代码写法：
1 import java.io.BufferedInputStream; 2 import java.io.BufferedOutputStream; 3 import java.io.ByteArrayInputStream; 4 import java.io.ByteArrayOutputStream; 5 import java.io.File; 6 import java.io.FileInputStream; 7 import java.io.FileOutputStream; 8 import java.io.IOException; 9 import java.io.InputStream; 10 import java.io.OutputStream; 11 import java.io.Reader; 12 import java.io.StringWriter; 13 import java.io.Writer; 14 15 /** 16 * 用于文件和流复制的简单实用方法。所有复制方法使用4096字节的块大小，并在完成后关闭所有受影响的流。 17 */ 18 public abstract class FileCopyUtils { 19 20 public static final int BUFFER_SIZE = 4096; 21 /** 22 * 将给定输入文件的内容复制到给定的输出文件。 23 * @param 要复制的文件 24 * @param 将文件复制到 25 * @return 复制的字节数 26 * @throws I / O错误时发生IOException 27 */ 28 public static int copy(File in, File out) throws IOException { 29 return copy(new BufferedInputStream(new FileInputStream(in)), 30 new BufferedOutputStream(new FileOutputStream(out))); 31 } 32 33 /** 34 * 将给定字节数组的内容复制到给定的输出文件。 35 * @param 要从中复制的字节数组 36 * @param 将文件复制到 37 * @throws I / O错误时发生IOException 38 */ 39 public static void copy(byte[] in, File out) throws IOException { 40 ByteArrayInputStream inStream = new ByteArrayInputStream(in); 41 OutputStream outStream = new BufferedOutputStream(new FileOutputStream(out)); 42 copy(inStream, outStream); 43 } 44 45 /** 46 * 将给定输入文件的内容复制到新的字节数组中。 47 * @param 要复制的文件 48 * @return 已复制到的新字节数组 49 * @throws I / O错误时发生IOException 50 */ 51 public static byte[] copyToByteArray(File in) throws IOException { 52 return copyToByteArray(new BufferedInputStream(new FileInputStream(in))); 53 } 54 /** 55 * 将给定InputStream的内容复制到给定的OutputStream。完成后关闭两个流。 56 * @param 复制到 57 * @return 复制的字节数 58 * @throws I / O错误时发生IOException 59 */ 60 public static int copy(InputStream in, OutputStream out) throws IOException { 61 try { 62 int byteCount = 0; 63 byte[] buffer = new byte[BUFFER_SIZE]; 64 int bytesRead = -1; 65 while ((bytesRead = in.read(buffer)) != -1) { 66 out.write(buffer, 0, bytesRead); 67 byteCount += bytesRead; 68 } 69 out.flush(); 70 return byteCount; 71 } 72 finally { 73 try { 74 in.close(); 75 } 76 catch (IOException ex) { 77 } 78 try { 79 out.close(); 80 } 81 catch (IOException ex) { 82 } 83 } 84 } 85 86 /** 87 * 将给定字节数组的内容复制到给定的OutputStream。完成后关闭流。 88 * @param 要复制的字节数组 89 * @param 输出要复制到的输出流 90 * @throws I / O错误时发生IOException 91 */ 92 public static void copy(byte[] in, OutputStream out) throws IOException { 93 try { 94 out.write(in); 95 } 96 finally { 97 try { 98 out.close(); 99 } 100 catch (IOException ex) { 101 } 102 } 103 } 104 105 /** 106 * 将给定输入流的内容复制到新的字节数组中，完成后关闭流。 107 * @return 已复制到的新字节数组 108 * @throws I / O错误时发生IOException 109 */ 110 public static byte[] copyToByteArray(InputStream in) throws IOException { 111 ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE); 112 copy(in, out); 113 return out.toByteArray(); 114 } 115 116 /*java.io.reader/java.io.writer的复制方法*/ 117 118 /** 119 * 将给定读者的内容复制到给定的作者,完成后都关闭。 120 */ 121 public static int copy(Reader in, Writer out) throws IOException { 122 try { 123 int byteCount = 0; 124 char[] buffer = new char[BUFFER_SIZE]; 125 int bytesRead = -1; 126 while ((bytesRead = in.read(buffer)) != -1) { 127 out.write(buffer, 0, bytesRead); 128 byteCount += bytesRead; 129 } 130 out.flush(); 131 return byteCount; 132 } 133 finally { 134 try { 135 in.close(); 136 } 137 catch (IOException ex) { 138 } 139 try { 140 out.close(); 141 } 142 catch (IOException ex) { 143 } 144 } 145 } 146 147 /** 148 * 将给定String的内容复制到给定的输出Writer。完成后关闭写入。 149 */ 150 public static void copy(String in, Writer out) throws IOException { 151 try { 152 out.write(in); 153 } 154 finally { 155 try { 156 out.close(); 157 } 158 catch (IOException ex) { 159 } 160 } 161 } 162 163 /** 164 * 将给定Reader的内容复制到String中。完成后关闭读取。 165 */ 166 public static String copyToString(Reader in) throws IOException { 167 StringWriter out = new StringWriter(); 168 copy(in, out); 169 return out.toString(); 170 } 171 172 }