java文本文件按行读取，然后每一行写入一个文件

步骤

1. 判断文本文件编码（避免乱码）
2. 读取文本文件
3. 写入

判断文本文件编码

public static void main(String[] args) throws IOException {
        BufferedInputStream bin = new BufferedInputStream(new FileInputStream("D:\\hanlp\\情感分析\\正向\\pos60000.txt"));
        int p = (bin.read() << 8) +bin.read();

        String code = null;

        switch (p) {
            case 0xefbb:
                code = "UTF-8";
                break;
            case 0xfffe:
                code = "Unicode";
                break;
            case 0xfeff:
                code = "UTF-16BE";
                break;
            default:
                code = "GBK";
        }
        System.out.println(code);
    }

读取文本文件

        try {
            InputStreamReader isr = new InputStreamReader(new FileInputStream("D:\\hanlp\\情感分析\\正向\\pos60000.txt"),"GBK");
            BufferedReader br = new BufferedReader(isr);
            String temp = null;
            while((temp = br.readLine()) != null){
                System.out.println(temp);
            }
            br.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

        }catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

读取加写入

public static void main(String[] args) throws IOException {
        FileWriter fwriter = null;
        String fileRootPath = "D:\\hanlp\\情感分析\\负向\\";
        try {
            InputStreamReader isr = new InputStreamReader(new FileInputStream("D:\\hanlp\\情感分析\\负向\\neg60000.txt"),"GBK");
            BufferedReader br = new BufferedReader(isr);

            StringBuffer sb = new StringBuffer();
            String temp = null;
            int i=1;
            while((temp = br.readLine()) != null){
                String filePath = fileRootPath+i+".txt";
                i++;
                try {
                    fwriter = new FileWriter(filePath);
                    fwriter.write(temp);
                } catch (IOException ex) {
                    ex.printStackTrace();
                } finally {
                    try {
                        fwriter.flush();
                        fwriter.close();
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }
            }
            br.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

        }catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

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参考：https://www.iteye.com/blog/herestay-1782903
参考：https://www.cnblogs.com/qyy1207/p/10255363.html