✨ 完善工具类

blade-core-tool/src/main/java/org/springblade/core/tool/utils/CharPool.java

@@ -21,16 +21,51 @@ package org.springblade.core.tool.utils;
  * @author L.cm
  */
 public interface CharPool {
-
+	// @formatter:off
-	char UPPER_A		= 'A';
+	char UPPER_A          = 'A';
-	char LOWER_A		= 'a';
+	char LOWER_A          = 'a';
-	char UPPER_Z		= 'Z';
+	char UPPER_Z          = 'Z';
-	char LOWER_Z		= 'z';
+	char LOWER_Z          = 'z';
-	char DOT			= '.';
+	char DOT              = '.';
-	char AT				= '@';
+	char AT               = '@';
-	char LEFT_BRACE		= '{';
+	char LEFT_BRACE       = '{';
-	char RIGHT_BRACE	= '}';
+	char RIGHT_BRACE      = '}';
-	char LEFT_BRACKET	= '(';
+	char LEFT_BRACKET     = '(';
-	char RIGHT_BRACKET	= ')';
+	char RIGHT_BRACKET    = ')';
-
+	char DASH             = '-';
+	char PERCENT          = '%';
+	char PIPE             = '|';
+	char PLUS             = '+';
+	char QUESTION_MARK    = '?';
+	char EXCLAMATION_MARK = '!';
+	char EQUALS           = '=';
+	char AMPERSAND        = '&';
+	char ASTERISK         = '*';
+	char STAR             = ASTERISK;
+	char BACK_SLASH       = '\\';
+	char COLON            = ':';
+	char COMMA            = ',';
+	char DOLLAR           = '$';
+	char SLASH            = '/';
+	char HASH             = '#';
+	char HAT              = '^';
+	char LEFT_CHEV        = '<';
+	char NEWLINE          = '\n';
+	char N                = 'n';
+	char Y                = 'y';
+	char QUOTE            = '\"';
+	char RETURN           = '\r';
+	char TAB              = '\t';
+	char RIGHT_CHEV       = '>';
+	char SEMICOLON        = ';';
+	char SINGLE_QUOTE     = '\'';
+	char BACKTICK         = '`';
+	char SPACE            = ' ';
+	char TILDA            = '~';
+	char LEFT_SQ_BRACKET  = '[';
+	char RIGHT_SQ_BRACKET = ']';
+	char UNDERSCORE       = '_';
+	char ONE              = '1';
+	char ZERO             = '0';
+	// @formatter:on
 }

blade-core-tool/src/main/java/org/springblade/core/tool/utils/DesensitizationUtil.java

@@ -0,0 +1,295 @@
+/**
+ * Copyright (c) 2018-2028, DreamLu 卢春梦 (qq596392912@gmail.com).
+ * <p>
+ * Licensed under the GNU LESSER GENERAL PUBLIC LICENSE 3.0;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.gnu.org/licenses/lgpl.html
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springblade.core.tool.utils;
+
+
+import org.springframework.lang.Nullable;
+import org.springframework.util.StringUtils;
+
+import java.util.Arrays;
+
+/**
+ * 脱敏工具类
+ *
+ * @author Katrel（同事）
+ * @author L.cm
+ */
+public class DesensitizationUtil {
+
+	/**
+	 * [中文姓名] 只显示第一个汉字，其他隐藏为2个星号<例子：李**>
+	 *
+	 * @param fullName 全名
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String chineseName(@Nullable final String fullName) {
+		return sensitive(fullName, 1, 0);
+	}
+
+	/**
+	 * [身份证号] 显示最后四位，其他隐藏。共计18位或者15位。<例子：*************5762>
+	 *
+	 * @param id 身份证号
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String idCardNum(@Nullable final String id) {
+		return sensitive(id, 0, 4);
+	}
+
+	/**
+	 * [固定电话] 后四位，其他隐藏<例子：****1234>
+	 *
+	 * @param num 固定电话号
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String phoneNo(@Nullable final String num) {
+		return sensitive(num, 0, 4);
+	}
+
+	/**
+	 * [手机号码] 前三位，后四位，其他隐藏<例子:138****1234>
+	 *
+	 * @param num 手机号
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String mobileNo(@Nullable final String num) {
