看例子练apache commons之lang篇 -优快云博客

本文通过多个示例展示了 Apache Commons Lang 库的强大功能，包括字符集操作、对象比较、序列化、随机字符串生成、字符串处理等。适用于希望提高 Java 编程效率的开发者。
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看commons包时的相关练习,可以用这个包提高编码效率。
 
  packagecn.org.c4c.test.apache; 
 importjava.io.File; 
 importjava.io.FileInputStream; 
 importjava.io.FileNotFoundException; 
 importjava.io.FileOutputStream; 
 importjava.io.IOException; 
 importjava.util.Calendar; 
 importjava.util.Date; 
 importjava.util.Iterator; 
 importorg.apache.commons.lang.ArrayUtils; 
 importorg.apache.commons.lang.CharSet; 
 importorg.apache.commons.lang.CharSetUtils; 
 importorg.apache.commons.lang.ClassUtils; 
 importorg.apache.commons.lang.ObjectUtils; 
 importorg.apache.commons.lang.RandomStringUtils; 
 importorg.apache.commons.lang.SerializationUtils; 
 importorg.apache.commons.lang.StringEscapeUtils; 
 importorg.apache.commons.lang.StringUtils; 
 importorg.apache.commons.lang.SystemUtils; 
 importorg.apache.commons.lang.builder.EqualsBuilder; 
 importorg.apache.commons.lang.builder.HashCodeBuilder; 
 importorg.apache.commons.lang.builder.ToStringBuilder; 
 importorg.apache.commons.lang.builder.ToStringStyle; 
 importorg.apache.commons.lang.math.NumberUtils; 
 importorg.apache.commons.lang.time.DateFormatUtils; 
 importorg.apache.commons.lang.time.DateUtils; 
 importorg.apache.commons.lang.time.StopWatch; 
 publicclassLangDemo{ 
 publicvoidcharSetDemo(){ 
 System.out.println("**CharSetDemo**"); 
 CharSetcharSet=CharSet.getInstance("aeiou"); 
 StringdemoStr="Thequickbrownfoxjumpsoverthelazydog."; 
 intcount=0; 
 for(inti=0,len=demoStr.length();i<len;i++){ 
 if(charSet.contains(demoStr.charAt(i))){ 
count++;
}
}
 System.out.println("count:"+count); 
}
 publicvoidcharSetUtilsDemo(){ 
 System.out.println("**CharSetUtilsDemo**"); 
 System.out.println("计算字符串中包含某字符数."); 
System.out.println(CharSetUtils.count(
 "Thequickbrownfoxjumpsoverthelazydog.","aeiou")); 
 System.out.println("删除字符串中某字符."); 
System.out.println(CharSetUtils.delete(
 "Thequickbrownfoxjumpsoverthelazydog.","aeiou")); 
 System.out.println("保留字符串中某字符."); 
System.out.println(CharSetUtils.keep(
 "Thequickbrownfoxjumpsoverthelazydog.","aeiou")); 
 System.out.println("合并重复的字符."); 
 System.out.println(CharSetUtils.squeeze("abbbbbbcdd","bd")); 
}
 publicvoidobjectUtilsDemo(){ 
 System.out.println("**ObjectUtilsDemo**"); 
 System.out.println("Object为null时，默认打印某字符."); 
 Objectobj=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."); 
 Objecta=newObject(); 
Objectb=a;
 Objectc=newObject(); 
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."); 
 Datedate=newDate(); 
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);
}
 publicvoidserializationUtilsDemo(){ 
 System.out.println("*SerializationUtils**"); 
 Datedate=newDate(); 
 byte[]bytes=SerializationUtils.serialize(date); 
System.out.println(ArrayUtils.toString(bytes));
System.out.println(date);
DatereDate=(Date)SerializationUtils.deserialize(bytes);
System.out.println(reDate);
System.out.println(ObjectUtils.equals(date,reDate));
System.out.println(date==reDate);
 FileOutputStreamfos=null; 
 FileInputStreamfis=null; 
 try{ 
 fos=newFileOutputStream(newFile("d:/test.txt")); 
 fis=newFileInputStream(newFile("d:/test.txt")); 
SerializationUtils.serialize(date,fos);
DatereDate2=(Date)SerializationUtils.deserialize(fis);
System.out.println(date.equals(reDate2));
 }catch(FileNotFoundExceptione){ 
e.printStackTrace();
 }finally{ 
 try{ 
fos.close();
fis.close();
 }catch(IOExceptione){ 
