####This Lang API is an extension to the java.lang package. https://wiki.apache.org/commons/Lang
###Lang aims to provide:
- Comprehensive String handling utilities
- Enumerated types (pre JDK 1.5)
- Nested exceptions (pre JDK 1.4)
- Builders to create hashCode, equals, toString and compareTo methods
- Utilities for Object, Date and Numbers 这里的工具类太多了，主要就是各个对象的基本操作. ###依赖
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.5</version>
</dependency>
###代码示例：
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.apache.commons.lang.RandomStringUtils;
import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.text.WordUtils;
import org.junit.Test;
import com.zx.common.log.LogUtil;
public class StringUtilsTest {
@Test
public void testIsEmpty() {
//isEmpty Checks if a CharSequence is empty ("") or null. 断某字符串是否为空，为空的标准是str null 或 str.length() == 0
//NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is available in isBlank().
assertTrue(StringUtils.isEmpty(null)); // true
assertTrue(StringUtils.isEmpty("")); // true
assertFalse(StringUtils.isEmpty(" ")); // false 这里要注意下
assertFalse(StringUtils.isEmpty("bob")); // false
assertFalse(StringUtils.isEmpty(" bob ")); // false
//isBlank 判断某字符串是否为空或长度为0或由空白符(whitespace)构成
assertTrue(StringUtils.isBlank(null)); // true
assertTrue(StringUtils.isBlank("")); // true
assertTrue(StringUtils.isBlank(" ")); // true
assertFalse(StringUtils.isBlank("bob")); // false
assertFalse(StringUtils.isBlank(" bob ")); // false
}
@Test
public void testTrim() {
//Removes control characters (char <= 32) from both ends of this String, handling null by returning null. 去掉字符串两端的控制符(control characters, char <= 32)
assertEquals(null, StringUtils.trim(null)); // null
assertEquals("", StringUtils.trim("")); // ""
assertEquals("", StringUtils.trim(" ")); // ""
assertEquals("abc", StringUtils.trim("abc")); // "abc"
assertEquals("abc", StringUtils.trim(" abc")); // "abc"
assertEquals("abc", StringUtils.trim(" abc ")); // "abc"
assertEquals("ab c", StringUtils.trim(" ab c ")); // "ab c"
}
@Test
public void testStrip() {
// Strips whitespace from the start and end of a String.
assertEquals(null, StringUtils.strip(null)); // null
assertEquals("", StringUtils.strip("")); // ""
assertEquals("", StringUtils.strip(" ")); // ""
assertEquals("abc", StringUtils.strip("abc")); // "abc"
assertEquals("abc", StringUtils.strip(" abc")); // "abc"
assertEquals("abc", StringUtils.strip("abc ")); // "abc"
assertEquals("abc", StringUtils.strip(" abc ")); // "abc"
assertEquals("ab c", StringUtils.strip(" ab c ")); // "ab c"
//Strips any of a set of characters from the start and end of a String. This is similar to String.trim() but allows the characters to be stripped to be controlled.
//strip 第二个参数中的每个参数都是要剔除的，不要当作一个整体
assertEquals(" abc", StringUtils.strip(" abcyx", "xyz")); // " abc"
assertEquals(" abc", StringUtils.strip(" abcyxz", "xyz")); // " abc"
//Strips any of a set of characters from the start of a String.
