理解IO：http://www.importnew.com/23708.html
一、读写文件：
FileInputStream
该流用于从文件读取数据，它的对象可以用关键字 new 来创建。
有多种构造方法可用来创建对象。
可以使用字符串类型的文件名来创建一个输入流对象来读取文件：
InputStream f = new FileInputStream("C:/java/hello");
也可以使用一个文件对象来创建一个输入流对象来读取文件。我们首先得使用 File() 方法来创建一个文件对象：
File f = new File("C:/java/hello");
InputStream out = new FileInputStream(f);
FileOutputStream
该类用来创建一个文件并向文件中写数据。
如果该流在打开文件进行输出前，目标文件不存在，那么该流会创建该文件。
有两个构造方法可以用来创建 FileOutputStream 对象。
使用字符串类型的文件名来创建一个输出流对象：
OutputStream f = new FileOutputStream("C:/java/hello")
也可以使用一个文件对象来创建一个输出流来写文件。我们首先得使用File()方法来创建一个文件对象：
File f = new File("C:/java/hello");
OutputStream f = new FileOutputStream(f);
import java.io.*; public class fileStreamTest2{ public static void main(String[] args) throws IOException { File f = new File("a.txt"); // 构建FileOutputStream对象,文件不存在会自动新建 FileOutputStream fop = new FileOutputStream(f); // 构建OutputStreamWriter对象,参数可以指定编码,默认为操作系统默认编码,windows上是gbk OutputStreamWriter writer = new OutputStreamWriter(fop, "UTF-8"); // 写入到缓冲区 writer.append("中文输入"); //换行 writer.append(" "); // 刷新缓存冲,写入到文件,如果下面已经没有写入的内容了,直接close也会写入 writer.append("English"); //关闭写入流,同时会把缓冲区内容写入文件,所以上面的注释掉 writer.close(); // 关闭输出流,释放系统资源 fop.close(); // 构建FileInputStream对象 FileInputStream fip = new FileInputStream(f); // 构建InputStreamReader对象,编码与写入相同 InputStreamReader reader = new InputStreamReader(fip, "UTF-8"); // 转成char加到StringBuffer对象中 StringBuffer sb = new StringBuffer(); while (reader.ready()) { sb.append((char) reader.read()); } System.out.println(sb.toString()); // 关闭读取流 reader.close(); // 关闭输入流,释放系统资源 fip.close(); } }
写文件：
String tPath = request.getSession().getServletContext().getRealPath("/");
FileOutputStream outputStream = null;
try {
if (fileType.equals("doc") || fileType.equals("docx")) {
String folderPath = tPath.substring(0,tPath.lastIndexOf("\")) + "/uploadfiles/conferencefile/"+topicInfo.getId();
tPath = folderPath +"/"+ fileName + "." + fileType;
//--------写入文件内容-----------------
File folder = new File(folderPath);
if(!folder.exists())
{
folder.mkdirs();
}
File file = new File(tPath);
if(!file.exists())
{
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
outputStream = new FileOutputStream(file);
byte[] bytes = Base64.decodeBase64(base64String);
outputStream.write(bytes,0,bytes.length);
//-----------------------------------
}
} catch (Exception e) {
}
finally {
try {
outputStream.close();
} catch (IOException e) {
// TODO 自动生成的 catch 块
e.printStackTrace();
}
}
二、创建目录：
判断文件是否存在
File file = new File(filePath + builder.toString()); if(!file.exists()) { try { file.createNewFile(); } catch (IOException e) { e.printStackTrace(); } }
判断文件夹是否存在
File类中有两个方法可以用来创建文件夹：
- mkdir( )方法创建一个文件夹，成功则返回true，失败则返回false。失败表明File对象指定的路径已经存在，或者由于整个路径还不存在，该文件夹不能被创建。
- mkdirs()方法创建一个文件夹和它的所有父文件夹。
File filePath = new File("D:\Video"); if (!filePath.exists()) { filePath.mkdirs(); }
三、读取目录：
判断是文件夹还是文件
import java.io.File; public class DirList { public static void main(String args[]) { String dirname = "/tmp"; File f1 = new File(dirname); if (f1.isDirectory()) { System.out.println( "目录 " + dirname); String s[] = f1.list(); for (int i=0; i < s.length; i++) { File f = new File(dirname + "/" + s[i]); if (f.isDirectory()) { System.out.println(s[i] + " 是一个目录"); } else { System.out.println(s[i] + " 是一个文件"); } } } else { System.out.println(dirname + " 不是一个目录"); } } }
四、删除目录或文件
删除文件可以使用 java.io.File.delete() 方法。
删除文件及目录
