在Java實體類中批量刪除注釋可以使用正則表達式進行匹配替換操作。以下是一個示例代碼：

import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class RemoveComments {

    public static void main(String[] args) {
        String entityClass = "public class User {\n" +
            "    // This is a comment\n" +
            "    private String name;\n" +
            "\n" +
            "    /*\n" +
            "     * This is a multi-line comment\n" +
            "     */\n" +
            "    private int age;\n" +
            "\n" +
            "    // Another comment\n" +
            "    private String email;\n" +
            "}";

        String regex = "(\\/\\/.*$)|(\\/\\*.*?\\*\\/)";
        Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.DOTALL);
        Matcher matcher = pattern.matcher(entityClass);

        String result = matcher.replaceAll("");
        System.out.println(result);
    }
}

上面的代碼會刪除Java實體類中的單行注釋（以//開頭）和多行注釋（/*和*/之間的內容）。可以根據實際情況修改正則表達式來匹配其他類型的注釋。