文件操作

文件写入

BufferedWriter out = new BufferedWriter(new FileWriter("nowcoder.txt"));
            out.write("牛客教程");
            out.close();

文件读取

BufferedReader in = new BufferedReader(new FileReader("test.log"));
            String str;
            while ((str = in.readLine()) != null) {
                System.out.println(str);
            }

创建临时文件

File temp = File.createTempFile("test", ".txt");
        System.out.println("文件路径: "+temp.getAbsolutePath());
        temp.deleteOnExit();//程序退出文件删除
        BufferedWriter out = new BufferedWriter(new FileWriter(temp));
        out.write("aString");
        System.out.println("临时文件已创建:");
        out.close();

修改最后修改时间

Date filetime = new Date(fileToChange.lastModified());
        System.out.println(filetime.toString());
        System.out.println(fileToChange.setLastModified(System.currentTimeMillis()));

获取文件大小

file.length()

重命名

File oldName = new File("C:/program.txt");
        File newName = new File("C:/java.txt");
        if(oldName.renameTo(newName)) {
            System.out.println("已重命名");
        } else {
            System.out.println("Error");
        }

设置文件只读

file.setReadOnly() 和 file.canWrite() 方法

检测文件是否存在

file.exists()

设置只读

        System.out.println(file.setReadOnly());
        System.out.println(file.canWrite());

在指定目录中创建文件

File dir = new File("C:/");
        file = File.createTempFile
        ("JavaTemp", ".javatemp", dir);