Java IO的常用方法

文件复制

1 使用IO复制

public static void ioCopy(String pathIn,String pathOut) throws IOException {
    BufferedInputStream inputStream = new BufferedInputStream(new FileInputStream(pathIn));
    BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(pathOut));
    int len = 0;
    byte[] buffer = new byte[1024];
    while ((len = inputStream.read(buffer)) != -1) {
        outputStream.write(buffer,0,len);
    }
    inputStream.close();
    outputStream.close();
}

2 使用NIO复制

public static void channelCopy(String pathIn, String pathOut) throws IOException {
    FileChannel fcIn = new FileInputStream(pathIn).getChannel(),
            fcOut = new FileOutputStream(pathOut).getChannel();
    fcIn.transferTo(0, fcIn.size(), fcOut);
    fcIn.close();
    fcOut.close();
}

向文件中写入字符

1 用Writer向文件中写入字符串

/**
* @param content
* @param path
* @return void
* @desc 用Writer向文件中写入字符串
* @method stringToFileByWriter
* @author YulinChen
* @date 2020/2/13 20:12
*/
public static void stringToFileByWriter(String content, String path) throws IOException {
   PrintWriter writer = new PrintWriter(new File(path));
   writer.print(content);
   writer.close();
}

2 用Channel向文件中写入字符串

/**
* @param content
* @param path
* @return void
* @desc 用Channel向文件中写入字符串
* @method stringToFileByChannel
* @author YulinChen
* @date 2020/2/13 20:12
*/
public static void stringToFileByChannel(String content, String path) throws IOException {
   FileChannel channel = new FileOutputStream(path).getChannel();
   //FileChannel channel = new RandomAccessFile(path, "rw").getChannel();
   channel.write(ByteBuffer.wrap(content.getBytes("UTF-8")));
   channel.close();
}

从输入中获取字符串

1 从流中获取字符串

/**
* @param in 输入流
* @return java.lang.String
* @desc 从流中获取字符串
* @method getString
* @author YulinChen
* @date 2020/2/13 19:49
*/
public static String getString(InputStream in) throws IOException {
   BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));
   StringBuilder sb = new StringBuilder();
   for (String line = reader.readLine(); line != null; line = reader.readLine()) {
       sb.append(line).append("\n");
   }
   reader.close();
   return sb.toString();
}

2 从Channel中获取字符串

中文乱码，不推荐