@Slf4j
public class AppTest {
    @Test
    public void stringUtils(){
        String a = "  ";
        String b = null;
        //判断字符对象是否为空以及内容是否为空串(有空格则认为不是空串)
        log.info("StringUtils.isEmpty(a): {}", StringUtils.isEmpty(a));
        //判断字符对象是否为空以及内容是否为空串(有空格也会认为是空串)
        log.info("StringUtils.isBlank(a): {}", StringUtils.isBlank(a));
        //当b=null时，如果b.trim()则会报空指针异常，使用StringUtils.trim(b)可以避免
        log.info("StringUtils.trim(d): {}", StringUtils.trim(b));

        String num = "12.3";
        //当b=null时，如果b.trim()则会报空指针异常，使用StringUtils.trim(b)可以避免
        log.info("org.apache.commons.lang3.StringUtils.isNumericSpace(): {} isNumber: {}", num, StringUtils.isNumericSpace(b));
        log.info("com.alibaba.druid.util.StringUtils.isNumber(): {} isNumber: {}", num, com.alibaba.druid.util.StringUtils.isNumber(num));
    }
}

@Test
   public void dateFormatUtils() throws Exception{
       String pattern = "yyyy-MM-dd HH:mm:ss";
       String timeStr = DateFormatUtils.format(new Date(), pattern);
       long timestamp = DateUtils.parseDate(timeStr, pattern).getTime();
       log.info("==> current time: {}", timeStr);
       log.info("==> current time timestamp: {}", timestamp);
   }

@Test
   public void beanUtils() throws InvocationTargetException, IllegalAccessException {
       CompanyBean bean = new CompanyBean();
       bean.setId(1);
       bean.setName("中国移动广州分公司");
       bean.setAddress("广州市天河区中山大道");
       bean.setTel("020-10086000");
       CompanyBean destObj = new CompanyBean();
       //复制bean之间复制内容, 新对象destObj需要先实例化
       BeanUtils.copyProperties(destObj, bean);
       //ToStringBuilder类来自commons-lang3库：将对象内容转换成字符串输出，方便于日志输出
       log.info("destObj from BeanUtils.copyProperties: {}", ToStringBuilder.reflectionToString(destObj));
       
       Map<String, Object> map = new HashMap<>();
       map.put("id", 2);
       map.put("name", "中国联通广州分公司");
       map.put("address", "广州市天河区中山大道2号");
       map.put("tel", "020-10000110");
       //将map(key,value)映射成bean
       BeanUtils.populate(destObj, map);
       log.info("destObj from BeanUtils.populate: {}", 	ToStringBuilder.reflectionToString(destObj));
       //复制对象，与copyProperties()方法比较，这里新对象可以不先实例化
       CompanyBean cloneBean = (CompanyBean)BeanUtils.cloneBean(destObj);
       log.info("cloneBean from BeanUtils.cloneBean: {}", ToStringBuilder.reflectionToString(cloneBean));
       //将JavaBean转换成Map
       Map newMap = BeanUtils.describe(cloneBean);
       log.info("newMap from BeanUtils.describe: {}", new Gson().toJson(newMap));
   }

@Test
   public void ioUtils() throws IOException {
       InputStream io = this.getClass().getClassLoader().getResourceAsStream("README.md");
       BufferedReader br = new BufferedReader(new InputStreamReader(io));
       log.info("==> IOUtils.toString(br): {}", IOUtils.toString(br));
       IOUtils.closeQuietly(br);
       IOUtils.closeQuietly(io);
   }

package com.monbuilder.util;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import java.text.SimpleDateFormat;
/***
 * JSON转换工具类
 * @author <a href="mailto:lcbiao34@gmail.com">Builder34</a>
 * @date 2018-11-01 11:14:26
 * */
@Slf4j
public class JacksonUtil {
    private static ObjectMapper objectMapper = new ObjectMapper();
    static {
        objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
        objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
        objectMapper.configure(JsonParser.Feature.ALLOW_BACKSLASH_ESCAPING_ANY_CHARACTER, true);
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        // 设置输入时忽略JSON字符串中存在而Java对象实际没有的属性
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

        //设置不输出值为 null 的属性
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
    }
    /**
     * 将JSON字符串根据指定的Class反序列化成Java对象(转换过程中出现异常则返回null对象)
     *
     * @param json      JSON字符串
     * @param objClass JavaObject对象Class
     * @return 反序列化生成的Java对象
     * */
    public static <T> T toJavaObject(String json, Class<T> objClass) {
        try {
            return objectMapper.readValue(json, objClass);
        } catch (Exception e) {
            log.error("", e);
            return null;
        }
    }
    /**
     * 将Java对象序列化成JSON字符串(转换过程中出现异常则返回空对象json串"{}")
     *
     * @param obj 待序列化生成JSON字符串的Java对象
     * @return JSON字符串
     */
    public static String toJsonString(Object obj) {
        try {
            return objectMapper.writeValueAsString(obj);
        } catch (Exception e) {
            log.error("",e);
        }
        return "{}";
    }
}