FileUtils_下载小应用

FileExportUtils

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;

public class FileExportUtils {
	
	private static HttpServletRequest excelRequest = null;
	private static HttpServletResponse excelResponse = null;
	private static FileOutputStream fileOut;
	
	public FileExportUtils(PageContext context) {
		this.excelRequest = (HttpServletRequest) context.getRequest();
		this.excelResponse = (HttpServletResponse) context.getResponse();
	}
	
	public FileExportUtils(HttpServletRequest request,
			HttpServletResponse response) {
		excelRequest = request;
		excelResponse = response;
	}
	
	public void outputTxt(String excelName, String resultStr) {
		//String realPath = "c:\\"+excelName+".xls";
		String realPath = getExcelRealPath(excelName);
		writerFileStream(realPath,resultStr);
		downloadFile(excelName);
	}
	
	private static String getExcelRealPath(String excelName) {
		String realPath = excelRequest.getRealPath("/UploadFile");
		File excelFile = new File(realPath);
		if(!excelFile.exists()) {
			excelFile.mkdirs();
		}
		excelName = realPath+ "\\" + excelName+".txt";
		return  excelName;
	} 
	
	private static void downloadFile(String strfileName) {
		try {
			// 获得ServletContext对象
			if(excelFileNotFund(strfileName)) {
				throw new IllegalArgumentException("File=["+strfileName+"] not fund file path");
			}
			// 取得文件的绝对路径
			File excelFile = getExcelDownloadPath(strfileName);
			putResponseStream(strfileName, excelFile);
		} catch (IOException e) {
			e.printStackTrace();
		} 
	}
	
	/**
	 * 
	 * @param strfileName : 文件名称
	 * @param excelName  : 文件的相对路径或绝对路径
	 * @throws UnsupportedEncodingException
	 * @throws FileNotFoundException
	 * @throws IOException
	 */
	private static void putResponseStream(String strfileName, File excelName)
			throws UnsupportedEncodingException, FileNotFoundException,
			IOException {
		strfileName = URLEncoder.encode(strfileName, "UTF-8");
		excelResponse.setHeader("Content-disposition","attachment; filename=" + strfileName+".txt");
		excelResponse.setContentLength((int) excelName.length());
//		excelResponse.setContentType("application/x-download");
//		excelResponse.setContentType("application/vnd.ms-Excel");
		excelResponse.setContentType("application/x-msdownload");
		byte[] buffer = new byte[4096];
		int i = 0;
		FileInputStream fis = new FileInputStream(excelName);
		while ((i = fis.read(buffer,0,4096)) > 0) {
			JspWriter out = null;
			excelResponse.getOutputStream().write(buffer, 0, i);
		}
		excelResponse.flushBuffer();
	}
	
	//用传入参数的判断
	private static boolean excelFileNotFund(String strfileName) {
		return strfileName ==  null|| strfileName.equals("");
	}
	
	public static File getExcelDownloadPath(String excelName) {
		String realPath = excelRequest.getRealPath("/UploadFile");
		excelName = realPath+ "\\" + excelName+".txt";
		File excelFile = new File(excelName);
		return  excelFile;
	}
	
	/**
	 * 输入当前WorkBook为下载临时文件记录
	 * 
	 * @param excelName
	 */
	public void writerFileStream(String excelName,String resultStr) {
		try {
			fileOut = new FileOutputStream(excelName);
			fileOut.write(resultStr.getBytes());
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				fileOut.flush();
				fileOut.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
	
	public static void main(String[] args) {
		//FileOutputStream fis = new FileOutputStream();
	}
}