如果你的项目是maven工程，首先在pom.xml中添加commons-lang3包的依赖 

<dependency>
	<groupId>org.apache.commons</groupId>
	<artifactId>commons-lang3</artifactId>
	<version>3.4</version>
</dependency>

字符串替换函数方法

	public static void main(String[] args) {
		
		String s=StringUtils.replace("java", "a", "b");//jbvb
                //-1代表全部替换,0代表不替换，非0和-1的数字就是从字符串开始到结尾需要替换的个数
		String s1=StringUtils.replace("java", "a", "", -1);//jv
		String s2=StringUtils.replace("java", "a", "b", -1);//jbvb
		String s3=StringUtils.replace("java", "a", "b", 0);//java
		String s4=StringUtils.replace("java", "a", "b", 1);//jbva
		String s5=StringUtils.replace("java", "a", "b", 2);//jbvb
		//replaceEach可精确替换指定的组合字符
		String s6=StringUtils.replaceEach("javase", new String[]{"av", "s"}, new String[]{"c", "d"});//jcade
		String s7=StringUtils.replaceChars("javase", "ase", "bcd");//jbvbcd
		//replaceOnce从字符串开始只替换一次
		String S1=StringUtils.replaceOnce("java", "j", "");//ava
		String S2=StringUtils.replaceOnce("java", "a", "b");//jbva
		//replaceEach和replaceEachRepeatedly观察结果没发现有何区别。。。。
		String S3=StringUtils.replaceEachRepeatedly("javase", new String[]{"av", "s"}, new String[]{"c", "d"});//jcade
		String S4=StringUtils.replaceEachRepeatedly("javaee", new String[]{"av", "e"}, new String[]{"c", "d"});//jcadd
		//
		String Str =StringUtils.overlay("", "abc", 0, 0);//abc
		String Str1=StringUtils.overlay("abcdef", null, 2, 4);//abef
		String Str2=StringUtils.overlay("abcdef", "", 2, 4);//abef
		String Str3=StringUtils.overlay("abcdef", "", 4, 2);//abef
		String Str4=StringUtils.overlay("abcdef", "zzzz", 2, 4);//abzzzzef
		String Str5=StringUtils.overlay("abcdef", "zzzz", 4, 2);//abzzzzef
		String Str6=StringUtils.overlay("abcdef", "zzzz", -1, 4);//zzzzef
		String Str7=StringUtils.overlay("abcdef", "zzzz", 2, 8);//abzzzz
		String Str8=StringUtils.overlay("abcdef", "zzzz", -2, -3);//zzzzabcdef
		String Str9=StringUtils.overlay("abcdef", "zzzz", 8, 10);//abcdefzzzz
		

	}