java如何在文件后面追加内容

只追加一次

try {
    Files.write(Paths.get("myfile.txt"), "the text".getBytes(), StandardOpenOption.APPEND);
}catch (IOException e) {
    //异常处理
}

文件不存在，则创建并追加

private void write(final String s) throws IOException {
    Files.writeString(
        Path.of(System.getProperty("java.io.tmpdir"), "filename.txt"),
        s + System.lineSeparator(),
        CREATE, APPEND
    );
}

多次追加内容

//第二个参数表示追加内容
try(FileWriter fw = new FileWriter("myfile.txt", true);
    BufferedWriter bw = new BufferedWriter(fw);
    PrintWriter out = new PrintWriter(bw))
{
    out.println("the text");
    //more code
    out.println("more text");
    //more code
} catch (IOException e) {
    //异常处理
}