+		return sensitive(num, 3, 4);
+	}
+
+	/**
+	 * [地址] 只显示到地区，不显示详细地址；我们要对个人信息增强保护<例子：北京市海淀区****>
+	 *
+	 * @param address       地区
+	 * @param sensitiveSize 敏感信息长度
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String address(@Nullable final String address, final int sensitiveSize) {
+		return sensitive(address, 0, sensitiveSize);
+	}
+
+	/**
+	 * [电子邮箱] 邮箱前缀仅显示第一个字母，前缀其他隐藏，用星号代替，@及后面的地址显示<例子:g**@163.com>
+	 *
+	 * @param email 邮箱
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String email(@Nullable final String email) {
+		if (email == null) {
+			return null;
+		}
+		if (!StringUtils.hasText(email)) {
+			return StringPool.EMPTY;
+		}
+		final int index = email.indexOf(CharPool.AT);
+		if (index <= 1) {
+			return email;
+		} else {
+			return sensitive(email, 1, email.length() - index);
+		}
+	}
+
+	/**
+	 * [银行卡号] 前六位，后四位，其他用星号隐藏每位1个星号<例子:622260***********1234>
+	 *
+	 * @param cardNum 银行卡号
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String bankCard(@Nullable final String cardNum) {
+		return sensitive(cardNum, 6, 4);
+	}
+
+	/**
+	 * [公司开户银行联号] 公司开户银行联行号,显示前两位，其他用星号隐藏，每位1个星号<例子:12********>
+	 *
+	 * @param code 银行联行号
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String cnApsCode(@Nullable final String code) {
+		return sensitive(code, 2, 0);
+	}
+
+	/**
+	 * 右边脱敏
+	 *
+	 * @param sensitiveStr 待脱敏的字符串
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String right(@Nullable final String sensitiveStr) {
+		if (sensitiveStr == null) {
+			return null;
+		}
+		if (!StringUtils.hasText(sensitiveStr)) {
+			return StringPool.EMPTY;
+		}
+		int length = sensitiveStr.length();
+		return sensitive(sensitiveStr, length / 2, 0);
+	}
+
+	/**
+	 * 左边脱敏
+	 *
+	 * @param sensitiveStr 待脱敏的字符串
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String left(@Nullable final String sensitiveStr) {
+		if (sensitiveStr == null) {
+			return null;
+		}
+		if (!StringUtils.hasText(sensitiveStr)) {
+			return StringPool.EMPTY;
+		}
+		int length = sensitiveStr.length();
+		return sensitive(sensitiveStr, 0, length / 2);
+	}
+
+	/**
+	 * 中间脱敏，保留两端
+	 *
+	 * @param sensitiveStr 待脱敏的字符串
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String middle(@Nullable final String sensitiveStr) {
+		if (sensitiveStr == null) {
+			return null;
+		}
+		if (!StringUtils.hasText(sensitiveStr)) {
+			return StringPool.EMPTY;
+		}
+		int length = sensitiveStr.length();
+		if (length < 3) {
+			return StringUtil.leftPad(StringPool.EMPTY, length, CharPool.STAR);
+		} else if (length < 6) {
+			// 小于6个字符，脱敏中间
+			char[] chars = new char[length];
+			int last = length - 1;
+			Arrays.fill(chars, 1, last, CharPool.STAR);
+			chars[0] = sensitiveStr.charAt(0);
+			chars[last] = sensitiveStr.charAt(last);
+			return new String(chars);
+		} else {
+			// 大于6个字符
+			int fromLastLen = length / 3;
+			return sensitive(sensitiveStr, fromLastLen, fromLastLen);
+		}
+	}
+
+	/**
+	 * 全部脱敏
+	 *
+	 * @param sensitiveStr 待脱敏的字符串
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String all(@Nullable final String sensitiveStr) {
+		return sensitive(sensitiveStr, 0, 0);
+	}
+
+	/**
+	 * 文本脱敏
+	 *
+	 * @param str       字符串
+	 * @param fromIndex 开始的索引
+	 * @param lastSize  尾部长度
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String sensitive(@Nullable String str, int fromIndex, int lastSize) {
