判空、判等、轉碼的StringUtil

目錄

• StringUtil類

StringUtil類

import java.io.UnsupportedEncodingException;

/**
 * 字元串工具
 */
public class StringUtil {


    /**
     * 比較兩個字元串（大小寫敏感）。
     * <pre>
     * StringUtil.equals(null, null)   = true
     * StringUtil.equals(null, "abc")  = false
     * StringUtil.equals("abc", null)  = false
     * StringUtil.equals("abc", "abc") = true
     * StringUtil.equals("abc", "ABC") = false
     * </pre>
     *
     * @param str1 要比較的字元串1
     * @param str2 要比較的字元串2
     *
     * @return 如果兩個字元串相同，或者都是<code>null</code>，則返回<code>true</code>
     */
    public static boolean equals(String str1, String str2) {
        if (str1 == null) {
            return str2 == null;
        }

        return str1.equals(str2);
    }
    // Empty checks
    //-----------------------------------------------------------------------
    /**
     * <p>Checks if a CharSequence is empty ("") or null.</p>
     * <pre>
     * StringUtils.isEmpty(null)      = true
     * StringUtils.isEmpty("")        = true
     * StringUtils.isEmpty(" ")       = false
     * StringUtils.isEmpty("bob")     = false
     * StringUtils.isEmpty("  bob  ") = false
     * </pre>
     * @param cs  the CharSequence to check, may be null
     * @return {@code true} if the CharSequence is empty or null
     */
    public static boolean isEmpty(CharSequence cs) {
        return cs == null || cs.length() == 0;
    }

    /**
     * <p>Checks if a CharSequence is not empty ("") and not null.</p>
     *
     * <pre>
     * StringUtils.isNotEmpty(null)      = false
     * StringUtils.isNotEmpty("")        = false
     * StringUtils.isNotEmpty(" ")       = true
     * StringUtils.isNotEmpty("bob")     = true
     * StringUtils.isNotEmpty("  bob  ") = true
     * </pre>
     *
     * @param cs  the CharSequence to check, may be null
     * @return {@code true} if the CharSequence is not empty and not null
     */
    public static boolean isNotEmpty(CharSequence cs) {
        return !StringUtils.isEmpty(cs);
    }

    /**
     * <p>Checks if a CharSequence is whitespace, empty ("") or null.</p>
     *
     * <pre>
     * StringUtils.isBlank(null)      = true
     * StringUtils.isBlank("")        = true
     * StringUtils.isBlank(" ")       = true
     * StringUtils.isBlank("bob")     = false
     * StringUtils.isBlank("  bob  ") = false
     * </pre>
     * @param cs  the CharSequence to check, may be null
     * @return {@code true} if the CharSequence is null, empty or whitespace
     * @since 2.0
     */
    public static boolean isBlank(CharSequence cs) {
        int strLen;
        if (cs == null || (strLen = cs.length()) == 0) {
            return true;
        }
        for (int i = 0; i < strLen; i++) {
            if (Character.isWhitespace(cs.charAt(i)) == false) {
                return false;
            }
        }
        return true;
    }

    /**
     * <p>Checks if a CharSequence is not empty (""), not null and not whitespace only.</p>
     *
     * <pre>
     * StringUtils.isNotBlank(null)      = false
     * StringUtils.isNotBlank("")        = false
     * StringUtils.isNotBlank(" ")       = false
     * StringUtils.isNotBlank("bob")     = true
     * StringUtils.isNotBlank("  bob  ") = true
     * </pre>
     * @param cs  the CharSequence to check, may be null
     * @return {@code true} if the CharSequence is
     *  not empty and not null and not whitespace
     */
    public static boolean isNotBlank(CharSequence cs) {
        return !StringUtils.isBlank(cs);
    }

    /**
     * @param content 需要加密串
     * @param charset 字元集
     * @return 加密後的位元組數組
     */
    public static byte[] getContentBytes(String content, String charset) {
        if (StringUtils.isEmpty(charset)) {
            return content.getBytes();
        }
        try {
            return content.getBytes(charset);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("轉碼過程中出現錯誤,指定的編碼集不對,您目前指定的編碼集是:" + charset);
        }
    }

}