看看这个博客:

Java逐行读取文件- Java教程

可以指定缓冲区大小或 可以使用默认大小。的 违约对大多数人来说已经足够大了 目的。

// Open the file
FileInputStream fstream = new FileInputStream("textfile.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));

String strLine;

//Read File Line By Line
while ((strLine = br.readLine()) != null)   {
  // Print the content on the console
  System.out.println (strLine);
}

//Close the input stream
fstream.close();

下面是一个完整的错误处理示例，并支持java 7之前的字符集规范。在Java 7中，您可以使用try-with-resources语法，这使得代码更简洁。

如果你只想要默认字符集，你可以跳过InputStream，使用FileReader。

InputStream ins = null; // raw byte-stream
Reader r = null; // cooked reader
BufferedReader br = null; // buffered for readLine()
try {
    String s;
    if (true) {
        String data = "#foobar\t1234\n#xyz\t5678\none\ttwo\n";
        ins = new ByteArrayInputStream(data.getBytes());
    } else {
        ins = new FileInputStream("textfile.txt");
    }
    r = new InputStreamReader(ins, "UTF-8"); // leave charset out for default
    br = new BufferedReader(r);
    while ((s = br.readLine()) != null) {
        System.out.println(s);
    }
}
catch (Exception e)
{
    System.err.println(e.getMessage()); // handle exception
}
finally {
    if (br != null) { try { br.close(); } catch(Throwable t) { /* ensure close happens */ } }
    if (r != null) { try { r.close(); } catch(Throwable t) { /* ensure close happens */ } }
    if (ins != null) { try { ins.close(); } catch(Throwable t) { /* ensure close happens */ } }
}

下面是Groovy版本，有完整的错误处理:

File f = new File("textfile.txt");
f.withReader("UTF-8") { br ->
    br.eachLine { line ->
        println line;
    }
}

使用Java 8读取文件

package com.java.java8;

import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.stream.Stream;

/**
 * The Class ReadLargeFile.
 *
 * @author Ankit Sood Apr 20, 2017
 */
public class ReadLargeFile {

    /**
     * The main method.
     *
     * @param args
     *            the arguments
     */
    public static void main(String[] args) {
        try {
            Stream<String> stream = Files.lines(Paths.get("C:\\Users\\System\\Desktop\\demoData.txt"));
            stream.forEach(System.out::println);
        }
        catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

FileReader不会让你指定编码，如果你需要指定它，使用inputstreamreader代替:

try {
    BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(filePath), "Cp1252"));         

    String line;
    while ((line = br.readLine()) != null) {
        // process the line.
    }
    br.close();

} catch (IOException e) {
    e.printStackTrace();
}

如果从Windows导入该文件，它可能具有ANSI编码(Cp1252)，因此必须指定编码。

BufferedReader br;
FileInputStream fin;
try {
    fin = new FileInputStream(fileName);
    br = new BufferedReader(new InputStreamReader(fin));

    /*Path pathToFile = Paths.get(fileName);
    br = Files.newBufferedReader(pathToFile,StandardCharsets.US_ASCII);*/

    String line = br.readLine();
    while (line != null) {
        String[] attributes = line.split(",");
        Movie movie = createMovie(attributes);
        movies.add(movie);
        line = br.readLine();
    }
    fin.close();
    br.close();
} catch (FileNotFoundException e) {
    System.out.println("Your Message");
} catch (IOException e) {
    System.out.println("Your Message");
}

这对我很管用。希望它也能帮助到你。

我的阅读习惯通常很简单:

void readResource(InputStream source) throws IOException {
    BufferedReader stream = null;
    try {
        stream = new BufferedReader(new InputStreamReader(source));
        while (true) {
            String line = stream.readLine();
            if(line == null) {
                break;
            }
            //process line
            System.out.println(line)
        }
    } finally {
        closeQuiet(stream);
    }
}

static void closeQuiet(Closeable closeable) {
    if (closeable != null) {
        try {
            closeable.close();
        } catch (IOException ignore) {
        }
    }
}