poi例子

具体的需求：在jsp页面上显示从数据库中取出的行列集，然后下面一个按钮，当点击按钮时直接调出Excel文件，excel文件中的内容和jsp页面上的内容一样。并且要求对excel中的内容的字体，字号，等进行格式化。

解决此问题，首先连库，输出

package cn.ityc.data;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBConn ...{
   
    private static Connection conn;
    private Statement stmt;
    private ResultSet rs;
    private Connection DBConn()...{
        try ...{
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            conn    =    DriverManager.getConnection("jdbc:mysql://localhost:3306/excel","root","111111");
        } catch (InstantiationException e) ...{
            e.printStackTrace();
        } catch (IllegalAccessException e) ...{
            e.printStackTrace();
        } catch (ClassNotFoundException e) ...{
            e.printStackTrace();
        } catch (SQLException e) ...{
            e.printStackTrace();
        }
        return conn;
    }
    public static DBConn getInstance()...{
        DBConn dbconn    =     new DBConn();
        return dbconn;
    }
    public boolean isExist(String sql)...{
        boolean isExist    =    false;
        try ...{
            Connection conn    =     DBConn.getInstance().DBConn();
            Statement stmt    =    conn.createStatement();
            rs                =    stmt.executeQuery(sql);
            if(rs.next())...{
                isExist    =    true;
            }
        } catch (SQLException e) ...{
            e.printStackTrace();
        }
        return isExist;
    }
    public boolean update(String sql)...{
        boolean isUpdate    =    false;
        try ...{
            conn    =     DBConn.getInstance().DBConn();
            stmt    =    conn.createStatement();
            int num    =    stmt.executeUpdate(sql);
            if(num>0)...{
                isUpdate    =    true;
            }
        } catch (SQLException e) ...{
            e.printStackTrace();
        }
        return isUpdate;
    }
    public ResultSet query(String sql)...{
        try ...{
            conn    =     DBConn.getInstance().DBConn();
            stmt    =     conn.createStatement();
            rs        =    stmt.executeQuery(sql);
        } catch (SQLException e) ...{
            e.printStackTrace();
        }       
       
        return rs;
    }
}

我采用了jdbc，连接数据库mysql数据库

 

然后用一个Getlist.java将结果集ResultSet转化成list

 

package cn.ityc.data;

import java.math.BigDecimal;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import cn.ityc.struts.form.GradeForm;

public class GetList ...{
    public static List<GradeForm> getData(String sql)...{
        List<GradeForm> list = new ArrayList<GradeForm>();
        ResultSet rs    =    DBConn.getInstance().query(sql);
        try ...{
            while(rs.next())...{
                GradeForm gradeForm     =    new GradeForm();
                String     name    =     rs.getString("name");
                String course    =    rs.getString("course");
                BigDecimal     grade    =    rs.getBigDecimal("grade");
                gradeForm.setName(name);
                gradeForm.setCourse(course);
                gradeForm.setGrade(grade);
                list.add(gradeForm);
            }   
        } catch (SQLException e) ...{
            e.printStackTrace();
        }
        return list;
    }
}

然后用一个测试输出的主方法类

 

package cn.ityc.data;

import java.util.ArrayList;
import java.util.List;

import cn.ityc.struts.form.GradeForm;

 

public class TestDemo ...{

    /** *//**
     * @param args
     */
    public static void main(String[] args) ...{
        String sql    =    "select * from excel";
        List<GradeForm> list    =    (ArrayList<GradeForm>)GetList.getData(sql);
        for(int i=0;i<list.size();i++)...{
            System.out.println(list.get(i).getName());
            System.out.println(list.get(i).getCourse());
            System.out.println(list.get(i).getGrade());
        }
    }
}

当然，我建的mysql的数据库是

 

--
-- 表的结构 `excel`
--

CREATE TABLE `excel` (
`id` int(10) NOT NULL,
`name` varchar(30) collate gb2312_bin default NULL,
`course` varchar(30) collate gb2312_bin default NULL,
`grade` decimal(10,0) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=gb2312 COLLATE=gb2312_bin;

