看例子练apache commons之lang篇-阿里云开发者社区

看commons包时的相关练习,可以用这个包提高编码效率。
 
  package cn.org.c4c.test.apache; 
 import java.io.File; 
 import java.io.FileInputStream; 
 import java.io.FileNotFoundException; 
 import java.io.FileOutputStream; 
 import java.io.IOException; 
 import java.util.Calendar; 
 import java.util.Date; 
 import java.util.Iterator; 
 import org.apache.commons.lang.ArrayUtils; 
 import org.apache.commons.lang.CharSet; 
 import org.apache.commons.lang.CharSetUtils; 
 import org.apache.commons.lang.ClassUtils; 
 import org.apache.commons.lang.ObjectUtils; 
 import org.apache.commons.lang.RandomStringUtils; 
 import org.apache.commons.lang.SerializationUtils; 
 import org.apache.commons.lang.StringEscapeUtils; 
 import org.apache.commons.lang.StringUtils; 
 import org.apache.commons.lang.SystemUtils; 
 import org.apache.commons.lang.builder.EqualsBuilder; 
 import org.apache.commons.lang.builder.HashCodeBuilder; 
 import org.apache.commons.lang.builder.ToStringBuilder; 
 import org.apache.commons.lang.builder.ToStringStyle; 
 import org.apache.commons.lang.math.NumberUtils; 
 import org.apache.commons.lang.time.DateFormatUtils; 
 import org.apache.commons.lang.time.DateUtils; 
 import org.apache.commons.lang.time.StopWatch; 
 public class LangDemo { 
     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("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.escapeHtml(" ")); 
         System.out.println("html:" + StringEscapeUtils.unescapeHtml("<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.stringToInt("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"); 
    }
     /** 
     * @param args
      */ 
     public static void main(String[] args) { 
         LangDemo langDemo = new LangDemo(); 
        langDemo.charSetDemo();
        langDemo.charSetUtilsDemo();
        langDemo.objectUtilsDemo();
        langDemo.serializationUtilsDemo();
        langDemo.randomStringUtilsDemo();
        langDemo.stringUtilsDemo();
        langDemo.systemUtilsDemo();
        langDemo.classUtilsDemo();
        langDemo.stringEscapeUtilsDemo();
        langDemo.builderDemo();
        langDemo.numberUtils();
        langDemo.dateFormatUtilsDemo();
    }
}
 
 
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