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怎樣用java代碼動(dòng)態(tài)生成數(shù)據(jù)庫表
Class.forName("oracle.jdbc.driver.OracleDriver");
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Connection conn=DriverManager.getConnection("數(shù)據(jù)庫url","帳號(hào)","密碼");
state=conn.createStatement();
state.executeUpdate("create 建表語句");
state.executeUpdate("insert 插入數(shù)據(jù)")------插入的值由頁面獲得,注意字符串拼接。
然后就是關(guān)閉連接,state.close();conn.close();
核心代碼就是這些,具體應(yīng)用你可以多寫幾個(gè)方法(增刪改查),都是類似的,注意異常的處理,關(guān)閉連接最好在finally中進(jìn)行。
java 開發(fā) jfreechar生成圖表問題
你代碼搞錯(cuò)了吧。。 肯定不會(huì)超出圖的高度的,你設(shè)置y軸最大值的參數(shù)肯定設(shè)錯(cuò)了,設(shè)小了
為什么我用java建不成數(shù)據(jù)庫中的表,不報(bào)錯(cuò),就是沒有表
你方法寫錯(cuò)了:
public class cexia{
public cexia(){
。。。
按照你的代碼,我猜你是想這樣。
不然就:
public static void main(String args[])
{
cexia ce = new cexia();
ce.cexia();
}
}
最后!類名首字母必須大寫?。。。。。。。。?!
public class Cexia{
如何用java代碼將數(shù)據(jù)庫中的數(shù)據(jù)生成excel表
java 讀excel 還是比較方便簡(jiǎn)單的,原理就是,先用java 讀取excel,然后,一行行的寫入數(shù)據(jù)庫,字段的話,你自己程序里面寫就行了,給你個(gè)例子:
從Excel讀取數(shù)據(jù),生成新的Excel,以及修改Excel
package common.util;
import jxl.*;
import jxl.format.UnderlineStyle;
import jxl.write.*;
import jxl.write.Number;
import jxl.write.Boolean;
import java.io.*;
/**
* Created by IntelliJ IDEA.
* User: xl
* Date: 2005-7-17
* Time: 9:33:22
* To change this template use File | Settings | File Templates.
*/
public class ExcelHandle
{
public ExcelHandle()
{
}
/**
* 讀取Excel
*
* @param filePath
*/
public static void readExcel(String filePath)
{
try
{
InputStream is = new FileInputStream(filePath);
Workbook rwb = Workbook.getWorkbook(is);
//Sheet st = rwb.getSheet("0")這里有兩種方法獲取sheet表,1為名字,而為下標(biāo),從0開始
Sheet st = rwb.getSheet("original");
Cell c00 = st.getCell(0,0);
//通用的獲取cell值的方式,返回字符串
String strc00 = c00.getContents();
//獲得cell具體類型值的方式
if(c00.getType() == CellType.LABEL)
{
LabelCell labelc00 = (LabelCell)c00;
strc00 = labelc00.getString();
}
//輸出
System.out.println(strc00);
//關(guān)閉
rwb.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
/**
* 輸出Excel
*
* @param os
*/
public static void writeExcel(OutputStream os)
{
try
{
/**
* 只能通過API提供的工廠方法來創(chuàng)建Workbook,而不能使用WritableWorkbook的構(gòu)造函數(shù),
* 因?yàn)轭怶ritableWorkbook的構(gòu)造函數(shù)為protected類型
* method(1)直接從目標(biāo)文件中讀取WritableWorkbook wwb = Workbook.createWorkbook(new File(targetfile));
* method(2)如下實(shí)例所示 將WritableWorkbook直接寫入到輸出流
*/
WritableWorkbook wwb = Workbook.createWorkbook(os);
//創(chuàng)建Excel工作表 指定名稱和位置
WritableSheet ws = wwb.createSheet("Test Sheet 1",0);
//**************往工作表中添加數(shù)據(jù)*****************
//1.添加Label對(duì)象
Label label = new Label(0,0,"this is a label test");
ws.addCell(label);
//添加帶有字型Formatting對(duì)象
WritableFont wf = new WritableFont(WritableFont.TIMES,18,WritableFont.BOLD,true);
WritableCellFormat wcf = new WritableCellFormat(wf);
Label labelcf = new Label(1,0,"this is a label test",wcf);
ws.addCell(labelcf);
