Java使用snakeyaml修改yaml方法_snakeyaml 更新yml

 一、依赖包

        pom引入snakeyaml依赖

<dependency>
    <groupId>org.yaml</groupId>
    <artifactId>snakeyaml</artifactId>
    <version>2.0</version>
</dependency>

二、代码实现yaml配置项修改

        上代码

public class UpdateYmlConfigUtil {
 
    public static void updateYmlConfig(String config, Object value) {
        String src;
        String path = System.getProperty("user.dir");
        // 根据环境确定配置文件路径
        String system = System.getProperty("os.name");
        if(system.toLowerCase().startsWith("win")){
            src = path + "/src/main/resources/application.yml";
        } else {
            src = path + "/config/application.yml";
        }
        File file = new File(src);
        Yaml yaml = new Yaml();
        // 记录 yaml 文件的注释信息
        UpdateYmlConfigUtil.CommentHolder holder = UpdateYmlConfigUtil.buildCommentHolder(file);
        FileWriter fileWriter = null;
        //层级map变量
        Map<String, Object> springMap, dataSourceMap, resultMap;
        try {
            //读取yaml文件，默认返回根目录结构
            resultMap = yaml.load(new FileInputStream(file));
            String[] split = config.split("\\.");
            //get出第一个节点项
            dataSourceMap = (Map<String, Object>) resultMap.get(split[0]);
            for (int i = 1; i < split.length -1; i++) {
                //get出倒数第二个节点项
                dataSourceMap = (Map<String, Object>) dataSourceMap.get(split[i]);
            }
            //修改最后节点项配置的数据
            dataSourceMap.put(split[split.length -1], value);
            //字符输出
            fileWriter = new FileWriter(new File(src));
            //用yaml方法把map结构格式化为yaml文件结构
            fileWriter.write(yaml.dumpAsMap(resultMap));
            //刷新
            fileWriter.flush();
            //关闭流
            fileWriter.close();
        } catch (Exception e) {
            throw new RuntimeException("yml file config update fail:", e);
        }
        // 填充注释信息
        holder.fillComments(file);
    }
 
    private static final String END = "END###";
    private static final Pattern COMMENT_LINE = Pattern.compile("^\\s*#.*$");
    private static final Pattern BLANK_LINE = Pattern.compile("^\\s*$");
    /**
     * 带注释的有效行,  使用非贪婪模式匹配有效内容
     */
    private static final Pattern LINE_WITH_COMMENT = Pattern.compile("^(.*?)\\s+#.*$");
 
    @Data
    @AllArgsConstructor
    private static class Comment {
        private String lineNoComment;
        private String lineWithComment;
        // 存在相同行时的索引 (不同key下相同的行, 如 a:\n name: 1  和  b:\n name: 1 )
        private Integer indexInDuplicates;
        private boolean isEndLine() {
            return END.equals(lineNoComment);
        }
    }
 
    @SneakyThrows
    private static UpdateYmlConfigUtil.CommentHolder buildCommentHolder(File file) {
        List<UpdateYmlConfigUtil.Comment> comments = new ArrayList<>();
        Map<String, Integer> duplicatesLineIndex = new HashMap<>();
        UpdateYmlConfigUtil.CommentHolder holder = new UpdateYmlConfigUtil.CommentHolder(comments);
        List<String> lines = FileUtils.readLines(file, StandardCharsets.UTF_8.toString());
        // 末尾加个标志, 防止最后的注释丢失
        lines.add(END);
        StringBuilder lastLinesWithComment = new StringBuilder();
        for (String line : lines) {
            if (StringUtils.isBlank(line) || BLANK_LINE.matcher(line).find()) {
                lastLinesWithComment.append(line).append('\n');
                continue;
            }
            // 注释行/空行 都拼接起来
            if (COMMENT_LINE.matcher(line).find()) {
                lastLinesWithComment.append(line).append('\n');
                continue;
            }
            String lineNoComment = line;
 
            boolean lineWithComment = false;
            // 如果是带注释的行, 也拼接起来, 但是记录非注释的部分
            Matcher matcher = LINE_WITH_COMMENT.matcher(line);
            if (matcher.find()) {
                lineNoComment = matcher.group(1);
                lineWithComment = true;
            }
            // 去除后面的空格
            lineNoComment = lineNoComment.replace("\\s*$", "");
            // 记录下相同行的索引
            Integer idx = duplicatesLineIndex.merge(lineNoComment, 1, Integer::sum);
            // 存在注释内容, 记录
            if (lastLinesWithComment.length() > 0 || lineWithComment) {
                lastLinesWithComment.append(line);
                comments.add(new UpdateYmlConfigUtil.Comment(lineNoComment, lastLinesWithComment.toString(), idx));
                // 清空注释内容
                lastLinesWithComment = new StringBuilder();
            }
        }
        return holder;
    }
 
    @AllArgsConstructor
    public static class CommentHolder {
        private List<UpdateYmlConfigUtil.Comment> comments;
        /**
         * 通过正则表达式移除匹配的行 (防止被移除的行携带注释信息, 导致填充注释时无法正常匹配)
         */
        public void removeLine(String regex) {
            comments.removeIf(comment -> comment.getLineNoComment().matches(regex));
        }
 
        @SneakyThrows
        private void fillComments(File file) {
            if (comments == null || comments.isEmpty()) {
                return;
            }
            if (file == null || !file.exists()) {
                throw new IllegalArgumentException("file is not exist");
            }
            List<String> lines = FileUtils.readLines(file, StandardCharsets.UTF_8.toString());
            Map<String, Integer> duplicatesLineIndex = new HashMap<>();
            int comIdx = 0;
            StringBuilder res = new StringBuilder();
            for (String line : lines) {
                Integer idx = duplicatesLineIndex.merge(line, 1, Integer::sum);
                UpdateYmlConfigUtil.Comment comment = getOrDefault(comments, comIdx);
                if (comment != null &&
                        Objects.equals(line, comment.lineNoComment)
                        && Objects.equals(comment.indexInDuplicates, idx)) {
                    res.append(comment.lineWithComment).append('\n');
                    comIdx++;
                } else {
                    res.append(line).append('\n');
                }
            }
            UpdateYmlConfigUtil.Comment last = comments.get(comments.size() - 1);
            if (last.isEndLine()) {
                res.append(last.lineWithComment, 0, last.lineWithComment.indexOf(END));
            }
            FileUtils.write(file, res.toString(), StandardCharsets.UTF_8.toString());
        }
    }
 
    private static <T> T getOrDefault(List<T> vals, int index) {
        if (vals == null || vals.isEmpty()) {
            return null;
        }
        if (index >= vals.size()) {
            return null;
        }
        return vals.get(index);
    }
 
}

三、效果

        测试：

public static void main(String[] args) {
    updateYmlConfig("a.b.c.d", "cd");
}

        修改前：

        修改后：

四、参考资料

Java snakeyaml 修改yaml文件保留注释工具类封装_java 代码修改yml-CSDN博客