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");
}
}