注意：1. StringUtils.isEmpty() 方法判断空格的情况

import org.springframework.util.StringUtils;

public class TestString {

public static void main(String[] args) {
    boolean empty1 = StringUtils.isEmpty(null);
    boolean empty2 = StringUtils.isEmpty("");
    boolean empty3 = StringUtils.isEmpty(" ");    //false

    boolean text1 = StringUtils.hasText(null);
    boolean text2 = StringUtils.hasText("");
    boolean text3 = StringUtils.hasText(" ");     //false

    // 统计一个子字符串在字符串出现的次数
    int i1 = StringUtils.countOccurrencesOf("erowoiueoiur", "e");
    int i2 = StringUtils.countOccurrencesOf("erowoiueoiur", "oiur");

    //字符串替换
    String inString = "a6AazAaa77abaa";
    String oldPattern = "aa";
    String newPattern = "foo";
    String s = StringUtils.replace(inString, oldPattern, newPattern);

    //删除字符串
    String tarString = "Thejumpedthelazydog";
    String noThe = StringUtils.delete(tarString, "the");  //Thejumpedlazydog

    System.out.println("empty1:"+empty1);
    System.out.println("empty2:"+empty2);
    System.out.println("empty3:"+empty3);
    System.out.println("text1:"+text1);
    System.out.println("text2:"+text2);
    System.out.println("text3:"+text3);
    System.out.println("i1:"+i1);
    System.out.println("i2:"+i2);
    System.out.println(s);
    System.out.println(noThe);
}

}