--
-- 导出表中的数据 `excel`
--

INSERT INTO `excel` (`id`, `name`, `course`, `grade`) VALUES
(1, 0x7573657231, 0xe789a9e79086, 91),
(2, 0x7573657232, 0xe789a9e79086, 90),
(3, 0x7573657233, 0xe58c96e5ada6, 91);

然后就可以在java的控制台进行最简单的数据库数据读取了。

那么如何将这些写入excel呢？我在网上找了半天找了一个poi的三个jar包，可以对excel就行一系列的操作

 

package cn.ityc.data;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;

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

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFPrintSetup;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hssf.util.Region;

import cn.ityc.struts.form.GradeForm;
public class Excel ...{
   
    private String sheetName;
    private HSSFWorkbook hwb;
    private short rowNumber;
    private short cellNumber;
    FileOutputStream fileOut;
    public void produce()...{
          try ...{
             fileOut = new FileOutputStream("aa.xls");
        } catch (FileNotFoundException e1) ...{
            e1.printStackTrace();
        }

        hwb =   new HSSFWorkbook();
        sheetName    =    "sheet1";
        HSSFSheet sheet = this.createSheet();
        HSSFRow row = sheet.createRow((short)0);
        sheet.addMergedRegion(new Region(0,(short)0,0,(short)2));//
        HSSFCell cell1 = row.createCell((short)0);
        HSSFCell cell2 = row.createCell((short)1);
        HSSFCell cell3 = row.createCell((short)2);
         // 定义表头的内容
        cell1.setCellValue("姓名");
//        cell2.setCellValue("课程");
//        cell3.setCellValue("分数");
        MyHSSFCellStyle mystyle    =    new MyHSSFCellStyle();
        mystyle.setFontName("楷体");
        mystyle.setFontSize((short)800);
        mystyle.setHwb(hwb);
        HSSFCellStyle style    =    mystyle.getHSSFCellStyle();
       // style.setWrapText(true);
        cell1.setCellStyle(style);
        cell2.setCellStyle(style);
        HSSFPrintSetup ps = sheet.getPrintSetup();   
        sheet.setAutobreaks(true);  
        ps.setFitHeight((short)800);
        ps.setFitWidth((short)800);

        String sql="select * from excel";
        List<GradeForm> list    =    GetList.getData(sql);
       
         for(int i=0;i<GetList.getData(sql).size();i++) ...{
             // 定义数据从第二行开始      
            row = sheet.createRow((short)i+1);
            cell1 = row.createCell((short)0);
            cell2 = row.createCell((short)1);
            cell3 = row.createCell((short)2);
            cell1.setCellValue(list.get(i).getName());
            cell2.setCellValue(list.get(i).getCourse());
            String grade    =    list.get(i).getGrade()+"";
            cell3.setCellValue(grade);
             mystyle    =    new MyHSSFCellStyle();
            mystyle.setFontName("楷体");
            mystyle.setFontSize((short)300);
            mystyle.setHwb(hwb);
             style    =    mystyle.getHSSFCellStyle();
            cell1.setCellStyle(style);
            cell2.setCellStyle(style);
        }
        try ...{
              hwb.write(fileOut);
              fileOut.close();
        } catch (IOException e) ...{
            e.printStackTrace();
        }
        try ...{
            Open.open("aa.xls");
        } catch (IOException e) ...{
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    private HSSFSheet createSheet()...{
        HSSFSheet sheet = hwb.createSheet(sheetName);
        return sheet;
    }
    private HSSFRow createRow()...{
        HSSFRow row    =    this.createSheet().createRow(rowNumber);
        return row;
    }
    private HSSFCell createCell()...{
        HSSFCell cell = this.createRow().createCell(cellNumber);
        return cell;
    }
}

其中此类用到下面的辅助的类，大家一看就会明白

 

package cn.ityc.data;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

public class MyHSSFCellStyle ...{
    private HSSFWorkbook hwb;
    private String fontName;
    private short fontSize;
    public String getFontName() ...{
        return fontName;
    }
    public void setFontName(String fontName) ...{
        this.fontName = fontName;
    }

    public short getFontSize() ...{
        return fontSize;
    }
    public void setFontSize(short i) ...{
        this.fontSize = i;
    }
    public HSSFCellStyle getHSSFCellStyle()...{
         HSSFCellStyle style=hwb.createCellStyle();
          style.setAlignment(style.ALIGN_CENTER);
          HSSFFont hf=hwb.createFont();
          hf.setFontName(this.getFontName());
          hf.setFontHeight(this.getFontSize());
          style.setFont(hf);
        return style;
    }
    public HSSFWorkbook getHwb() ...{
        return hwb;
    }
    public void setHwb(HSSFWorkbook hwb) ...{
        this.hwb = hwb;
    }
}