//删除文件及目录 public static void deleteFolder(File folder) { File[] files = folder.listFiles(); if(files!=null) { for(File f: files) { if(f.isDirectory()) { deleteFolder(f); } else { f.delete(); } } } folder.delete(); }
五、读写excel文件
需要jxl.jar jar包支持，jxl.jar好像不支持.xlsx格式excel文件，需要把.xlsx格式的excel文件另存为.xls格式文件
使用poi读取excel文件，HSSFWorkbook与XSSFWorkbook，前一个可以用来解析以.xls结尾的excel，后一个可以用来解析.xlsx结尾的excel
poi:
//读取excel文件内容 List<User> userExcel = new ArrayList<>(); File file = null; try { file = new File(filePath); } catch (Exception e) { responseResult.setMsg("检查文件路径是否正确："+filePath); return responseResult; } FileInputStream fStream = new FileInputStream(file); XSSFWorkbook xss = new XSSFWorkbook(fStream); XSSFSheet sheet = xss.getSheetAt(0); for(int i=0;i<sheet.getLastRowNum();i++) { Row row = sheet.getRow(i); User user = new User(); for(int j=0;j<row.getLastCellNum();j++) { Cell cell = row.getCell(j, Row.CREATE_NULL_AS_BLANK); switch (cell.getCellType()) { case Cell.CELL_TYPE_BLANK: break; case Cell.CELL_TYPE_BOOLEAN: break; case Cell.CELL_TYPE_NUMERIC: // 数值 break; case Cell.CELL_TYPE_STRING: if (i != 0) { String valueStr = cell.getStringCellValue(); if (j == 7) { //登录名 user.setUserLoginNameHY(valueStr); }else if (j == 9) { //身份证 user.setUserCardEncryptionHY(valueStr); } } break; case Cell.CELL_TYPE_ERROR: break; default: break; } } if (i!=0) { userExcel.add(user); } }
jxl:
public void readExcel(File file) { try { //读取excel文件内容 List<ExcelPollution> listPollution = new ArrayList<>(); List<ExcelClinic> listClinic = new ArrayList<>(); // 创建输入流，读取Excel InputStream is = new FileInputStream(file.getAbsolutePath()); // jxl提供的Workbook类 Workbook wb = Workbook.getWorkbook(is); // Excel的页签数量 //int sheet_size = wb.getNumberOfSheets(); //for (int index = 0; index < sheet_size; index++) { // 每个页签创建一个Sheet对象 Sheet sheet = wb.getSheet(0); // sheet.getRows()返回该页的总行数 for (int i = 0; i < sheet.getRows(); i++) { ExcelPollution excelPollution = new ExcelPollution(); // sheet.getColumns()返回该页的总列数 for (int j = 0; j < sheet.getColumns(); j++) { String cellinfo = sheet.getCell(j, i).getContents(); if (j == 0) { excelPollution.setLocation(cellinfo); } else if (j == 1) { String dString = cellinfo; if (i > 0) { dString = "20" + cellinfo.replace("-", "/"); } excelPollution.setDate(dString); } else if (j == 2) { excelPollution.setSO2(cellinfo); } else if (j == 3) { excelPollution.setNO2(cellinfo); } else if (j == 4) { excelPollution.setPM10(cellinfo); } else if (j == 5) { excelPollution.setCO(cellinfo); } else if (j == 6) { excelPollution.setO3(cellinfo); } else if (j == 7) { excelPollution.setPM25(cellinfo); } } listPollution.add(i, excelPollution); } } File file2 = new File("D://Java//DoWork//clinic1.xls"); // 创建输入流，读取Excel InputStream is2 = new FileInputStream(file2.getAbsolutePath()); // jxl提供的Workbook类 Workbook wb2 = Workbook.getWorkbook(is2); // Excel的页签数量 //int sheet_size2 = wb2.getNumberOfSheets(); //for (int index = 0; index < sheet_size2; index++) { // 每个页签创建一个Sheet对象 Sheet sheet2 = wb2.getSheet(1); // sheet.getRows()返回该页的总行数 for (int i = 0; i < sheet2.getRows(); i++) { ExcelClinic excelClinic = new ExcelClinic(); // sheet.getColumns()返回该页的总列数 for (int j = 0; j < sheet2.getColumns(); j++) { String cellinfo = sheet2.getCell(j, i).getContents(); if (j == 0) { excelClinic.setStation(cellinfo); } else if (j == 1) { String dString = cellinfo; if (i > 0) { dString = "20" + cellinfo.replace("-", "/"); } excelClinic.setDate(dString); } else if (j == 2) { excelClinic.setSO2(cellinfo); } else if (j == 3) { excelClinic.setNO2(cellinfo); } else if (j == 