java获取本地文件的多种方式实现与比较

package com.example.demo.utils;

import java.io.*;
import java.util.Scanner;

public class TestCode {

	public static void main(String[] args) throws Exception,IOException{
//		testCode();
//		getFileContent();
//		getFileContentTwo();
		getFileContentThree();
	}

	//方法一
	public static void getFileContent() throws IOException{
		FileReader fr = new FileReader("E:\\testfile\\test_utf8.txt");
		BufferedReader br = new BufferedReader(fr);
		while(br.ready()){
			System.out.println(br.readLine());
		}
	}

	//方法二
	public static void getFileContentTwo() throws IOException{
		String encoding="GBK";
		File file=new File("E:\\testfile\\test.txt");
		//判断文件是否存在
		if(file.isFile() && file.exists()) {
			//考虑到编码格式
			InputStreamReader read = new InputStreamReader(new FileInputStream(file), encoding);
			BufferedReader bufferedReader = new BufferedReader(read);
			String lineTxt = null;
			while ((lineTxt = bufferedReader.readLine()) != null) {
				System.out.println(lineTxt);
			}
			read.close();
		}else {
			System.out.println("该文件不存在");
		}
	}

	//方法三
	public static void getFileContentThree() throws IOException{
		Scanner in = new Scanner(new File("E:\\testfile\\test_utf8.txt"));
		while (in.hasNextLine()) {
			System.out.println(in.nextLine());
		}
	}

	/**
	 *
	 *@param:
	 *@return:获得txt文件编码格式
	 *@Date:2019/8/26
	 */
	public static void testCode() throws Exception{
		BufferedInputStream bin=new BufferedInputStream(new FileInputStream("E:\\testfile\\test.txt"));
		int p=(bin.read()<<8)+bin.read();
		String code=null;
		switch (p){
			case 0xefbb:
				code="UTF-8";
				break;
			case 0xfffe:
				code="Unicode";
				break;
			case 0xfeff:
				code="UTF-16BE";
				break;
			default:
				code="GBK";
		}
		System.out.println(String.format("测试文件的编码格式是:"+code));
	}

}