+		return sensitive(str, fromIndex, lastSize, CharPool.STAR);
+	}
+
+	/**
+	 * 文本脱敏
+	 *
+	 * @param str       字符串
+	 * @param fromIndex 开始的索引
+	 * @param lastSize  尾部长度
+	 * @param padSize   填充的长度
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String sensitive(@Nullable String str, int fromIndex, int lastSize, int padSize) {
+		return sensitive(str, fromIndex, lastSize, CharPool.STAR, padSize);
+	}
+
+	/**
+	 * 文本脱敏
+	 *
+	 * @param str       字符串
+	 * @param fromIndex 开始的索引
+	 * @param lastSize  尾部长度
+	 * @param padChar   填充的字符
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String sensitive(@Nullable String str, int fromIndex, int lastSize, char padChar) {
+		return sensitive(str, fromIndex, lastSize, padChar, -1);
+	}
+
+	/**
+	 * 文本脱敏
+	 *
+	 * @param str       字符串
+	 * @param fromIndex 开始的索引
+	 * @param lastSize  尾部长度
+	 * @param padChar   填充的字符
+	 * @param padSize   填充的长度
+	 * @return 脱敏后的字符串
+	 */
+	@Nullable
+	public static String sensitive(@Nullable String str, int fromIndex, int lastSize, char padChar, int padSize) {
+		if (str == null) {
+			return null;
+		}
+		if (!StringUtils.hasText(str)) {
+			return StringPool.EMPTY;
+		}
+		int length = str.length();
+		// 全部脱敏
+		if (fromIndex == 0 && lastSize == 0) {
+			int padSiz = padSize > 0 ? padSize : length;
+			return StringUtil.repeat(CharPool.STAR, padSiz);
+		}
+		int toIndex = length - lastSize;
+		int padSiz = padSize > 0 ? padSize : toIndex - fromIndex;
+		// 头部脱敏
+		if (fromIndex == 0) {
+			String tail = str.substring(toIndex);
+			return StringUtil.repeat(padChar, padSiz).concat(tail);
+		}
+		// 尾部脱敏
+		if (toIndex == length) {
+			String head = str.substring(0, fromIndex);
+			return head.concat(StringUtil.repeat(padChar, padSiz));
+		}
+		// 中部
+		String head = str.substring(0, fromIndex);
+		String tail = str.substring(toIndex);
+		return head + StringUtil.repeat(padChar, padSiz) + tail;
+	}
+
+}

blade-core-tool/src/main/java/org/springblade/core/tool/utils/StringUtil.java

@@ -19,6 +19,7 @@ import org.springblade.core.tool.support.StrFormatter;
 import org.springblade.core.tool.support.StrSpliter;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 import org.springframework.web.util.HtmlUtils;
 
 import java.io.StringReader;
@@ -36,6 +37,10 @@ import java.util.stream.Stream;
 public class StringUtil extends org.springframework.util.StringUtils {
 
 	public static final int INDEX_NOT_FOUND = -1;
+	/**
+	 * <p>The maximum size to which the padding constant(s) can expand.</p>
+	 */
+	private static final int PAD_LIMIT = 8192;
 
 	/**
 	 * Check whether the given {@code CharSequence} contains actual <em>text</em>.
@@ -1473,5 +1478,396 @@ public class StringUtil extends org.springframework.util.StringUtils {
 	}
 
 
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Returns padding using the specified delimiter repeated
+	 * to a given length.</p>
+	 *
+	 * <pre>
+	 * StringUtils.repeat('e', 0)  = ""
+	 * StringUtils.repeat('e', 3)  = "eee"
+	 * StringUtils.repeat('e', -2) = ""
+	 * </pre>
+	 *
+	 * <p>Note: this method does not support padding with
+	 * <a href="http://www.unicode.org/glossary/#supplementary_character">Unicode Supplementary Characters</a>
+	 * as they require a pair of {@code char}s to be represented.
