如何在Java中将CamelCase转换为人类可读的名称？

Question

我想编写一种将CamelCase转换为人类可读名称的方法。

这是测试用例：

public void testSplitCamelCase() {
    assertEquals("lowercase", splitCamelCase("lowercase"));
    assertEquals("Class", splitCamelCase("Class"));
    assertEquals("My Class", splitCamelCase("MyClass"));
    assertEquals("HTML", splitCamelCase("HTML"));
    assertEquals("PDF Loader", splitCamelCase("PDFLoader"));
    assertEquals("A String", splitCamelCase("AString"));
    assertEquals("Simple XML Parser", splitCamelCase("SimpleXMLParser"));
    assertEquals("GL 11 Version", splitCamelCase("GL11Version"));
}

Answer 1

这适用于你的测试用例：

static String splitCamelCase(String s) {
   return s.replaceAll(
      String.format("%s|%s|%s",
         "(?<=[A-Z])(?=[A-Z][a-z])",
         "(?<=[^A-Z])(?=[A-Z])",
         "(?<=[A-Za-z])(?=[^A-Za-z])"
      ),
      " "
   );
}

这是一个测试工具：

    String[] tests = {
        "lowercase",        // [lowercase]
        "Class",            // [Class]
        "MyClass",          // [My Class]
        "HTML",             // [HTML]
        "PDFLoader",        // [PDF Loader]
        "AString",          // [A String]
        "SimpleXMLParser",  // [Simple XML Parser]
        "GL11Version",      // [GL 11 Version]
        "99Bottles",        // [99 Bottles]
        "May5",             // [May 5]
        "BFG9000",          // [BFG 9000]
    };
    for (String test : tests) {
        System.out.println("[" + splitCamelCase(test) + "]");
    }

它使用零长度匹配正则表达式以及后向和前向查找在哪里插入空格。基本上有3种模式，我习惯String.format将它们放在一起以使其更具可读性。

这三种模式是：

UC behind me, UC followed by LC in front of me

  XMLParser   AString    PDFLoader
    /\        /\           /\

non-UC behind me, UC in front of me

 MyClass   99Bottles
  /\        /\

Letter behind me, non-letter in front of me

 GL11    May5    BFG9000
  /\       /\      /\