Spring中常用的IO工具类的学习

    在项目中如果有文件拷贝，读取等操作，如果项目中采用了Spring可以使用Spring的文件操作工具类FileCopyUtils ，如果没有引入Spring也好，如果项目中引入Commons-IOs可以采用文件操作类FileCopyUtils ，功能更多更强大。

  如果两者均没有引入，个人认为最好将Spring中的中FileCopyUtils 拷贝到项目中简单省事。

    在spring中的FileCopyUtils 和Apache的Commons-IO中的方法比较相似，功能相同，但是Spring中的FileCopyUtils 不是采用Commons-IO中文件操作类。spring采用JAVA JDK中IO自己定义的类并且不依赖他类Spring类。

 

public abstract class FileCopyUtils {

 public static final int BUFFER_SIZE = 4096;

 //---------------------------------------------------------------------
 // Copy methods for java.io.File
 //---------------------------------------------------------------------

 /**
  * Copy the contents of the given input File to the given output File.
  * @param in the file to copy from
  * @param out the file to copy to
  * @return the number of bytes copied
  * @throws IOException in case of I/O errors
  */
 public static int copy(File in, File out) throws IOException {
  Assert.notNull(in, "No input File specified");
  Assert.notNull(out, "No output File specified");
  return copy(new BufferedInputStream(new FileInputStream(in)),
      new BufferedOutputStream(new FileOutputStream(out)));
 }

 /**
  * Copy the contents of the given byte array to the given output File.
  * @param in the byte array to copy from
  * @param out the file to copy to
  * @throws IOException in case of I/O errors
  */
 public static void copy(byte[] in, File out) throws IOException {
  Assert.notNull(in, "No input byte array specified");
  Assert.notNull(out, "No output File specified");
  ByteArrayInputStream inStream = new ByteArrayInputStream(in);
  OutputStream outStream = new BufferedOutputStream(new FileOutputStream(out));
  copy(inStream, outStream);
 }

 /**
  * Copy the contents of the given input File into a new byte array.
  * @param in the file to copy from
  * @return the new byte array that has been copied to
  * @throws IOException in case of I/O errors
  */
 public static byte[] copyToByteArray(File in) throws IOException {
  Assert.notNull(in, "No input File specified");
  return copyToByteArray(new BufferedInputStream(new FileInputStream(in)));
 }

 //---------------------------------------------------------------------
 // Copy methods for java.io.InputStream / java.io.OutputStream
 //---------------------------------------------------------------------

 /**
  * Copy the contents of the given InputStream to the given OutputStream.
  * Closes both streams when done.
  * @param in the stream to copy from
  * @param out the stream to copy to
  * @return the number of bytes copied
  * @throws IOException in case of I/O errors
  */
 public static int copy(InputStream in, OutputStream out) throws IOException {
  Assert.notNull(in, "No InputStream specified");
  Assert.notNull(out, "No OutputStream specified");
  try {
   int byteCount = 0;
   byte[] buffer = new byte[BUFFER_SIZE];
   int bytesRead = -1;
   while ((bytesRead = in.read(buffer)) != -1) {
    out.write(buffer, 0, bytesRead);
    byteCount += bytesRead;
   }
   out.flush();
   return byteCount;
  }
  finally {
   try {
    in.close();
   }
   catch (IOException ex) {
   }
   try {
    out.close();
   }
   catch (IOException ex) {
   }
  }
 }

 /**
  * Copy the contents of the given byte array to the given OutputStream.
  * Closes the stream when done.
  * @param in the byte array to copy from
  * @param out the OutputStream to copy to
  * @throws IOException in case of I/O errors
  */
 public static void copy(byte[] in, OutputStream out) throws IOException {
  Assert.notNull(in, "No input byte array specified");
  Assert.notNull(out, "No OutputStream specified");
  try {
   out.write(in);
  }
  finally {
   try {
    out.close();
   }
   catch (IOException ex) {
   }
  }
 }

 /**
  * Copy the contents of the given InputStream into a new byte array.
  * Closes the stream when done.
  * @param in the stream to copy from
  * @return the new byte array that has been copied to
  * @throws IOException in case of I/O errors
  */
 public static byte[] copyToByteArray(InputStream in) throws IOException {
  ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE);
  copy(in, out);
  return out.toByteArray();
 }

 //---------------------------------------------------------------------
 // Copy methods for java.io.Reader / java.io.Writer
 //---------------------------------------------------------------------

 /**
  * Copy the contents of the given Reader to the given Writer.
  * Closes both when done.
  * @param in the Reader to copy from
  * @param out the Writer to copy to
  * @return the number of characters copied
  * @throws IOException in case of I/O errors
  */
 public static int copy(Reader in, Writer out) throws IOException {
  Assert.notNull(in, "No Reader specified");
  Assert.notNull(out, "No Writer specified");
  try {
   int byteCount = 0;
   char[] buffer = new char[BUFFER_SIZE];
   int bytesRead = -1;
   while ((bytesRead = in.read(buffer)) != -1) {
    out.write(buffer, 0, bytesRead);
    byteCount += bytesRead;
   }
   out.flush();
   return byteCount;
  }
  finally {
   try {
    in.close();
   }
   catch (IOException ex) {
   }
   try {
    out.close();
   }
   catch (IOException ex) {
   }
  }
 }

 /**
  * Copy the contents of the given String to the given output Writer.
  * Closes the write when done.
  * @param in the String to copy from
  * @param out the Writer to copy to
  * @throws IOException in case of I/O errors
  */
 public static void copy(String in, Writer out) throws IOException {
  Assert.notNull(in, "No input String specified");
  Assert.notNull(out, "No Writer specified");
  try {
   out.write(in);
  }
  finally {
   try {
    out.close();
   }
   catch (IOException ex) {
   }
  }
 }

 /**
  * Copy the contents of the given Reader into a String.
  * Closes the reader when done.
  * @param in the reader to copy from
  * @return the String that has been copied to
  * @throws IOException in case of I/O errors
  */
 public static String copyToString(Reader in) throws IOException {
  StringWriter out = new StringWriter();
  copy(in, out);
  return out.toString();
 }

}