DownloadBase64Png

自己用到的时候方便查找，也希望对你有所帮助。

# 二维码下载

## 思路一：

## 思路二：

当然是思路二比较好，不管从哪个方面讲。Z 直接上思路二的代码：

### 环境

```xml

环境：easyui、springmvc、maven

需要的jar

core

3.1.0

commons-codec

commons-codec

1.8

javase

3.3.0

```

### 前端代码

```js

//下载图片

function downloadPng() {

let imgData,

$.ajax({

type: "POST",

url: "后台接口",

async: false,

data: ,

success: function (downloadUrl) {

imgData = 'data:image/png;base64,' + downloadUrl;

}

});

this.downloadFile('二维码.png', imgData);

}

//下载

function downloadFile(fileName, content) {

let aLink = document.createElement('a');

//new Blob([content]);

let blob = this.base64ToBlob(content);

let evt = document.createEvent("HTMLEvents");

//initEvent 不加后两个参数在FF下会报错 事件类型，是否冒泡，是否阻止浏览器的默认行为

evt.initEvent("click", true, true);

aLink.download = fileName;

aLink.href = URL.createObjectURL(blob);

// aLink.dispatchEvent(evt);

aLink.click()

}

//base64转blob

function base64ToBlob(code) {

let parts = code.split(';base64,');

let contentType = parts[0].split(':')[1];

let raw = window.atob(parts[1]);

let rawLength = raw.length;

let uInt8Array = new Uint8Array(rawLength);

for (let i = 0; i

uInt8Array[i] = raw.charCodeAt(i);

}

return new Blob([uInt8Array], );

}

