java中创建写入文件的6种方式详解与源码实例

try(管道流、连接等实现了Closeable接口的类){
  //这里使用类对象操作
}
//用try()包含起来，就不用在finally里面自己手动的去 Object.close()了，会自动的关闭

@Test
void testCreateFile1() throws IOException {
  String fileName = "D:\\data\\test\\newFile.txt";
 
  Path path = Paths.get(fileName);
  // 使用newBufferedWriter创建文件并写文件
  // 这里使用了try-with-resources方法来关闭流，不用手动关闭
  try (BufferedWriter writer =
          Files.newBufferedWriter(path, StandardCharsets.UTF_8)) {
   writer.write("Hello World -创建文件!!");
  }
 
  //追加写模式
  try (BufferedWriter writer =
        Files.newBufferedWriter(path,
            StandardCharsets.UTF_8,
            StandardOpenOption.APPEND)){
    writer.write("Hello World -字母哥!!");
  }
}

@Test
void testCreateFile2() throws IOException {
  String fileName = "D:\\data\\test\\newFile2.txt";
 
  // 从JDK1.7开始提供的方法
  // 使用Files.write创建一个文件并写入
  Files.write(Paths.get(fileName),
        "Hello World -创建文件!!".getBytes(StandardCharsets.UTF_8));
 
  // 追加写模式
  Files.write(
     Paths.get(fileName),
     "Hello World -字母哥!!".getBytes(StandardCharsets.UTF_8),
     StandardOpenOption.APPEND);
}

@Test
void testCreateFile3() throws IOException {
  String fileName = "D:\\data\\test\\newFile3.txt";
 
  // JSD 1.5开始就已经存在的方法
  try (PrintWriter writer = new PrintWriter(fileName, "UTF-8")) {
   writer.println("Hello World -创建文件!!");
   writer.println("Hello World -字母哥!!");
  }
 
  // Java 10进行了改进，支持使用StandardCharsets指定字符集
  /*try (PrintWriter writer = new PrintWriter(fileName, StandardCharsets.UTF_8)) {
 
   writer.println("first line!");
   writer.println("second line!");
 
  } */
 
}

@Test
void testCreateFile4() throws IOException {
  String fileName = "D:\\data\\test\\newFile4.txt";
 
  File file = new File(fileName);
 
  // 返回true表示文件成功
  // false 表示文件已经存在
  if (file.createNewFile()) {
   System.out.println("创建文件成功！");
  } else {
   System.out.println("文件已经存在不需要重复创建");
  }
 
  // 使用FileWriter写文件
  try (FileWriter writer = new FileWriter(file)) {
   writer.write("Hello World -创建文件!!");
  }
 
}

@Test
void testCreateFile5() throws IOException {
  String fileName = "D:\\data\\test\\newFile5.txt";
  try(FileOutputStream fos = new FileOutputStream(fileName);
   OutputStreamWriter osw = new OutputStreamWriter(fos);
   BufferedWriter bw = new BufferedWriter(osw);){
   bw.write("Hello World -创建文件!!");
   bw.flush();
   bw.close();
  }
}

import org.apache.commons.io.FileUtils;
​​​​​​​public static void saveTxt(String filePath, String fileName, String data){
    try{
        File folder = new File(filePath);
        if(!folder.exists()){
            folder.mkdirs();
        }
        File file = new File(filePath + "/" + fileName);
        FileUtils.writeStringToFile(file,data,"UTF-8");
    }catch(IOEException e){
        log.error("error")
    }
}