+	 * </p>
+	 *
+	 * @param ch     character to repeat
+	 * @param repeat number of times to repeat char, negative treated as zero
+	 * @return String with repeated character
+	 */
+	public static String repeat(final char ch, final int repeat) {
+		if (repeat <= 0) {
+			return StringPool.EMPTY;
+		}
+		final char[] buf = new char[repeat];
+		Arrays.fill(buf, ch);
+		return new String(buf);
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Gets the leftmost {@code len} characters of a String.</p>
+	 *
+	 * <p>If {@code len} characters are not available, or the
+	 * String is {@code null}, the String will be returned without
+	 * an exception. An empty String is returned if len is negative.</p>
+	 *
+	 * <pre>
+	 * StringUtils.left(null, *)    = null
+	 * StringUtils.left(*, -ve)     = ""
+	 * StringUtils.left("", *)      = ""
+	 * StringUtils.left("abc", 0)   = ""
+	 * StringUtils.left("abc", 2)   = "ab"
+	 * StringUtils.left("abc", 4)   = "abc"
+	 * </pre>
+	 *
+	 * @param str the CharSequence to get the leftmost characters from, may be null
+	 * @param len the length of the required String
+	 * @return the leftmost characters, {@code null} if null String input
+	 */
+	@Nullable
+	public static String left(@Nullable final String str, final int len) {
+		if (str == null) {
+			return null;
+		}
+		if (len < 0) {
+			return StringPool.EMPTY;
+		}
+		if (str.length() <= len) {
+			return str;
+		}
+		return str.substring(0, len);
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Gets the rightmost {@code len} characters of a String.</p>
+	 *
+	 * <p>If {@code len} characters are not available, or the String
+	 * is {@code null}, the String will be returned without an
+	 * an exception. An empty String is returned if len is negative.</p>
+	 *
+	 * <pre>
+	 * StringUtils.right(null, *)    = null
+	 * StringUtils.right(*, -ve)     = ""
+	 * StringUtils.right("", *)      = ""
+	 * StringUtils.right("abc", 0)   = ""
+	 * StringUtils.right("abc", 2)   = "bc"
+	 * StringUtils.right("abc", 4)   = "abc"
+	 * </pre>
+	 *
+	 * @param str the String to get the rightmost characters from, may be null
+	 * @param len the length of the required String
+	 * @return the rightmost characters, {@code null} if null String input
+	 */
+	@Nullable
+	public static String right(@Nullable final String str, final int len) {
+		if (str == null) {
+			return null;
+		}
+		if (len < 0) {
+			return StringPool.EMPTY;
+		}
+		int length = str.length();
+		if (length <= len) {
+			return str;
+		}
+		return str.substring(length - len);
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Right pad a String with spaces (' ').</p>
+	 *
+	 * <p>The String is padded to the size of {@code size}.</p>
+	 *
+	 * <pre>
+	 * StringUtils.rightPad(null, *)   = null
+	 * StringUtils.rightPad("", 3)     = "   "
+	 * StringUtils.rightPad("bat", 3)  = "bat"
+	 * StringUtils.rightPad("bat", 5)  = "bat  "
+	 * StringUtils.rightPad("bat", 1)  = "bat"
+	 * StringUtils.rightPad("bat", -1) = "bat"
+	 * </pre>
+	 *
+	 * @param str  the String to pad out, may be null
+	 * @param size the size to pad to
+	 * @return right padded String or original String if no padding is necessary,
+	 * {@code null} if null String input
+	 */
+	@Nullable
+	public static String rightPad(@Nullable final String str, final int size) {
+		return rightPad(str, size, CharPool.SPACE);
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Right pad a String with a specified character.</p>
+	 *
+	 * <p>The String is padded to the size of {@code size}.</p>
+	 *
+	 * <pre>
+	 * StringUtils.rightPad(null, *, *)     = null
+	 * StringUtils.rightPad("", 3, 'z')     = "zzz"
+	 * StringUtils.rightPad("bat", 3, 'z')  = "bat"
+	 * StringUtils.rightPad("bat", 5, 'z')  = "batzz"
+	 * StringUtils.rightPad("bat", 1, 'z')  = "bat"
+	 * StringUtils.rightPad("bat", -1, 'z') = "bat"
+	 * </pre>
+	 *
