Category Archives: Java

HBase Client 2.5.5 in JDK 11

Posted on 2023 年 10 月 02 日 by cowman.chiang

Because of the vulnerability scan results of the project, the JDK version must be upgraded from 8 to 11 to complete the repair. The original HBase Client version 1.2 we used was incompatible with JDK 11, so we had to … Continue reading →

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[Java] Create CSV files with BOM

Posted on 2023 年 03 月 10 日 by cowman.chiang

public static final String UTF8_BOM = "\uFEFF";

public ByteArrayInputStream createFile(Object object) {
    try {
        CSV csv = (CSV) object;
        StringBuffer sb = new StringBuffer();
        sb.append(UTF8_BOM);

        if (csv.getHeaderList() != null) {
            sb.append(StringUtils.join(csv.getHeaderList().toArray(new String[0]), ",")).append("\n");
        }

        for (List&lt;String&gt; row : csv.getDataList()) {
            sb.append(StringUtils.join(row.toArray(new String[0]), ",")).append("\n");
        }

        return new ByteArrayInputStream(sb.toString().getBytes("UTF-8"));
    } catch (Exception e) {
        return null;
    }
}

public static final String UTF8_BOM = "\uFEFF";

public ByteArrayInputStream createFile(Object object) {

try {

CSV csv = (CSV) object;

StringBuffer sb = new StringBuffer();

sb.append(UTF8_BOM);

if (csv.getHeaderList() != null) {

sb.append(StringUtils.join(csv.getHeaderList().toArray(new String[0]), ",")).append("\n");

}

for (List<String> row : csv.getDataList()) {

sb.append(StringUtils.join(row.toArray(new String[0]), ",")).append("\n");

}

return new ByteArrayInputStream(sb.toString().getBytes("UTF-8"));

} catch (Exception e) {

return null;

}

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[Java] Google authenticator

Posted on 2023 年 02 月 22 日 by cowman.chiang

Reference: 1. Greddy’s Blogs: Google Authenticator實作 2. 菜鳥工程師肉豬: Spring Boot 使用Google身分驗證器做TOTP驗證 Google Authenticator TOTP auth

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[Java] Download file without saving

Posted on 2023 年 02 月 17 日 by cowman.chiang

Source: CSDN: InputStream类available和read方法可能读取不到完整的流数据 stackoverflow: How to read a http file inmemory without saving on local drive?

private static InputStream download(String sourceURL) throws Exception {
        InputStream inputStream = new URL(sourceURL).openStream();
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        byte[] buffer = new byte[4096];
        int n = 0;
        while (-1 != (n = inputStream.read(buffer))) {
            output.write(buffer, 0, n);
        }
        return new ByteArrayInputStream(output.toByteArray());
}

private static InputStream download(String sourceURL) throws Exception {

InputStream inputStream = new URL(sourceURL).openStream();

ByteArrayOutputStream output = new ByteArrayOutputStream();

byte[] buffer = new byte[4096];

int n = 0;

while (-1 != (n = inputStream.read(buffer))) {

output.write(buffer, 0, n);

}

return new ByteArrayInputStream(output.toByteArray());

}

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[Java] String with number format

Posted on 2023 年 01 月 07 日 by cowman.chiang

Reference

public static void main(String[] args) throws Exception {
    String number = "1000500000";
    double amount = Double.parseDouble(number);
    DecimalFormat intFormatter = new DecimalFormat("#,###");
    DecimalFormat floatFormatter = new DecimalFormat("#,###.00");

    System.out.println("==int==");
    System.out.println(intFormatter.format(amount));
    System.out.println(String.format("%,d", Integer.parseInt((number))));
    System.out.println(number.replaceAll("(\\d)(?=(\\d{3})+$)", "$1,"));

    System.out.println("==float==");
    System.out.println(floatFormatter.format(amount));
    System.out.println(String.format("%,.2f", Float.parseFloat((number))));
}


==int==
1,000,500,000
1,000,500,000
1,000,500,000
==float==
1,000,500,000.00
1,000,499,968.00

public static void main(String[] args) throws Exception {

String number = "1000500000";

double amount = Double.parseDouble(number);