assertEquals("abcxyz ", StringUtils.stripStart("yxabcxyz ", "xyz")); // "abcxyz "
assertEquals("abcxyz ", StringUtils.stripStart("yxyxyxabcxyz ", "xyz ")); // "abcxyz "
assertEquals("abcxyz ", StringUtils.stripStart(" yxyxyxabcxyz ", "xyz ")); // "abcxyz "
assertEquals("bcxyz ", StringUtils.stripStart(" yxyxyxabcxyz ", "xyz a")); // "abcxyz "
assertEquals("abcxyz ", StringUtils.stripStart(" yxyxyxabcxyz ", "xyz b")); // "abcxyz "
assertEquals(" xyzabc", StringUtils.stripEnd(" xyzabcyx", "xyz")); // " xyzabc"
}
@Test
public void testsplit() {
assertEquals(0, StringUtils.split("").length);//[]
assertEquals("abc", StringUtils.split(" abc ")[0]);//["abc"]
//默认半角空格分割
String str1 = "aaa bbb ccc";
String[] dim1 = StringUtils.split(str1); // => ["aaa", "bbb", "ccc"]
assertEquals(3, dim1.length);//3
assertEquals("aaa", dim1[0]);//"aaa"
assertEquals("bbb", dim1[1]);//"bbb"
assertEquals("ccc", dim1[2]);//"ccc"
//指定分隔符
String str2 = ",aaa,bbb,ccc,";
String[] dim2 = StringUtils.split(str2, ","); // => ["aaa", "bbb", "ccc"]
assertEquals(3, dim2.length);//3
assertEquals("aaa", dim2[0]);//"aaa"
assertEquals("bbb", dim2[1]);//"bbb"
assertEquals("ccc", dim2[2]);//"ccc"
//去除空字符串
String str3 = "aaa,,bbb";
String[] dim3 = StringUtils.split(str3, ","); // => ["aaa", "bbb"]
assertEquals(2, dim3.length);//2
assertEquals("aaa", dim3[0]);//"aaa"
assertEquals("bbb", dim3[1]);//"bbb"
//包含空字符串
String str4 = "aaa,,bbb";
String[] dim4 = StringUtils.splitPreserveAllTokens(str4, ","); // => ["aaa", "", "bbb"]
assertEquals(3, dim4.length);//3
assertEquals("aaa", dim4[0]);//"aaa"
assertEquals("", dim4[1]);//""
assertEquals("bbb", dim4[2]);//"bbb"
//指定分割的最大次数（超过后不分割）
String str5 = "aaa,bbb,ccc";
String[] dim5 = StringUtils.split(str5, ",", 2); // => ["aaa", "bbb,ccc"]
assertEquals(2, dim5.length);//2
assertEquals("aaa", dim5[0]);//"aaa"
assertEquals("bbb,ccc", dim5[1]);//"bbb,ccc"
}
@Test
public void testJoin() {
//数组元素拼接
String[] array = {"aaa", "bbb", "ccc"};
String result1 = StringUtils.join(array, ",");
assertEquals("aaa,bbb,ccc", result1);//"aaa,bbb,ccc"
//集合元素拼接
List<String> list = new ArrayList<String>();
list.add("aaa");
list.add("bbb");
list.add("ccc");
String result2 = StringUtils.join(list, ",");
assertEquals("aaa,bbb,ccc", result2);//"aaa,bbb,ccc"
}
@Test
public void testEscape() {
assertEquals("测试测试哦", StringEscapeUtils.escapeCsv("测试测试哦"));//"测试测试哦"
assertEquals("\"测试,测试哦\"", StringEscapeUtils.escapeCsv("测试,测试哦"));//"\"测试,测试哦\""
assertEquals("\"测试\n测试哦\"", StringEscapeUtils.escapeCsv("测试\n测试哦"));//"\"测试\n测试哦\""
assertEquals("测试测试哦", StringEscapeUtils.escapeHtml4("测试测试哦"));//"<p>测试测试哦</p>"
//StringEscapeUtils.escapeJava
//StringEscapeUtils.escapeEcmaScript
//StringEscapeUtils.escapeXml
assertEquals("He didn't say, \\\"Stop!\\\"", StringEscapeUtils.escapeJava("He didn't say, \"Stop!\""));//"\"rensaninng\"\uFF0C\u6B22\u8FCE\u60A8\uFF01"
assertEquals("He didn\\\'t say, \\\"Stop!\\\"", StringEscapeUtils.escapeEcmaScript("He didn't say, \"Stop!\""));//"\u6D4B\u8BD5\'\u6D4B\u8BD5\u54E6"
}
@Test
public void testRandom() {
// 10位英字
assertEquals(10, RandomStringUtils.randomAlphabetic(10).length());
// 10位英数
assertEquals(10, RandomStringUtils.randomAlphanumeric(10).length());
// 10位ASCII码
assertEquals(10, RandomStringUtils.randomAscii(10).length());