 

值得提一下的是下面这个Open，他是一个在windows的环境下打开文件一个方法。不能快平台。这是个缺陷

 

package cn.ityc.data;

import java.io.IOException;

public class Open ...{

              public   static   void   open(String fileName)   throws   IOException  
              ...{  
                     Runtime   r   =   Runtime.getRuntime();  
                      Process   p   =   null;  
                      String   strwinapp   =   "excel.exe";  
                      try  
                      ...{  
                              p   =   Runtime.getRuntime().exec("cmd /c start "+fileName);
                      }  
                      catch(Exception   e)  
                      ...{  
                              e.printStackTrace();  
                      }  
              }  
}

主要的代码就是这些。

然后我用了struts1。2来实现的

所以下面有action，form，和struts-config.xml文件

action

 

package cn.ityc.struts.action;

import java.util.List;

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

import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.actions.DispatchAction;

import cn.ityc.data.Excel;
import cn.ityc.data.GetList;

public class GradeAction extends DispatchAction ...{

    public ActionForward list(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) ...{
        List list    =    GetList.getData("select * from excel");
        request.getSession().setAttribute("list", list);
        return mapping.findForward("showlist");
    }
    public ActionForward excel(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response) ...{
        Excel ee    =    new Excel();
        ee.produce();
        return mapping.findForward("success");
    }
}

form

/**//*
* Generated by MyEclipse Struts
* Template path: templates/java/JavaClass.vtl
*/
package cn.ityc.struts.form;

import java.math.BigDecimal;

import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;

/** *//**
* MyEclipse Struts
* Creation date: 11-30-2007
*
* XDoclet definition:
* @struts.form name="gradeForm"
*/
public class GradeForm extends ActionForm ...{
    /**//*
     * Generated fields
     */

    /** *//** grade property */
    private BigDecimal grade;

    /** *//** course property */
    private String course;

    /** *//** name property */
    private String name;

    /**//*
     * Generated Methods
     */

    /** *//**
     * Method validate
     * @param mapping
     * @param request
     * @return ActionErrors
     */
    public ActionErrors validate(ActionMapping mapping,
            HttpServletRequest request) ...{
        // TODO Auto-generated method stub
        return null;
    }

    /** *//**
     * Method reset
     * @param mapping
     * @param request
     */
    public void reset(ActionMapping mapping, HttpServletRequest request) ...{
        // TODO Auto-generated method stub
    }

    /** *//**
     * Returns the grade.
     * @return String
     */

    /** *//**
     * Returns the course.
     * @return String
     */
    public String getCourse() ...{
        return course;
    }

    /** *//**
     * Set the course.
     * @param course The course to set
     */
    public void setCourse(String course) ...{
        this.course = course;
    }

    /** *//**
     * Returns the name.
     * @return String
     */
    public String getName() ...{
        return name;
    }

    /** *//**
     * Set the name.
     * @param name The name to set
     */
    public void setName(String name) ...{
        this.name = name;
    }

    public BigDecimal getGrade() ...{
        return grade;
    }

    public void setGrade(BigDecimal grade) ...{
        this.grade = grade;
    }
}
struts-config.xml

 

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd">

<struts-config>
<data-sources />
<form-beans >
    <form-bean name="gradeForm" type="cn.ityc.struts.form.GradeForm" />

</form-beans>

<global-exceptions />
<global-forwards />
<action-mappings >
    <action
      attribute="gradeForm"
      input="/form/grade.jsp"
      name="gradeForm"
      parameter="method"
      path="/grade"
      scope="request"
      type="cn.ityc.struts.action.GradeAction">
      <forward name="success" path="/index.jsp" />
      <forward name="showlist" path="/showlist.jsp" />
    </action>

</action-mappings>

<message-resources parameter="cn.ityc.struts.ApplicationResources" />
</struts-config>