java FileWriter 追加文件及文件改名

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
public class FileWriterUtil {

    /**
     * 追加文件：使用FileWriter
     */
    public static void appendMethod(String fileName, String content) {
        try {
            //打开一个写文件器，构造函数中的第二个参数true表示以追加形式写文件
            FileWriter writer = new FileWriter(fileName, true);
            writer.write(content);
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 修改文件名
     * @param oldFilePath
     * @param newFileName
     */
    public static void reNameLogFile(String oldFilePath,String newFileName){
        File f=new File(oldFilePath);
        String c=f.getParent();
//        File mm=new File(c + File.pathSeparator + newFileName + "_" + CommonUtil.getCurrTimeForString());
        File mm=new File(c + "/" + newFileName + "_" + CommonUtil.getBeforeDateStr());
        if(f.renameTo(mm)){
            System.out.println("修改文件名成功!");
        }else{
            System.out.println("修改文件名失败");
        }
    }

    public static void main(String[] args) {
        String fileName = "/Users/qin/Downloads/callLog.txt";
        String content = "new append!";
        FileWriterUtil.appendMethod(fileName, content);
        FileWriterUtil.appendMethod(fileName, "append end. \n");
        FileWriterUtil.reNameLogFile("/Users/qin/Downloads/callLog.txt","rayda");
    }
}