String StingUtil 常用格式化

org.apache.commons.lang.StringUtils;
StringUtils.join(null)            = null
StringUtils.join([])                 = ""
StringUtils.join([null])          = ""
StringUtils.join(["a", "b", "c"]) = "abc"
StringUtils.join([null, "", "a"]) = "a"
String[] str = { "1", "2", "a", "b" };
// 将数组变成字符串
StringUtils.join(str)
// 将数组用逗号分隔变成字符串
StringUtils.join(str, ",")
 
  
 
  
 String str = String.format("%04d", 12); 结果："0012"
 
  
 String str = String.format("%4d", 12); 结果："  12"
 
  
 String str = String.format("%,d", 121212); 结果："121,212"
 
  
 String str = String.format("%1$5s", "abc");结果："  abc"
 
  
 String str = String.format("%1$tF %1$tT", new Date());结果："2009-01-19 17:39:25"
 
  
 String.format("%1$tY%1$tm%1$td%1$tH%1$tM%1$tS%1$tL", new Date())结果：20090414092113796
 
  
 String.format("%1$tm", new Date());结果为月份
 String.format("%1$tY%1$tm%1$td%1$tH%1$tM%1$tS", new Date());