使用Java对yaml和properties互转
一、 前言
浏览了一圈网上的版本，大多存在以下问题：
- 转换后顺序错乱
- 遗漏子节点
基于此进行了优化，如果只是想直接转换，可直接使用我发布的 在线版本
如果想在工程中使用，可继续往下看，源码在文末。
1.1 顺序错乱的原因
大部分代码都是使用了 java.util.Properties 类来转换，这个类是基于 ConcurrentHashMap 来存储键值对的，必然会顺序错乱
这是截取的 Properties 类的部分源码：
java
/**
* Properties does not store values in its inherited Hashtable, but instead
* in an internal ConcurrentHashMap. Synchronization is omitted from
* simple read operations. Writes and bulk operations remain synchronized,
* as in Hashtable.
*/
private transient volatile ConcurrentHashMap<Object, Object> map;
/**
* Creates an empty property list with the specified defaults.
*
* @implNote The initial capacity of a {@code Properties} object created
* with this constructor is unspecified.
*
* @param defaults the defaults.
*/
public Properties(Properties defaults) {
this(defaults, 8);
}
private Properties(Properties defaults, int initialCapacity) {
// use package-private constructor to
// initialize unused fields with dummy values
super((Void) null);
map = new ConcurrentHashMap<>(initialCapacity);
this.defaults = defaults;
// Ensure writes can't be reordered
UNSAFE.storeFence();
}1.2 遗漏子节点的原因
主要还是代码不够严谨，解析的时候没有判断子节点是否是数组或对象，粗暴的转为 String 直接赋值了
二、优化措施
-
基于
LinkedHashMap来存储键值对 -
递归遍历时判断子节点类型，不同类型采用不同的处理方式
三、源码
java
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.util.StrUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.CollectionUtils;
import org.yaml.snakeyaml.Yaml;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* @author Deng.Weiping
* @since 2023/11/28 13:57
*/
@Slf4j
public class PropertiesUtil {
/**
* yaml 转 Properties
*
* @param input
* @return
*/
public static String castToProperties(String input) {
Map<String, Object> propertiesMap = new LinkedHashMap<>();
Map<String, Object> yamlMap = new Yaml().load(input);
flattenMap("", yamlMap, propertiesMap);
StringBuffer strBuff = new StringBuffer();
propertiesMap.forEach((key, value) -> strBuff.append(key)
.append("=")
.append(value)
.append(StrUtil.LF));
return strBuff.toString();
}
/**
* Properties 转 Yaml
*
* @param input
* @return
*/
public static String castToYaml(String input) {
try {
Map<String, Object> properties = readProperties(input);
return properties2Yaml(properties);
} catch (Exception e) {
log.error("property 转 Yaml 转换失败", e);
}
return null;
}
private static Map<String, Object> readProperties(String input) {
// 使用 LinkedHashMap 保证顺序
Map<String, Object> propertiesMap = new LinkedHashMap<>();
for (String line : input.split(StrUtil.LF)) {
if (StrUtil.isNotBlank(line)) {
// 使用正则表达式解析每一行中的键值对
Pattern pattern = Pattern.compile("\\s*([^=\\s]*)\\s*=\\s*(.*)\\s*");
Matcher matcher = pattern.matcher(line);
if (matcher.matches()) {
String key = matcher.group(1);
String value = matcher.group(2);
propertiesMap.put(key, value);
}
}
}
return propertiesMap;
}
/**
* 递归 Map 集合，转为 Properties集合
*
* @param prefix
* @param yamlMap
* @param treeMap
*/
private static void flattenMap(String prefix, Map<String, Object> yamlMap, Map<String, Object> treeMap) {
yamlMap.forEach((key, value) -> {
String fullKey = prefix + key;
if (value instanceof LinkedHashMap) {
flattenMap(fullKey + ".", (LinkedHashMap) value, treeMap);
} else if (value instanceof ArrayList) {
List values = (ArrayList) value;
for (int i = 0; i < values.size(); i++) {
String itemKey = String.format("%s[%d]", fullKey, i);
Object itemValue = values.get(i);
if (itemValue instanceof String) {
treeMap.put(itemKey, itemValue);
} else {
flattenMap(itemKey + ".", (LinkedHashMap) itemValue, treeMap);
}
}
} else {
treeMap.put(fullKey, value.toString());
}
});
}
/**
* properties 格式转化为 yaml 格式字符串
*
* @param properties
* @return
*/
