File类的总结：
1.文件和文件夹的创建
2.文件的读取
3.文件的写入
4.文件的复制（字符流、字节流、处理流）
5.以图片地址下载图片
文件和文件夹
相关函数
(boolean) mkdir() 创建此抽象路径名指定的目录
(boolean) mkdirs() 创建此抽象路径名指定的目录，包括所有必需但不存在的父目录。
(boolean) delete() 删除此抽象路径名表示的文件或目录
(boolean) createNewFile() 当不存在此路径名指定名称的文件时，创建一个新的空文件。
(boolean) mkdirs() 创建此抽象路径名指定的目录，包括所有必需但不存在的父目录。
(boolean) delete() 删除此抽象路径名表示的文件或目录
(boolean) createNewFile() 当不存在此路径名指定名称的文件时，创建一个新的空文件。
创建文件
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public static void NewFile(String pathString) { File file = new File(pathString); if (!file.exists()) { try { if (file.createNewFile()) { System.out.println("文件创建成功"); } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } else { System.out.println("文件已存在"); }} |
创建文件夹
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public static void NewFileBox(String pathString) { File file2 = new File(pathString); if (!file2.exists()) { if (file2.mkdirs()) { System.out.println("文件夹成功"); } } else { System.out.println("文件夹存在"); file2.delete();//销毁文件 }} |
应用：
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public static void main(String[] args) { NewFile("test/file.txt"); NewFileBox("test/a/a/a/a");} |
Writer写入文件
用FileWriter写入文件
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public static void ForFileWriter(String string,String fileName) { File file = new File(fileName); try { FileWriter fWriter = new FileWriter(file); fWriter.write(string); fWriter.close(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); }} |
用BufferedWriter写入文件
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public static void ForBufferedWriter(String string,String desFile) { BufferedWriter bWriter = null; try { bWriter = new BufferedWriter(new FileWriter(new File(desFile))); bWriter.write(string.toString()); bWriter.close(); } catch (Exception e) { e.printStackTrace(); }} |
应用：
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public static void main(String[] args) { ForFileWriter("用FileWriter写入文件", "test/writer1.txt"); ForBufferedWriter("用BufferedWriter写入文件", "test/writer2.txt");} |
Reader读取文件
用FileReader读取文件
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public static void testReadByReader(String fileName){ File file = new File(fileName); FileReader fis = null; try { fis = new FileReader(file); char[] arr = new char[1024 * 1000 * 6]; int len = fis.read(arr); String data = new String(arr, 0, len); fis.close(); System.out.println(fileName+"中按FileReader读取的文件内容是：
"+data); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }} |
用FileInputStream读取文件
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public static void testReadByInputStream(String fileName){ File file = new File(fileName); FileInputStream fis = null; try { fis = new FileInputStream(file); byte[] arr = new byte[1024 * 1000 * 6]; int len = fis.read(arr); String data = new String(arr, 0, len); fis.close(); System.out.println(fileName+"中按FileInputStream读取的文件内容是：
"+data); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }} |
用BufferedReader读取文件
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public static void testReadByBufferedReader(String fileName) { BufferedReader bReader = null; String line = null; StringBuffer buffer = new StringBuffer(); try { bReader =new BufferedReader(new FileReader(new File(fileName))); while ((line = bReader.readLine())!=null) { buffer.append(line).append("
"); } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } System.out.println(fileName+"中按BufferedReader读取的文件内容是：
"+buffer.toString());} |
应用：
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public static void main(String[] args) { testReadByInputStream("res/我.txt"); testReadByReader("res/我.txt"); testReadByBufferedReader("res/我.txt");} |
文件的复制操作
字符流复制
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public static void FileCopy1(String readfile,String writeFile) { try { FileReader input = new FileReader(readfile); FileWriter output = new FileWriter(writeFile); int read = input.read(); while ( read != -1 ) { output.write(read); read = input.read(); } input.close(); output.close(); } catch (IOException e) { System.out.println(e); }} |
字节流复制
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public static void FileCopy2(String readfile,String writeFile) { try { FileInputStream input = new FileInputStream(readfile); FileOutputStream output = new FileOutputStream(writeFile); int read = input.read(); while ( read != -1 ) { output.write(read); read = input.read(); } input.close(); output.close(); } catch (IOException e) { System.out.println(e); }} |
处理流复制
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public static void FileCopy3(String readfile,String writeFile) { BufferedReader bReader = null; BufferedWriter bWriter = null; String line = null; try { bReader = new BufferedReader(new FileReader(new File(readfile))); bWriter = new BufferedWriter(new FileWriter(new File(writeFile))); while ((line = bReader.readLine())!=null) { bWriter.write(line); bWriter.newLine(); } bWriter.close(); bReader.close(); } catch (Exception e) { // TODO: handle exception e.printStackTrace(); }} |
应用：
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public static void main(String[] args) { FileCopy1("res/我.txt", "test/1.txt"); FileCopy2("res/我.txt", "test/2.txt"); FileCopy3("res/我.txt", "test/3.txt"); FileCopy2("res/me.jpg", "test/33.jpg");} |