对于JDK版本>= 7

你可以使用这个简单的方法将给定的内容追加到指定的文件:

void appendToFile(String filePath, String content) {
  try (FileWriter fw = new FileWriter(filePath, true)) {
    fw.write(content + System.lineSeparator());
  } catch (IOException e) { 
    // TODO handle exception
  }
}

我们正在以追加模式构造FileWriter对象。

图书馆

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);
    }
}

    String str;
    String path = "C:/Users/...the path..../iin.txt"; // you can input also..i created this way :P

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter pw = new PrintWriter(new FileWriter(path, true));

    try 
    {
       while(true)
        {
            System.out.println("Enter the text : ");
            str = br.readLine();
            if(str.equalsIgnoreCase("exit"))
                break;
            else
                pw.println(str);
        }
    } 
    catch (Exception e) 
    {
        //oh noes!
    }
    finally
    {
        pw.close();         
    }

这将达到你的目的。

这可以在一行代码中完成。希望这对你有所帮助。

Files.write(Paths.get(fileName), msg.getBytes(), StandardOpenOption.APPEND);

我只是补充了一个小细节:

    new FileWriter("outfilename", true)

2.nd parameter (true) is a feature (or, interface) called appendable (http://docs.oracle.com/javase/7/docs/api/java/lang/Appendable.html). It is responsible for being able to add some content to the end of particular file/stream. This interface is implemented since Java 1.5. Each object (i.e. BufferedWriter, CharArrayWriter, CharBuffer, FileWriter, FilterWriter, LogStream, OutputStreamWriter, PipedWriter, PrintStream, PrintWriter, StringBuffer, StringBuilder, StringWriter, Writer) with this interface can be used for adding content

换句话说，您可以向gzip文件或http进程添加一些内容

在Java-7中也可以这样做:

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

//---------------------

Path filePath = Paths.get("someFile.txt");
if (!Files.exists(filePath)) {
    Files.createFile(filePath);
}
Files.write(filePath, "Text to be added".getBytes(), StandardOpenOption.APPEND);