DecimalFormat intFormatter = new DecimalFormat("#,###");

DecimalFormat floatFormatter = new DecimalFormat("#,###.00");

System.out.println("==int==");

System.out.println(intFormatter.format(amount));

System.out.println(String.format("%,d", Integer.parseInt((number))));

System.out.println(number.replaceAll("(\\d)(?=(\\d{3})+$)", "$1,"));

System.out.println("==float==");

System.out.println(floatFormatter.format(amount));

System.out.println(String.format("%,.2f", Float.parseFloat((number))));

}

==int==

1,000,500,000

==float==

1,000,500,000.00

1,000,499,968.00

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[Java] Mask some part of String

Posted on 2023 年 01 月 06 日 by cowman.chiang

Reference: [stackoverflow] Mask some part of String

return String.replaceAll("\\b(\\d{3})\\d+(\\d{3})", "$1****$2");  
# 1234567890 =&gt; 123****890

return String.replaceAll("\\b(\\d{3})\\d+(\\d{3})", "$1****$2");

# 1234567890 => 123****890

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[Java] Append string with adaptive font size to image

Posted on 2021 年 05 月 04 日 by cowman.chiang

Ref: https://blog.csdn.net/zengrenyuan/article/details/80281738

public static ByteArrayOutputStream encodeWithWaterMark(String content) {
    if (FRONT_IMAGE == null) {
        return encode(content);
    }

    ByteArrayOutputStream os = null;

    try {
        BitMatrix matrix = new QRCodeWriter().encode(content, BarcodeFormat.QR_CODE, WIDTH, HEIGHT);
        BufferedImage backImage = QRCodeUtils.toBufferedImage(matrix);

        int fontSize = 20;
        String stringContent = "邀請QRCode (一般)";

        Font font = new Font("Noto Sans TC", Font.PLAIN, fontSize);
        FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);
        int width = getWordWidth(font, stringContent);

        while (width &gt; WIDTH) {  //if string width ＞ image width ➔ use smaller font
            fontSize = fontSize - 1;
            font = new Font("Noto Sans TC", Font.PLAIN, fontSize);
            metrics = FontDesignMetrics.getMetrics(font);
            width = getWordWidth(font, stringContent);
        }

        Graphics2D g = backImage.createGraphics();

        g.setFont(font);
        g.setColor(Color.BLACK);
        //text-align:center ＆ bottom
        g.drawString(stringContent, (WIDTH - width) / 2, HEIGHT - metrics.getAscent());              
        g.dispose();

        os = new ByteArrayOutputStream();
        if (!ImageIO.write(backImage, IMAGE_FORMAT, os)) {
            throw new IOException("Could not write an image of format png");
        }

    } catch (Exception e) {
        LOG.error(Constants.EXCEPTION_PREFIX, e);
    }

    return os;
}

private static BufferedImage toBufferedImage(BitMatrix matrix) {
    int width = matrix.getWidth();
    int height = matrix.getHeight();
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    for (int x = 0; x &lt; width; x++) {
        for (int y = 0; y &lt; height; y++) {
            image.setRGB(x, y, matrix.get(x, y)
                               ? BLACK
                               : WHITE);
        }
    }
    return image;
}

public static int getWordWidth(Font font, String content) {
    FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);
    int width = 0;
    for (int i = 0; i &lt; content.length(); i++) {
        width += metrics.charWidth(content.charAt(i));
    }
    return width;
}

public static ByteArrayOutputStream encodeWithWaterMark(String content) {

if (FRONT_IMAGE == null) {

return encode(content);

}

ByteArrayOutputStream os = null;

try {

BitMatrix matrix = new QRCodeWriter().encode(content, BarcodeFormat.QR_CODE, WIDTH, HEIGHT);

BufferedImage backImage = QRCodeUtils.toBufferedImage(matrix);

int fontSize = 20;

String stringContent = "邀請QRCode (一般)";

Font font = new Font("Noto Sans TC", Font.PLAIN, fontSize);

FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);

int width = getWordWidth(font, stringContent);

while (width > WIDTH) { //if string width ＞ image width ➔ use smaller font

fontSize = fontSize - 1;

font = new Font("Noto Sans TC", Font.PLAIN, fontSize);

metrics = FontDesignMetrics.getMetrics(font);

width = getWordWidth(font, stringContent);

}

Graphics2D g = backImage.createGraphics();

g.setFont(font);

g.setColor(Color.BLACK);

//text-align:center ＆ bottom

g.drawString(stringContent, (WIDTH - width) / 2, HEIGHT - metrics.getAscent());

g.dispose();

os = new ByteArrayOutputStream();

if (!ImageIO.write(backImage, IMAGE_FORMAT, os)) {

throw new IOException("Could not write an image of format png");

}

} catch (Exception e) {

LOG.error(Constants.EXCEPTION_PREFIX, e);

}

return os;

}

private static BufferedImage toBufferedImage(BitMatrix matrix) {

int width = matrix.getWidth();

int height = matrix.getHeight();

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

for (int x = 0; x < width; x++) {

for (int y = 0; y < height; y++) {

image.setRGB(x, y, matrix.get(x, y)

? BLACK

: WHITE);

}

return image;

}

public static int getWordWidth(Font font, String content) {

FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);

int width = 0;

for (int i = 0; i < content.length(); i++) {

width += metrics.charWidth(content.charAt(i));

}

return width;

}

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[HBase] security issue

Posted on 2019 年 03 月 18 日 by cowman.chiang

error message: com.a.b.c.exception.BaseDAOException: org.apache.hadoop.hbase.security.AccessDeniedException: org.apache.hadoop.hbase.security.AccessDeniedException: Insufficient permissions for user ‘Cowman’ (table=ABC, action=READ) in jvm conf. add “-DHADOOP_USER_NAME=webuser”

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[HBase] convert long value to bytes

Posted on 2018 年 11 月 13 日 by cowman.chiang

Java code:

public static void main(String[] args) {
    String stringValue = Bytes.toStringBinary(Bytes.toBytes(1532080782183l));
    System.out.println(stringValue);
    Long longValue = Bytes.toLong(Bytes.toBytesBinary(stringValue));
    System.out.println(longValue);
}

public static void main(String[] args) {

String stringValue = Bytes.toStringBinary(Bytes.toBytes(1532080782183l));

System.out.println(stringValue);

Long longValue = Bytes.toLong(Bytes.toBytesBinary(stringValue));

System.out.println(longValue);

}

HBase shell command:

hbase(main):056:0> Bytes.toStringBinary(Bytes.to_bytes(1532080782183))
=> "\\x00\\x00\\x01d\\xB7!{g"
hbase(main):057:0> Bytes.toLong("\x00\x00\x01d\xB7!{g".to_java_bytes)
=> 1532080782183

hbase(main):056:0> Bytes.toStringBinary(Bytes.to_bytes(1532080782183))

=> "\\x00\\x00\\x01d\\xB7!{g"

hbase(main):057:0> Bytes.toLong("\x00\x00\x01d\xB7!{g".to_java_bytes)

=> 1532080782183

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[Java] Convert Hex to String

Posted on 2017 年 08 月 14 日 by cowman.chiang

&lt;code&gt;
public static byte[] hexStringToByteArray(String s) {
    int len = s.length();
    byte[] data = new byte[len / 2];
    for (int i = 0; i &amp;lt; len; i += 2) {
        data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) &amp;lt;&amp;lt; 4)
          + Character.digit(s.charAt(i+1), 16));
    }
    return data;
}
&lt;/code&gt;

<code>

public static byte[] hexStringToByteArray(String s) {

int len = s.length();

byte[] data = new byte[len / 2];

for (int i = 0; i &lt; len; i += 2) {

data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) &lt;&lt; 4)

+ Character.digit(s.charAt(i+1), 16));

}

return data;

}

</code>

stackoverflow: Convert a string representation of a hex dump to a byte array using Java?

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