http://commons.apache.org/
1)Commons Lang是对JDK中java.lang包的补充，提供了各种各样的Utilities工具类，这里说说最常用的几个工具类。
版本：commons-lang3-3.1.jar
1、字符串的空判断
Java代码 
//isEmpty
System.out.println(StringUtils.isEmpty(null)); // true
System.out.println(StringUtils.isEmpty("")); // true
System.out.println(StringUtils.isEmpty(" ")); // false
System.out.println(StringUtils.isEmpty("bob")); // false
System.out.println(StringUtils.isEmpty(" bob ")); // false
//isBlank
System.out.println(StringUtils.isBlank(null)); // true
System.out.println(StringUtils.isBlank("")); // true
System.out.println(StringUtils.isBlank(" ")); // true
System.out.println(StringUtils.isBlank("bob")); // false
System.out.println(StringUtils.isBlank(" bob ")); // false
2、字符串的Trim
Java代码
//trim
System.out.println(StringUtils.trim(null)); // null
System.out.println(StringUtils.trim("")); // ""
System.out.println(StringUtils.trim(" ")); // ""
System.out.println(StringUtils.trim("abc")); // "abc"
System.out.println(StringUtils.trim(" abc")); // "abc"
System.out.println(StringUtils.trim(" abc ")); // "abc"
System.out.println(StringUtils.trim(" ab c ")); // "ab c"
//strip
System.out.println(StringUtils.strip(null)); // null
System.out.println(StringUtils.strip("")); // ""
System.out.println(StringUtils.strip(" ")); // ""
System.out.println(StringUtils.strip("abc")); // "abc"
System.out.println(StringUtils.strip(" abc")); // "abc"
System.out.println(StringUtils.strip("abc ")); // "abc"
System.out.println(StringUtils.strip(" abc ")); // "abc"
System.out.println(StringUtils.strip(" ab c ")); // "ab c"
System.out.println(StringUtils.strip(" abcyx", "xyz")); // " abc"
System.out.println(StringUtils.stripStart("yxabcxyz ", "xyz")); // "abcxyz "
System.out.println(StringUtils.stripEnd(" xyzabcyx", "xyz")); // " xyzabc"
3、字符串的分割
Java代码
//默认半角空格分割
String str1 = "aaa bbb ccc";
String[] dim1 = StringUtils.split(str1); // => ["aaa", "bbb", "ccc"]
System.out.println(dim1.length);//3
System.out.println(dim1[0]);//"aaa"
System.out.println(dim1[1]);//"bbb"
System.out.println(dim1[2]);//"ccc"
//指定分隔符
String str2 = "aaa,bbb,ccc";
String[] dim2 = StringUtils.split(str2, ","); // => ["aaa", "bbb", "ccc"]
System.out.println(dim2.length);//3
System.out.println(dim2[0]);//"aaa"
System.out.println(dim2[1]);//"bbb"
System.out.println(dim2[2]);//"ccc"
//去除空字符串
String str3 = "aaa,,bbb";
String[] dim3 = StringUtils.split(str3, ","); // => ["aaa", "bbb"]
System.out.println(dim3.length);//2
System.out.println(dim3[0]);//"aaa"
System.out.println(dim3[1]);//"bbb"
//包含空字符串
String str4 = "aaa,,bbb";
String[] dim4 = StringUtils.splitPreserveAllTokens(str4, ","); // => ["aaa", "", "bbb"]
System.out.println(dim4.length);//3
System.out.println(dim4[0]);//"aaa"
System.out.println(dim4[1]);//""
System.out.println(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"]
System.out.println(dim5.length);//2
System.out.println(dim5[0]);//"aaa"
System.out.println(dim5[1]);//"bbb,ccc"
4、字符串的连接
Java代码
//数组元素拼接
String[] array = {"aaa", "bbb", "ccc"};
String result1 = StringUtils.join(array, ",");
System.out.println(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, ",");
System.out.println(result2);//"aaa,bbb,ccc"
5、字符串的Escape
Java代码
System.out.println(StringEscapeUtils.escapeCsv("测试测试哦"));//"测试测试哦"
System.out.println(StringEscapeUtils.escapeCsv("测试,测试哦"));//"\"测试,测试哦\""
System.out.println(StringEscapeUtils.escapeCsv("测试\n测试哦"));//"\"测试\n测试哦\""
System.out.println(StringEscapeUtils.escapeHtml4("测试测试哦
