写Java程序时经常碰到要读如txt或写入txt文件的情况，但是由于要定义好多变量，经常记不住，每次都要查，特此整理一下，简单易用，方便好懂！
[java] view plain copypackage edu.thu.keyword.test
import java.io.File
import java.io.InputStreamReader
import java.io.BufferedReader
import java.io.BufferedWriter
import java.io.FileInputStream
import java.io.FileWriter
public class cin_txt {
static void main(String args[]) {
try { // 防止文件建立或读取失败，用catch捕捉错误并打印，也可以throw
/* 读入TXT文件 */
String pathname = "D:\\twitter\\13_9_6\\dataset\\en\\input.txt" // 绝对路径或相对路径都可以，这里是绝对路径，写入文件时演示相对路径
File filename = new File(pathname) // 要读取以上路径的input。txt文件
InputStreamReader reader = new InputStreamReader(
new FileInputStream(filename)) // 建立一个输入流对象reader
BufferedReader br = new BufferedReader(reader) // 建立一个对象，它把文件内容转成计算机能读懂的语言
String line = ""
line = br.readLine()
while (line != null) {
line = br.readLine() // 一次读入一行数据
}
/* 写入Txt文件 */
File writename = new File(".\\result\\en\\output.txt") // 相对路径，如果没有则要建立一个新的output。txt文件
writename.createNewFile() // 创建新文件
BufferedWriter out = new BufferedWriter(new FileWriter(writename))
out.write("我会写入文件啦\r\n") // \r\n即为换行
out.flush() // 把缓存区内容压入文件
out.close() // 最后记得关闭文件
} catch (Exception e) {
e.printStackTrace()
}
}
}
不管你用什么东东，你下文件总得给出文件地址或者文件参数再下载，所以本质上没太多区别。你的逻辑是从数据库拿数据然后生成文件，然后再下载；
首先你得把数据拿出来，然后用io类生成临时文件，如果为了偷懒，想直接给个url就完了，那就把文件生在工程根目录下比如：proname/downtemp/1234.doc
然后把绝对路径给出，就可以下载了 ，这中间可能要跳转一下，因为你是临时产生，不是直接下载。
第一个类：package totabel.action
import java.awt.event.ActionEvent
import java.awt.event.ActionListener
import javax.swing.JOptionPane
import topdf.TableToPdf
import totabel.view.TabelData
import totabel.xls.ExcelDemo
public class TableAction implements ActionListener {
TabelData data
public TableAction(TabelData data) {
this.data = data
}
public void actionPerformed(ActionEvent e) {
String str = e.getActionCommand()
if ("添加".equals(str)) {
data.addData()
} else if ("导出到Excel".equals(str)) {
ExcelDemo demo = new ExcelDemo()
demo.method(data)
} else if ("删除".equals(str)) {
if (data.getRow() != -1) {
data.delRow()
} else {
JOptionPane.showMessageDialog(null, "请选择要删除的行！")
}
}else if("从Excel导入".equals(str)){
data.getXlsInfo()
}else if("从Excel导入到数据库".equals(str)){
data.toDb()
}else if("从table导出到pdf".equals(str)){
TableToPdf pdf=new TableToPdf()
pdf.newPage(data)
}else if("计算学分".equals(str)){
data.getXlsInfoToCredit()
}
}
}
第二个类：数据库连接
package totabel.db
import java.sql.Connection
import java.sql.DriverManager
import java.sql.ResultSet
import java.sql.SQLException
import java.sql.Statement
public class JdbcConnection {
private static JdbcConnection con
public static JdbcConnection getCon() {
if (con == null) {
con = new JdbcConnection()
}
return con
}
public Connection getConnection() {
Connection connection=null
try {
Class.forName("oracle.jdbc.OracleDriver")
String url = "jdbc:oracle:thin:@127.0.0.1:1521:oracle"
String user = "scott"
String password = "tiger"
connection = DriverManager.getConnection(url, user,
password)
} catch (ClassNotFoundException e) {
e.printStackTrace()
} catch (SQLException e) {
e.printStackTrace()
}
return connection
}
// public static void main(String[] args) {
// JdbcConnection connection=new JdbcConnection()
// connection.getConnection("asd", "99")
// }
}
第三个类：主类（入口）
package totabel.db
import java.sql.Connection
import java.sql.DriverManager
import java.sql.ResultSet
import java.sql.SQLException
import java.sql.Statement
public class JdbcConnection {
private static JdbcConnection con
public static JdbcConnection getCon() {
if (con == null) {
con = new JdbcConnection()
}
return con
}
public Connection getConnection() {
Connection connection=null
try {
Class.forName("oracle.jdbc.OracleDriver")
String url = "jdbc:oracle:thin:@127.0.0.1:1521:oracle"
String user = "scott"
String password = "tiger"
connection = DriverManager.getConnection(url, user,
password)
} catch (ClassNotFoundException e) {
e.printStackTrace()
} catch (SQLException e) {
e.printStackTrace()
}
return connection
}
// public static void main(String[] args) {
// JdbcConnection connection=new JdbcConnection()
// connection.getConnection("asd", "99")
// }
}
第四个类：
