轉載記錄:http://www.cnblogs.com/coprince/p/5756422.html
文件下載(四個步驟),java通用
1.設置文件ContentType類型
2.設置文件頭
3.通過response獲取ServletOutputStream對象(out)
4.寫到輸出流(out)中
下載代碼:
這裏使用的是SpringMVC,不過它在這裏的唯一用途就是用來獲取ServletContext對象,這個對象的用途,下面實例中有說明
下載,需要用到兩個jar包:commons-fileupload.jar和commons-io.jar
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.context.ServletContextAware;
import javax.servlet.ServletContext;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
@Controller
public class FileController implements ServletContextAware{
//Spring這裏是通過實現ServletContextAware接口來注入ServletContext對象
private ServletContext servletContext;
@RequestMapping("file/download")
public void fileDownload(HttpServletResponse response){
//獲取網站部署路徑(通過ServletContext對象),用於確定下載文件位置,從而實現下載
String path = servletContext.getRealPath("/");
//1.設置文件ContentType類型,這樣設置,會自動判斷下載文件類型
response.setContentType("multipart/form-data");
//2.設置文件頭:最後一個參數是設置下載文件名(假如我們叫a.pdf)
response.setHeader("Content-Disposition", "attachment;fileName="+"a.pdf");
ServletOutputStream out;
//通過文件路徑獲得File對象(假如此路徑中有一個download.pdf文件)
File file = new File(path + "download/" + "download.pdf");
try {
FileInputStream inputStream = new FileInputStream(file);
//3.通過response獲取ServletOutputStream對象(out)
out = response.getOutputStream();
int b = 0;
byte[] buffer = new byte[512];
while (b != -1){
b = inputStream.read(buffer);
//4.寫到輸出流(out)中
out.write(buffer,0,b);
}
inputStream.close();
out.close();
out.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}
}