import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;

public class Test {
    public static void main(String[] args) {
        //文件所在目录
        File f = new File("F:/workspace/projects/src/test.txt");
        try {
            OutputStreamWriter write = new OutputStreamWriter(
                    new FileOutputStream(f), "UTF-8");
            BufferedWriter writer = new BufferedWriter(write);
            //替换值
            writer.write("1");
            writer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

------解决方案--------------------

调用系统命令输出重定向，比如 echo 1 > 文件
Runtime.getRunTime().exec("echo 1 > test.txt"); //LZ自己把test.txt的路径补全吧