```

### 后台代码

```java

// controller 只需要把base64字符串响应给前端就ok，Z 这里直接给工具类

public class ZXingCode {

/**

* 二维码宽度(默认)

*/

private static final int WIDTH = 300;

/**

* 二维码高度(默认)

*/

private static final int HEIGHT = 300;

/**

* 二维码文件格式

*/

private static final String FORMAT = "png";

/**

* 二维码参数

*/

private static final Map hints = new HashMap();

/**

* 默认是黑色

*/

private static final int QRCOLOR = 0xFF000000;

/**

* 背景颜色

*/

private static final int BGWHITE = 0xFFFFFFFF;

static {

//字符编码

hints.put( EncodeHintType.CHARACTER_SET, "utf-8" );

//容错等级 H为最高

hints.put( EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H );

//边距

hints.put( EncodeHintType.MARGIN, 2 );

}

public static void main(String[] args) {

try {

String a = getLogoQRCode( "https://www.baidu.com/", "跳转到百度的二维码" );

log.info( "------------------:" + a );

} catch (Exception e) {

e.printStackTrace();

}

}

/**

* 生成带logo的二维码图片

*

* @param qrUrl

* @param productName

* @return

*/

public static String getLogoQRCode(String qrUrl, String productName) {

// String filePath = (javax.servlet.http.HttpServletRequest)request.getSession().getServletContext().getRealPath("/") + "resources/static/code/logo.png";

// String filePath = "ClassPath:/resources/static/code/logo.png"; //这个路径有问题，到时候看直接弄绝对路径

//filePath是二维码logo的路径，但是实际中我们是放在项目的某个路径下面的，所以路径用上面的，把下面的注释就好

String filePath = "绝对路径";

String content = qrUrl;

try {

ZXingCode zp = new ZXingCode();

BufferedImage bim = zp.getQR_CODEBufferedImage( content, BarcodeFormat.QR_CODE, 400, 400, zp.getDecodeHintType() );

return zp.addLogo_QRCode( bim, new File( filePath ), new LogoConfig(), productName );

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

/**

* 将二维码图片输出到一个流中

*

* @param content 二维码内容

* @param stream 输出流

* @param width 宽

* @param height 高

*/

public static void writeToStream(String content, OutputStream stream, int width, int height) throws WriterException, IOException {

BitMatrix bitMatrix = new MultiFormatWriter().encode( content, BarcodeFormat.QR_CODE, width, height, hints );

MatrixToImageWriter.writeToStream( bitMatrix, FORMAT, stream );

}

/**

* 给二维码图片添加Logo

*

* @param bim

* @param logoPic

* @param logoConfig

* @param productName

* @return

*/

public String addLogo_QRCode(BufferedImage bim, File logoPic, LogoConfig logoConfig, String productName) {

try {

/**

* 读取二维码图片，并构建绘图对象

*/

BufferedImage image = bim;

Graphics2D g = image.createGraphics();

/**

* 读取Logo图片

*/

BufferedImage logo = ImageIO.read( logoPic );

/**

* 设置logo的大小,本人设置为二维码图片的20%,因为过大会盖掉二维码

*/

int widthLogo = logo.getWidth( null ) > image.getWidth() * 3 / 10 ? (image.getWidth() * 3 / 10) : logo.getWidth( null ), heightLogo =

logo.getHeight( null ) > image.getHeight() * 3 / 10 ? (image.getHeight() * 3 / 10) : logo.getWidth( null );

/**

* logo放在中心

*/

int x = (image.getWidth() - widthLogo) / 2;

int y = (image.getHeight() - heightLogo) / 2;

/**

* logo放在右下角

* int x = (image.getWidth() - widthLogo);

* int y = (image.getHeight() - heightLogo);

*/

//开始绘制图片

g.drawImage( logo, x, y, widthLogo, heightLogo, null );

// g.drawRoundRect(x, y, widthLogo, heightLogo, 15, 15);

// g.setStroke(new BasicStroke(logoConfig.getBorder()));

// g.setColor(logoConfig.getBorderColor());

// g.drawRect(x, y, widthLogo, heightLogo);

g.dispose();

//把商品名称添加上去，商品名称不要太长哦，这里最多支持两行。太长就会自动截取啦

if (productName != null && !productName.equals( "" )) {

//新的图片，把带logo的二维码下面加上文字

BufferedImage outImage = new BufferedImage( 400, 445, BufferedImage.TYPE_4BYTE_ABGR );

Graphics2D outg = outImage.createGraphics();

//画二维码到新的面板

outg.drawImage( image, 0, 0, image.getWidth(), image.getHeight(), null );

//画文字到新的面板

outg.setColor( Color.BLACK );

//字体、字型、字号

outg.setFont( new Font( "宋体", Font.BOLD, 30 ) );

int strWidth = outg.getFontMetrics().stringWidth( productName );

if (strWidth > 399) {

// //长度过长就截取前面部分

// outg.drawString(productName, 0, image.getHeight() + (outImage.getHeight() - image.getHeight())/2 + 5 ); //画文字

//长度过长就换行

String productName1 = productName.substring( 0, productName.length() / 2 );

String productName2 = productName.substring( productName.length() / 2, productName.length() );