//添加帶有字體顏色的Formatting對(duì)象
WritableFont wfc = new WritableFont(WritableFont.ARIAL,10,WritableFont.NO_BOLD,false,
UnderlineStyle.NO_UNDERLINE,jxl.format.Colour.RED);
WritableCellFormat wcfFC = new WritableCellFormat(wfc);
Label labelCF = new Label(1,0,"This is a Label Cell",wcfFC);
ws.addCell(labelCF);
//2.添加Number對(duì)象
Number labelN = new Number(0,1,3.1415926);
ws.addCell(labelN);
//添加帶有formatting的Number對(duì)象
NumberFormat nf = new NumberFormat("#.##");
WritableCellFormat wcfN = new WritableCellFormat(nf);
Number labelNF = new jxl.write.Number(1,1,3.1415926,wcfN);
ws.addCell(labelNF);
//3.添加Boolean對(duì)象
Boolean labelB = new jxl.write.Boolean(0,2,false);
ws.addCell(labelB);
//4.添加DateTime對(duì)象
jxl.write.DateTime labelDT = new jxl.write.DateTime(0,3,new java.util.Date());
ws.addCell(labelDT);
//添加帶有formatting的DateFormat對(duì)象
DateFormat df = new DateFormat("dd MM yyyy hh:mm:ss");
WritableCellFormat wcfDF = new WritableCellFormat(df);
DateTime labelDTF = new DateTime(1,3,new java.util.Date(),wcfDF);
ws.addCell(labelDTF);
//添加圖片對(duì)象,jxl只支持png格式圖片
File image = new File("f:\\2.png");
WritableImage wimage = new WritableImage(0,1,2,2,image);
ws.addImage(wimage);
//寫入工作表
wwb.write();
wwb.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
/**
* 拷貝后,進(jìn)行修改,其中file1為被copy對(duì)象,file2為修改后創(chuàng)建的對(duì)象
* 盡單元格原有的格式化修飾是不能去掉的,我們還是可以將新的單元格修飾加上去,
* 以使單元格的內(nèi)容以不同的形式表現(xiàn)
* @param file1
* @param file2
*/
public static void modifyExcel(File file1,File file2)
{
try
{
Workbook rwb = Workbook.getWorkbook(file1);
WritableWorkbook wwb = Workbook.createWorkbook(file2,rwb);//copy
WritableSheet ws = wwb.getSheet(0);
WritableCell wc = ws.getWritableCell(0,0);
//判斷單元格的類型,做出相應(yīng)的轉(zhuǎn)換
if(wc.getType == CellType.LABEL)
{
Label label = (Label)wc;
label.setString("The value has been modified");
}
wwb.write();
wwb.close();
rwb.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
//測(cè)試
public static void main(String[] args)
{
try
{
//讀Excel
ExcelHandle.readExcel("f:/testRead.xls");
//輸出Excel
File fileWrite = new File("f:/testWrite.xls");
fileWrite.createNewFile();
OutputStream os = new FileOutputStream(fileWrite);
ExcelHandle.writeExcel(os);
//修改Excel
ExcelHandle.modifyExcel(new file(""),new File(""));
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
2.在jsp中做相關(guān)測(cè)試,創(chuàng)建一個(gè)writeExcel.jsp
%
response.reset();//清除Buffer
response.setContentType("application/vnd.ms-excel");
File fileWrite = new File("f:/testWrite.xls");
fileWrite.createNewFile();
new FileOutputStream(fileWrite);
ExcelHandle.writeExcel(new FileOutputStream(fileWrite));
%
在IE中瀏覽writeExcel.jsp就可以動(dòng)態(tài)生成Excel文檔了,其中response.setContentType("application/vnd.ms- excel");語句必須要,才能確保不亂碼,在jsp中輸入%@page contentType="application/vnd.ms- excel;charset=GBK"%不行。
當(dāng)前標(biāo)題:java代碼生成不了表,java代碼生成不了表格
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