文件与流练习题_<练习题-文件和流>

3、创建c:/test.txt文件并在其中输入"hello world" 创建一个输入流读取该文件中的文本 并且把小写的l变成大写L再利用输出流写入到d:\test.txt中
3.1 实现步骤：
    3.1.1 在本地硬盘C盘下创建一个文件test.txt
    3.1.2 创建一个包含main()方法的类，并在main中编写代码
    3.1.3 运行代码并且测试结果
3.2 实现过滤器的功能

这里总共写了三个方法：

package com.neuedu.chapter03._文件管理Java7特性;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Arrays;

public class FileReader_FileWriter_Homework3 {
	/**
	 * 方法1
	 */
	public static void methodOne() {
		FileReader reader = null;
		FileWriter writer = null;
		 try {
			reader = new FileReader("file/test.txt");   //读取文件
			writer = new FileWriter("file/test_back.txt");   //写文件						
			int content = -1;
			while((content = reader.read()) !=-1) {
				//将字符数组一个一个地比较，将“l”转化为“L”
				if(content == 'l') {
					content = 'L';				
				}
				writer.write(content);
			}			
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//关闭资源
			try {
				reader.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			try {
				writer.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
	/**
	 * 方法2
	 */
	public static void methodTow() {
		FileReader reader = null;
		FileWriter writer = null;
		try {
			reader = new FileReader("file/test.txt");  //字符流输入
			writer = new FileWriter("file/test_back.txt");  //字符流输出
			
			char[] ch = new char[11];
			int length;
			while((length = reader.read(ch)) != -1) {
				System.out.println(ch);
				System.out.println(length);
				//将字符数组转换为一个字符串，在用字符串的replace（）方法将“l”转化为“L”
				//再见转化号的字符串用toCharArray（）方法转化为字符数组
				ch = new String(ch).replace("l", "L").toCharArray();  			
				writer.write(ch,0,length);  //写入指定文件
			}
			writer.flush();  //强制刷新			
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			try {
				writer.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
			try {
				reader.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}		
	}
	/**
	 * 方法3
	 */
	public static void methodThree() {
		
		FileReader file=null;
		String s = "";
		BufferedReader br = null;
		BufferedWriter writer =null;
		
		try {
			file = new FileReader("file/test.txt");
			br = new BufferedReader(file);
			s = br.readLine();  //使用吃力流的方法
			System.out.println("原文件"+s);
			s = s.replace("l","L");
			System.out.println(s);
			FileWriter fw = new FileWriter("file/test_back.txt");
			
			writer = new BufferedWriter(fw);
			writer.write(s);
			
			writer.flush();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			try {
				br.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
				try {
					writer.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
		}

	}
	public static void main(String[] args) {
		//methodTow();
		methodThree();
	}
}

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