按指定格式讀取/寫入檔案

關鍵：InputStreamReader(InputStream in, String charsetName)，OutputStreamWriter(OutputStream out, String charsetName)

通過InputStreamReader，OutputStreamWriter，我們可以指定輸入/輸出流的格式，從而進行檔案的格式轉換

 1 /**
 2      * 指定格式讀取GBK檔案/寫入UTF-8檔案
 3      */
 4 private static void characterIOCharsetTest() {
 5     String s = "./resources/dir1/dir11/123.txt";
 
 6     File f = new File(s);
 7     File f2 = new File("./resources/dir1/dir11/123-CharsetCopy.txt");
 8     StringBuilder sb = new StringBuilder();
 9 
10     //f是GBK格式檔案，所以以GBK格式的InputStreamReader讀取，再被BufferedReader包裝一層
11     try (BufferedReader gbkReader = new BufferedReader(new InputStreamReader(new FileInputStream(f), "GBK"));) {
 
12         String line;
13         while ((line = gbkReader.readLine()) != null) {
14             sb.append(line);
15             //因為line不包含最後的換行符，所以要手動加上去
16             sb.append("\n");
17         }
18     } catch (IOException e) {
19         e.printStackTrace();
20     }
21     //f2是目的檔案，以UTF-8格式儲存，所以以UTF-8格式的OutputStreamWriter寫入，被BufferedWriter包裝一層
 

22     try (BufferedWriter utf8Writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(f2), "UTF-8"))) {
23         utf8Writer.write(sb.toString());
24     } catch (IOException e) {
25         e.printStackTrace();
26     }
27 
28 }

整合版本

 1 /**
 2      * 整合版
 3      * 相當於將GBK格式的檔案轉換到UTF8格式的檔案
 4      */
 5 private static void characterIOCharsetTest2() {
 6     String s = "./resources/dir1/dir11/123.txt";
 7     File f = new File(s);
 8     File f2 = new File("./resources/dir1/dir11/123-CharsetCopy.txt");
 9     //f是GBK格式檔案，所以以GBK格式的InputStreamReader讀取，再被BufferedReader包裝一層
10     //f2是目的檔案，以UTF-8格式儲存，所以以UTF-8格式的OutputStreamWriter寫入，被BufferedWriter包裝一層
11     try (BufferedReader gbkReader = new BufferedReader(new InputStreamReader(new FileInputStream(f), "GBK"));
12          BufferedWriter utf8Writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(f2), "UTF-8"))) {
13         String line;
14         while ((line = gbkReader.readLine()) != null) {
15             //因為line不包含最後的換行符，所以要手動加上去
16             utf8Writer.write(line + "\n");
17         }
18     } catch (IOException e) {
19         e.printStackTrace();
20     }
21 }