方法一

try {

BufferedWriter out = new BufferedWriter(new FileWriter(fileName));

out.write("aString1\n");

out.close();

out = new BufferedWriter(new FileWriter(fileName,true));

out.write("aString2");

out.close();

BufferedReader in = new BufferedReader(new FileReader(fileName));

String str;

while ((str = in.readLine()) != null) {

System.out.println(str);

}

in.close();

}

catch (IOException e) {

System.out.println("exception occoured"+ e);

}

方法二

//写入数据测试

FileOutputStream fos = new FileOutputStream("D:/log/aa.txt",true);

String cc = "写入数据测试\r\n地方东风街道龙卷风";

fos.write(cc.getBytes());

fos.close();