# ZXing 应用指南

* [简介](https://hezhiqiang8909.gitbook.io/java/docs/javalib/pages/-LyNWIpJGyl3vAPrr1rW#简介)
* [实战](https://hezhiqiang8909.gitbook.io/java/docs/javalib/pages/-LyNWIpJGyl3vAPrr1rW#实战)
  * [安装](https://hezhiqiang8909.gitbook.io/java/docs/javalib/pages/-LyNWIpJGyl3vAPrr1rW#安装)
  * [生成二维码图片](https://hezhiqiang8909.gitbook.io/java/docs/javalib/pages/-LyNWIpJGyl3vAPrr1rW#生成二维码图片)
  * [解析二维码图片](https://hezhiqiang8909.gitbook.io/java/docs/javalib/pages/-LyNWIpJGyl3vAPrr1rW#解析二维码图片)
* [参考](https://hezhiqiang8909.gitbook.io/java/docs/javalib/pages/-LyNWIpJGyl3vAPrr1rW#参考)

## 简介

`ZXing` 是一个开源 Java 类库用于解析多种格式的 1D/2D 条形码。目标是能够对 QR 编码、Data Matrix、UPC 的 1D 条形码进行解码。 其提供了多种平台下的客户端包括：J2ME、J2SE 和 Android。

官网：[ZXing github 仓库](https://github.com/zxing/zxing)

## 实战

***本例演示如何在一个非 android 的 Java 项目中使用 ZXing 来生成、解析二维码图片。***

### 安装

maven 项目只需引入依赖：

```markup
<dependency>
  <groupId>com.google.zxing</groupId>
  <artifactId>core</artifactId>
  <version>3.3.0</version>
</dependency>
<dependency>
  <groupId>com.google.zxing</groupId>
  <artifactId>javase</artifactId>
  <version>3.3.0</version>
</dependency>
```

如果非 maven 项目，就去官网下载发布版本：[下载地址](https://github.com/zxing/zxing/releases)

### 生成二维码图片

ZXing 生成二维码图片有以下步骤：

1. `com.google.zxing.MultiFormatWriter` 根据内容以及图像编码参数生成图像 2D 矩阵。
2. ​ `com.google.zxing.client.j2se.MatrixToImageWriter` 根据图像矩阵生成图片文件或图片缓存 `BufferedImage` 。

```java
public void encode(String content, String filepath) throws WriterException, IOException {
    int width = 100;
    int height = 100;
    Map<EncodeHintType, Object> encodeHints = new HashMap<EncodeHintType, Object>();
    encodeHints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
    BitMatrix bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, width, height, encodeHints);
    Path path = FileSystems.getDefault().getPath(filepath);
    MatrixToImageWriter.writeToPath(bitMatrix, "png", path);
}
```

### 解析二维码图片

ZXing 解析二维码图片有以下步骤：

1. 使用 `javax.imageio.ImageIO` 读取图片文件，并存为一个 `java.awt.image.BufferedImage` 对象。
2. 将 `java.awt.image.BufferedImage` 转换为 ZXing 能识别的 `com.google.zxing.BinaryBitmap` 对象。
3. `com.google.zxing.MultiFormatReader` 根据图像解码参数来解析 `com.google.zxing.BinaryBitmap` 。

```java
public String decode(String filepath) throws IOException, NotFoundException {
    BufferedImage bufferedImage = ImageIO.read(new FileInputStream(filepath));
    LuminanceSource source = new BufferedImageLuminanceSource(bufferedImage);
    Binarizer binarizer = new HybridBinarizer(source);
    BinaryBitmap bitmap = new BinaryBitmap(binarizer);
    HashMap<DecodeHintType, Object> decodeHints = new HashMap<DecodeHintType, Object>();
    decodeHints.put(DecodeHintType.CHARACTER_SET, "UTF-8");
    Result result = new MultiFormatReader().decode(bitmap, decodeHints);
    return result.getText();
}
```

完整参考示例：[测试例代码](https://github.com/dunwu/JavaParty/blob/master/toolbox/image/src/test/java/org/zp/image/QRCodeUtilTest.java)

以下是一个生成的二维码图片示例：

![img](http://upload-images.jianshu.io/upload_images/3101171-26b73730088f0ab8.png)

## 参考

[ZXing github 仓库](https://github.com/zxing/zxing)


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