Spring 表达式语言 (SpEL)

官方文档：https://docs.spring.io/spring-framework/docs/6.0.x/reference/html/core.html#expressions

模板占位符 替换 {$name}

import org.springframework.context.expression.MapAccessor;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.util.PropertyPlaceholderHelper;import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Map;
/*** 内容占位符 替换* <p>* 模板占位符格式{$name}*/
public class ContentHolderUtil {/*** 占位符前缀*/private static final String PLACE_HOLDER_PREFIX = "{$";/*** 占位符后缀*/private static final String PLACE_HOLDER_SUFFIX = "}";private static final StandardEvaluationContext EVALUATION_CONTEXT;private static final PropertyPlaceholderHelper PROPERTY_PLACEHOLDER_HELPER = new PropertyPlaceholderHelper(PLACE_HOLDER_PREFIX, PLACE_HOLDER_SUFFIX);static {EVALUATION_CONTEXT = new StandardEvaluationContext();EVALUATION_CONTEXT.addPropertyAccessor(new MapAccessor());}public static String replacePlaceHolder(final String template, final Map<String, String> paramMap) {String replacedPushContent = PROPERTY_PLACEHOLDER_HELPER.replacePlaceholders(template,new CustomPlaceholderResolver(template, paramMap));return replacedPushContent;}private static class CustomPlaceholderResolver implements PropertyPlaceholderHelper.PlaceholderResolver {private final String template;private final Map<String, String> paramMap;public CustomPlaceholderResolver(String template, Map<String, String> paramMap) {super();this.template = template;this.paramMap = paramMap;}@Overridepublic String resolvePlaceholder(String placeholderName) {String value = paramMap.get(placeholderName);if (null == value) {String errorStr = MessageFormat.format("template:{0} require param:{1},but not exist! paramMap:{2}",template, placeholderName, paramMap.toString());throw new IllegalArgumentException(errorStr);}return value;}}public static void main(String[] args) {Map<String,String> map = new HashMap<>();map.put("name","张三");map.put("age","12");// 注意：{$}内不能有空格final String s = replacePlaceHolder("我叫 {$name}， 我今年 {$age} 岁了。", map);System.out.println(s);}
}

common-text 方式：模板字符转替换 ${}

1. 添加依赖

   <dependency><groupId>org.apache.commons</groupId><artifactId>commons-text</artifactId><version>1.10.0</version>
   </dependency><!-- lombok -->
   <dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional>
   </dependency>
   

2. 测试

   import lombok.extern.slf4j.Slf4j;
   import org.apache.commons.text.StringSubstitutor;
   import org.springframework.util.CollectionUtils;
   import org.springframework.util.StringUtils;import java.util.HashMap;
   import java.util.List;
   import java.util.Map;
   import java.util.stream.Collectors;@Slf4j
   public class CommonTextUtil {// 占位符前缀private static final String prefix = "${";// 占位符后缀private static final String suffix = "}";/** commons-text* */public static String replaceVar(Map<String, Object> vars, String template) {if (!StringUtils.hasLength(template)) {log.info(String.format("调用%s方法失败,模板字符串替换失败,模板字符串不能为空",Thread.currentThread().getStackTrace()[1].getMethodName()));return null;}if (CollectionUtils.isEmpty(vars)) {log.info(String.format("调用%s方法失败,模板字符串替换失败,map不能为空",Thread.currentThread().getStackTrace()[1].getMethodName()));return null;}List<String> tempStrs = vars.keySet().stream().map(s -> prefix + s + suffix).collect(Collectors.toList());tempStrs.forEach(t -> {if (!template.contains(t)) {throw new RuntimeException(String.format("调用%s方法失败,模板字符串替换失败,map的key必须存在于模板字符串中",Thread.currentThread().getStackTrace()[1].getMethodName()));}});StringSubstitutor stringSubstitutor = new StringSubstitutor(vars);return stringSubstitutor.replace(template);}public static void main(String[] args) {/** 错误的场景：比如${变量}，{}内不能含有空格等等* System.out.println(replaceVar(vals, "我叫${ name},今年${age }岁."));* System.out.println(replaceVar(new HashMap<>(), temp));* System.out.println(replaceVar(vals, "我叫张三"));* System.out.println(replaceVar(vals, "我叫${name},今年${age1}岁."));* */Map<String, Object> vals = new HashMap<>();vals.put("name", "张三");vals.put("age", "20");String temp = "我叫${name},今年${age}岁.";System.out.println(replaceVar(vals, temp));}
   }