学java，要注意什么

如果想学好java最好注意以下五点：1、做学习计划并保持自律：在我们学习Java的过程中，尽量减少干扰，把自己的全部注意力集中在Java上。无论你注意力的持续时间是多久，都应该将全部精力放在Java上。千锋教育就有线上免费Java线上公开课。 2、通过编码来学习：很多新手在学习Java时都会经历一个阶段，那就是看书、看视频，一段时间后感觉自己都会了，但是真的要写代码却怎么都写不出来，这种情况除了多编码外，没有其他方法了。3、手写代码：在电脑上敲代码也很好，当然不反对这种学习方式。但在我们在手写代码的时候，会激活机械记忆，能帮助你更好地记住东西。此外，在面试中，很多公司的笔试都会让你在纸上写代码。所以在学习过程中这是初学者一定要具备的专业技能了。4、工作产出：可以将你自己写的一些代码、小项目等发布在公共论坛上，虽然有时候他们给出很严厉的评价，但也能进一步指出你的不足，从而加以改正。5、坚持编码：一定要坚持编码，从小项目做起，然后慢慢扩大你的项目范围。如果想了解Java更多相关知识，建议到千锋教育了解一下。千锋教育目前在18个城市拥有22个校区，年培养优质人才20000余人，与国内20000余家企业建立人才输送合作关系，院校合作超600所。

import javaio;

import orgdom4j;

import orgdom4jioOutputFormat;

import orgdom4jioXMLWriter;

public class DOM4JTest {

public static void main(String[] args) {

Document doc = DocumentHelpercreateDocument();

docaddProcessingInstruction("xml-stylesheet", "type='text/xsl href='studentsxsl'");

Element root = docaddElement("students");

Element eltStu1 = rootaddElement("student")addAttribute("sn", "01");

Element eltName1 = eltStu1addElement("name");

Element eltAge1 = eltStu1addElement("age");

eltName1setText("张三");

eltAge1setText("20");

Element eltStu2 = rootaddElement("student")addAttribute("sn", "02");

Element eltName2 = eltStu2addElement("name");

Element eltAge2 = eltStu2addElement("age");

eltName2setText("李四");

eltAge2setText("18");

try {

OutputFormat format = new OutputFormat(" ", true);

formatsetEncoding("gb2312");

// 可以把Systemout改为你要的流。

XMLWriter xmlWriter = new XMLWriter(new PrintWriter(Systemout), format);

xmlWriterwrite(doc);

xmlWriterclose();

} catch (IOException e) {

eprintStackTrace();

