Java文件内容拷贝替换时丢失换行符问题求助

• 核心原因1：BufferedReader.readLine()方法读取每行内容时，会自动丢弃行尾的换行符（\n/\r\n），直接追加字符串自然不会保留换行格式。
• 核心原因2：现有循环逻辑存在错误：每行读取后连续追加3次修改后的行内容，会导致原文件每行被重复写入3次，并非在同一行完成所有关键词替换。
• 额外问题：代码中定义了pathwriter变量但未使用，写入时用到的pathscxmlout没有声明定义，会导致编译报错。

修改读取替换的循环逻辑，同一行完成所有关键词替换后，手动追加跨平台兼容的换行符即可，同时推荐使用try-with-resources语法自动关闭流资源，避免资源泄漏。

public class FileDefinition {

    String result = "";

    String pathxml = pathxmlin;
    String pathconf = pathfileconf;

    //func to be recalled in the main for the different files
    public String getPropValues() throws IOException {
        try {
            Properties prop = new Properties();
            String pathconf = this.pathconf;
            String pathxml = this.pathxml;

            //Read file conf
            try (InputStream is = new FileInputStream(pathconf);
                 BufferedReader br = new BufferedReader(new InputStreamReader(is))) {
                prop.load(br);
            }

            // get the property value and print it out
            String name = prop.getProperty("name");
            String loc = prop.getProperty("location");
            String id = prop.getProperty("PropID");

            //research fields to be changed
            String searchname = "RotaionToInside";
            String searchlocation = "location";
            String searchpropid = "PropOfJobID";

            String lineContent;
            StringBuilder contentBuilder = new StringBuilder();

            //Read scxml file to get the format
            try (BufferedReader rb = new BufferedReader(new FileReader(pathxml))) {
                while ((lineContent = rb.readLine()) != null) {
                    // 同一行完成所有关键词替换
                    String modifiedLine = lineContent.replaceAll(searchlocation, loc)
                            .replaceAll(searchpropid, id)
                            .replaceAll(searchname, name);
                    // 追加修改后的行 + 跨平台兼容换行符
                    contentBuilder.append(modifiedLine).append(System.lineSeparator());
                }
            }

            String pathwriter = pathxml + name + ".scxml";
            // 写入新文件
            try (BufferedWriter bw = new BufferedWriter(new FileWriter(new File(pathwriter)))) {
                bw.write(contentBuilder.toString());
            }

        } catch (Exception e) {
            System.out.println("Exception: " + e);
        }
        return result;
    }
}

内容的提问来源于stack exchange，提问作者Webpe