int strWidth1 = outg.getFontMetrics().stringWidth( productName1 );

int strWidth2 = outg.getFontMetrics().stringWidth( productName2 );

outg.drawString( productName1, 200 - strWidth1 / 2, image.getHeight() + (outImage.getHeight() - image.getHeight()) / 2 + 12 );

BufferedImage outImage2 = new BufferedImage( 400, 485, BufferedImage.TYPE_4BYTE_ABGR );

Graphics2D outg2 = outImage2.createGraphics();

outg2.drawImage( outImage, 0, 0, outImage.getWidth(), outImage.getHeight(), null );

outg2.setColor( Color.BLACK );

//字体、字型、字号

outg2.setFont( new Font( "宋体", Font.BOLD, 30 ) );

outg2.drawString( productName2, 200 - strWidth2 / 2,

outImage.getHeight() + (outImage2.getHeight() - outImage.getHeight()) / 2 + 5 );

outg2.dispose();

outImage2.flush();

outImage = outImage2;

} else {

//画文字

outg.drawString( productName, 200 - strWidth / 2, image.getHeight() + (outImage.getHeight() - image.getHeight()) / 2 + 12 );

}

outg.dispose();

outImage.flush();

image = outImage;

}

logo.flush();

image.flush();

ByteArrayOutputStream baos = new ByteArrayOutputStream();

baos.flush();

ImageIO.write( image, "png", baos );

/*

二维码生成的路径

*/

ImageIO.write( image, "png", new File(

"绝对路径" + System.currentTimeMillis() + ".png" ) );

BASE64Encoder base64Encoder = new BASE64Encoder();

String imageBase64QRCode = base64Encoder.encode( baos.toByteArray() );

baos.close();

return imageBase64QRCode;

} catch (Exception e) {

e.printStackTrace();

}

return "";

}

/**

* 构建初始化二维码

*

* @param bm

* @return

*/

public BufferedImage fileToBufferedImage(BitMatrix bm) {

BufferedImage image = null;

try {

int w = bm.getWidth(), h = bm.getHeight();

image = new BufferedImage( w, h, BufferedImage.TYPE_INT_RGB );

for (int x = 0; x

for (int y = 0; y

image.setRGB( x, y, bm.get( x, y ) ? 0xFF000000 : 0xFFCCDDEE );

}

}

} catch (Exception e) {

e.printStackTrace();

}

return image;

}

/**

* 生成二维码bufferedImage图片

*

* @param content 编码内容

* @param barcodeFormat 编码类型

* @param width 图片宽度

* @param height 图片高度

* @param hints 设置参数

* @return

*/

public BufferedImage getQR_CODEBufferedImage(String content, BarcodeFormat barcodeFormat, int width, int height, Map hints) {

MultiFormatWriter multiFormatWriter = null;

BitMatrix bm = null;

BufferedImage image = null;

try {

multiFormatWriter = new MultiFormatWriter();

// 参数顺序分别为：编码内容，编码类型，生成图片宽度，生成图片高度，设置参数

bm = multiFormatWriter.encode( content, barcodeFormat, width, height, hints );

int w = bm.getWidth();

int h = bm.getHeight();

image = new BufferedImage( w, h, BufferedImage.TYPE_INT_RGB );

// 开始利用二维码数据创建Bitmap图片，分别设为黑（0xFFFFFFFF）白（0xFF000000）两色

for (int x = 0; x

for (int y = 0; y

image.setRGB( x, y, bm.get( x, y ) ? QRCOLOR : BGWHITE );

}

}

} catch (WriterException e) {

e.printStackTrace();

}

return image;

}

/**

* 设置二维码的格式参数

*

* @return

*/

public Map getDecodeHintType() {

// 用于设置QR二维码参数

Map hints = new HashMap( 16 );

// 设置QR二维码的纠错级别（H为最高级别）具体级别信息

hints.put( EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H );

// 设置编码方式

hints.put( EncodeHintType.CHARACTER_SET, "utf-8" );

hints.put( EncodeHintType.MARGIN, 0 );

hints.put( EncodeHintType.MAX_SIZE, 350 );

hints.put( EncodeHintType.MIN_SIZE, 100 );

return hints;

}

}

class LogoConfig {

// logo默认边框颜色

public static final Color DEFAULT_BORDERCOLOR = Color.WHITE;

// logo默认边框宽度

public static final int DEFAULT_BORDER = 2;

// logo大小默认为照片的1/5

public static final int DEFAULT_LOGOPART = 5;

private final int border = DEFAULT_BORDER;

private final Color borderColor;

private final int logoPart;

/**

* Creates a default config with on color and off color

* , generating normal black-on-white barcodes.

*/

public LogoConfig() {

this( DEFAULT_BORDERCOLOR, DEFAULT_LOGOPART );

}

public LogoConfig(Color borderColor, int logoPart) {

this.borderColor = borderColor;

this.logoPart = logoPart;

}

public Color getBorderColor() {

return borderColor;

}

public int getBorder() {

return border;

}

public int getLogoPart() {

return logoPart;

}

}

```

### 结果：

# 总结：

自己用到的时候方便查找，也希望对你有所帮助。

回复：“博客”，我会告诉你博客网址，可读性比这个可能会好点。

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