WAREAMS/warewms-base/src/main/java/com/ruoyi/base/utils/CommonUtils.java

package com.ruoyi.base.utils;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.*;
import java.util.stream.Collectors;

/**
 * Created by IntelliJ IDEA.
 * User: andy.qu
 * Date: 2019/11/14
 */
public class CommonUtils {

    //转变的依赖字符
    public static final char UNDERLINE = '_';

    /**
     * 文件下载
     *
     * @param file
     * @param res
     * @throws IOException
     */
    public static void download(File file, HttpServletResponse res) throws IOException {
        // 发送给客户端的数据
        OutputStream outputStream = res.getOutputStream();
        byte[] buff = new byte[1024];
        BufferedInputStream bis = null;
        // 读取filename
        bis = new BufferedInputStream(new FileInputStream(file));
        int i = bis.read(buff);
        while (i != -1) {
            outputStream.write(buff, 0, buff.length);
            outputStream.flush();
            i = bis.read(buff);
        }
    }

    /**
     * 文件下载
     *
     * @param inputStream
     * @param res
     * @throws IOException
     */
    public static void download(InputStream inputStream, HttpServletResponse res) throws IOException {
        // 发送给客户端的数据
        OutputStream outputStream = res.getOutputStream();
        byte[] buff = new byte[1024];
        BufferedInputStream bis = null;
        // 读取filename
        bis = new BufferedInputStream(inputStream);
        int i = bis.read(buff);
        while (i != -1) {
            outputStream.write(buff, 0, buff.length);
            outputStream.flush();
            i = bis.read(buff);
        }
    }

    /**
     * 对象字符串转换null判断
     *
     * @return
     */
    public static String objectStringConvert(Object object) {
        return object == null ? "" : object.toString();
    }

    public static String getString(String string) {
        if (string == null) {
            return "";
        } else {
            return string;
        }
    }

    /**
     * 检查是否为Int
     *
     * @param value    值
     * @param fildName 提示字段名称
     * @return
     */
    public static void checkInt(String value, String fildName) {
        try {
            Integer i = Integer.parseInt(value);
        } catch (Exception e) {
            throw new RuntimeException(fildName + "必须是整数");
        }
    }

    /**
     * 对象转map
     *
     * @param obj
     * @return
     */
    public static Map<String, String> objToMap(Object obj) {
        if (obj == null) {
            return null;
        }
        JSONObject jsonObj = (JSONObject) JSON.toJSON(obj);
        Map<String, String> map = JSONObject.parseObject(jsonObj.toJSONString(), new TypeReference<Map<String, String>>() {
        });
        return map;
    }

    /**
     * 将驼峰转换成"_"(userId:user_id)
     *
     * @param param
     * @return
     */
    public static String camelToUnderline(String param) {
        if (param == null || "".equals(param.trim())) {
            return "";
        }
        int len = param.length();
        StringBuilder sb = new StringBuilder(len);
        for (int i = 0; i < len; i++) {
            char c = param.charAt(i);
            if (Character.isUpperCase(c)) {
                sb.append(UNDERLINE);
                sb.append(Character.toLowerCase(c));
            } else {
                sb.append(c);
            }
        }
        return sb.toString();
    }

    /**
     * 将"_"转成驼峰(user_id:userId)
     *
     * @param param
     * @return
     */
    public static String underlineToCamel(String param) {
        if (param == null || "".equals(param.trim())) {
            return "";
        }
        int len = param.length();
        StringBuilder sb = new StringBuilder(len);
        for (int i = 0; i < len; i++) {
            char c = param.charAt(i);
            if (c == UNDERLINE) {
                if (++i < len) {
                    sb.append(Character.toUpperCase(param.charAt(i)));
                }
            } else {
                sb.append(c);
            }
        }
        return sb.toString();
    }

    public static String lpad(String s, int n, String replace) {
        while (s.length() < n) {
            s = replace + s;
        }
        return s;
    }

    public static void main(String[] args) {

        //String pwd = RandomUtil.randomNumbers(6);

        //System.out.println(DigestUtils.sha256Hex("583817"));
        List<Map<String, Object>> arr = new ArrayList<>();
        Map<String, Object> map1 = new HashMap<>();
        map1.put("key", "123");
        map1.put("value", "1");
        arr.add(map1);
        List<Object> map = arr.stream().map(e -> e.put("key", "")).collect(Collectors.toList());
        System.out.println(JSON.toJSONString(map));
        //System.out.println(StringUtils.join(arr,","));

    }
}