Question

jsp页面如何实现下载文档

Answer 1

jsp页面下载文档是在jsp中有一个a标签 ，当用户点击a标签的时候下载文件。
一般采用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);
}
后台处理下载逻辑的java代码：

/**
* 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();
}
}
}
}

Answer 2

在jsp页面上想把一个字符串写入到文本文件中,并且让用户下载,实现方法如下在网页页面上如下语句&lt;a href=&quot;getData.jsp&quot;&gt;下载数据&lt;/a&gt;getData.jsp如下写&lt;%@ page import=&quot;java.io.OutputStream&quot; %&gt;&lt;%@ page language=&quot;java&quot; contentType=&quot;text/html; charset=UTF-8&quot; pageEncoding=&quot;UTF-8&quot; %&gt;&lt;% String s = &quot;data to be write in the txt file&quot;; OutputStream os = response.getOutputStream(); response.setHeader(&quot;Content-disposition&quot;, &quot;attachment;filename=&quot; + &quot;data.txt&quot;); response.setContentType(&quot;application/txt&quot;); byte[] byteDate = s.toString().getBytes(); os.write(byteDate); os.flush(); os.close();%&gt;这样就行了.