}

}

}

我现在刚用的就是jxl的东西。不过，我里面的文件path没有弄好，设了个死的进去啦 package comjincommshare; import javaioFile; import javautilArrayList;import jxlWorkbook; import jxlwriteLabel; import jxlwriteWritableSheet; import jxlwriteWritableWorkbook; import comjinbeansCustomerInfor;public class ExportFile { public void expToXSL(ArrayList datalist, String path)throws Exception{ WritableWorkbook book = WorkbookcreateWorkbook(new File(path)); // 设置表名 WritableSheet sheet = bookcreateSheet("客户信息",0); // 生成表格题头 Label labe1 = new Label(0, 0, "编码" ); Label labe2 = new Label(1, 0, "旅行社简称"); Label labe3 = new Label(2, 0, "销售代表"); Label labe4 = new Label(3, 0, "客户级别"); Label labe5 = new Label(4, 0, "合作情况"); Label labe6 = new Label(5, 0, "类型"); Label labe7 = new Label(6, 0, "可信任值"); Label labe8 = new Label(7, 0, "开始合作日期" ); Label labe9 = new Label(8, 0, "终止合作日期"); Label labe10 = new Label(9, 0, "付款方式"); Label labe11 = new Label(10, 0, "旅行社全称"); Label labe12 = new Label(11, 0, "国家/地区"); Label labe13 = new Label(12, 0, "省/直辖市"); Label labe14 = new Label(13, 0, "城市"); Label labe15 = new Label(14, 0, "街道" ); Label labe16 = new Label(15, 0, "邮政编码"); Label labe17 = new Label(16, 0, "电话"); Label labe18 = new Label(17, 0, "传真"); Label labe19 = new Label(18, 0, "电子邮件"); Label labe20 = new Label(19, 0, "web页地址"); Label labe21 = new Label(20, 0, "开户银行"); Label labe22 = new Label(21, 0, "银行账号" ); Label labe23 = new Label(22, 0, "所属机构"); Label labe24 = new Label(23, 0, "所属部门"); Label labe25 = new Label(24, 0, "维护人"); Label labe26 = new Label(25, 0, "维护时间"); Label labe27 = new Label(26, 0, "备注"); //将生成的单元格添加到工作表中 sheetaddCell(labe1); sheetaddCell(labe2); sheetaddCell(labe3); sheetaddCell(labe4); sheetaddCell(labe5); sheetaddCell(labe6); sheetaddCell(labe7); sheetaddCell(labe8); sheetaddCell(labe9); sheetaddCell(labe10); sheetaddCell(labe11); sheetaddCell(labe12); sheetaddCell(labe13); sheetaddCell(labe14); sheetaddCell(labe15); sheetaddCell(labe16); sheetaddCell(labe17); sheetaddCell(labe18); sheetaddCell(labe19); sheetaddCell(labe20); sheetaddCell(labe21); sheetaddCell(labe22); sheetaddCell(labe23); sheetaddCell(labe24); sheetaddCell(labe25); sheetaddCell(labe26); sheetaddCell(labe27); for(int i=1; i<=datalistsize(); i++){ CustomerInfor infor = (CustomerInfor)datalistget(i-1); Label label1=new Label(0,i,inforgetCode()); Label label2=new Label(1,i,inforgetDepartment()); Label label3=new Label(2,i,inforgetSales()); Label label4=new Label(3,i,inforgetLevel()); Label label5=new Label(4,i,inforgetTecase()); Label label6=new Label(5,i,inforgetTetype()); Label label7=new Label(6,i,inforgetTrust()); Label label8=new Label(7,i,inforgetStarttime()==null null : inforgetStarttime()toString()); Label label9=new Label(8,i,inforgetEndtime()==null null : inforgetEndtime()toString()); Label label10=new Label(9,i,inforgetPaytype() ); Label label11=new Label(10,i,inforgetFullname() ); Label label12=new Label(11,i,inforgetCountry() ); Label label13=new Label(12,i,inforgetProvince() ); Label label14=new Label(13,i,inforgetLocality() ); Label label15=new Label(14,i,inforgetStreet() ); Label label16=new Label(15,i,inforgetPostal() ); Label label17=new Label(16,i,inforgetPhone() ); Label label18=new Label(17,i,inforgetFax() ); Label label19=new Label(18,i,inforgetEmail() ); Label label20=new Label(19,i,inforgetWebsite() ); Label label21=new Label(20,i,inforgetBankname() ); Label label22=new Label(21,i,inforgetBanknum() ); Label label23=new Label(22,i,inforgetInstitution() ); Label label24=new Label(23,i,inforgetIndepart() ); Label label25=new Label(24,i,inforgetKeepby() ); Label label26=new Label(25,i,inforgetKeepday()==null null :inforgetKeepday()toString()); Label label27=new Label(26,i,inforgetComment() ); //将生成的单元格添加到工作表中 sheetaddCell(label1); sheetaddCell(label2); sheetaddCell(label3); sheetaddCell(label4); sheetaddCell(label5); sheetaddCell(label6); sheetaddCell(label7); sheetaddCell(label8); sheetaddCell(label9); sheetaddCell(label10); sheetaddCell(label11); sheetaddCell(label12); sheetaddCell(label13); sheetaddCell(label14); sheetaddCell(label15); sheetaddCell(label16); sheetaddCell(label17); sheetaddCell(label18); sheetaddCell(label19); sheetaddCell(label20); sheetaddCell(label21); sheetaddCell(label22); sheetaddCell(label23); sheetaddCell(label24); sheetaddCell(label25); sheetaddCell(label26); sheetaddCell(label27); } bookwrite(); bookclose(); }

看看下面的代码，应该对你有帮助：

<%@ page import="netExcelBean" %>

<%@ page import="javaio" %>

<%@ page import="netcreateExcelCreateExcelST" %>

<%@ page import="javautil" %>

<%@ page import="comseipherdwrafterServiceDWRFinanceDWR" %>

<%@ page import="netTimeUtil" %>

<%@ page import="netNumberUtil" %>

<%@ page import="comseipherpojoafterServiceDetachCharge" %>

<%@ page import="comseipherpojosystemSetSupplyTrader" %>

<%@ page import="comseipherpojoafterServiceFinance" %>

<%@ page import="comseipherdwrafterServiceDWRAbondDWR" %>

<%@ page import="comseipherpojoafterServiceAbond" %>

<%@ page contentType="text/html;charset=utf-8" language="java" %>

<html>

<head>

<title></title>

</head>

<body>

<%

String supplyName = requestgetParameter("supplyName1");

