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import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

代码

public void append()
{
    try
    {
        String path = "D:/sample.txt";

        File file = new File(path);

        FileWriter fileWriter = new FileWriter(file,true);

        BufferedWriter bufferFileWriter  = new BufferedWriter(fileWriter);

        fileWriter.append("Sample text in the file to append");

        bufferFileWriter.close();

        System.out.println("User Registration Completed");

    }catch(Exception ex)
    {
        System.out.println(ex);
    }
}

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

public class Writer {


    public static void main(String args[]){
        doWrite("output.txt","Content to be appended to file");
    }

    public static void doWrite(String filePath,String contentToBeAppended){

       try(
            FileWriter fw = new FileWriter(filePath, true);
            BufferedWriter bw = new BufferedWriter(fw);
            PrintWriter out = new PrintWriter(bw)
          )
          {
            out.println(contentToBeAppended);
          }  
        catch( IOException e ){
        // File writing/opening failed at some stage.
        }

    }

}

使用Apache Commons 2.1:

import org.apache.logging.log4j.core.util.FileUtils;

FileUtils.writeStringToFile(file, "String to append", true);

用番石榴做的样品:

File to = new File("C:/test/test.csv");

for (int i = 0; i < 42; i++) {
    CharSequence from = "some string" + i + "\n";
    Files.append(from, to, Charsets.UTF_8);
}

我建议你加入阿帕奇公共项目。这个项目已经提供了一个框架来做你需要的事情(即灵活的集合过滤)。

在项目的任何地方创建一个函数，并在任何需要的地方简单地调用该函数。

伙计们，你们要记住，你们调用的是活动线程，而不是异步调用，因为它可能需要5到10页才能完成。 为什么不花更多的时间在你的项目上，忘掉已经写好的东西。 正确

    //Adding a static modifier would make this accessible anywhere in your app

    public Logger getLogger()
    {
       return java.util.logging.Logger.getLogger("MyLogFileName");
    }
    //call the method anywhere and append what you want to log 
    //Logger class will take care of putting timestamps for you
    //plus the are ansychronously done so more of the 
    //processing power will go into your application

    //from inside a function body in the same class ...{...

    getLogger().log(Level.INFO,"the text you want to append");

    ...}...
    /*********log file resides in server root log files********/

三行代码，实际上是两行，因为第三行实际上是追加文本。: P