"));//"<p>测试测试哦</p>"
System.out.println(StringEscapeUtils.escapeJava("\"rensaninng\"，欢迎您！"));//"\"rensaninng\"\uFF0C\u6B22\u8FCE\u60A8\uFF01"
System.out.println(StringEscapeUtils.escapeEcmaScript("测试'测试哦"));//"\u6D4B\u8BD5\'\u6D4B\u8BD5\u54E6"
System.out.println(StringEscapeUtils.escapeXml("<tt>\"bread\" & \"butter\"</tt>"));//"<tt>"bread" & "butter"</tt>"
6、随机数
Java代码
// 10位英字
System.out.println(RandomStringUtils.randomAlphabetic(10));
// 10位英数
System.out.println(RandomStringUtils.randomAlphanumeric(10));
// 10位ASCII码
System.out.println(RandomStringUtils.randomAscii(10));
// 指定文字10位
System.out.println(RandomStringUtils.random(10, "abcde"));
7、数组
Java代码
// 追加元素到数组尾部
int[] array1 = {1, 2};
array1 = ArrayUtils.add(array1, 3); // => [1, 2, 3]
System.out.println(array1.length);//3
System.out.println(array1[2]);//3
// 删除指定位置的元素
int[] array2 = {1, 2, 3};
array2 = ArrayUtils.remove(array2, 2); // => [1, 2]
System.out.println(array2.length);//2
// 截取部分元素
int[] array3 = {1, 2, 3, 4};
array3 = ArrayUtils.subarray(array3, 1, 3); // => [2, 3]
System.out.println(array3.length);//2
// 数组拷贝
String[] array4 = {"aaa", "bbb", "ccc"};
String[] copied = (String[]) ArrayUtils.clone(array4); // => {"aaa", "bbb", "ccc"}
System.out.println(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
System.out.println(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
System.out.println(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
System.out.println(result3);//3
// 数组转Map
Map<Object, Object> map = ArrayUtils.toMap(new String[][]{
{"key1", "value1"},
{"key2", "value2"}
});
System.out.println(map.get("key1"));//"value1"
System.out.println(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"};
System.out.println(ArrayUtils.isEmpty(array61));//true
System.out.println(ArrayUtils.isEmpty(array62));//true
System.out.println(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"};
System.out.println(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"};
System.out.println(ArrayUtils.isEquals(array81, array82));
// Integer[] 转化为 int[]
Integer[] array9 = new Integer[]{1, 2};
int[] result = ArrayUtils.toPrimitive(array9);
System.out.println(result.length);//2
System.out.println(result[0]);//1
// int[] 转化为 Integer[]
int[] array10 = new int[]{1, 2};
Integer[] result10 = ArrayUtils.toObject(array10);
System.out.println(result.length);//2
System.out.println(result10[0].intValue());//1
8、日期
Java代码
// 生成Date对象
Date date = DateUtils.parseDate("2010/01/01 11:22:33", new String[]{"yyyy/MM/dd HH:mm:ss"});
// 10天后
Date tenDaysAfter = DateUtils.addDays(date, 10); // => 2010/01/11 11:22:33
System.out.println(DateFormatUtils.format(tenDaysAfter, "yyyy/MM/dd HH:mm:ss"));
// 前一个月
Date prevMonth = DateUtils.addMonths(date, -1); // => 2009/12/01 11:22:33
System.out.println(DateFormatUtils.format(prevMonth, "yyyy/MM/dd HH:mm:ss"));
// 判断是否是同一天
Date date1 = DateUtils.parseDate("2010/01/01 11:22:33", new String[]{"yyyy/MM/dd HH:mm:ss"});
Date date2 = DateUtils.parseDate("2010/01/01 22:33:44", new String[]{"yyyy/MM/dd HH:mm:ss"});
System.out.println(DateUtils.isSameDay(date1, date2));// true
// 日期格式化
System.out.println(DateFormatUtils.format(new Date(), "yyyy/MM/dd HH:mm:ss"));
2)Commons Beanutils是一组专门用于操作Bean的工具类，目前很多流行的框架基本都离不开他。
版本：commons-beanutils-1.8.3.jar
1、获取字段值
Java代码
SampleBean bean1 = new SampleBean();
bean1.setName("rensanning");
bean1.setAge(31);
String name = BeanUtils.getProperty(bean1, "name");