String usersName = requestgetParameter("usersName1");

String startTimeA = requestgetParameter("startTimeA1");

String endTimeA = requestgetParameter("endTimeA1");

String pageNum = requestgetParameter("pageNum1")toString();

ExcelBean excelBean = new ExcelBean();

CreateExcelST createExcel = new CreateExcelST();

excelBeansetPath("/twoxls");

List dataResult = new ArrayList();

List titleList = new ArrayList();

if (null == pageNum) return;

if (pageNumequals("")) return;

AbondDWR abondDWR = new AbondDWR();

Map form = new HashMap();

formput("supplyName", supplyName);

formput("usersName", usersName);

formput("startTimeA", startTimeA);

formput("endTimeA", endTimeA);

formput("pageNum", pageNum);

List result = abondDWRselectAllByRows(LongparseLong(pageNum), "1", form);

List list = (ArrayList) resultget(0);

titleListadd("供应商名称");

titleListadd("供应商编码");

titleListadd("起始时间");

titleListadd("截止时间");

titleListadd("开票金额");

titleListadd(" *** 作时间");

titleListadd(" *** 作人");

titleListadd("备注");

List dataList;

for (Object o : list) {

dataList = new ArrayList();

Abond abond = (Abond) o;

dataListadd(abondgetSupplyTrader()getName());

dataListadd(abondgetSupplyTrader()getCode());

if (null != abondgetStartTime()) {

String timeA = TimeUtilgetYYYY_MM_DD(abondgetStartTime());

if (null != timeA && !timeAequals("") && !timeAequals("1970-01-01")) {

dataListadd(timeA);

} else {

dataListadd("");

}

} else dataListadd("");

if (null != abondgetEndTime()) {

String timeA = TimeUtilgetYYYY_MM_DD(abondgetEndTime());

if (null != timeA && !timeAequals("") && !timeAequals("1970-01-01")) {

dataListadd(timeA);

} else {

dataListadd("");

}

} else dataListadd("");

dataListadd(abondgetMoney() + "");

if (null != abondgetOperateTime()) {

String timeA = TimeUtilgetYYYYMMDDHHMMSSLiuPC(abondgetOperateTime());

if (null != timeA && !timeAequals("") && !timeAequals("1970-01-01")) {

dataListadd(timeA);

} else {

dataListadd("");

}

} else dataListadd("");

dataListadd(abondgetUsersManage()getName());

dataListadd(abondgetMessages());

dataResultadd(dataList);

}

int[] width = {100, 40, 40, 40, 40, 40, 40, 40};

excelBeansetReportName(startTimeA + "到" + endTimeA + "开票信息查询");

excelBeansetDataList(dataResult);

excelBeansetSheetName(startTimeA + "到" + endTimeA + "开票信息查询");

excelBeansetTitleList(titleList);

excelBeansetColumnWidth(width);

excelBeansetFlag(false);

try {

createExcelcreateExcelFile(excelBean);

} catch (Exception e) {

eprintStackTrace();

}

try {

responsesetContentType("application/x-msdownload");

responseaddHeader("Content-Disposition", "attachment;filename=" + "kaipiaoxinxi" + "xls");

FileInputStream finput = new FileInputStream(excelBeangetPath());

OutputStream output = responsegetOutputStream();

BufferedInputStream buffin = new BufferedInputStream(finput);

BufferedOutputStream buffout = new BufferedOutputStream(output);

outclear();

out = pageContextpushBody();

byte[] buffer = new byte[4096];

int count = 0;

while ((count = buffinread(buffer, 0, bufferlength)) > 0) {

buffoutwrite(buffer, 0, count);

}

buffinclose();

buffoutclose();

finputclose();

outputclose();

} catch (Exception e) {

eprintStackTrace();

} finally {

File srcExcel = new File(excelBeangetPath());

srcExceldelete();

}

%>

</body>

</html>

=============CreateExcelSTjava======================

package netcreateExcel;

import orgapachecommonsloggingLog;

import orgapachecommonsloggingLogFactory;

import orgapachepoihssfusermodel;

import orgapachepoihssfutilRegion;

import orgapachepoihssfutilHSSFColor;

import javautilList;

import javaioFileOutputStream;

import netExcelBean;

