添加引用
<dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.4</version></dependency>
按行写：
public static void writeFileLineByApacheIO(String fileContent) throws IOException {String fileName = "";String nowday = DateUtil.getNowDayString();String os = System.getProperty("os.name");if (os.toLowerCase().startsWith("win")) {fileName = "C:\\log\\" + nowday + ".txt";} else {fileName = "//log//" + nowday + ".txt";}File file = new File(fileName);List<String> lines=new ArrayList<String>();lines.add(fileContent);FileUtils.writeLines(file,"UTF-8",lines,true);}
import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.Date;public final class DateUtil {//返回当前时间public static String getNowTimeString() {Date date = new Date();DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String time = format.format(date);return time;}//设置日期格式public static String getNowDayString() {SimpleDateFormat dfday = new SimpleDateFormat("yyyy-MM-dd");String nowday=dfday.format(new Date());return nowday;}}
注意还有个writeStringToFile需要自己手动添加换行不然连在一起了。
FileUtils.writeStringToFile和FileUtils.writeLines如果不加true就是替换而不是增量写。
参考：
使用FileUtils简化你的文件操作
Apache Commons工具集简介
