cn.leancloud.utils.StringUtil Maven / Gradle / Ivy

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package cn.leancloud.utils;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.Random;
import java.util.TimeZone;

public class StringUtil {
  private static final String dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";

  public static boolean isEmpty(String str) {
    return null == str || str.trim().length() == 0;
  }

  public static boolean isDigitString(String s) {
    if (s == null) return false;
    for (int i = 0; i < s.length(); i++) {
      char c = s.charAt(i);
      if (!Character.isDigit(c)) {
        return false;
      }
    }
    return true;
  }

  public static boolean equals(String left, String right) {
    if (null == left || null == right) {
      return false;
    }
    return left.equals(right);
  }

  public static boolean equals(List left, List right) {
    if (null == left || null == right) {
      return false;
    }
    if (left.size() != right.size()) {
      return false;
    }
    return left.containsAll(right);
  }

  public static boolean equalsIgnoreCase(String left, String right) {
    if (null == left || null == right) {
      return false;
    }
    return left.equalsIgnoreCase(right);
  }

  public static String stringFromDate(Date date) {
    if (null == date) {
      return null;
    }

    SimpleDateFormat df = new SimpleDateFormat(dateFormat);
    df.setTimeZone(TimeZone.getTimeZone("UTC"));
    String isoDate = df.format(date);
    return isoDate;
  }

  public static Date dateFromString(String content) {
    if (isEmpty(content)) return null;
    if (isDigitString(content)) {
      return new Date(Long.parseLong(content));
    }
    Date date = null;
    SimpleDateFormat format = new SimpleDateFormat(dateFormat);
    format.setTimeZone(TimeZone.getTimeZone("UTC"));

    try {
      date = format.parse(content);
    } catch (Exception exception) {
    }
    return date;
  }

  public static String stringFromBytes(byte[] data) {
    try {
      return new String(data, "UTF-8");
    } catch (Exception e) {
      // e.printStackTrace();
    }
    return null;
  }

  public static String join(CharSequence delimiter,
                            Iterable elements) {
    if (null == delimiter || null == elements) {
      return "";
    }
    StringBuilder sb = new StringBuilder();
    boolean isFirstElem = true;
    for (CharSequence cs: elements) {
      if (!isFirstElem) {
        sb.append(delimiter);
      } else {
        isFirstElem = false;
      }
      sb.append(cs);
    }
    return sb.toString();
  }

  static Random random = new Random(System.currentTimeMillis());

  public static String getRandomString(int length) {
    String letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    StringBuilder randomString = new StringBuilder(length);

    for (int i = 0; i < length; i++) {
      randomString.append(letters.charAt(random.nextInt(letters.length())));
    }

    return randomString.toString();
  }
}