String age = BeanUtils.getProperty(bean1, "age");
System.out.println(name);
System.out.println(age);
2、设置字段值
Java代码
SampleBean bean2 = new SampleBean();
BeanUtils.setProperty(bean2, "name", "rensanning");
BeanUtils.setProperty(bean2, "age", 31);
System.out.println(bean2.getName());
System.out.println(bean2.getAge());
3、赋值Bean
Java代码
SampleBean bean3 = new SampleBean();
bean3.setName("rensanning");
bean3.setAge(31);
SampleBean clone = (SampleBean) BeanUtils.cloneBean(bean3);
System.out.println(clone.getName());
System.out.println(clone.getAge());
4、Bean的describe
Java代码
SampleBean bean4 = new SampleBean();
bean4.setName("rensanning");
bean4.setAge(31);
@SuppressWarnings("unchecked")
Map<String, String> map4 = BeanUtils.describe(bean4);
System.out.println(map4.get("name"));
System.out.println(map4.get("age"));
5、Bean的populate
Java代码
SampleBean bean5 = new SampleBean();
Map<String, String> map5 = new HashMap<String, String>();
map5.put("name", "rensanning");
map5.put("age", "31");
BeanUtils.populate(bean5, map5);
System.out.println(bean5.getName());
System.out.println(bean5.getAge());
6、获取Bean的数组集合字段值
Java代码
SampleBean bean6 = new SampleBean();
bean6.setArray(new String[]{"a", "b", "c"});
List<String> list0 = new ArrayList<String>();
list0.add("d");
list0.add("e");
list0.add("f");
bean6.setList(list0);
String[] array = BeanUtils.getArrayProperty(bean6, "array");
System.out.println(array.length);//3
System.out.println(array[0]);//"a"
System.out.println(array[1]);//"b"
System.out.println(array[2]);//"c"
String[] list = BeanUtils.getArrayProperty(bean6, "list");
System.out.println(list.length);//3
System.out.println(list[0]);//"d"
System.out.println(list[1]);//"e"
System.out.println(list[2]);//"f"
System.out.println(BeanUtils.getProperty(bean6, "array[1]"));//"b"
System.out.println(BeanUtils.getIndexedProperty(bean6, "array", 2));//"c"
7、获取Bean的Map字段值
Java代码
SampleBean bean7 = new SampleBean();
Map<String, String> map = new HashMap<String, String>();
map.put("key1", "value1");
map.put("key2", "value2");
bean7.setMap(map);
String value1 = BeanUtils.getMappedProperty(bean7, "map", "key1");
System.out.println(value1);//"value1"
String value2 = BeanUtils.getMappedProperty(bean7, "map", "key2");
System.out.println(value2);//"value2"
System.out.println(BeanUtils.getProperty(bean7, "map.key1"));//"value1"
System.out.println(BeanUtils.getProperty(bean7, "map.key2"));//"value2"
8、获取Bean的嵌套字段值
Java代码
SampleBean bean = new SampleBean();
NestedBean nestedBean = new NestedBean();
nestedBean.setNestedProperty("xxx");
bean.setNestedBean(nestedBean);
String value = BeanUtils.getNestedProperty(bean, "nestedBean.nestedProperty");
System.out.println(value);//"xxx"
System.out.println(BeanUtils.getProperty(bean, "nestedBean.nestedProperty"));//"xxx"
9、URL字段的特殊处理
Java代码
SampleBean bean8 = new SampleBean();
BeanUtils.setProperty(bean8, "url", "http://www.google.com/");
URL url = bean8.getUrl();
System.out.println(url.getProtocol());//"http"
System.out.println(url.getHost());//"www.google.com"
System.out.println(url.getPath());//"/"
10、日期的转化
Java代码
SampleBean bean9 = new SampleBean();
DateConverter converter = new DateConverter();
converter.setPattern("yyyy/MM/dd HH:mm:ss");
ConvertUtils.register(converter, Date.class);
ConvertUtils.register(converter, String.class);
BeanUtils.setProperty(bean9, "date", "2010/12/19 23:40:00");
String value9 = BeanUtils.getProperty(bean9, "date");
System.out.println(value9);//"2010/12/19 23:40:00"