Java后台生成二维码，前台实现图片下载

布满荆棘的人生 2023-02-09 14:17 5阅读 0赞

# 前台html代码展示： #

<div class="col-xs-11 post-control">
                  <button class="btn btn-primary" id="userSavePic" type="button" onclick="savePiceture()"><i class="fa fa-save"></i>二维码下载</button>
                            
    
     </div>
    
    
    
    <script type="text/javascript">
    	
    			function savePiceture(){
    				console.log("1");
    				var url ="/areaExt/downloadQrCode";
    				window.open("<%=request.getContextPath()%>/areaExt/downloadQrCode");
    			}
    		
    </script>

# 后端Java代码： #

@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();
    		//生成图片二维码========================================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);
    		//带文字
    		//计算文字开始的位置
    		//x开始的位置：（图片宽度-字体大小*字的个数）/2
    		g.setColor(new Color(255,255,255));
    		int startX = (width-(20*areaName.length()))/2+50;
    		//y开始的位置：图片高度-（图片高度-图片宽度）/2
    		int startY = 435;    
    		Font font=new Font(null, Font.BOLD, 30);
    		
    		g.setFont(font);
    
            g.drawString(areaName+"结亲二维码", startX, startY);
    		//
    		g.dispose();
    		//=====================================================
    		//步骤一：BufferedImage 转 InputStream
    	    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    	    ImageOutputStream imageOutput = ImageIO.createImageOutputStream(byteArrayOutputStream);
    	    ImageIO.write(image, "png", imageOutput);
    	    InputStream inputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
    	    //步骤二：获得文件长度
    	    long length = imageOutput.length();
    		try {
    			// 文件名
    			String fileName = "二维码信息-" + TimeUtil.getTime(TimeUtil.getNow(), "yyyy-MM-dd")+".png";
    			//设置文件长度
    			response.setContentLength((int)length);
    			//步骤三：传入文件名、输入流、响应
    			fileDownload(fileName,inputStream,response);
    			
    		} catch (Exception e) {
    				e.printStackTrace();
    		}   
    	}
    	
    	//文件下载方法，工具类
    	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();
    	        // 设置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();
    	        //关闭，即下载
    	        toClient.close();
    	    }catch (Exception e){
    	        e.printStackTrace();
    	    }
    	}

工具类：

//文件下载方法，工具类
    	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();
    	        // 设置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();
    	        //关闭，即下载
    	        toClient.close();
    	    }catch (Exception e){
    	        e.printStackTrace();
    	    }
    	}