1. .*
.It means match any single character except newline \ n addition, and *represents zero or more times. So .*together, they appear to represent any character zero or more times. No ?representation greedy. For example a.*b, it will be the longest match to a start to end of the string b. If you use it to search for aababit, it will match the entire string aabab. This is known as greedy matching.
Another example mode src = `. *` , It will match the longest in src = ` start, the longest string ending with`. It is used to search <img src = `` test.jpg` width = `60px` height =` 80px` /> time, will return src = `` test.jpg` width = ` 60px` height =` 80px`
2. .*?
?* Or + followed when behind, showing a lazy mode. Also known as non-greedy mode. That is, matching as few characters. It means match any number of repetition, but with minimal repeats make the whole premise of a successful match.
a.*?bMatching the shortest, to a start to end of the string b. If you apply it aabab, then it will match aab(first to third character) and ab(fourth to fifth character).
Another example mode src = `. *? ' , It will match src =` beginning to the end of the `shortest possible string. And the start and end of an intermediate character can not, because * means zero or more . It is used to search <img src = `` test.jpg` width = `60px` height =` 80px` /> time, will return the src = `` .
3. .+?
Above, ?with the * or + when behind, showing a lazy mode. Also known as non-greedy mode. It means match any number of repetition, but with minimal repeats make the whole premise of a successful match.
a.+?bMatching the shortest, to a start end of the string b, a and b but should be at least an intermediate character. If you apply it ababccaab, then it will match abab(first to fourth character) and aab(seventh to ninth character). Note that at this time the result is not a match ab, aband aab. Since the intermediate a and b must be at least one character.
Another example mode src = `. +? ' , It will match src =` beginning to the end of the `shortest possible string. And the beginning and end of the middle must have character, because + 1 to represent more . It is used to search <img src = `` test.jpg` width = `60px` height =` 80px` /> time, will return the src = `` test.jpg` . Note that the .*?difference at this time will not match src = `` , since src = ` and ` at least one character between.
4. Sample Code
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.junit.jupiter.api.Test;
public class TestRegx {
@Test
public void testRegx(){
String str = "<img src=``test.jpg` width=`60px` height=`80px`/>";
String pattern1 = "src=`.*`";
String pattern2 = "src=`.*?`";
String pattern3 = "src=`.+?`";
Pattern p1 = Pattern.compile(pattern1);
Pattern p2 = Pattern.compile(pattern2);
Pattern p3 = Pattern.compile(pattern3);
Matcher m1 = p1.matcher(str);
Matcher m2 = p2.matcher(str);
Matcher m3 = p3.matcher(str);
System.out.println("根据pattern1匹配的结果：");
if (m1.find()) {
for(int i=0; i<=m1.groupCount(); i++){
System.out.println(m1.group(i));
}
}
System.out.println("根据pattern2匹配的结果：");
if (m2.find()) {
for(int i=0; i<=m2.groupCount(); i++){
System.out.println(m2.group(i));
}
}
System.out.println("根据pattern3匹配的结果：");
if (m3.find()) {
for(int i=0; i<=m3.groupCount(); i++){
System.out.println(m3.group(i));
}
}
String[] str1 = p1.split(str);
String[] str2 = p2.split(str);
String[] str3 = p3.split(str);
System.out.println("根据pattern1切分的结果");
for (int i=0; i< str1.length; i++) {
System.out.println(str1[i]);
}
System.out.println("根据pattern2切分的结果");
for (int i=0; i< str2.length; i++) {
System.out.println(str2[i]);
}
System.out.println("根据pattern3切分的结果");
for (int i=0; i< str3.length; i++) {
System.out.println(str3[i]);
}
}
}
Example 5. Results
