创新实训——工具类：代码优化

1.简介  

合理地将重复使用的方法抽离出来，并放到工具类里会有效的优化代码结构，使代码更简洁。

2.一些工具类和常用的方法

public class ToolUtil {
    //关闭继承自AutoCloseable的流
    public static void closeQuietly(@NotNull AutoCloseable... closeable) {
        for (int i = 0; i < closeable.length; i++) {
            try {
                closeable.clone();
            } catch (Exception e) {
                //ignore
            }
        }
    }
    //将字符串写入到response中
    public static void responseJson(HttpServletResponse response, String str) {
        PrintWriter pw = null;
        try {
            pw = response.getWriter();
            pw.write(str);
            pw.flush();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (pw != null) {
                pw.close();
            }
        }
    }
    //设置request和response的编码，避免出现中文乱码
    public static void setEncode(HttpServletRequest request, HttpServletResponse response) {
        try {
            request.setCharacterEncoding("UTF-8");
            response.setContentType("application/json;charset=UTF-8");
            response.setCharacterEncoding("UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }
}

public class CmdUtil {
    //执行linux命令行
    public static boolean exec(String cmd) {
        try {
            Runtime.getRuntime().exec(new String[]{"/bin/sh", "-c", cmd}).destroy();
            return true;
        } catch (IOException e) {
            return false;
        }
    }
    //执行linux命令行，并返回输出结果
    public static List<String> execWithOutput(String cmd) {
        List<String> list = null;
        try {
            Process process = Runtime.getRuntime().exec(new String[]{"/bin/sh", "-c", cmd});
            InputStream in = process.getInputStream();
            BufferedReader bs = new BufferedReader(new InputStreamReader(in));
            list = new ArrayList<>();
            String result;
            while ((result = bs.readLine()) != null) {
                list.add(result);
            }
            in.close();
            process.destroy();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            return list;
        }
    }
}

public class ImageUtil {

    /**
     * 上传文件到七牛云服务器
     *
     * @param imgPath 图片的存储路径
     * @return 图片的url
     */
    public static String uploadImage(String imgPath) {
        Auth auth = Auth.create(BaseConsts.ACCESS_KEY, BaseConsts.SECRET_KEY);
        String token = auth.uploadToken(BaseConsts.BUCKET);

        Configuration configuration = new Configuration(Zone.autoZone());
        UploadManager manager = new UploadManager(configuration);
        try {
            Response response = manager.put(imgPath, null, token);
            DefaultPutRet putRet = new Gson().fromJson(response.bodyString(), DefaultPutRet.class);
            return BaseConsts.BASE_IMG_URL + putRet.hash;
        } catch (QiniuException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 下载图片
     *
     * @param url     图片的url
     * @param imgPath 指定图片的存储路径
     */
    public static void downloadImage(String url, String imgPath) {
        try {
            URL url1 = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) url1.openConnection();
            connection.setRequestMethod("GET");
            connection.connect();
            int responseCode = connection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                InputStream is = connection.getInputStream();
                OutputStream os = new FileOutputStream(imgPath);
                byte[] bytes = new byte[1024 * 128];
                int len;
                while ((len = is.read(bytes)) != -1) {
                    os.write(bytes, 0, len);
                }
            }
            System.out.println("responseCode is "+responseCode+"\n"
                +"url is "+url);
        } catch (Exception e) {
            e.printStackTrace();
        }finally {

        }
    }
}