commons-lang3包中对我们有用的类主要有:
1.StringUtils 该类主要提供对字符串的操作,对null是安全的,主要提供了字符串查找,替换,分割,去空白,去掉非法字符等等操作
2.ObjectUtils 主要是对null进行安全处理,可以设置为null时的默认返回值,比较相等时是调用对象的equals方法,因此需要对对象进行方法进行覆盖
3.SystemUtils 主要获取一些系统属性,例如工作目录等等
4.DateUtils/CalendarUtils 主要提供了对日期的操作,包括日期加减,日期格式化,日期比较,一定时间范围内日期的迭代等等
5.StopWatch 提供秒表的计时,暂停等功能
6. EqualsBuilder/HashCodeBuilder提供了方便的方法来覆盖equals() 和hashCode()方法
7.以Range结尾的类主要提供一些范围的操作,包括判断某些字符,数字等是否在这个范围以内
8.ArrayUtils 提供了数组的复制,查找,获取子数组,反转等功能
public class TestLangDemo {
public void charSetDemo() {
System.out.println("**CharSetDemo**");
CharSet charSet = CharSet.getInstance("aeiou");
String demoStr = "The quick brown fox jumps over the lazy dog.";
int count = 0;
for (int i = 0, len = demoStr.length(); i < len; i++) {
if (charSet.contains(demoStr.charAt(i))) {
count++;
}
}
System.out.println("count: " + count);
}
public void charSetUtilsDemo() {
System.out.println("**CharSetUtilsDemo**");
System.out.println("计算字符串中包含某字符数.");
System.out.println(CharSetUtils.count("The quick brown fox jumps over the lazy dog.", "aeiou"));
System.out.println("删除字符串中某字符.");
System.out.println(CharSetUtils.delete("The quick brown fox jumps over the lazy dog.", "aeiou"));
System.out.println("保留字符串中某字符.");
System.out.println(CharSetUtils.keep("The quick brown fox jumps over the lazy dog.", "aeiou"));
System.out.println("合并重复的字符.");
System.out.println(CharSetUtils.squeeze("a bbbbbb c dd", "b d"));
}
public void objectUtilsDemo() {
System.out.println("**ObjectUtilsDemo**");
System.out.println("Object为null时，默认打印某字符.");
Object obj = null;
System.out.println(ObjectUtils.defaultIfNull(obj, "空"));
System.out.println("验证两个引用是否指向的Object是否相等,取决于Object的equals()方法.");
Object a = new Object();
Object b = a;
Object c = new Object();
System.out.println(ObjectUtils.equals(a, b));
System.out.println(ObjectUtils.equals(a, c));
System.out.println("用父类Object的toString()方法返回对象信息.");
Date date = new Date();
System.out.println(ObjectUtils.identityToString(date));
System.out.println(date);
System.out.println("返回类本身的toString()方法结果,对象为null时，返回0长度字符串.");
System.out.println(ObjectUtils.toString(date));
System.out.println(ObjectUtils.toString(null));
System.out.println(date);
}
public void serializationUtilsDemo() {
System.out.println("*SerializationUtils**");
Date date = new Date();
byte[] bytes = SerializationUtils.serialize(date);
System.out.println(ArrayUtils.toString(bytes));
System.out.println(date);
Date reDate = (Date) SerializationUtils.deserialize(bytes);
System.out.println(reDate);
System.out.println(ObjectUtils.equals(date, reDate));
System.out.println(date == reDate);
FileOutputStream fos = null;
FileInputStream fis = null;
try {
fos = new FileOutputStream(new File("d:/test.txt"));
fis = new FileInputStream(new File("d:/test.txt"));
SerializationUtils.serialize(date, fos);
Date reDate2 = (Date) SerializationUtils.deserialize(fis);
System.out.println(date.equals(reDate2));
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
try {
fos.close();
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public void randomStringUtilsDemo() {
System.out.println("**RandomStringUtilsDemo**");
System.out.println("生成指定长度的随机字符串,好像没什么用.");
System.out.println(RandomStringUtils.random(500));
System.out.println("在指定字符串中生成长度为n的随机字符串.");
System.out.println(RandomStringUtils.random(5, "abcdefghijk"));
System.out.println("指定从字符或数字中生成随机字符串.");
System.out.println(RandomStringUtils.random(5, true, false));
System.out.println(RandomStringUtils.random(5, false, true));
}
public void stringUtilsDemo() {
System.out.println("**StringUtilsDemo**");
System.out.println("将字符串重复n次，将文字按某宽度居中，将字符串数组用某字符串连接.");
