Java之FileReader和FileWriter操作文本文件

╰+攻爆jí腚メ 2022-04-25 05:08 192阅读 0赞

## 直接说重点！ ##

FileReader和FileWriter只能应用于文本文件，对于非文本文件只能使用字节流！

![20190501213929618.png][]

### 标准姿势1！读取文本文件内容 ###

private static final String pathname = "./src/IOStream/HelloWorld.txt";
    
        public static void testFileReader() {
            File file = new File(pathname);
            FileReader fr = null;
    
            char[] readStr = new char[26];
            int len;
    
            try {
                fr = new FileReader(file);
                while ((len = fr.read(readStr)) != -1) {
                    String str = new String(readStr, 0, len);
                    System.out.print(str);
                }
    
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (fr != null) {
                    try {
                        fr.close();
                        System.out.println("Complete!");
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
    
        }

### 标准姿势2！实现文件的读取和写入（实现文件复制） ###

private static void testFileCopy(String file, String dest) {
            if (file.equals("")) {
                System.out.println("需要复制的文件参数为空");
            } else if (dest.equals("")) {
                System.out.println("目标文件名为空");
            } else {
                FileReader fr = null;
                FileWriter fw = null;
                try {
                    char[] readStr = new char[26];
                    int len;
                    fr = new FileReader(file);
                    fw = new FileWriter(dest);
                    while ((len = fr.read(readStr)) != -1) {
                        fw.write(readStr,0,len);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if (fr != null) {
                        try {
                            fr.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fw != null) {
                        try {
                            fw.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    System.out.println("Complete!");
                }
            }
    
        }
    
    
        public static void main(String[] args) {
            String file = "./src/IOStream/HelloWorld.txt";
            String dest = "./src/IOStream/HelloWorld2.txt";
            testFileCopy(file, dest);
        }

[20190501213929618.png]: /images/20220210/edbae60626f74cacab5b1a9f719ec58e.png