Jsp/Servlet

Development Platform:
Java

BookCaseDAO.java：Code Content
							package com.dao;
import com.core.ConnDB;
import com.actionForm.BookCaseForm;
import java.util.*;
import java.sql.*;
public class BookCaseDAO {
    private ConnDB conn=new ConnDB();
    //查询数据
    public Collection query(String strif){
        BookCaseForm bookCaseForm1=null;
        Collection bookcaseColl=new ArrayList();
        String sql="";
        if(strif!="all" && strif!=null && strif!=""){
            sql="select * from tb_bookcase where "+strif+"";
        }else{
            sql="select * from tb_bookcase";
        }
        ResultSet rs=conn.executeQuery(sql);
        try {
            while (rs.next()) {
                bookCaseForm1=new BookCaseForm();
                bookCaseForm1.setId(Integer.valueOf(rs.getString(1)));
                bookCaseForm1.setName(rs.getString(2));
                bookcaseColl.add(bookCaseForm1);
            }
        } catch (SQLException ex) {
        }
        conn.close();
        return bookcaseColl;
    }
    //用于修改的查询
    public BookCaseForm queryM(BookCaseForm bookCaseForm){
        BookCaseForm bookCaseForm1=null;
        String sql="select * from tb_bookcase where id="+bookCaseForm.getId()+"";
        System.out.println("修改时的SQL："+sql);
        ResultSet rs=conn.executeQuery(sql);
        try {
            while (rs.next()) {
                bookCaseForm1=new BookCaseForm();
                bookCaseForm1.setId(Integer.valueOf(rs.getString(1)));
                bookCaseForm1.setName(rs.getString(2));
            }
        } catch (SQLException ex) {
        }
        conn.close();
        return bookCaseForm1;
    }
   //添加数据
    public int insert(BookCaseForm bookCaseForm){
    String sql1="SELECT * FROM tb_bookcase WHERE name='"+bookCaseForm.getName()+"'";
    ResultSet rs = conn.executeQuery(sql1);
    String sql = "";
    int falg = 0;
    try {
        if (rs.next()) {
            falg = 2;
        } else {
            sql ="Insert into tb_bookcase (name) values('"+bookCaseForm.getName()+"')";
            falg = conn.executeUpdate(sql);
            System.out.println("添加书架信息的SQL：" + sql);
            conn.close();
        }
    } catch (SQLException ex) {
        falg = 0;
    }
    System.out.println("falg:"+falg);
    return falg;
}
    //修改数据
    public int update(BookCaseForm bookCaseForm){
    String sql="Update tb_bookcase set name='"+bookCaseForm.getName()+"' where id="+bookCaseForm.getId()+"";
    int falg=conn.executeUpdate(sql);
    System.out.println("修改数据时的SQL："+sql);
    conn.close();
    return falg;
}
    //删除数据
    public int delete(BookCaseForm bookCaseForm){
    String sql="Delete from tb_bookcase where id="+bookCaseForm.getId()+"";
    int falg=conn.executeUpdate(sql);
    System.out.println("删除时的SQL："+sql);
    return falg;
}
}

						