Java IO流（字节流、字符流、管道） -- 实现写日记功能

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.time.LocalDate;
import org.junit.Test;

public class WriteDiary {
	
	/**
	 * 字节流 复制文件内容
	 */
	@Test
	public void test1() {
		FileInputStream fi = null;
		FileOutputStream fo = null;
		try {
            fi = new FileInputStream("G:\2222\1.txt");
            fo = new FileOutputStream("G:\2222\2.txt");
            int a;
            while ((a=fi.read())!=-1){/*这里的.read方法是把字
                  节一个接一个的传给a,当为空的时候则返回-1；*/
                fo.write(a);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
			try {
				fi.close();
				fo.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
	
	/**
	 * 字符流 复制文件内容
	 */
	@Test
	public void test2() {
		FileReader fr = null;
		FileWriter fw = null;
		try {
	        fr = new FileReader("G:\2222\2.txt");
	        fw = new FileWriter("G:\2222\3.txt");
	        int a;
	        while ((a=fr.read())!=-1){
	        	fw.write(a);
	        }
	    } catch (IOException e) {
	        e.printStackTrace();
	    } finally {
			try {
				fr.close();
				fw.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}  
	}
	
	/**
	 * 字符流 写日记
	 * @throws IOException 
	 */
	@Test
	public void test3() throws IOException {
		//创建日期
		LocalDate now = LocalDate.now();
		StringBuffer content = new StringBuffer("");
		
		File dir = new File("G:\2222\diary.txt");
		if(dir.exists()) {
			//读取日记内容
		    InputStreamReader diary = new InputStreamReader(new FileInputStream("G:\2222\diary.txt"));
		    BufferedReader buffer = new BufferedReader(diary);
		    
		    //有内容就读取
		    String line="";
	    	while((line = buffer.readLine()) != null) {
	    		content.append(line);
	    	}
		    
		    //關閉IO流
		    buffer.close();
		    diary.close();
		}
	    
	    //创建管道
		InputStreamReader reader = new InputStreamReader(System.in);
		OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream("G:\2222\diary.txt"));
	    BufferedReader in = new BufferedReader(reader);
	  	    
	    boolean flag = true;
	    do {
	    	System.out.println("今天日期:" + now);
		    content.append("日期:" + now);
		    System.out.println("输入日记内容: ");
		    content.append(" 日记内容:" + in.readLine());
		    System.out.println("输入作者: ");
		    content.append(" 作者:" + in.readLine() + "
");
		    System.out.println("是否繼續寫日記?(Y/N)");
		    //跳出循環
		    String choose = in.readLine();
		    if(choose.equals("N") || choose.equals("n")) {
		    	flag = false;
		    	writer.write(content.toString());
		    }
		} while (flag);
	    
	    //关闭IO流
	    reader.close();
	    writer.close();
	    in.close();
	}

}