handledatabase.java

纯粹jsp的留言板,使用了mvc

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package messagepad.servlets;
import messagepad.beans.*;
import com.sun.rowset.*;
import java.sql.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.sql.rowset.*;

/**
 *
 * @author Administrator
 */
public class HandleDatabase extends HttpServlet{
    int segments;
    CachedRowSetImpl rowSet=null;
    public void init(ServletConfig config)throws ServletException{
        super.init(config);
        try{
            Class.forName("com.mysql.jdbc.Driver");
        }
        catch(Exception e){
        }
    }
    public void doPost(HttpServletRequest request,HttpServletResponse response)
            throws ServletException,IOException{
            Connection con;
            StringBuffer presentPageResult=new StringBuffer();
            ShowRecordByPage databaseBean=null;
            HttpSession session=request.getSession(true);
            try{
                databaseBean=(ShowRecordByPage)session.getAttribute("database");
                if(databaseBean==null){
                    databaseBean=new ShowRecordByPage();
                    session.setAttribute("database", databaseBean);
                }                
            }
            catch(Exception exp){
                databaseBean=new ShowRecordByPage();
                session.setAttribute("database", databaseBean);
            }
            String databaseName="taotao";//request.getParameter("databaseName");
            String tableName="messages";//request.getParameter("tableName");
            String ps="10";//request.getParameter("pageSize");
            if(ps!=null){
                try{
                    int mm=Integer.parseInt(ps);
                    databaseBean.setPageSize(mm);
                }
                catch(NumberFormatException exp){
                    databaseBean.setPageSize(1);
                }
            }
            int showPage=databaseBean.getShowPage();
            int pageSize=databaseBean.getPageSize();
            boolean boo=databaseName!=null&&tableName!=null
                        &&databaseName.length()>0&&tableName.length()>0;
            if(boo){
                databaseBean.setDatabaseName(databaseName);
                databaseBean.setTableName(tableName);//数据存储在databaseBean中
                String url="jdbc:mysql://127.0.0.1/"+databaseName;
                try{
                    segments=0;
                    con=DriverManager.getConnection(url,"taotao",".nothing");
                    DatabaseMetaData metadata=con.getMetaData();
                    ResultSet rs1=metadata.getColumns(null, null, tableName, null);
                    int k=0;
                    String segment[]=new String[100];
                    while(rs1.next()){
                        segments++;
                        segment[k]=rs1.getString(4);
                        k++;
                    }
                    StringBuffer str=new StringBuffer();
                    str.append("<tr>");
                    for(int i=0;i<segments;i++)
                        str.append("<th>"+segment[i]+"</th>");
                    str.append("</tr>");
                    databaseBean.setFormTitle(str);
                    Statement sql=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
                    ResultSet rs=sql.executeQuery("select * from "+tableName+" Order By number Desc");
                    rowSet=new CachedRowSetImpl();
                    rowSet.populate(rs);
                    con.close();
                    databaseBean.setRowset(rowSet);
                    rowSet.last();
                    int m=rowSet.getRow();
                    int n=pageSize;
                    int pageAllCount=((m%n)==0)?(m/n):(m/n+1);
                    databaseBean.setPageAllCount(pageAllCount);
                }
                catch(SQLException exp){
                }
            }
            String whichPage=request.getParameter("whichPage");
            if(whichPage==null||whichPage.length()==0){
                showPage=1;
                databaseBean.setShowPage(showPage);
                CachedRowSetImpl rowSet=databaseBean.getRowSet();
                if(rowSet!=null){
                    presentPageResult=show(showPage,pageSize,rowSet);
                    databaseBean.setPresentPageResult(presentPageResult);
                }
            }
            else if(whichPage.equals("nextPage")){
                showPage++;
                if(showPage>databaseBean.getPageAllCount())
                    showPage=1;
                databaseBean.setShowPage(showPage);
                CachedRowSetImpl rowSet=databaseBean.getRowSet();
                if(rowSet!=null){
                    presentPageResult=show(showPage,pageSize,rowSet);
                    databaseBean.setPresentPageResult(presentPageResult);
                }
            }
            else if(whichPage.equals("previousPage")){
                showPage--;
                if(showPage<=0)
                    showPage=databaseBean.getPageAllCount();
                databaseBean.setShowPage(showPage);
                CachedRowSetImpl rowSet=databaseBean.getRowSet();
                if(rowSet!=null){
                    presentPageResult=show(showPage,pageSize,rowSet);
                    databaseBean.setPresentPageResult(presentPageResult);
                }
            }
            databaseBean.setPresentPageResult(presentPageResult);
            RequestDispatcher dispatcher=request.getRequestDispatcher("showRecord.jsp");
            dispatcher.forward(request, response);
            //response.sendRedirect("showRecord.jsp");
            
    }
    public StringBuffer show(int page,int pageSize,CachedRowSetImpl rowSet){
        StringBuffer str=new StringBuffer();
        try{
            rowSet.absolute((page-1)*pageSize+1);
            for(int i=1;i<=pageSize;i++){
                str.append("<tr>");
                for(int k=1;k<=segments;k++){
                    str.append("<td>"+rowSet.getString(k)+"</td>");
                }
                //str.append("<a href=\"handleDelete\">Del</a>");
                str.append("</tr>");
                rowSet.next();
            }
        }
        catch(SQLException exp){
        }
        return str;
    }
    public void doGet(HttpServletRequest request,HttpServletResponse response)
            throws ServletException,IOException{
            doPost(request,response);
    }
}