我已经用下面这个成语有一段时间了。这似乎是传播最广的,至少在我访问过的网站上。

在Java中有没有更好/不同的方法将文件读入字符串?

private String readFile(String file) throws IOException {
    BufferedReader reader = new BufferedReader(new FileReader (file));
    String         line = null;
    StringBuilder  stringBuilder = new StringBuilder();
    String         ls = System.getProperty("line.separator");

    try {
        while((line = reader.readLine()) != null) {
            stringBuilder.append(line);
            stringBuilder.append(ls);
        }

        return stringBuilder.toString();
    } finally {
        reader.close();
    }
}

当前回答

对于Java 7,这是我读取UTF-8文件的首选选项:

String content = new String(Files.readAllBytes(Paths.get(filename)), "UTF-8");

自Java7以来,JDK有了新的Java.nio.file API,它提供了许多快捷方式,因此简单的文件操作并不总是需要第三方库。


由于人们仍然对这个答案投赞成票,这里有一个在Java 11中引入的更好的解决方案:

String content = Files.readString(path);

其他回答

import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;

Java 7

String content = new String(Files.readAllBytes(Paths.get("readMe.txt")), StandardCharsets.UTF_8);

Java 11

String content = Files.readString(Paths.get("readMe.txt"));
import java.nio.file.Files;

.......

 String readFile(String filename) {
            File f = new File(filename);
            try {
                byte[] bytes = Files.readAllBytes(f.toPath());
                return new String(bytes,"UTF-8");
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return "";
    }

自JDK 11以来:

String file = ...
Path path = Paths.get(file);
String content = Files.readString(path);
// Or readString(path, someCharset), if you need a Charset different from UTF-8
Scanner sc = new Scanner(new File("yourFile.txt"));
sc.useDelimiter("\\Z");

String s = sc.next();

纯kotlin代码,无依赖关系

适用于所有android版本

val fileAsString = file.bufferedReader().use { it.readText() }