[Java I/O] TextFile 工具类

Posted 2020-07-17 TonyYPZhang

一种常见的编程任务是，从一个文件读取内容，修改内容，再把内容写到另一个文件里。 Java 要实现读取、写入操作，需要创建多个类才能产生一个 Stream 进行操作。

下面是一个简单的工具类，封装对文件的读、写操作，提供简洁的接口。

 

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;

public class TextFile {

    /**
     * 
     * @param fileName The full path of the target file
     * @return
     */
    public static String read(String fileName){
        
        StringBuilder sb = new StringBuilder();
        
        try {
            BufferedReader in = new BufferedReader(new FileReader(new File(fileName).getAbsoluteFile()));
            
            String s;
            try {
                while( (s = in.readLine()) != null ){
                    sb.append(s);
                    sb.append("\n");
                }
            }finally{
                in.close();
            }
            
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        return sb.toString();
    }
    
    /**
     * 
     * @param fileName The full path of the target file 
     * @param text The content which is written to the target file
     */
    public static void write(String fileName, String text){
        try {
            PrintWriter out = new PrintWriter(new File(fileName).getAbsoluteFile());
            out.print(text);
            out.close();            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
}

 

TextFile 工具类演示

public class TextFileDemo {
    public static void main(){
        String fileName = "/tmp/dirTest/aaa.txt";
        String content = TextFile.read(fileName);
        System.out.print(content);
        
        System.out.println("[ Read End ]");
        
        String content2 = "aaaaaaaa";
        TextFile.write(fileName, content2);
    }
}

 

参考资料

Page 672, File reading & writing utilities, Thinking in Java 4th.