用Java创建和写入(文本)文件的最简单方法是什么?


当前回答

如果您希望获得相对轻松的体验,还可以查看Apache Commons IO包,更具体地说是FileUtils类。

永远不要忘记检查第三方库。用于日期操作的Joda Time、用于常见字符串操作的Apache Commons Lang StringUtils等可以使代码更可读。

Java是一种很棒的语言,但标准库有时有点低级。功能强大,但级别较低。

其他回答

如果您已经有了要写入文件的内容(而不是动态生成的),那么Java7中作为本机I/O的一部分添加的java.nio.file.Files提供了实现目标的最简单、最有效的方法。

基本上,创建和写入文件只需一行,而且只需一个简单的方法调用!

以下示例创建并写入6个不同的文件,以展示如何使用它:

Charset utf8 = StandardCharsets.UTF_8;
List<String> lines = Arrays.asList("1st line", "2nd line");
byte[] data = {1, 2, 3, 4, 5};

try {
    Files.write(Paths.get("file1.bin"), data);
    Files.write(Paths.get("file2.bin"), data,
            StandardOpenOption.CREATE, StandardOpenOption.APPEND);
    Files.write(Paths.get("file3.txt"), "content".getBytes());
    Files.write(Paths.get("file4.txt"), "content".getBytes(utf8));
    Files.write(Paths.get("file5.txt"), lines, utf8);
    Files.write(Paths.get("file6.txt"), lines, utf8,
            StandardOpenOption.CREATE, StandardOpenOption.APPEND);
} catch (IOException e) {
    e.printStackTrace();
}

在Java 7及以上版本中:

try (Writer writer = new BufferedWriter(new OutputStreamWriter(
              new FileOutputStream("filename.txt"), "utf-8"))) {
   writer.write("something");
}

但有一些有用的实用程序:

来自commons io的FileUtils.writeStringtoFile(..)来自番石榴的文件.write(..)

还要注意,您可以使用FileWriter,但它使用默认编码,这通常是一个坏主意-最好显式指定编码。

以下是Java 7之前的原始答案


Writer writer = null;

try {
    writer = new BufferedWriter(new OutputStreamWriter(
          new FileOutputStream("filename.txt"), "utf-8"));
    writer.write("Something");
} catch (IOException ex) {
    // Report
} finally {
   try {writer.close();} catch (Exception ex) {/*ignore*/}
}

另请参阅:读取、写入和创建文件(包括NIO2)。

以下是编写文件的代码,也在退出帮助内容网页时删除:

public String writeHelpContent(String filePath, String helpPageContent) throws IOException{
        logger.info("HowToUseRiskOfficeHelpService - writeHelpContent start");
        File file = new File(filePath);
        try(FileWriter fw = new FileWriter(file);){
            file.deleteOnExit();
            if(file.createNewFile()) {
                logger.info("HowToUseRiskOfficeHelpService - file created successfully");
            }else {
                logger.info("HowToUseRiskOfficeHelpService - file already exists");
            }
            fw.write(helpPageContent); 
            fw.flush();
        }

        return "Sucessfully write into help page file";
    }

有一些简单的方法,例如:

File file = new File("filename.txt");
PrintWriter pw = new PrintWriter(file);

pw.write("The world I'm coming");
pw.close();

String write = "Hello World!";

FileWriter fw = new FileWriter(file);
BufferedWriter bw = new BufferedWriter(fw);

fw.write(write);

fw.close();

要创建文件而不覆盖现有文件,请执行以下操作:

System.out.println("Choose folder to create file");
JFileChooser c = new JFileChooser();
c.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
c.showOpenDialog(c);
c.getSelectedFile();
f = c.getSelectedFile(); // File f - global variable
String newfile = f + "\\hi.doc";//.txt or .doc or .html
File file = new File(newfile);

try {
    //System.out.println(f);
    boolean flag = file.createNewFile();

    if(flag == true) {
        JOptionPane.showMessageDialog(rootPane, "File created successfully");
    }
    else {
        JOptionPane.showMessageDialog(rootPane, "File already exists");
    }
    /* Or use exists() function as follows:
        if(file.exists() == true) {
            JOptionPane.showMessageDialog(rootPane, "File already exists");
        }
        else {
            JOptionPane.showMessageDialog(rootPane, "File created successfully");
        }
    */
}
catch(Exception e) {
    // Any exception handling method of your choice
}