4) { excelClinic.setPM10(cellinfo); } else if (j == 5) { excelClinic.setCO(cellinfo); } else if (j == 6) { excelClinic.setO3(cellinfo); } else if (j == 7) { excelClinic.setPM25(cellinfo); } else if (j == 8) { excelClinic.setDiagnose(cellinfo); } else if (j == 9) { excelClinic.setICD_10(cellinfo); } else if (j == 10) { String dString = cellinfo; if (i > 0) { dString = "20" + cellinfo.replace("-", "/"); } excelClinic.setDate_birth(dString); } else if (j == 11) { excelClinic.setAge_0(cellinfo); } else if (j == 12) { excelClinic.setGender(cellinfo); } else if (j == 13) { excelClinic.setAge_1(cellinfo); } else if (j == 14) { String dString = "20" + cellinfo.replace("-", "/"); excelClinic.setDate_discharge(dString); } else if (j == 15) { excelClinic.setRegisted_address(cellinfo); } else if (j == 16) { excelClinic.setAdmission_cost(cellinfo); } else if (j == 17) { excelClinic.setAddress_present(cellinfo); } else if (j == 18) { excelClinic.setICD(cellinfo); } else if (j == 19) { excelClinic.setID(cellinfo); } } listClinic.add(i, excelClinic); } } if (listClinic.size() >0 && listPollution.size() > 0) { for (ExcelClinic clinic : listClinic) { for (ExcelPollution pollution : listPollution) { if (pollution.getLocation().equals(clinic.getStation()) && pollution.getDate().equals(clinic.getDate())) { clinic.setSO2(pollution.getSO2()); clinic.setNO2(pollution.getNO2()); clinic.setPM10(pollution.getPM10()); clinic.setCO(pollution.getCO()); clinic.setO3(pollution.getO3()); clinic.setPM25(pollution.getPM25()); try { if (pollution.getPM10().equals("PM10") && pollution.getPM25().equals("PM2.5")) { clinic.setPMc("PMc"); } else if (!pollution.getPM10().equals("") && !pollution.getPM25().equals("") && pollution.getPM10() != null && pollution.getPM25() != null) { Integer pMc = Integer.parseInt(clinic.getPM25()) - Integer.parseInt(clinic.getPM10()); clinic.setPMc(pMc.toString()); } } catch (Exception e) { e.printStackTrace(); } break; } } } } //按照对象中的date日期进行排序 Collections.sort(listClinic, new Comparator<ExcelClinic>() { @Override public int compare(ExcelClinic o1, ExcelClinic o2) { SimpleDateFormat format = new SimpleDateFormat("yyyy/MM/dd"); try { Date dt1 = format.parse(o1.getDate()); Date dt2 = format.parse(o2.getDate()); if (dt1.getTime() > dt2.getTime()) { return 1; } else if (dt1.getTime() < dt2.getTime()) { return -1; } else { return 0; } } catch (Exception e) { e.printStackTrace(); } return 0; } }); //写入excel文件 try { // 打开文件 WritableWorkbook book = Workbook.createWorkbook(new File("D://Java//DoWork//test.xls")); // 生成名为“sheet1”的工作表，参数0表示这是第一页 WritableSheet sheet = book.createSheet("sheet1", 0); for (int i = 0; i<listClinic.size();i++) { // 在Label对象的构造子中指名单元格位置是第一列第一行(0,0),单元格内容为string Label label0 = new Label(0, i, listClinic.get(i).getStation()); // 将定义好的单元格添加到工作表中 sheet.addCell(label0); Label label1 = new Label(1, i, listClinic.get(i).getDate()); sheet.addCell(label1); Label label2 = new Label(2, i, listClinic.get(i).getSO2()); sheet.addCell(label2); Label label3 = new Label(3, i, listClinic.get(i).getNO2()); sheet.addCell(label3); Label label4 = new Label(4, i, listClinic.get(i).getPM10()); sheet.addCell(label4); Label label5 = new Label(5, i, listClinic.get(i).getCO()); sheet.addCell(label5); Label label6 = new Label(6, i, listClinic.get(i).getO3()); sheet.addCell(label6); Label label7 = new Label(7, i, listClinic.get(i).getPM25()); sheet.addCell(label7); Label label8 = new Label(8, i, listClinic.get(i).getPMc()); sheet.addCell(label8); Label label9 = new