java追加到文件末尾_Java追加到文件

清疚 2023-02-28 08:40 16阅读 0赞

java追加到文件末尾

Today we will look into how to append to a file in java. Java append to file is a common [java IO][] operation. For example, whenever we print something to server logs, it gets appended to the existing file.

今天，我们将研究如何在Java中附加文件。 Java追加到文件是一种常见的[Java IO][java IO]操作。 例如，每当我们将某些内容打印到服务器日志时，它就会被附加到现有文件中。

## Java追加到文件 **(****Java append to file****)** ##

We can append to file in java using following classes.

我们可以使用以下类在Java中追加文件。

1.  Java append to file using `FileWriter`
    
    Java使用`FileWriter`附加到文件
2.  Java append content to existing file using `BufferedWriter`
    
    Java使用`BufferedWriter`将内容追加到现有文件
3.  Append text to file in java using `PrintWriter`
    
    使用`PrintWriter`将文本追加到Java中的文件
4.  Append to file in java using `FileOutputStream`
    
    使用`FileOutputStream`附加到Java中的文件

If you are working on text data and the number of write operations is less, use FileWriter and use its constructor with append flag value as `true`. If the number of write operations is huge, you should use the [BufferedWriter][].

如果您正在处理文本数据并且写入操作的次数较少，请使用FileWriter并将其构造函数的附加标志值设置为`true` 。 如果写入操作的数量很多，则应使用[BufferedWriter][] 。

To append binary or raw stream data to an existing file, you should use FileOutputStream.

要将二进制或原始流数据附加到现有文件，应使用FileOutputStream。

### Java使用`FileWriter`附加到文件 **(****Java append to file using `FileWriter`****)** ###

Here is the short program to append to file in java using [FileWriter][]. We will look into a complete Java append to file example program later on.

这是使用[FileWriter][]附加到java中文件的简短程序。 稍后，我们将研究完整的Java追加到文件示例程序。

File file = new File("append.txt");
    FileWriter fr = new FileWriter(file, true);
    fr.write("data");
    fr.close();

### Java使用`BufferedWriter`将内容追加到现有文件 **(****Java append content to existing file using `BufferedWriter`****)** ###

File file = new File("append.txt");
    FileWriter fr = new FileWriter(file, true);
    BufferedWriter br = new BufferedWriter(fr);
    br.write("data");
    
    br.close();
    fr.close();

### 使用`PrintWriter`将文本追加到Java中的文件 **(****Append text to file in java using `PrintWriter`****)** ###

We can also use PrintWriter to append to file in java.

我们还可以使用PrintWriter附加到java中的文件。

File file = new File("append.txt");
    FileWriter fr = new FileWriter(file, true);
    BufferedWriter br = new BufferedWriter(fr);
    PrintWriter pr = new PrintWriter(br);
    pr.println("data");
    pr.close();
    br.close();
    fr.close();

### 使用`FileOutputStream`附加到Java中的文件 **(****Append to file in java using `FileOutputStream`****)** ###

You should use [FileOutputStream][] to append data to file when it’s raw data, binary data, images, videos etc.

当数据是原始数据，二进制数据，图像，视频等时，应使用[FileOutputStream][]将数据追加到文件中。

OutputStream os = new FileOutputStream(new File("append.txt"), true);
    os.write("data".getBytes(), 0, "data".length());
    os.close();

### Java附加到文件示例 **(****Java append to file example****)** ###

Here is the final java append to file program showing all the different options we discussed above.

这是文件程序的最后java追加，显示了我们上面讨论的所有不同选项。

package com.journaldev.files;
    
    import java.io.BufferedWriter;
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.io.OutputStream;
    import java.io.PrintWriter;
    
    public class JavaAppendToFile {
    
    	/**
    	 * Java append to file example
    	 * 
    	 * @param args
    	 */
    	public static void main(String[] args) {
    		String filePath = "/Users/pankaj/Downloads/append.txt";
    
