util

package cn.itcast.util;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

public class DownloadUtil {

/**
* @param filePath 要下载的文件路径
* @param returnName 返回的文件名
* @param response HttpServletResponse
* @param delFlag 是否删除文件
*/
protected void download(String filePath,String returnName,HttpServletResponse response,boolean delFlag){
this.prototypeDownload(new File(filePath), returnName, response, delFlag);
}

/**
* @param file 要下载的文件
* @param returnName 返回的文件名
* @param response HttpServletResponse
* @param delFlag 是否删除文件
*/
protected void download(File file,String returnName,HttpServletResponse response,boolean delFlag){
this.prototypeDownload(file, returnName, response, delFlag);
}

/**
* @param file 要下载的文件
* @param returnName 返回的文件名
* @param response HttpServletResponse
* @param delFlag 是否删除文件
*/
public void prototypeDownload(File file,String returnName,HttpServletResponse response,boolean delFlag){
// 下载文件
FileInputStream inputStream = null;
ServletOutputStream outputStream = null;
try {
if(!file.exists()) return;
response.reset();
//设置响应类型 PDF文件为"application/pdf"，WORD文件为："application/msword"， EXCEL文件为："application/vnd.ms-excel"。
response.setContentType("application/octet-stream;charset=utf-8");

//设置响应的文件名称,并转换成中文编码
//returnName = URLEncoder.encode(returnName,"UTF-8");
returnName = response.encodeURL(new String(returnName.getBytes(),"iso8859-1")); //保存的文件名,必须和页面编码一致,否则乱码

//attachment作为附件下载；inline客户端机器有安装匹配程序，则直接打开；注意改变配置，清除缓存，否则可能不能看到效果
response.addHeader("Content-Disposition", "attachment;filename="+returnName);

//将文件读入响应流
inputStream = new FileInputStream(file);
outputStream = response.getOutputStream();
int length = 1024;
int readLength=0;
byte buf[] = new byte[1024];
readLength = inputStream.read(buf, 0, length);
while (readLength != -1) {
outputStream.write(buf, 0, readLength);
readLength = inputStream.read(buf, 0, length);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
outputStream.flush();
} catch (IOException e) {
e.printStackTrace();
}
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
//删除原文件

if(delFlag) {
file.delete();
}
}
}

/**
* by tony 2013-10-17
* @param byteArrayOutputStream 将文件内容写入ByteArrayOutputStream
* @param response HttpServletResponse 写入response
* @param returnName 返回的文件名
*/
public void download(ByteArrayOutputStream byteArrayOutputStream, HttpServletResponse response, String returnName) throws IOException{
response.setContentType("application/octet-stream;charset=utf-8");
returnName = response.encodeURL(new String(returnName.getBytes(),"iso8859-1")); //保存的文件名,必须和页面编码一致,否则乱码
response.addHeader("Content-Disposition", "attachment;filename=" + returnName);
response.setContentLength(byteArrayOutputStream.size());

ServletOutputStream outputstream = response.getOutputStream(); //取得输出流
byteArrayOutputStream.writeTo(outputstream); //写到输出流
byteArrayOutputStream.close(); //关闭
outputstream.flush(); //刷数据
}
}