e.printStackTrace();
}
}
}
 publicvoidrandomStringUtilsDemo(){ 
 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)); 
}
 publicvoidstringUtilsDemo(){ 
 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=newString[3]; 
 header[0]=StringUtils.repeat("*",50); 
 header[1]=StringUtils.center("StringUtilsDemo",50,"^O^"); 
 header[2]=header[0]; 
 Stringhead=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(
 "Thequickbrownfoxjumpsoverthelazydog.",10)); 
System.out.println(StringUtils.abbreviate(
 "Thequickbrownfoxjumpsoverthelazydog.",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("aabbcc")); 
 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")); 
}
 publicvoidsystemUtilsDemo(){ 
 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);
}
 publicvoidclassUtilsDemo(){ 
 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)); 
}
 publicvoidstringEscapeUtilsDemo(){ 
 System.out.println(genHeader("StringEcsapeUtils")); 
 System.out.println("转换特殊字符."); 
 System.out.println("html:"+StringEscapeUtils.escapeHtml("")); 
 System.out.println("html:"+StringEscapeUtils.unescapeHtml("<p>")); 
}
 privatefinalclassBuildDemo{ 
Stringname;
 intage; 
 publicBuildDemo(Stringname,intage){ 
 this.name=name; 
 this.age=age; 
}
 publicStringtoString(){ 
 ToStringBuildertsb=newToStringBuilder(this, 
ToStringStyle.MULTI_LINE_STYLE);
 tsb.append("Name",name); 
 tsb.append("Age",age); 
 returntsb.toString(); 
}
 publicinthashCode(){ 
 HashCodeBuilderhcb=newHashCodeBuilder(); 
hcb.append(name);
hcb.append(age);
 returnhcb.hashCode(); 
}
 publicbooleanequals(Objectobj){ 
 if(!(objinstanceofBuildDemo)){ 
 returnfalse; 
}
BuildDemobd=(BuildDemo)obj;
 EqualsBuildereb=newEqualsBuilder(); 
eb.append(name,bd.name);
eb.append(age,bd.age);
 returneb.isEquals(); 
}
}
 publicvoidbuilderDemo(){ 
 System.out.println(genHeader("BuilderDemo")); 
 BuildDemoobj1=newBuildDemo("a",1); 
 BuildDemoobj2=newBuildDemo("b",2); 
 BuildDemoobj3=newBuildDemo("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));
}
 publicvoidnumberUtils(){ 
 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.stringToInt("ba",33)); 
 System.out.println("从数组中选出最大值."); 
 System.out.println(NumberUtils.max(newint[]{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")); 
}
 publicvoiddateFormatUtilsDemo(){ 
 System.out.println(genHeader("DateFormatUtilsDemo")); 
 System.out.println("格式化日期输出."); 
System.out.println(DateFormatUtils.format(System.currentTimeMillis(),
 "yyyy-MM-ddHH:mm:ss")); 
 System.out.println("秒表."); 
 StopWatchsw=newStopWatch(); 
sw.start();
 for(Iteratoriterator=DateUtils.iterator(newDate(), 
DateUtils.RANGE_WEEK_CENTER);iterator.hasNext();){
Calendarcal=(Calendar)iterator.next();
System.out.println(DateFormatUtils.format(cal.getTime(),
 "yy-MM-ddHH:mm")); 
}
sw.stop();
 System.out.println("秒表计时:"+sw.getTime()); 
}
 privateStringgenHeader(Stringhead){ 
 String[]header=newString[3]; 
 header[0]=StringUtils.repeat("*",50); 
 header[1]=StringUtils.center(""+head+"",50,"^O^"); 
 header[2]=header[0]; 
 returnStringUtils.join(header,"\n"); 
}
 /** 
*@paramargs
 */ 
 publicstaticvoidmain(String[]args){ 
 LangDemolangDemo=newLangDemo(); 
langDemo.charSetDemo();
langDemo.charSetUtilsDemo();
langDemo.objectUtilsDemo();
langDemo.serializationUtilsDemo();
langDemo.randomStringUtilsDemo();
langDemo.stringUtilsDemo();
langDemo.systemUtilsDemo();
langDemo.classUtilsDemo();
langDemo.stringEscapeUtilsDemo();
langDemo.builderDemo();
langDemo.numberUtils();
langDemo.dateFormatUtilsDemo();
}
}
 
 