用Java创建和写入(文本)文件的最简单方法是什么?
当前回答
Use:
try (Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("myFile.txt"), StandardCharsets.UTF_8))) {
writer.write("text to write");
}
catch (IOException ex) {
// Handle me
}
使用try()将自动关闭流。此版本短、快(缓冲),并支持选择编码。
这个特性是在Java7中引入的。
其他回答
只需包含此包:
java.nio.file
然后,您可以使用以下代码编写文件:
Path file = ...;
byte[] buf = ...;
Files.write(file, buf);
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
}
最好的方法是使用Java7:Java7引入了一种处理文件系统的新方法,以及一个新的实用程序类—Files。使用Files类,我们还可以创建、移动、复制、删除文件和目录;它还可以用于读取和写入文件。
public void saveDataInFile(String data) throws IOException {
Path path = Paths.get(fileName);
byte[] strToBytes = data.getBytes();
Files.write(path, strToBytes);
}
使用FileChannel写入如果您正在处理大型文件,FileChannel可以比标准IO更快。以下代码使用FileChannel将字符串写入文件:
public void saveDataInFile(String data)
throws IOException {
RandomAccessFile stream = new RandomAccessFile(fileName, "rw");
FileChannel channel = stream.getChannel();
byte[] strBytes = data.getBytes();
ByteBuffer buffer = ByteBuffer.allocate(strBytes.length);
buffer.put(strBytes);
buffer.flip();
channel.write(buffer);
stream.close();
channel.close();
}
使用DataOutputStream写入
public void saveDataInFile(String data) throws IOException {
FileOutputStream fos = new FileOutputStream(fileName);
DataOutputStream outStream = new DataOutputStream(new BufferedOutputStream(fos));
outStream.writeUTF(data);
outStream.close();
}
使用FileOutputStream写入
现在让我们看看如何使用FileOutputStream将二进制数据写入文件。以下代码转换String int字节,并使用FileOutputStream将字节写入文件:
public void saveDataInFile(String data) throws IOException {
FileOutputStream outputStream = new FileOutputStream(fileName);
byte[] strToBytes = data.getBytes();
outputStream.write(strToBytes);
outputStream.close();
}
使用PrintWriter写入我们可以使用PrintWriter将格式化文本写入文件:
public void saveDataInFile() throws IOException {
FileWriter fileWriter = new FileWriter(fileName);
PrintWriter printWriter = new PrintWriter(fileWriter);
printWriter.print("Some String");
printWriter.printf("Product name is %s and its price is %d $", "iPhone", 1000);
printWriter.close();
}
使用BufferedWriter写入:使用BufferedWriter将字符串写入新文件:
public void saveDataInFile(String data) throws IOException {
BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
writer.write(data);
writer.close();
}
将字符串附加到现有文件:
public void saveDataInFile(String data) throws IOException {
BufferedWriter writer = new BufferedWriter(new FileWriter(fileName, true));
writer.append(' ');
writer.append(data);
writer.close();
}
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();
public class Program {
public static void main(String[] args) {
String text = "Hello world";
BufferedWriter output = null;
try {
File file = new File("example.txt");
output = new BufferedWriter(new FileWriter(file));
output.write(text);
} catch ( IOException e ) {
e.printStackTrace();
} finally {
if ( output != null ) {
try {
output.close();
}catch (IOException e){
e.printStackTrace();
}
}
}
}
}
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