SpringBoot 引入 SPEL 模板字符串替换的两种方式
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;
}
@Override
public 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);
}
}