+	 * @param str     the String to pad out, may be null
+	 * @param size    the size to pad to
+	 * @param padChar the character to pad with
+	 * @return right padded String or original String if no padding is necessary,
+	 * {@code null} if null String input
+	 */
+	@Nullable
+	public static String rightPad(@Nullable final String str, final int size, final char padChar) {
+		if (str == null) {
+			return null;
+		}
+		final int pads = size - str.length();
+		if (pads <= 0) {
+			// returns original String when possible
+			return str;
+		}
+		if (pads > PAD_LIMIT) {
+			return rightPad(str, size, String.valueOf(padChar));
+		}
+		return str.concat(repeat(padChar, pads));
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Right pad a String with a specified String.</p>
+	 *
+	 * <p>The String is padded to the size of {@code size}.</p>
+	 *
+	 * <pre>
+	 * StringUtils.rightPad(null, *, *)      = null
+	 * StringUtils.rightPad("", 3, "z")      = "zzz"
+	 * StringUtils.rightPad("bat", 3, "yz")  = "bat"
+	 * StringUtils.rightPad("bat", 5, "yz")  = "batyz"
+	 * StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
+	 * StringUtils.rightPad("bat", 1, "yz")  = "bat"
+	 * StringUtils.rightPad("bat", -1, "yz") = "bat"
+	 * StringUtils.rightPad("bat", 5, null)  = "bat  "
+	 * StringUtils.rightPad("bat", 5, "")    = "bat  "
+	 * </pre>
+	 *
+	 * @param str    the String to pad out, may be null
+	 * @param size   the size to pad to
+	 * @param padStr the String to pad with, null or empty treated as single space
+	 * @return right padded String or original String if no padding is necessary,
+	 * {@code null} if null String input
+	 */
+	@Nullable
+	public static String rightPad(@Nullable final String str, final int size, String padStr) {
+		if (str == null) {
+			return null;
+		}
+		if (!StringUtils.hasLength(padStr)) {
+			padStr = StringPool.SPACE;
+		}
+		final int padLen = padStr.length();
+		final int strLen = str.length();
+		final int pads = size - strLen;
+		if (pads <= 0) {
+			// returns original String when possible
+			return str;
+		}
+		if (padLen == 1 && pads <= PAD_LIMIT) {
+			return rightPad(str, size, padStr.charAt(0));
+		}
+		if (pads == padLen) {
+			return str.concat(padStr);
+		} else if (pads < padLen) {
+			return str.concat(padStr.substring(0, pads));
+		} else {
+			final char[] padding = new char[pads];
+			final char[] padChars = padStr.toCharArray();
+			for (int i = 0; i < pads; i++) {
+				padding[i] = padChars[i % padLen];
+			}
+			return str.concat(new String(padding));
+		}
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Left pad a String with spaces (' ').</p>
+	 *
+	 * <p>The String is padded to the size of {@code size}.</p>
+	 *
+	 * <pre>
+	 * StringUtils.leftPad(null, *)   = null
+	 * StringUtils.leftPad("", 3)     = "   "
+	 * StringUtils.leftPad("bat", 3)  = "bat"
+	 * StringUtils.leftPad("bat", 5)  = "  bat"
+	 * StringUtils.leftPad("bat", 1)  = "bat"
+	 * StringUtils.leftPad("bat", -1) = "bat"
+	 * </pre>
+	 *
+	 * @param str  the String to pad out, may be null
+	 * @param size the size to pad to
+	 * @return left padded String or original String if no padding is necessary,
+	 * {@code null} if null String input
+	 */
+	@Nullable
+	public static String leftPad(@Nullable final String str, final int size) {
+		return leftPad(str, size, CharPool.SPACE);
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Left pad a String with a specified character.</p>
+	 *
+	 * <p>Pad to a size of {@code size}.</p>
+	 *
+	 * <pre>
+	 * StringUtils.leftPad(null, *, *)     = null
+	 * StringUtils.leftPad("", 3, 'z')     = "zzz"
+	 * StringUtils.leftPad("bat", 3, 'z')  = "bat"
+	 * StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
+	 * StringUtils.leftPad("bat", 1, 'z')  = "bat"
+	 * StringUtils.leftPad("bat", -1, 'z') = "bat"
+	 * </pre>
+	 *
+	 * @param str     the String to pad out, may be null
