java IO 文件读入，写入，重定向

最新推荐文章于 2025-09-06 09:33:29 发布

转载最新推荐文章于 2025-09-06 09:33:29 发布 · 81 阅读

文章标签：

#java

本文介绍Java中如何使用IO流进行文件读写及重定向操作。通过实例展示了如何利用BufferedReader、PrintStream等类实现从文件读取内容并在控制台输出，以及将系统输出重定向到文件。

java IO 文件读入，写入，重定向 - 天堂有路慢慢走，俯首甘为博之牛 - ITeye技术网站

java IO 文件读入，写入，重定向

博客分类： java IO
Java
Java代码

package star20110526;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.io.PrintWriter;


public class Redirecting {
    public static void main(String[] args) throws IOException {
        redirect();
//      readFile();
//      write("B05\\star20110526\\Redirecting.txt", read());
    }
    private static void redirect() throws IOException{
        //将输出定位到PrintStrem，将 System.out重新定义ouputStream
        PrintStream printStream = System.out;

        //定义输入流
        BufferedInputStream bufferedInputStream = new BufferedInputStream(
                new FileInputStream("B05\\star20110526\\Redirecting.java"));
        //定义输出流
        PrintStream printStream2 = new PrintStream(
                new BufferedOutputStream(new FileOutputStream("B05\\star20110526\\Redirect.out")));

        //本来System.in是接受控制台参数的，现在将System.in重新定义到bufferedInputStream
        System.setIn(bufferedInputStream);
        System.setErr(printStream2);
        System.setOut(printStream2);

        //InputStreamReader 为适配器，转换inputStream到Reader，你懂的
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

        String string;
        while((string = bufferedReader.readLine()) != null){
            System.out.println(string);
        }
        printStream.close();
        printStream2.close();
        bufferedReader.close();
        System.setOut(printStream);
    }

    /**
     * 读取文件，然后直接在控制台打印出来
     * @throws IOException
     */
    private static void readFile() throws IOException{
        File file = new File("B05\\star20110526\\Redirecting.java");
        FileReader fileReader = new FileReader(file);
        BufferedReader bufferedReader = new BufferedReader(fileReader);
        int i = 1;
        String string;
        while((string = bufferedReader.readLine()) != null){
            System.out.println(i++ +":"+string);
        }
        bufferedReader.close();
    }
    /**
     * 读取文件，返回文件内容，提供文件写入操作
     * @return
     * @throws IOException
     */
    private static String read() throws IOException{
        File file = new File("B05\\star20110526\\Redirecting.java");
        BufferedReader bufferedReader = new BufferedReader(
                new FileReader(file));
        StringBuilder stringBuilder = new StringBuilder();
        String string;
        while((string  = bufferedReader.readLine()) != null){
            stringBuilder.append(string+"\n");
        }
        return stringBuilder.toString();
    }

    /**
     * 新建一个文件，然后往文件里面写文件咯
     * @param file
     * @param text
     * @throws FileNotFoundException
     */
    private static void write(String file,String text) throws FileNotFoundException{
        File file2 = new File(file);
        PrintWriter printWriter = new PrintWriter(file2);
        printWriter.write(text);
        //必须关闭流，要不然出不来结果的，(╰_╯)#(╰_╯)#(╰_╯)#
        printWriter.close();
    }
}
package star20110526;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.io.PrintWriter;

public class Redirecting {
	public static void main(String[] args) throws IOException {
		redirect();
//		readFile();
//		write("B05\\star20110526\\Redirecting.txt", read());
	}
	private static void redirect() throws IOException{
		//将输出定位到PrintStrem，将 System.out重新定义ouputStream
		PrintStream printStream = System.out;

		//定义输入流
		BufferedInputStream bufferedInputStream = new BufferedInputStream(
				new FileInputStream("B05\\star20110526\\Redirecting.java"));
		//定义输出流
		PrintStream printStream2 = new PrintStream(
				new BufferedOutputStream(new FileOutputStream("B05\\star20110526\\Redirect.out")));

		//本来System.in是接受控制台参数的，现在将System.in重新定义到bufferedInputStream
		System.setIn(bufferedInputStream);
		System.setErr(printStream2);
		System.setOut(printStream2);

		//InputStreamReader 为适配器，转换inputStream到Reader，你懂的
		BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

		String string;
		while((string = bufferedReader.readLine()) != null){
			System.out.println(string);
		}
		printStream.close();
		printStream2.close();
		bufferedReader.close();
		System.setOut(printStream);
	}

	/**
	 * 读取文件，然后直接在控制台打印出来
	 * @throws IOException
	 */
	private static void readFile() throws IOException{
		File file = new File("B05\\star20110526\\Redirecting.java");
		FileReader fileReader = new FileReader(file);
		BufferedReader bufferedReader = new BufferedReader(fileReader);
		int i = 1;
		String string;
		while((string = bufferedReader.readLine()) != null){
			System.out.println(i++ +":"+string);
		}
		bufferedReader.close();
	}
	/**
	 * 读取文件，返回文件内容，提供文件写入操作
	 * @return
	 * @throws IOException
	 */
	private static String read() throws IOException{
		File file = new File("B05\\star20110526\\Redirecting.java");
		BufferedReader bufferedReader = new BufferedReader(
				new FileReader(file));
		StringBuilder stringBuilder = new StringBuilder();
		String string;
		while((string  = bufferedReader.readLine()) != null){
			stringBuilder.append(string+"\n");
		}
		return stringBuilder.toString();
	}

	/**
	 * 新建一个文件，然后往文件里面写文件咯
	 * @param file
	 * @param text
	 * @throws FileNotFoundException
	 */
	private static void write(String file,String text) throws FileNotFoundException{
		File file2 = new File(file);
		PrintWriter printWriter = new PrintWriter(file2);
		printWriter.write(text);
		//必须关闭流，要不然出不来结果的，(╰_╯)#(╰_╯)#(╰_╯)#
		printWriter.close();
	}
}