private static String properties2Yaml(Map<String, Object> properties) {
if (CollUtil.isEmpty(properties)) {
return null;
}
Map<String, Object> map = parseToMap(properties);
StringBuffer stringBuffer = map2Yaml(map);
return stringBuffer.toString();
}
/**
* 递归解析为 LinkedHashMap
*
* @param propMap
* @return
*/
private static Map<String, Object> parseToMap(Map<String, Object> propMap) {
Map<String, Object> resultMap = new LinkedHashMap<>();
try {
if (CollectionUtils.isEmpty(propMap)) {
return resultMap;
}
propMap.forEach((key, value) -> {
if (key.contains(".")) {
String currentKey = key.substring(0, key.indexOf("."));
if (resultMap.get(currentKey) != null) {
return;
}
Map<String, Object> childMap = getChildMap(propMap, currentKey);
Map<String, Object> map = parseToMap(childMap);
resultMap.put(currentKey, map);
} else {
resultMap.put(key, value);
}
});
} catch (Exception e) {
e.printStackTrace();
}
return resultMap;
}
/**
* 获取拥有相同父级节点的子节点
*
* @param propMap
* @param currentKey
* @return
*/
private static Map<String, Object> getChildMap(Map<String, Object> propMap, String currentKey) {
Map<String, Object> childMap = new LinkedHashMap<>();
try {
propMap.forEach((key, value) -> {
if (key.contains(currentKey + ".")) {
key = key.substring(key.indexOf(".") + 1);
childMap.put(key, value);
}
});
} catch (Exception e) {
e.printStackTrace();
}
return childMap;
}
/**
* map集合转化为yaml格式字符串
*
* @param map
* @return
*/
public static StringBuffer map2Yaml(Map<String, Object> map) {
//默认deep 为零，表示不空格，deep 每加一层，缩进两个空格
return map2Yaml(map, 0);
}
/**
* 把Map集合转化为yaml格式 String字符串
*
* @param propMap map格式配置文件
* @param deep 树的层级，默认deep 为零，表示不空格，deep 每加一层，缩进两个空格
* @return
*/
private static StringBuffer map2Yaml(Map<String, Object> propMap, int deep) {
StringBuffer yamlBuffer = new StringBuffer();
try {
if (CollectionUtils.isEmpty(propMap)) {
return yamlBuffer;
}
String space = getSpace(deep);
for (Map.Entry<String, Object> entry : propMap.entrySet()) {
Object valObj = entry.getValue();
if (entry.getKey().contains("[") && entry.getKey().contains("]")) {
String key = entry.getKey().substring(0, entry.getKey().indexOf("[")) + ":";
yamlBuffer.append(space + key + "\n");
propMap.forEach((itemKey, itemValue) -> {
if (itemKey.startsWith(key.substring(0, entry.getKey().indexOf("[")))) {
yamlBuffer.append(getSpace(deep + 1) + "- ");
if (itemValue instanceof Map) {
StringBuffer valStr = map2Yaml((Map<String, Object>) itemValue, 0);
String[] split = valStr.toString().split(StrUtil.LF);
for (int i = 0; i < split.length; i++) {
if (i > 0) {
yamlBuffer.append(getSpace(deep + 2));
}
yamlBuffer.append(split[i]).append(StrUtil.LF);
}
} else {
yamlBuffer.append(itemValue + "\n");
}
}
});
break;
} else {
String key = space + entry.getKey() + ":";
if (valObj instanceof String) { //值为value 类型，不用再继续遍历
yamlBuffer.append(key + " " + valObj + "\n");
} else if (valObj instanceof List) { //yaml List 集合格式
yamlBuffer.append(key + "\n");
List<String> list = (List<String>) entry.getValue();
String lSpace = getSpace(deep + 1);
for (String str : list) {
yamlBuffer.append(lSpace + "- " + str + "\n");
}
} else if (valObj instanceof Map) { //继续递归遍历
Map<String, Object> valMap = (Map<String, Object>) valObj;
yamlBuffer.append(key + "\n");
StringBuffer valStr = map2Yaml(valMap, deep + 1);
yamlBuffer.append(valStr.toString());
} else {
yamlBuffer.append(key + " " + valObj + "\n");
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return yamlBuffer;
}
/**
* 获取缩进空格
*
* @param deep
* @return
*/
private static String getSpace(int deep) {
StringBuffer buffer = new StringBuffer();
if (deep == 0) {
return "";
}
for (int i = 0; i < deep; i++) {
buffer.append(" ");
}
return buffer.toString();
}
}