java 下载功能的实现

在jsp中有一个a标签 ，当用户点击a标签的时候下载文件。我们采用href属性直接指向一个服务器地址，只要链接的文件存在,就会给出弹出保存对话框.点击a标签 先执行onclick事件，再请求href中指向的地址。前端jsp：<a href="#" onclick="javascript:downloadtest('${app.id}')" id="pluginurl" style="color: #83AFE2;text-decoration:underline;"></a>
然后在js中： function downloadtest(id){
var url = "<%=request.getContextPath()%>/app/download" + "/" + id;
$("#pluginurl").attr("href",url);
}

后台java代码： 我的是springmvc
[java] view plaincopy
/**

* 下载文件

* @param id appid

* @param response

*/

@RequestMapping(value="/download/{id}")

public void download(@PathVariable String id, HttpServletResponse response){

String filepath = "";

Result result = appService.getAppById(id);

App app = (App) result.getMap().get("app");

if(app == null){

return;

}

filepath = app.getUrl();

File file = new File(filepath);

InputStream inputStream = null;

OutputStream outputStream = null;

byte[] b= new byte[1024];

int len = 0;

try {

inputStream = new FileInputStream(file);

outputStream = response.getOutputStream();

response.setContentType("application/force-download");

String filename = file.getName();

filename = filename.substring(36, filename.length());

response.addHeader("Content-Disposition","attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));

response.setContentLength( (int) file.length( ) );

while((len = inputStream.read(b)) != -1){

outputStream.write(b, 0, len);

}

} catch (Exception e) {

e.printStackTrace();

}finally{

if(inputStream != null){

try {

inputStream.close();

inputStream = null;

} catch (IOException e) {

e.printStackTrace();

}

}

if(outputStream != null){

try {

outputStream.close();

outputStream = null;

} catch (IOException e) {

e.printStackTrace();

}

}

}

}

注意：response.addHeader("Content-Disposition","attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));