    		String appendText = "This String will be appended to the file, Byte=0x0A 0xFF";
    
    		appendUsingFileWriter(filePath, appendText);
    
    		appendUsingBufferedWriter(filePath, appendText, 2);
    
    		appendUsingPrintWriter(filePath, appendText);
    
    		appendUsingFileOutputStream(filePath, appendText);
    	}
    
    	private static void appendUsingPrintWriter(String filePath, String text) {
    		File file = new File(filePath);
    		FileWriter fr = null;
    		BufferedWriter br = null;
    		PrintWriter pr = null;
    		try {
    			// to append to file, you need to initialize FileWriter using below constructor
    			fr = new FileWriter(file, true);
    			br = new BufferedWriter(fr);
    			pr = new PrintWriter(br);
    			pr.println(text);
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				pr.close();
    				br.close();
    				fr.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    
    	/**
    	 * Use Stream for java append to file when you are dealing with raw data, binary
    	 * data
    	 * 
    	 * @param data
    	 */
    	private static void appendUsingFileOutputStream(String fileName, String data) {
    		OutputStream os = null;
    		try {
    			// below true flag tells OutputStream to append
    			os = new FileOutputStream(new File(fileName), true);
    			os.write(data.getBytes(), 0, data.length());
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				os.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    
    	/**
    	 * Use BufferedWriter when number of write operations are more
    	 * 
    	 * @param filePath
    	 * @param text
    	 * @param noOfLines
    	 */
    	private static void appendUsingBufferedWriter(String filePath, String text, int noOfLines) {
    		File file = new File(filePath);
    		FileWriter fr = null;
    		BufferedWriter br = null;
    		try {
    			// to append to file, you need to initialize FileWriter using below constructor
    			fr = new FileWriter(file, true);
    			br = new BufferedWriter(fr);
    			for (int i = 0; i < noOfLines; i++) {
    				br.newLine();
    				// you can use write or append method
    				br.write(text);
    			}
    
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				br.close();
    				fr.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    
    	/**
    	 * Use FileWriter when number of write operations are less
    	 * 
    	 * @param filePath
    	 * @param text
    	 * @param noOfLines
    	 */
    	private static void appendUsingFileWriter(String filePath, String text) {
    		File file = new File(filePath);
    		FileWriter fr = null;
    		try {
    			// Below constructor argument decides whether to append or override
    			fr = new FileWriter(file, true);
    			fr.write(text);
    
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				fr.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    
    }

That’s all for append to file in java program.

这就是将所有内容追加到java程序中的文件。

[GitHub Repository][]. [GitHub存储库中][GitHub Repository]签出更多Java IO示例。

References:

参考文献：

*  [PrintWriter API Doc][]
    
    [PrintWriter API文档][PrintWriter API Doc]
 *  [FileWriter API Doc][]
    
    [FileWriter API文档][FileWriter API Doc]
 *  [BufferedWriter API Doc][]
    
    [BufferedWriter API文档][BufferedWriter API Doc]
 *  [FileOutputStream API Doc][]
    
    [FileOutputStream API文档][FileOutputStream API Doc]

> 翻译自: [https://www.journaldev.com/881/java-append-to-file][https_www.journaldev.com_881_java-append-to-file]

java追加到文件末尾

[java IO]: https://www.journaldev.com/942/java-io-tutorial
[BufferedWriter]: https://www.journaldev.com/20601/java-bufferedwriter
[FileWriter]: https://www.journaldev.com/20891/java-filewriter-example
[FileOutputStream]: https://www.journaldev.com/19438/java-fileoutputstream
[GitHub Repository]: https://github.com/journaldev/journaldev/tree/master/CoreJavaProjects/CoreJavaExamples
[PrintWriter API Doc]: https://docs.oracle.com/javase/8/docs/api/java/io/PrintWriter.html
[FileWriter API Doc]: https://docs.oracle.com/javase/8/docs/api/java/io/FileWriter.html
[BufferedWriter API Doc]: https://docs.oracle.com/javase/8/docs/api/java/io/BufferedWriter.html
[FileOutputStream API Doc]: https://docs.oracle.com/javase/8/docs/api/java/io/FileOutputStream.html
[https_www.journaldev.com_881_java-append-to-file]: https://www.journaldev.com/881/java-append-to-file