String[] header = new String[3];
header[0] = StringUtils.repeat("*", 50);
header[1] = StringUtils.center(" StringUtilsDemo ", 50, "^O^");
header[2] = header[0];
String head = StringUtils.join(header, "\n");
System.out.println(head);
System.out.println("缩短到某长度,用...结尾.");
System.out.println(StringUtils.abbreviate("The quick brown fox jumps over the lazy dog.", 10));
System.out.println(StringUtils.abbreviate("The quick brown fox jumps over the lazy dog.", 15, 10));
System.out.println("返回两字符串不同处索引号.");
System.out.println(StringUtils.indexOfDifference("aaabc", "aaacc"));
System.out.println("返回两字符串不同处开始至结束.");
System.out.println(StringUtils.difference("aaabcde", "aaaccde"));
System.out.println("截去字符串为以指定字符串结尾的部分.");
System.out.println(StringUtils.chomp("aaabcde", "de"));
System.out.println("检查一字符串是否为另一字符串的子集.");
System.out.println(StringUtils.containsOnly("aad", "aadd"));
System.out.println("检查一字符串是否不是另一字符串的子集.");
System.out.println(StringUtils.containsNone("defg", "aadd"));
System.out.println("检查一字符串是否包含另一字符串.");
System.out.println(StringUtils.contains("defg", "ef"));
System.out.println(StringUtils.containsOnly("ef", "defg"));
System.out.println("返回可以处理null的toString().");
System.out.println(StringUtils.defaultString("aaaa"));
System.out.println("?" + StringUtils.defaultString(null) + "!");
System.out.println("去除字符中的空格.");
System.out.println(StringUtils.deleteWhitespace("aa bb cc"));
System.out.println("分隔符处理成数组.");
String[] strArray = StringUtils.split("a,b,,c,d,null,e", ",");
System.out.println(strArray.length);
System.out.println(strArray.toString());
System.out.println("判断是否是某类字符.");
System.out.println(StringUtils.isAlpha("ab"));
System.out.println(StringUtils.isAlphanumeric("12"));
System.out.println(StringUtils.isBlank(""));
System.out.println(StringUtils.isNumeric("123"));
}
public void systemUtilsDemo() {
System.out.println(genHeader("SystemUtilsDemo"));
System.out.println("获得系统文件分隔符.");
System.out.println(SystemUtils.FILE_SEPARATOR);
System.out.println("获得源文件编码.");
System.out.println(SystemUtils.FILE_ENCODING);
System.out.println("获得ext目录.");
System.out.println(SystemUtils.JAVA_EXT_DIRS);
System.out.println("获得java版本.");
System.out.println(SystemUtils.JAVA_VM_VERSION);
System.out.println("获得java厂商.");
System.out.println(SystemUtils.JAVA_VENDOR);
}
public void classUtilsDemo() {
System.out.println(genHeader("ClassUtilsDemo"));
System.out.println("获取类实现的所有接口.");
System.out.println(ClassUtils.getAllInterfaces(Date.class));
System.out.println("获取类所有父类.");
System.out.println(ClassUtils.getAllSuperclasses(Date.class));
System.out.println("获取简单类名.");
System.out.println(ClassUtils.getShortClassName(Date.class));
System.out.println("获取包名.");
System.out.println(ClassUtils.getPackageName(Date.class));
System.out.println("判断是否可以转型.");
System.out.println(ClassUtils.isAssignable(Date.class, Object.class));
System.out.println(ClassUtils.isAssignable(Object.class, Date.class));
}
public void stringEscapeUtilsDemo() {
System.out.println(genHeader("StringEcsapeUtils"));
System.out.println("转换特殊字符.");
System.out.println("html:" + StringEscapeUtils.escapeHtml3(" "));
System.out.println("html:" + StringEscapeUtils.escapeHtml4(" "));
System.out.println("html:" + StringEscapeUtils.unescapeHtml3("<p>"));
System.out.println("html:" + StringEscapeUtils.unescapeHtml4("<p>"));
}
private final class BuildDemo {
String name;
int age;
public BuildDemo(String name, int age) {
this.name = name;
this.age = age;
}
public String toString() {
ToStringBuilder tsb = new ToStringBuilder(this, ToStringStyle.MULTI_LINE_STYLE);
tsb.append("Name", name);
tsb.append("Age", age);