Label(9, i, listClinic.get(i).getDiagnose()); sheet.addCell(label9); Label label10 = new Label(10, i, listClinic.get(i).getICD_10()); sheet.addCell(label10); Label label11 = new Label(11, i, listClinic.get(i).getDate_birth()); sheet.addCell(label11); Label label12 = new Label(12, i, listClinic.get(i).getAge_0()); sheet.addCell(label12); Label label13 = new Label(13, i, listClinic.get(i).getGender()); sheet.addCell(label13); Label label14 = new Label(14, i, listClinic.get(i).getAge_1()); sheet.addCell(label14); Label label15 = new Label(15, i, listClinic.get(i).getDate_discharge()); sheet.addCell(label15); Label label16 = new Label(16, i, listClinic.get(i).getRegisted_address()); sheet.addCell(label16); Label label17 = new Label(17, i, listClinic.get(i).getAdmission_cost()); sheet.addCell(label17); Label label18 = new Label(18, i, listClinic.get(i).getAddress_present()); sheet.addCell(label18); Label label19 = new Label(19, i, listClinic.get(i).getICD()); sheet.addCell(label19); Label label20 = new Label(20, i, listClinic.get(i).getID()); sheet.addCell(label20); } // 写入数据并关闭文件 book.write(); book.close(); } catch (Exception e) { System.out.println(e); } } catch (Exception e) { e.printStackTrace(); } }
六、读取文件内容：
org.apache.commons.codec.binary.Base64 String path = tPath.substring(0,tPath.lastIndexOf("\")) + file.getUrl(); File f = new File(path); InputStream iStream = new FileInputStream(f); byte[] bytes = new byte[(int)f.length()];//或new byte[iStream.available()] iStream.read(bytes); String content = new String(Base64.encodeBase64(bytes),"utf-8"); iStream.close(); //------------------------------------------------------------------------------
InputStream inputStream = new BufferedInputStream(new FileInputStream(file)); InputStreamReader iReader = new InputStreamReader(inputStream); char len; while (iReader.ready()) { len = (char) iReader.read(); String string2 = String.valueOf(len); ss += string2; } inputStream.close(); iReader.close();
问题：
1、代码调试正常，发布war包在tomcat运行，读取html页面内容出现乱码：
原因：读取的时候，编码没有设置（修改为UTF-8读取）
例：
OutputStreamWriter bw = null; FileOutputStream fop = null; BufferedReader br =null; InputStreamReader isr=null; FileInputStream fis=null; File file = new File(filename); fop = new FileOutputStream(file); bw = new OutputStreamWriter(fop, "UTF-8");
..... File fileR = new File(fromPath); fis = new FileInputStream(fileR); isr = new InputStreamReader(fis, "UTF-8"); br = new BufferedReader(isr); String tempStr; String len=""; while((tempStr = br.readLine()) != null)
{
len += tempStr;
}
// 关闭输入流,释放系统资源
iStream.close();
iReader.close();
br.close();
效率较高：
InputStream inputStream = null; BufferedInputStream input = null; ByteArrayOutputStream outputStream = null; try { inputStream = ftpClient.retrieveFileStream(fileName); input = new BufferedInputStream(inputStream); outputStream = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int len = -1; while ((len=input.read(buffer))!=-1){ outputStream.write(buffer,0,len); } xmlStr = new String( outputStream.toByteArray(),"GBK"); }
bufferedInputStream = new BufferedInputStream(inputStream); byte[] bytes = new byte[inputStream.available()]; bufferedInputStream.read(bytes); xmlStr = new String(bytes,"GBK");
int len; while ((len = bInputStream.read(bytes)) != -1){ outputStream.write(bytes,0,len); }
BASE64Encoder encoder = new BASE64Encoder();
String base64Str = encoder.encode(outputStream.toByteArray());
效率较低：
String len; while ((len = bufferedReader.readLine()) != null){ xmlStr += len; }