第十五章，输入输出流代码

package 例题;

import java.io.File;

public class 例题1 {

	public static void main(String[] args) {
		//创建文件对象
		File file = new File("D:\\Java15-1.docx");
		//判断，如果该文件存在。exists存在的意思
		if (file.exists()) {
			//删除
			//file.delete();
			//System.out.println("文件已删除");
			//获取文件名
			String name = file.getName();
			System.out.println("文件名叫：" + name);
			//判断文件是否可写入
			Boolean a = file.canWrite();
			System.out.println("文件是否可写入：" + a);
		}
		//如果文件不存在
		else {
			//捕捉异常。不捕捉异常会报输入输出异常
			try {
				//创建文件
				file.createNewFile();
				System.out.println("文件已创建");
			}
			//抛出异常
			catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

}

 

package 例题;

import java.io.File;

public class 例题2 {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		File file=new File("c:\\happy\\word.txt"); //创建文件对象
		if(file.exists()) {
			String name=file.getName();  //获取文件名称
			long length=file.length();  //获取文件长度
			boolean hidden=file.isHidden(); //判断文件是否为隐藏文件
			System.out.println("文件名称："+name);
			System.out.println("文件长度是："+length);
			System.out.println("该文件是隐藏文件吗？"+hidden);
		}
		else {//如果文件不存在
			System.out.println("该文件不存在");
		}
	}
 
}

 

package 例题;

import java.io.File;                   //缓冲流                //字节流  FileOutputStream输出流   FileInputStream输入流
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
 
public class 例题3 {
	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		File file = new File("C:\\happy\\word.txt");
		FileOutputStream out = new FileOutputStream(file); //输出字节流
		byte[]by = "hello world".getBytes(); 
		out.write(by);  //往文件中写入数据
		out.close();
		
		FileInputStream in = new FileInputStream(file);
		byte[] by1 = new byte[1024];
		int len = in.read(by1);
		System.out.println(new String(by1,0,len));//从零号位开始打印，只打印len长度
	}
 
}

 

package 例题;

import java.io.BufferedReader;                //文件流
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;                        //字符流   FileWriter输出流  FileReader输入流
import java.io.FileWriter;
import java.io.IOException;
 
public class 例题4 {
             
	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		File file = new File("C:\\happy\\word.txt");
		FileWriter writer = new FileWriter(file);  //输出字符流
		//char[]by = new char[] {'h','e','l','l','o'}; //输入数据
		//带缓存的输出流
		BufferedWriter bw = new BufferedWriter(writer); //BufferedWriter缓存流
		//String str="门前大桥下，游过一群鸭";
		bw.write("门前大桥下，游过一群鸭");
		bw.newLine();                       //换行
		bw.write("快来快来数一数，二四六七八");
		bw.newLine();
		bw.write("咕嘎咕嘎，真呀真多");
		bw.newLine();
		bw.write("数不清到底多少鸭");
		bw.close();
		//writer.write(str);  //往文件中写入数据
		writer.close();
		
		 FileReader reader = new  FileReader(file);
	 
		 /*char[] ch1 = new char[1024];
		int len = reader.read(ch1);
		System.out.println(new String(ch1,0,len));*/
		 
		 BufferedReader br =new  BufferedReader(reader);
		 String s1 = br.readLine();
		 System.out.println("第一行:"+ s1);
		System.out.println("第二行:"+ br .readLine());
		 System.out.println("第三行:"+ br .readLine());
		System.out.println("第四行:"+ br .readLine());
		reader.close();
	}
 
}

 

package 例题;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class 例题5 {

	public static void main(String[] args) throws IOException {
		//定义一个String类型数组
		String conten[] = {"好久不见","最近好吗","常联系"};
		//创建文件类对象
		File file = new File("D:\\word.txt");
		//文件字符输出流
		FileWriter fw = new FileWriter(file);
		//带缓存字符输出流
		BufferedWriter bw = new BufferedWriter(fw);
		//循环次数
		for(int k = 0; k < conten.length; k++) {
			//写入循环的次数
			bw.write(conten[k]);
			//换行
			bw.newLine();
		}
		bw.close();
		fw.close();
		
		//文件字符输入流
		FileReader fr = new FileReader(file);
		//带缓存文件字符输入流
		BufferedReader br = new BufferedReader(fr);
		//定义String类型变量值为空
		String tmp = null;
		//定义int类型变量
		int i = 1;
		//while循环，条件是tmp不等于空进入循环
		while ((tmp = br.readLine())!=null) {
			System.out.println("第" + i + "行：" + tmp);
			i++;
			
		}
		br.close();
		fr.close();
	}

}

 

package 例题;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
 
public class 例题6 {
 
	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		File file = new File("C:\\happy\\word.txt"); // 创建文件对象
		FileOutputStream fos = new FileOutputStream(file);
		DataOutputStream dos = new DataOutputStream(fos);
		dos.writeBoolean(false);
		dos.writeUTF("你好世界");
		dos.writeDouble(13.25);
		dos.close();
		fos.close();
		
		
		FileInputStream fis = new FileInputStream(file);
		DataInputStream dis = new DataInputStream (fis);
		System.out.println(dis.readBoolean());
		System.out.println(dis.readUTF());//输出字符串
		System.out.println(dis.readDouble());
		dis.close();
		fis.close();
		
	}
 
}