return tsb.toString();
}
public int hashCode() {
HashCodeBuilder hcb = new HashCodeBuilder();
hcb.append(name);
hcb.append(age);
return hcb.hashCode();
}
public boolean equals(Object obj) {
if (!(obj instanceof BuildDemo)) {
return false;
}
BuildDemo bd = (BuildDemo) obj;
EqualsBuilder eb = new EqualsBuilder();
eb.append(name, bd.name);
eb.append(age, bd.age);
return eb.isEquals();
}
}
public void builderDemo() {
System.out.println(genHeader("BuilderDemo"));
BuildDemo obj1 = new BuildDemo("a", 1);
BuildDemo obj2 = new BuildDemo("b", 2);
BuildDemo obj3 = new BuildDemo("a", 1);
System.out.println("toString()");
System.out.println(obj1);
System.out.println(obj2);
System.out.println(obj3);
System.out.println("hashCode()");
System.out.println(obj1.hashCode());
System.out.println(obj2.hashCode());
System.out.println(obj3.hashCode());
System.out.println("equals()");
System.out.println(obj1.equals(obj2));
System.out.println(obj1.equals(obj3));
}
public void numberUtils() {
System.out.println(genHeader("NumberUtils"));
System.out.println("字符串转为数字(不知道有什么用).");
System.out.println(NumberUtils.toInt("ba", 33));
System.out.println("从数组中选出最大值.");
System.out.println(NumberUtils.max(new int[] { 1, 2, 3, 4 }));
System.out.println("判断字符串是否全是整数.");
System.out.println(NumberUtils.isDigits("123.1"));
System.out.println("判断字符串是否是有效数字.");
System.out.println(NumberUtils.isNumber("0123.1"));
}
public void dateFormatUtilsDemo() {
System.out.println(genHeader("DateFormatUtilsDemo"));
System.out.println("格式化日期输出.");
System.out.println(DateFormatUtils.format(System.currentTimeMillis(), "yyyy-MM-dd HH:mm:ss"));
System.out.println("秒表.");
StopWatch sw = new StopWatch();
sw.start();
for (Iterator iterator = DateUtils.iterator(new Date(), DateUtils.RANGE_WEEK_CENTER); iterator.hasNext();) {
Calendar cal = (Calendar) iterator.next();
System.out.println(DateFormatUtils.format(cal.getTime(), "yy-MM-dd HH:mm"));
}
sw.stop();
System.out.println("秒表计时:" + sw.getTime());
}
private String genHeader(String head) {
String[] header = new String[3];
header[0] = StringUtils.repeat("*", 50);
header[1] = StringUtils.center(" " + head + " ", 50, "^O^");
header[2] = header[0];
return StringUtils.join(header, "\n");
}
private void validateDemo() {
String[] strarray = { "a", "b", "c" };
System.out.println("验证功能");
System.out.println(Validate.notEmpty(strarray));
}
private void wordUtilsDemo() {
System.out.println("单词处理功能");
String str1 = "wOrD";
String str2 = "ghj\nui\tpo";
System.out.println(WordUtils.capitalize(str1)); // 首字母大写
System.out.println(WordUtils.capitalizeFully(str1)); // 首字母大写其它字母小写
char[] ctrg = { '.' };
System.out.println(WordUtils.capitalizeFully("i aM.fine", ctrg)); // 在规则地方转换
System.out.println(WordUtils.initials(str1)); // 获取首字母
System.out.println(WordUtils.initials("Ben John Lee", null)); // 取每个单词的首字母
char[] ctr = { ' ', '.' };
System.out.println(WordUtils.initials("Ben J.Lee", ctr)); // 按指定规则获取首字母
System.out.println(WordUtils.swapCase(str1)); // 大小写逆转
System.out.println(WordUtils.wrap(str2, 1)); // 解析\n和\t等字符
}
/**
* @param args
*/
public static void main(String[] args) {
TestLangDemo langDemo = new TestLangDemo();
langDemo.charSetDemo();
langDemo.charSetUtilsDemo();
langDemo.objectUtilsDemo();
langDemo.serializationUtilsDemo();
langDemo.randomStringUtilsDemo();
langDemo.stringUtilsDemo();
langDemo.systemUtilsDemo();
langDemo.classUtilsDemo();
langDemo.stringEscapeUtilsDemo();
langDemo.builderDemo();
langDemo.numberUtils();
langDemo.dateFormatUtilsDemo();
langDemo.validateDemo();
langDemo.wordUtilsDemo();
}
}来源：oschina
链接：https://my.oschina.net/u/131940/blog/598925