如果你想在特定的行中添加一些文本，你可以先读取整个文件，在你想要的地方追加文本，然后覆盖下面代码中的所有内容:

public static void addDatatoFile(String data1, String data2){


    String fullPath = "/home/user/dir/file.csv";

    File dir = new File(fullPath);
    List<String> l = new LinkedList<String>();

    try (BufferedReader br = new BufferedReader(new FileReader(dir))) {
        String line;
        int count = 0;

        while ((line = br.readLine()) != null) {
            if(count == 1){
                //add data at the end of second line                    
                line += data1;
            }else if(count == 2){
                //add other data at the end of third line
                line += data2;
            }
            l.add(line);
            count++;
        }
        br.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }       
    createFileFromList(l, dir);
}

public static void createFileFromList(List<String> list, File f){

    PrintWriter writer;
    try {
        writer = new PrintWriter(f, "UTF-8");
        for (String d : list) {
            writer.println(d.toString());
        }
        writer.close();             
    } catch (FileNotFoundException | UnsupportedEncodingException e) {
        e.printStackTrace();
    }
}

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);
}

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);

/**********************************************************************
 * it will write content to a specified  file
 * 
 * @param keyString
 * @throws IOException
 *********************************************************************/
public static void writeToFile(String keyString,String textFilePAth) throws IOException {
    // For output to file
    File a = new File(textFilePAth);

    if (!a.exists()) {
        a.createNewFile();
    }
    FileWriter fw = new FileWriter(a.getAbsoluteFile(), true);
    BufferedWriter bw = new BufferedWriter(fw);
    bw.append(keyString);
    bw.newLine();
    bw.close();
}// end of writeToFile()

1.7的方法:

void appendToFile(String filePath, String content) throws IOException{

    Path path = Paths.get(filePath);

    try (BufferedWriter writer = 
            Files.newBufferedWriter(path, 
                    StandardOpenOption.APPEND)) {
        writer.newLine();
        writer.append(content);
    }

    /*
    //Alternative:
    try (BufferedWriter bWriter = 
            Files.newBufferedWriter(path, 
                    StandardOpenOption.WRITE, StandardOpenOption.APPEND);
            PrintWriter pWriter = new PrintWriter(bWriter)
            ) {
        pWriter.println();//to have println() style instead of newLine();   
        pWriter.append(content);//Also, bWriter.append(content);
    }*/
}

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