+	 * @param size    the size to pad to
+	 * @param padChar the character to pad with
+	 * @return left padded String or original String if no padding is necessary,
+	 * {@code null} if null String input
+	 * @since 2.0
+	 */
+	@Nullable
+	public static String leftPad(@Nullable final String str, final int size, final char padChar) {
+		if (str == null) {
+			return null;
+		}
+		final int pads = size - str.length();
+		if (pads <= 0) {
+			// returns original String when possible
+			return str;
+		}
+		if (pads > PAD_LIMIT) {
+			return leftPad(str, size, String.valueOf(padChar));
+		}
+		return repeat(padChar, pads).concat(str);
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Left pad a String with a specified String.</p>
+	 *
+	 * <p>Pad to a size of {@code size}.</p>
+	 *
+	 * <pre>
+	 * StringUtils.leftPad(null, *, *)      = null
+	 * StringUtils.leftPad("", 3, "z")      = "zzz"
+	 * StringUtils.leftPad("bat", 3, "yz")  = "bat"
+	 * StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
+	 * StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
+	 * StringUtils.leftPad("bat", 1, "yz")  = "bat"
+	 * StringUtils.leftPad("bat", -1, "yz") = "bat"
+	 * StringUtils.leftPad("bat", 5, null)  = "  bat"
+	 * StringUtils.leftPad("bat", 5, "")    = "  bat"
+	 * </pre>
+	 *
+	 * @param str    the String to pad out, may be null
+	 * @param size   the size to pad to
+	 * @param padStr the String to pad with, null or empty treated as single space
+	 * @return left padded String or original String if no padding is necessary,
+	 * {@code null} if null String input
+	 */
+	@Nullable
+	public static String leftPad(@Nullable final String str, final int size, String padStr) {
+		if (str == null) {
+			return null;
+		}
+		if (!StringUtils.hasLength(padStr)) {
+			padStr = StringPool.SPACE;
+		}
+		final int padLen = padStr.length();
+		final int strLen = str.length();
+		final int pads = size - strLen;
+		if (pads <= 0) {
+			// returns original String when possible
+			return str;
+		}
+		if (padLen == 1 && pads <= PAD_LIMIT) {
+			return leftPad(str, size, padStr.charAt(0));
+		}
+		if (pads == padLen) {
+			return padStr.concat(str);
+		} else if (pads < padLen) {
+			return padStr.substring(0, pads).concat(str);
+		} else {
+			final char[] padding = new char[pads];
+			final char[] padChars = padStr.toCharArray();
+			for (int i = 0; i < pads; i++) {
+				padding[i] = padChars[i % padLen];
+			}
+			return new String(padding).concat(str);
+		}
+	}
+
+	/**
+	 * 参考自 commons lang 微调
+	 *
+	 * <p>Gets {@code len} characters from the middle of a String.</p>
+	 *
+	 * <p>If {@code len} characters are not available, the remainder
+	 * of the String will be returned without an exception. If the
+	 * String is {@code null}, {@code null} will be returned.
+	 * An empty String is returned if len is negative or exceeds the
+	 * length of {@code str}.</p>
+	 *
+	 * <pre>
+	 * StringUtils.mid(null, *, *)    = null
+	 * StringUtils.mid(*, *, -ve)     = ""
+	 * StringUtils.mid("", 0, *)      = ""
+	 * StringUtils.mid("abc", 0, 2)   = "ab"
+	 * StringUtils.mid("abc", 0, 4)   = "abc"
+	 * StringUtils.mid("abc", 2, 4)   = "c"
+	 * StringUtils.mid("abc", 4, 2)   = ""
+	 * StringUtils.mid("abc", -2, 2)  = "ab"
+	 * </pre>
+	 *
+	 * @param str the String to get the characters from, may be null
+	 * @param pos the position to start from, negative treated as zero
+	 * @param len the length of the required String
+	 * @return the middle characters, {@code null} if null String input
+	 */
+	@Nullable
+	public static String mid(@Nullable final String str, int pos, final int len) {
+		if (str == null) {
+			return null;
+		}
+		int length = str.length();
+		if (len < 0 || pos > length) {
+			return StringPool.EMPTY;
+		}
+		if (pos < 0) {
+			pos = 0;
+		}
+		if (length <= pos + len) {
+			return str.substring(pos);
+		}
+		return str.substring(pos, pos + len);
+	}
+
 }