import static org.junit.Assert.*;

 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;

 import org.junit.Test;

 public class MyTest {
     //通过字符流写入数据到指定的文件中
     @Test
     public void testWrite() {
         String path = "F:"+File.separator+"demo.txt";
 //        如果文件不存在的话，就先创建这个文件
         File file = new File(path);
         if(!file.exists()){
             try {
                 file.createNewFile();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         FileWriter fileWriter = null;
         try {
             //在Windows中，一定要确保路径为path的文件是存在的
             fileWriter = new FileWriter(path);
             fileWriter.write("you are not a good boy!");
             fileWriter.flush();
             fileWriter.close();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }finally{
             //如果抛出异常的话，说明fileWriter对象时候创建不了的
             if(fileWriter!=null){
                 try {
                     fileWriter.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }

         }

     }

 }