/

User: marlboro Date: 2008-2-15 Time: 10:15:38

@author Marlboro

@mailto marlboro027@gmailcom

/

public class CreateExcelST {

private Log log = LogFactorygetFactory()getInstance(thisgetClass()getName());

@SuppressWarnings("unchecked")

public void createExcelFile(ExcelBean excelBean) throws Exception {

// 创建工作薄

HSSFWorkbook wb = new HSSFWorkbook();

HSSFSheet sheet = wbcreateSheet(excelBeangetSheetName());

// 打印页面设置

HSSFPrintSetup ps = sheetgetPrintSetup();

sheetsetMargin(HSSFSheetBottomMargin, 05);// 页边距

sheetsetMargin(HSSFSheetLeftMargin, 01);

sheetsetMargin(HSSFSheetRightMargin, 01);

sheetsetMargin(HSSFSheetTopMargin, 05);

pssetLandscape(true); // 打印方向，true：横向，false：纵向

pssetPaperSize(HSSFPrintSetupA4_PAPERSIZE); // 纸张

// 设置列宽

thissetColumnWidth(sheet, excelBeangetColumnWidth());

// 标题栏设置字体

HSSFFont cellFontReport = wbcreateFont();

cellFontReportsetFontHeightInPoints((short) 16); // 字号

cellFontReportsetBoldweight(HSSFFontU_SINGLE); // 加粗

cellFontReportsetFontName("Courier New");

// 字段栏设置字体

HSSFFont cellFontColumn = wbcreateFont();

cellFontColumnsetFontHeightInPoints((short) 12); // 字号

cellFontColumnsetBoldweight(HSSFFontU_SINGLE); // 加粗

cellFontColumnsetFontName("Courier New");

cellFontColumnsetColor(HSSFFontSS_NONE);

// 设置字体

HSSFFont cellFont = wbcreateFont();

cellFontsetFontHeightInPoints((short) 10); // 字号

cellFontsetBoldweight(HSSFFontU_SINGLE); // 加粗

cellFontsetFontName("Courier New");

//自定义颜色

HSSFPalette palette = wbgetCustomPalette();

palettesetColorAtIndex(HSSFColorAQUAindex, (byte) 252, (byte) 254, (byte) 236);

// 设置标题栏单元格格式

HSSFCellStyle cellStyleReport = wbcreateCellStyle();

cellStyleReportsetFont(cellFontReport);

cellStyleReportsetAlignment(HSSFCellStyleALIGN_CENTER); // 左右居中

cellStyleReportsetVerticalAlignment(HSSFCellStyleVERTICAL_CENTER); // 上下居中

cellStyleReportsetBorderBottom(HSSFCellStyleBORDER_THIN); // 下边框

cellStyleReportsetBorderLeft(HSSFCellStyleBORDER_THIN); // 左边框

cellStyleReportsetBorderRight(HSSFCellStyleBORDER_THIN); // 右边框

cellStyleReportsetBorderTop(HSSFCellStyleBORDER_THIN); // 上边框

cellStyleReportsetWrapText(true);// 自动换行

cellStyleReportsetFillForegroundColor(HSSFColorAQUAindex);

cellStyleReportsetFillPattern(HSSFCellStyleSOLID_FOREGROUND);

// 设置标题栏单元格格式

HSSFCellStyle cellStyleColumn = wbcreateCellStyle();

cellStyleColumnsetFont(cellFontColumn);

cellStyleColumnsetAlignment(HSSFCellStyleALIGN_CENTER); // 左右居中

cellStyleColumnsetVerticalAlignment(HSSFCellStyleVERTICAL_CENTER); // 上下居中

cellStyleColumnsetBorderBottom(HSSFCellStyleBORDER_THIN); // 下边框

cellStyleColumnsetBorderLeft(HSSFCellStyleBORDER_THIN); // 左边框

cellStyleColumnsetBorderRight(HSSFCellStyleBORDER_THIN); // 右边框

cellStyleColumnsetBorderTop(HSSFCellStyleBORDER_THIN); // 上边框

cellStyleColumnsetWrapText(true);// 自动换行

cellStyleColumnsetFillForegroundColor(HSSFColorGREY_25_PERCENTindex);

cellStyleColumnsetFillPattern(HSSFCellStyleSOLID_FOREGROUND);

