Java如何实现判断并输出文件大小

package 包名;

import java.io.File;

public class FileAction {

    public static void main(String[] args) {

        File file = new File("chaoyue.jpeg");
        long size = file.length() / 1024;
        System.out.println("文件大小：" + size + "kb");

    }
}

package encryption;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.NIO.channels.FileChannel;
 
public class Test02 {
 
	public static void main(String[] args) throws IOException {
 
		// 获取文件大小的三种方法
		
		//大文件
		String fileStr = "E:\\src\\cn_windows_7_ultimate_with_sp1_x64_dvd_618537.iso";
		//小文件
        String fileStr01 = "E:\\src\\Chrome-Goagent.7z";
		
		File file = new File(fileStr);
 
		long size01 = getFileSize01(file);
		long size02 = getFileSize02(file);
		int  size03 = getFileSize03(file);
		
		System.out.println("小文件计算文件大小");
		System.out.println("文件名称:"+file.getName());
		System.out.println("length方法获取文件大小:"+size01+" byte.");
		System.out.println("FileChannel方法获取文件大小:"+size02+" byte.");
		System.out.println("available方法获取文件大小:"+size03+" byte.");
		System.out.println("\nInteger类型数据的最大值:"+Integer.MAX_VALUE);
 
	}
 
 
	
	private static long getFileSize01(File file) {
 
		return file.length();
	}
 
	 
	private static long getFileSize02(File file) throws IOException {
 
		FileInputStream fis = new FileInputStream(file);
		FileChannel fc = fis.getChannel();
		return fc.size();
	}
	
	 
		private static int getFileSize03(File file) throws IOException {
 
			FileInputStream fis = new FileInputStream(file);
			
			return fis.available();
		}
}