可能没有缓冲I/O那么快，但是非常简洁:

    String content;
    try (Scanner scanner = new Scanner(textFile).useDelimiter("\\Z")) {
        content = scanner.next();
    }

\Z模式告诉扫描器分隔符是EOF。

import java.util.stream.Stream;
import java.nio.file.*;
import java.io.*;

class ReadFile {

 public static void main(String[] args) {

    String filename = "Test.txt";

    try(Stream<String> stream = Files.lines(Paths.get(filename))) {

          stream.forEach(System.out:: println);

    } catch (IOException e) {

        e.printStackTrace();
    }

 }

 }

只需使用java 8流。

Java 11 Files.readString中引入了最直观的方法

import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;

public class App {
    public static void main(String args[]) throws IOException {
        String content = Files.readString(Paths.get("D:\\sandbox\\mvn\\my-app\\my-app.iml"));
        System.out.print(content);
    }
}

PHP几十年来一直享有这种特权!☺

如果您有一个大文件，您可以使用Apache Commons IO迭代处理该文件，而不会耗尽可用内存。

try (LineIterator it = FileUtils.lineIterator(theFile, "UTF-8")) {
    while (it.hasNext()) {
        String line = it.nextLine();
        // do something with line
    }
}

我编写的这段代码对于非常大的文件要快得多:

public String readDoc(File f) {
    String text = "";
    int read, N = 1024 * 1024;
    char[] buffer = new char[N];

    try {
        FileReader fr = new FileReader(f);
        BufferedReader br = new BufferedReader(fr);

        while(true) {
            read = br.read(buffer, 0, N);
            text += new String(buffer, 0, read);

            if(read < N) {
                break;
            }
        }
    } catch(Exception ex) {
        ex.printStackTrace();
    }

    return text;
}

org.apache.commons.io.FileUtils中的方法也可能非常方便，例如:

/**
 * Reads the contents of a file line by line to a List
 * of Strings using the default encoding for the VM.
 */
static List readLines(File file)