Java通过多种方法打印到文件并附加文本

Question

我想用几种方法编写一个小程序，并且希望能够将不同方法的不同内容打印到输出文件中。如何从 main 之外的每个方法打印到最后一行后附加的同一文件中。我也对 PrintWriter 之外的其他方法持开放态度。

package tennisoddssimulator;

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;

public class TennisOddsSimulator {

    private static final int TOTALMATCHES = 1000;
    private boolean bestOf5Sets;
    private boolean P2ToServe;

    public static void main(String[] args)
            throws
            FileNotFoundException,
            UnsupportedEncodingException {

        PrintWriter writer
                = new PrintWriter("output.txt", "UTF-8");

        for (int i = 0; i < TOTALMATCHES; i++) {

        }
        writer.close();
    }

    public static void printMatchNo(int matchNo) {
        /*I want to print the number
        of the match currently being
        simulated from this method by
        calling this method after the
        start of every match*/
    }

    public static void printGameScore() {
        /*I want to print the current
        game score from this method by
        calling this method after every
        point has scored in a match*/
    }

    public static void furtherMethodForPrinting1() {
        /*You've probably got the
        idea by now*/
    }

    public static void furtherMethodForPrinting2() {
    }
}

Answer 1

我实际上建议在每个辅助方法中打开一个新的 PrintWriter，例如

public static void printMatchNo(int matchNo) {
    try {
        OutputStream os = new FileOutputStream("output.txt", true); // append mode
        Writer writer = new OutputStreamWriter(outputStream, "UTF8");
        PrintWriter pwFile = new PrintWriter(writer);
        pwFile.write("The match number is: " + matchNo);
    }
    catch (Exception e) {
        e.printStackTrace();
    }
    finally {
        if (pwFile != null) {
            pwFile.close();
        }
    }
}

我推荐这种方法的原因是，在程序中保持 PrintWriter 永久打开可能没有意义。相反，您应该只打开一个，写入，然后在需要时关闭。

顺便说一句，如果您这样做只是为了提供信息，您可能需要考虑使用可用于 Java 的日志框架之一。配置完成后，您只需调用一个简单的方法即可写入日志文件。