我需要在Java中反复向现有文件追加文本。我怎么做呢?
当前回答
使用Apache Commons 2.1:
import org.apache.logging.log4j.core.util.FileUtils;
FileUtils.writeStringToFile(file, "String to append", true);
其他回答
您可以使用fileWriter将标志设置为true,用于追加。
try
{
String filename= "MyFile.txt";
FileWriter fw = new FileWriter(filename,true); //the true will append the new data
fw.write("add a line\n");//appends the string to the file
fw.close();
}
catch(IOException ioe)
{
System.err.println("IOException: " + ioe.getMessage());
}
/**********************************************************************
* 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);
}*/
}
稍微扩展一下基普的回答, 下面是一个简单的Java 7+方法来追加一个新行到一个文件,如果它不存在就创建它:
try {
final Path path = Paths.get("path/to/filename.txt");
Files.write(path, Arrays.asList("New line to append"), StandardCharsets.UTF_8,
Files.exists(path) ? StandardOpenOption.APPEND : StandardOpenOption.CREATE);
} catch (final IOException ioe) {
// Add your own exception handling...
}
进一步指出:
The above uses the Files.write overload that writes lines of text to a file (i.e. similar to a println command). To just write text to the end (i.e. similar to a print command), an alternative Files.write overload can be used, passing in a byte array (e.g. "mytext".getBytes(StandardCharsets.UTF_8)). The CREATE option will only work if the specified directory already exists - if it doesn't, a NoSuchFileException is thrown. If required, the following code could be added after setting path to create the directory structure: Path pathParent = path.getParent(); if (!Files.exists(pathParent)) { Files.createDirectories(pathParent); }
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);
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