// 指定文字10位
assertEquals(10, RandomStringUtils.random(10, "abcde").length());
LogUtil.get(this.getClass()).debug(RandomStringUtils.randomAlphabetic(10));
LogUtil.get(this.getClass()).debug(RandomStringUtils.randomAlphanumeric(10));
LogUtil.get(this.getClass()).debug(RandomStringUtils.randomAscii(10));
LogUtil.get(this.getClass()).debug(RandomStringUtils.random(10, "abced"));
LogUtil.get(this.getClass()).debug(RandomStringUtils.random(10));
LogUtil.get(this.getClass()).debug(RandomStringUtils.randomNumeric(10));
}
@Test
public void testArray() {
// 追加元素到数组尾部
int[] array1 = {1, 2};
array1 = ArrayUtils.add(array1, 3); // => [1, 2, 3]
assertEquals(3, array1.length);//3
assertEquals(3, array1[2]);//3
// 删除指定位置的元素
int[] array2 = {1, 2, 3};
array2 = ArrayUtils.remove(array2, 2); // => [1, 2]
assertEquals(2, array2.length);//2
// 截取部分元素
int[] array3 = {1, 2, 3, 4};
array3 = ArrayUtils.subarray(array3, 1, 3); // => [2, 3]
assertEquals(2, array3.length);//2
// 数组拷贝
String[] array4 = {"aaa", "bbb", "ccc"};
String[] copied = (String[]) ArrayUtils.clone(array4); // => {"aaa", "bbb", "ccc"}
assertEquals(3, copied.length);//3
// 判断是否包含某元素
String[] array5 = {"aaa", "bbb", "ccc", "bbb"};
boolean result1 = ArrayUtils.contains(array5, "bbb"); // => true
assertTrue(result1);//true
// 判断某元素在数组中出现的位置（从前往后，没有返回-1）
int result2 = ArrayUtils.indexOf(array5, "bbb"); // => 1
assertEquals(1, result2);//1
result2 = ArrayUtils.indexOf(array5, "bbbb"); // => 1
assertEquals(-1, result2);//1
// 判断某元素在数组中出现的位置（从后往前，没有返回-1）
int result3 = ArrayUtils.lastIndexOf(array5, "bbb"); // => 3
assertEquals(3, result3);//3
// 数组转Map
Map<Object, Object> map = ArrayUtils.toMap(new String[][] {{"key1", "value1"}, {"key2", "value2"}});
assertEquals("value1", map.get("key1"));//"value1"
assertEquals("value2", map.get("key2"));//"value2"
// 判断数组是否为空
Object[] array61 = new Object[0];
Object[] array62 = null;
Object[] array63 = new Object[] {"aaa"};
assertTrue(ArrayUtils.isEmpty(array61));//true
assertTrue(ArrayUtils.isEmpty(array62));//true
assertTrue(ArrayUtils.isNotEmpty(array63));//true
// 判断数组长度是否相等
Object[] array71 = new Object[] {"aa", "bb", "cc"};
Object[] array72 = new Object[] {"dd", "ee", "ff"};
assertTrue(ArrayUtils.isSameLength(array71, array72));//true
// // 判断数组元素内容是否相等
// Object[] array81 = new Object[] {"aa", "bb", "cc"};
// Object[] array82 = new Object[] {"aa", "bb", "cc"};
// assertEquals("", ArrayUtils.isEquals(array81, array82));
// Integer[] 转化为 int[]
Integer[] array9 = new Integer[] {1, 2};
int[] result = ArrayUtils.toPrimitive(array9);
assertEquals(2, result.length);//2
assertEquals(1, result[0]);//1
// int[] 转化为 Integer[]
int[] array10 = new int[] {1, 2};
Integer[] result10 = ArrayUtils.toObject(array10);
assertEquals(2, result.length);//2
assertEquals(1, result10[0].intValue());//1
}
@Test(expected = IllegalArgumentException.class)
public void testAbbreviateException() {
assertEquals("abcdefg", StringUtils.abbreviate("abcdefg", 3));
}
@Test
public void testAbbreviate() {
//对长字符串中的多余指定位数用 省略号表示 ， Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."
//Specifically:
//•If the number of characters in str is less than or equal to maxWidth, return str.
//•Else abbreviate it to (substring(str, 0, max-3) + "...").
