Scanner.findAll（） 和 Matcher.results（） 对于相同的输入文本和模式，工作方式不同

问：

我在使用正则表达式拆分属性字符串期间看到了这个有趣的事情。我无法找到根本原因。

我有一个字符串，其中包含诸如属性键=值对之类的文本。 我有一个正则表达式，它根据 = 位置将字符串拆分为键/值。它将 first = 视为拆分点。value 也可以包含 =。

我尝试在 Java 中使用两种不同的方法来做到这一点。

1. 使用 Scanner.findAll（） 方法

   这不符合预期。它应该根据模式提取和打印所有键。但我发现它的行为很奇怪。我有一个键值对，如下所示

    SectionError.ErrorMessage=errorlevel=Warning {HelpMessage:This is very important message This is very important .....}

应提取的键是 SectionError.ErrorMessage=，但它也将 errorlevel= 视为键。

有趣的一点是，如果我从属性中删除其中一个字符 String passed，它的行为正常，并且只提取 SectionError.ErrorMessage= 键。

2. 使用 Matcher.results（） 方法

   这工作正常。无论我们在属性字符串中放入什么，都没有问题。

我尝试的示例代码：

import java.util.Scanner;
import java.util.regex.MatchResult;
import java.util.regex.Pattern;

import static java.util.regex.Pattern.MULTILINE;

public class MessageSplitTest {

    static final Pattern pattern = Pattern.compile("^[a-zA-Z0-9._]+=", MULTILINE);

    public static void main(String[] args) {
        final String properties =
                "SectionOne.KeyOne=first value\n" + // removing one char from here would make the scanner method print expected keys
                        "SectionOne.KeyTwo=second value\n" +
                        "SectionTwo.UUIDOne=379d827d-cf54-4a41-a3f7-1ca71568a0fa\n" +
                        "SectionTwo.UUIDTwo=384eef1f-b579-4913-a40c-2ba22c96edf0\n" +
                        "SectionTwo.UUIDThree=c10f1bb7-d984-422f-81ef-254023e32e5c\n" +
                        "SectionTwo.KeyFive=hello-world-sample\n" +
                        "SectionThree.KeyOne=first value\n" +
                        "SectionThree.KeyTwo=second value additional text just to increase the length of the text in this value still not enough adding more strings here n there\n" +
                        "SectionError.ErrorMessage=errorlevel=Warning {HelpMessage:This is very important message This is very important message This is very important messageThis is very important message This is very important message This is very important message This is very important message This is very important message This is very important message This is very important message This is very important messageThis is very important message This is very important message This is very important message This is very important message This is very important message}\n" +
                        "SectionFour.KeyOne=sixth value\n" +
                        "SectionLast.KeyOne=Country";

        printKeyValuesFromPropertiesUsingScanner(properties);
        System.out.println();
        printKeyValuesFromPropertiesUsingMatcher(properties);
    }

    private static void printKeyValuesFromPropertiesUsingScanner(String properties) {
        System.out.println("===Using Scanner===");
        try (Scanner scanner = new Scanner(properties)) {
            scanner
                    .findAll(pattern)
                    .map(MatchResult::group)
                    .forEach(System.out::println);
        }
    }

    private static void printKeyValuesFromPropertiesUsingMatcher(String properties) {
        System.out.println("===Using Matcher===");
        pattern.matcher(properties).results()
                .map(MatchResult::group)
                .forEach(System.out::println);

    }
}

打印输出：

===Using Scanner===
SectionOne.KeyOne=
SectionOne.KeyTwo=
SectionTwo.UUIDOne=
SectionTwo.UUIDTwo=
SectionTwo.UUIDThree=
SectionTwo.KeyFive=
SectionThree.KeyOne=
SectionThree.KeyTwo=
SectionError.ErrorMessage=
errorlevel=
SectionFour.KeyOne=
SectionLast.KeyOne=

===Using Matcher===
SectionOne.KeyOne=
SectionOne.KeyTwo=
SectionTwo.UUIDOne=
SectionTwo.UUIDTwo=
SectionTwo.UUIDThree=
SectionTwo.KeyFive=
SectionThree.KeyOne=
SectionThree.KeyTwo=
SectionError.ErrorMessage=
SectionFour.KeyOne=
SectionLast.KeyOne=

造成这种情况的根本原因可能是什么？扫描仪的 findAll 的工作方式与匹配器不同吗？

如果需要更多信息，请告诉我。