Java後臺生成二維碼，前臺實現圖片下載

前臺html代碼展示：

 <div class="col-xs-11 post-control">
              <button class="btn btn-primary" id="userSavePic" type="button" onclick="savePiceture()"><i class="fa fa-save"></i>二維碼下載</button>
                        

 </div>



<script type="text/javascript">
	
			function savePiceture(){
				console.log("1");
				var url ="/areaExt/downloadQrCode";
				window.open("<%=request.getContextPath()%>/areaExt/downloadQrCode");
			}
		
</script>

 

後端Java代碼：

@RequestMapping("/downloadQrCode")
	@ResponseBody
	public void dowanload(HttpServletRequest request,HttpServletResponse response,HttpSession session) throws Exception {
		UserBean userBean = (UserBean) session.getAttribute(SessionDefine.USER);
		String areaCode = userBean.getDefaultArea().getAreaCode();
		String areaName = userBean.getDefaultArea().getAreaName();
		//生成圖片二維碼========================================webSite+"esc/index?zmbh="+1+"&v="+System.currentTimeMillis()
		String imgStr = qrService.createQrCode(webSite+"/html5/jqsq.html?sqbm="+areaCode);
		BASE64Decoder decoder = new BASE64Decoder(); 
        InputStream input = new ByteArrayInputStream(decoder.decodeBuffer(imgStr));
        Image src = ImageIO.read(input);        
		int width = src.getWidth(null);
		int height = src.getHeight(null);  
		BufferedImage image = new BufferedImage(400, 450,BufferedImage.TYPE_INT_RGB);  
		Graphics2D g = image.createGraphics();
		g.drawImage(src, 0, 0, 400, 400, null);
		//帶文字
		//計算文字開始的位置
		//x開始的位置：（圖片寬度-字體大小*字的個數）/2
		g.setColor(new Color(255,255,255));
		int startX = (width-(20*areaName.length()))/2+50;
		//y開始的位置：圖片高度-（圖片高度-圖片寬度）/2
		int startY = 435;    
		Font font=new Font(null, Font.BOLD, 30);
		
		g.setFont(font);

        g.drawString(areaName+"結親二維碼", startX, startY);
		//
		g.dispose();
		//=====================================================
		//步驟一：BufferedImage 轉 InputStream
	    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
	    ImageOutputStream imageOutput = ImageIO.createImageOutputStream(byteArrayOutputStream);
	    ImageIO.write(image, "png", imageOutput);
	    InputStream inputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
	    //步驟二：獲得文件長度
	    long length = imageOutput.length();
		try {
			// 文件名
			String fileName = "二維碼信息-" + TimeUtil.getTime(TimeUtil.getNow(), "yyyy-MM-dd")+".png";
			//設置文件長度
			response.setContentLength((int)length);
			//步驟三：傳入文件名、輸入流、響應
			fileDownload(fileName,inputStream,response);
			
		} catch (Exception e) {
				e.printStackTrace();
		}   
	}
	
	//文件下載方法，工具類
	public static void fileDownload(String filename, InputStream input, HttpServletResponse response){
	    try {
	        byte[] buffer = new byte[input.available()];
	        input.read(buffer);
	        input.close();
	        // 清空response
	        response.reset();
	        // 設置response的Header
	        response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes("utf-8"), "ISO-8859-1"));
	        OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
	        response.setContentType("application/octet-stream");
	        toClient.write(buffer);
	        toClient.flush();
	        //關閉，即下載
	        toClient.close();
	    }catch (Exception e){
	        e.printStackTrace();
	    }
	}

工具類：

//文件下載方法，工具類
	public static void fileDownload(String filename, InputStream input, HttpServletResponse response){
	    try {
	        byte[] buffer = new byte[input.available()];
	        input.read(buffer);
	        input.close();
	        // 清空response
	        response.reset();
	        // 設置response的Header
	        response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes("utf-8"), "ISO-8859-1"));
	        OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
	        response.setContentType("application/octet-stream");
	        toClient.write(buffer);
	        toClient.flush();
	        //關閉，即下載
	        toClient.close();
	    }catch (Exception e){
	        e.printStackTrace();
	    }
	}