//•If maxWidth is less than 4, throw an IllegalArgumentException.
//•In no case will it return a String of length greater than maxWidth.
assertEquals("Pl...", StringUtils.abbreviate("Please check the logs for an error.", 5));
assertEquals("Please...", StringUtils.abbreviate("Please check the logs for an error.", 9));
assertEquals("Please ...", StringUtils.abbreviate("Please check the logs for an error.", 10));
assertEquals(null, StringUtils.abbreviate(null, 1));
assertEquals("abc...", StringUtils.abbreviate("abcdefg", 6));
assertEquals("abcdefg", StringUtils.abbreviate("abcdefg", 7));
assertEquals("abcdefg", StringUtils.abbreviate("abcdefg", 8));
assertEquals("abcdefg", StringUtils.abbreviate("abcdefg", 8));
}
@Test
public void testcapitalize() {
// 首字符大写
assertEquals("Jakarta commons", StringUtils.capitalize("jakarta commons"));
assertEquals(null, StringUtils.capitalize(null));
assertEquals("", StringUtils.capitalize(""));
assertEquals("Cat", StringUtils.capitalize("cat"));
assertEquals("CAt", StringUtils.capitalize("cAt"));
assertEquals("'cat'", StringUtils.capitalize("'cat'"));
}
@Test
public void testwordcapitalize() {
// 首字符大写,这个是针对一个句子中的所有的字符的
assertEquals("Jakarta Commons", WordUtils.capitalize("jakarta commons"));
assertEquals("I Am FINE", WordUtils.capitalize("i am FINE"));//WordUtils.capitalize("i am FINE") = "I Am FINE"
assertEquals("Jakarta Commons", WordUtils.capitalizeFully("jakarta COMMONS"));
assertEquals("I Am Fine", WordUtils.capitalizeFully("i am FINE"));
}
@Test
public void testcenter() {
// 字符居中
assertEquals(" java ", StringUtils.center("java", 10));
}
@Test
public void testreplace() {
// 字符替换
assertEquals("This is a illustration for replace and overlay feature", StringUtils.replace("This is a demo for replace and overlay feature", "demo", "illustration"));
String message = "Your password is: somepassword";
assertEquals("Your password is: *****", StringUtils.overlay(message, "*****", 18, message.length()));
}
@Test
public void testrepeat() {
// 字符重复
assertEquals("abcabc", StringUtils.repeat("abc", 2));
}
@Test
public void testUpper() {
// 字符大小写判断
assertTrue(StringUtils.isAllLowerCase("abcabc"));
assertTrue(StringUtils.isAllUpperCase("ABCABC"));
}
@Test
public void testZc() {
// 字符组成判断
assertTrue(StringUtils.isAlphanumericSpace("abcabc"));
assertTrue(StringUtils.isAlphanumericSpace("abcabc123 "));
assertFalse(StringUtils.isAlphaSpace("abcabc123 "));
assertTrue(StringUtils.isAlphanumeric("abcabc123"));
assertFalse(StringUtils.isNumeric("abcabc123"));
assertTrue(StringUtils.isAlpha("ABCABC"));
assertTrue(StringUtils.isNumericSpace("123 "));
assertTrue(StringUtils.isAsciiPrintable("123 "));
assertTrue(StringUtils.isWhitespace(" "));
}
@Test
public void testOther() {
// 其它判断
assertEquals(4,StringUtils.countMatches("ababsssababa", "ab"));//小字符串在大字符串中的匹配次数
assertEquals("fedcba",StringUtils.reverse("abcdef"));//字符串倒转
assertEquals("i AM A-a*A",StringUtils.swapCase("I am a-A*a") );//大小写转换，空格不动
assertEquals("abcTTT",StringUtils.rightPad("abc", 6, 'T') );//在右边加下字符,使之总长度为6
assertEquals("ab",StringUtils.left("abc", 2));//取得一个字符串左边的两个字符
assertEquals("bc",StringUtils.right("abc", 2));//取得一个字符串右边的两个字符
assertTrue(StringUtils.contains("abc", "ab"));//判断是否包含这个字符
}
}
2016-11-06 15:32:41 星期日
来源：oschina
链接：https://my.oschina.net/u/1261935/blog/782464