// 设置单元格格式

HSSFCellStyle cellStyle = wbcreateCellStyle();

cellStylesetFont(cellFont);

cellStylesetAlignment(HSSFCellStyleALIGN_CENTER); // 左右居中

cellStylesetVerticalAlignment(HSSFCellStyleVERTICAL_CENTER); // 上下居中

cellStylesetBorderBottom(HSSFCellStyleBORDER_THIN); // 下边框

cellStylesetBorderLeft(HSSFCellStyleBORDER_THIN); // 左边框

cellStylesetBorderRight(HSSFCellStyleBORDER_THIN); // 右边框

cellStylesetBorderTop(HSSFCellStyleBORDER_THIN); // 上边框

cellStylesetWrapText(true);// 自动换行

List dataList = excelBeangetDataList();

if (null != dataList) {

// 报表的标题

List titleList = excelBeangetTitleList();

// 创建行 设置报表名称

HSSFRow rowReportName = sheetcreateRow(0);

HSSFCell cellReportName = rowReportNamecreateCell((short) 0);

sheetaddMergedRegion(new Region(0, (short) 0, 0, (short) (titleListsize() - 1)));

HSSFRichTextString reportString = new HSSFRichTextString(excelBeangetReportName());

cellReportNamesetCellValue(reportString);

cellReportNamesetCellStyle(cellStyleReport);

HSSFCell endReportName = rowReportNamecreateCell((short) (titleListsize() - 1));

endReportNamesetCellStyle(cellStyleReport);

// 创建行

HSSFRow rowTitle = sheetcreateRow(1);

for (int i = 0; i < titleListsize(); i++) {

String s_title = (String) titleListget(i);

HSSFCell cellx_y = rowTitlecreateCell((short) i);

HSSFRichTextString hssfRichTextString = new HSSFRichTextString(s_title);

// 单元格内容

cellx_ysetCellValue(hssfRichTextString);

// 单元格格式

cellx_ysetCellStyle(cellStyleColumn);

}

// 报表数据

for (int i = 0; i < dataListsize(); i++) {

HSSFRow row = sheetcreateRow(i + 2);

List list_row = (List) dataListget(i);

for (int j = 0; j < list_rowsize(); j++) {

String strtmp = (String) list_rowget(j);

// String strtmp = list_rowget(j)toString();

if (" "equals(strtmp)) {

strtmp = " ";

}

HSSFCell cell = rowcreateCell((short) j);

HSSFRichTextString hssfRichTextString = new HSSFRichTextString(strtmp);

cellsetCellValue(hssfRichTextString);

cellsetCellStyle(cellStyle);

}

}

}

// 另外一个标题

List otherTitleList = excelBeangetOtherTitleList();

if (otherTitleList != null) {

// 创建行

HSSFRow otherRowTitle = sheetcreateRow(dataListsize() + 2);

for (int i = 0; i < otherTitleListsize(); i++) {

String s_title = (String) otherTitleListget(i);

HSSFCell cellx_y = otherRowTitlecreateCell((short) i);

HSSFRichTextString hssfRichTextString = new HSSFRichTextString(s_title);

cellx_ysetCellValue(hssfRichTextString); // 单元格内容

cellx_ysetCellStyle(cellStyle); // 单元格格式

}

// 另外的数据集

List otherDataList = excelBeangetOtherDataList();

// 报表数据

for (int i = 0; i < otherDataListsize(); i++) {

HSSFRow row = sheetcreateRow(dataListsize() + 3 + i);

List list_row = (List) otherDataListget(i);

for (int j = 0; j < list_rowsize(); j++) {

String strtmp = (String) list_rowget(j);

if (" "equals(strtmp)) {

strtmp = " ";

}

HSSFCell cell = rowcreateCell((short) j);

HSSFRichTextString hssfRichTextString = new HSSFRichTextString(strtmp);

cellsetCellValue(hssfRichTextString);

cellsetCellStyle(cellStyle);

}

}

}

try {

FileOutputStream fileOut = new FileOutputStream(excelBeangetPath());

logdebug("===FilePath>>>>>>>>>>>>>>>>>===>>>>>>" + excelBeangetPath());

wbwrite(fileOut);

fileOutclose();

} catch (Exception e) {

throw new Exception("文件已经打开，请关闭后再生成");

}

}

public void setColumnWidth(HSSFSheet sheet, int[] width) {

for (int i = 0; i < widthlength; i++) {

sheetsetColumnWidth((short) i, (short) (width[i] 100));

}

}

}

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