package totabel.xls
import java.io.File
import java.io.IOException
import java.util.Vector
import java.util.regex.Matcher
import java.util.regex.Pattern
import javax.swing.JOptionPane
import totabel.view.TabelData
import jxl.Cell
import jxl.Sheet
import jxl.Workbook
import jxl.read.biff.BiffException
import jxl.write.Label
import jxl.write.WritableSheet
import jxl.write.WritableWorkbook
import jxl.write.WriteException
import jxl.write.biff.RowsExceededException
public class ExcelDemo {
/**
*
* @param args
*/
private Vector title = new Vector()
private Vector[] array
// public static void main(String[] args) {
// ExcelDemo demo = new ExcelDemo()
// demo.getXlsInfo()
//
// }
public void method(TabelData table) {
int row = table.getRowSize()
int column = table.getColumnSize()
WritableWorkbook book = null
Vector title = table.setTitle()
Object[] str = title.toArray()
try {
book = Workbook.createWorkbook(new File("test.xls"))
WritableSheet sheet = book.createSheet("成绩表", 0)
for (int i = 0i <str.lengthi++) {
sheet.addCell(new Label(i, 0, (String) str[i]))
}
for (int i = 1i <row + 1i++) {
for (int j = 1j <column + 1j++) {
sheet.addCell(new Label(j - 1, i, table.getTableInfo(i - 1,
j - 1)))
}
}
book.write()
JOptionPane.showMessageDialog(null, "导出完成！")
} catch (IOException e) {
e.printStackTrace()
} catch (RowsExceededException e) {
e.printStackTrace()
} catch (WriteException e) {
e.printStackTrace()
} finally {
try {
book.close()
} catch (WriteException e) {
e.printStackTrace()
} catch (IOException e) {
e.printStackTrace()
}
}
}
/**
* 输出Excel的数据到表单
*
* @return
*/
public Vector getXlsInfo() {
Vector v = new Vector()
jxl.Workbook rwb = null
int index = 0
try {
rwb = jxl.Workbook.getWorkbook(new File("test.xls"))
Sheet[] sheet = rwb.getSheets()
for (int i = 0i <sheet.lengthi++) {
int rs = sheet[i].getRows()
array = new Vector[rs - 1]
for (int j = 1j <rsj++) {
Cell[] cell = sheet[i].getRow(j)
Vector info = new Vector()
for (int k = 0k <cell.lengthk++) {
info.add(cell[k].getContents())
}
array[index] = info
index++
v.add(info)
}
Cell[] titleCell = sheet[i].getRow(0)
for (int j = 0j <titleCell.lengthj++) {
title.add(titleCell[j].getContents())
}
}
} catch (BiffException e) {
e.printStackTrace()
} catch (IOException e) {
e.printStackTrace()
} finally {
rwb.close()
}
return v
}
public Vector getXlsInfoToCredit() {
Vector v = new Vector()
jxl.Workbook rwb = null
try {
rwb = jxl.Workbook.getWorkbook(new File("d:/test/信科0821（南迁）.xls"))
Sheet[] sheet = rwb.getSheets()
for (int i = 0i <sheet.lengthi++) {
int rs = sheet[i].getRows()
array = new Vector[rs - 1]
for (int j = 1j <rsj++) {
Cell[] cell = sheet[i].getRow(j)
Vector info = new Vector()
for (int k = 0k <cell.lengthk++) {
// if(){
Pattern p = Pattern.compile("[0-9]{1,}")
Matcher m = p.matcher(cell[k].getContents())
if (m.matches()) {
int score = Integer.valueOf(cell[k].getContents())
float result = getScore(score)
info.add(result)
} else {
info.add(cell[k].getContents())
}
}
v.add(info)
}
Cell[] titleCell = sheet[i].getRow(0)
for (int j = 0j <titleCell.lengthj++) {
title.add(titleCell[j].getContents())
}
}
} catch (BiffException e) {
e.printStackTrace()
} catch (IOException e) {
e.printStackTrace()
} finally {
rwb.close()
}
return v
}
public float getScore(int n) {
float score = n
if (n <60) {
score = 0
return score
} else {
if (n >= 60 &&n <= 63) {
score = (float) 1.0
} else if (n >= 64 &&n <= 67) {
score = (float) 1.3
} else if (n >= 68 &&n <= 71) {
score = (float) 1.7
} else if (n >= 72 &&n <= 75) {
score = (float) 2.0
} else if (n >= 76 &&n <= 79) {
score = (float) 2.3
} else if (n >= 80 &&n <= 83) {
score = (float) 2.7
} else if (n >= 84 &&n <= 87) {
score = (float) 3.0
} else if (n >= 88 &&n <= 91) {
score = (float) 3.3
} else if (n >= 92 &&n <= 95) {
score = (float) 3.7
} else if (n >= 96 &&n <= 100) {
score = (float) 4.0
}
return score
}
}
public Vector getTitle() {
// getXlsInfo()
return title
}
public Vector[] getArray() {
getXlsInfo()
return array
}
}
因为时间问题就没有再写了，上面是我以前做的，不懂就q我
欢迎分享，转载请注明来源：内存溢出
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