java 常用工具类

ApplicationContextUtils
从 springBean 中，获取 Bean

场景

如果要在一个没有被 spring 托管的类中使用 RedisTemplate 等 需要 @Autowired 自动注入的类, 那么就得用这种方式从 spring 容器中获取需要的 bean

/**

• 用来获取 springboot 创建好的工厂
  /
  @Component
  public class ApplicationContextUtils implements ApplicationContextAware {
  /*
  • 用这个变量保留工厂
    /
    private static ApplicationContext applicationContext;
    /*
  • 将创建好的工厂 以参数的形式传递给这个类
  • @param context 创建好的工厂
    /
    @Override
    public void setApplicationContext(ApplicationContext context) throws BeansException {
    applicationContext = context;
    }
    /*
  • 通过 bean 的名称从工厂中获取对象的方法
  • @param beanName bean的名称

    举例：getBean(redisTemplate)  就能获取 RedisTemplate 对象

    */
    public static Object getBean(String beanName) {
    return applicationContext.getBean(beanName);
    }
    }

JWTUtils
封装了生成 jwt 和验证 jwt 的工具类

jwt 相关的依赖选用 java-jwt
RabbitMQUtils
/**

• 获取连接对象和释放资源(关闭通道和关闭连接)
  /
  public class RabbitMQUtil {
  private static final ConnectionFactory factory;
  static {
  factory = new ConnectionFactory();
  // 设置连接 rabbitmq 主机
  factory.setHost(“xx.xx.xx.xx”);
  // 端口号
  factory.setPort(5672);
  // 设置连接哪个虚拟主机 ems
  factory.setVirtualHost(“/xxx”);
  // 设置访问虚拟主机的用户名和密码
  factory.setUsername(“xxx”);
  factory.setPassword(“xxx”);
  }
  /*
  • 定义提供连接对象的方法
  • Connection 获取连接对象
    /
    public static Connection getConnection() {
    try {
    return factory.newConnection();
    } catch (IOException | TimeoutException e) {
    e.printStackTrace();
    }
    return null;
    }
    /*
  • 关闭通道和关闭连接工具
    */
    public static void closeChannelAndConnection(Channel channel, Connection conn) {
    try {
    if (channel != null) {
    channel.close();
    }
    if (conn != null) {
    conn.close();
    }
    } catch (IOException | TimeoutException e) {
    e.printStackTrace();
    }
    }
    }

VerificationCodeUtils
验证码生成工具类

/**

• 生成验证码的工具类
  /
  public class VerificationCode {
  private final int WIDTH = 100;// 生成验证码图片的宽度
  private final int HEIGHT = 30;// 生成验证码图片的高度
  private final String[] FONT_NAMES = {“宋体”, “楷体”, “隶书”, “微软雅黑”};
  private final Color BG_COLOR = new Color(255, 255, 255);// 定义验证码图片的背景颜色为白色
  private Random random = new Random();
  private String text;// 记录随机字符串
  /*
  • 获取一个随意颜色
    /
    private Color randomColor() {
    int red = random.nextInt(150);
    int green = random.nextInt(150);
    int blue = random.nextInt(150);
    return new Color(red, green, blue);
    }
    /*
  • 获取一个随机字体
    /
    private Font randomFont() {
    String name = FONT_NAMES[random.nextInt(FONT_NAMES.length)];
    int style = random.nextInt(4);
    int size = random.nextInt(5) + 24;
    return new Font(name, style, size);
    }
    /*
  • 获取一个随机字符
    /
    private char randomChar() {
    String codes = “0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ”;
    return codes.charAt(random.nextInt(codes.length()));
    }
    /*
  • 创建一个空白的BufferedImage对象
    /
    private BufferedImage createImage() {
    BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPEINT_RGB);
    Graphics2D g2 = (Graphics2D) image.getGraphics();
    g2.setColor(BG_COLOR);// 设置验证码图片的背景颜色
    g2.fillRect(0, 0, WIDTH, HEIGHT);
    return image;
    }
    public BufferedImage getImage() {
    BufferedImage image = createImage();
    Graphics2D g2 = (Graphics2D) image.getGraphics();
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < 4; i++) {
    String s = randomChar() + “”;
    sb.append(s);
    g2.setColor(randomColor());
    g2.setFont(randomFont());
    float x = i WIDTH _ 1.0f / 4;
    g2.drawString(s, x, HEIGHT - 8);
    }
    this.text = sb.toString();
    drawLine(image);
    return image;
    }
    /*
  • 绘制干扰线
    */
    private void drawLine(BufferedImage image) {
    Graphics2D g2 = (Graphics2D) image.getGraphics();
    int num = 5;
    for (int i = 0; i < num; i++) {
    int x1 = random.nextInt(WIDTH);
    int y1 = random.nextInt(HEIGHT);
    int x2 = random.nextInt(WIDTH);
    int y2 = random.nextInt(HEIGHT);
    g2.setColor(randomColor());
    g2.setStroke(new BasicStroke(1.5f));
    g2.drawLine(x1, y1, x2, y2);
    }
    }
    public String getText() {
    return text;
    }
    public static void output(BufferedImage image, OutputStream out) throws IOException {
    ImageIO.write(image, “JPEG”, out);
    }
    }
    使用该工具类

以一个提供验证码的 Controller 为例

@GetMapping(“/verifyCode”)
public void verifyCode(HttpSession session, HttpServletResponse response) throws IOException {
// 实例化对象
VerificationCode code = new VerificationCode();
// 获取验证码图片
BufferedImage image = code.getImage();
// 获取验证码的字符串
String text = code.getText();
// 将验证码字符串存到 session
session.setAttribute(“verify_code”, text);
// 将图片通过流, 传到前端页面
VerificationCode.output(image, response.getOutputStream());
}

验证码(kaptcha)
可以用 kaptcha 生成验证码

步骤：

导入依赖
@Configuration
public class VerifyCodeConfig {
@Bean
Producer verifyCode() {
// 保存配置
Properties properties = new Properties();
// 宽度
properties.setProperty(“kaptcha.image.width”, “150”);
// 高度
properties.setProperty(“kaptcha.image.height”, “50”);
// 里面包含那些字符
properties.setProperty(“kaptcha.textproducer.char.string”, “0123456789”);
// 长度
properties.setProperty(“kaptcha.textproducer.char.length”, “4”);
// 实例化 DefaultKaptcha
DefaultKaptcha defaultKaptcha = new DefaultKaptcha();
// 写入上面的配置
defaultKaptcha.setConfig(new Config(properties));
return defaultKaptcha;
}
}
接口

@Autowired
Producer producer;
@GetMapping(“/vf”)
public void getVerifyCode(HttpServletResponse response, HttpSession session) throws IOException {
response.setContentType(“image/jpeg”);
// 获取验证码的文本
String text = producer.createText();
// 将验证码文本写入 session
session.setAttribute(“verifyCode”, text);
// 把验证码文本转换成图片格式 并获取流
BufferedImage bi = producer.createImage(text);
// 把图片验证码写到前端
try(ServletOutputStream out = response.getOutputStream()) {
ImageIO.write(bi, “jpg”, out);
}
}
在 SpringSecurityConfig中设置所有人都可以访问

@Override
protected void configure(HttpSecurity http) throws Exception {
http.authorizeRequests()
.antMatchers(“/vf”).permitAll();