'add' : 'edit' }">
书籍ID：<input type="text" name="bid" value="${book.bid }"><br>
书籍名称：<input type="text" name="bname" value="${book.bname }"><br>
书籍价格：<input type="text" name="price" value="${book.price }"><br>
<input type="submit">
</form>
</body>
</html>
5、结果展示
5.1新增（查询）
5.2修改
5.3删除
谢谢观看^-^！！！
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