0 常用代码段 代码块 daima

1 集合快速分组

List<List<EcontResourcesDto>> partition = com.google.common.collect.Lists.partition(list, 20);
集合快速拆分；  每组20调数据
guava的依赖
<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>28.0-jre</version>
</dependency>

2 方法返回两个返回值

<dependency> 
   <groupId>org.apache.commons</groupId>
   <artifactId>commons-lang3</artifactId>
   <version>3.11</version>
</dependency>
MutablePair<String, String> mutablePair = MutablePair.of("1", "第二个值");
System.out.println(mutablePair.getLeft() + "，" + mutablePair.getRight());

3 方法返回三个返回值

<dependency> 
   <groupId>org.apache.commons</groupId>
   <artifactId>commons-lang3</artifactId>
   <version>3.11</version>
</dependency>
MutableTriple<Integer, String, Date> mutableTriple = MutableTriple.of(2, "中间值", new Date());
System.out.println(mutableTriple.getLeft() + "，" + mutableTriple.getMiddle() + "，" + mutableTriple.getRight());

4 事物方法模拟回退、回滚、异常

 // // binc_rollback 实验代码稍后删除  模拟这里发生异常，看看能否回退
            int i  = 1;
            int j = 1;
            if (i-j == 0){
                throw BusinessRtException.of("------------------------------------------------------" +
                        "---------------------------------------------------------------------------------" +
                        "-----------------------------------模拟发生异常，强制数据库执行回退---------------------------------------------" +
                        "---------------------------------------------------------------------------------" +
                        "--------------------------------------------------------------");
            }

5 mapper.xml 默认值问题

            <if test="item.state != null">
                #{state} ,
            </if>
            <if test="item.state == null">
                1 ,
            </if>

6 string 一些操作

StringUtils.hasText(字符串) 里面的值为  null  、""   、 "  "，

那么返回值为false，否则为true

7 option

            accountsRefundDto.setTradeStatus(Optional.ofNullable(accountVo).map(o -> Optional.ofNullable(o.getPayStatus()).orElse(FundAccountFlowConstants.TRADE_STATUS_FAIL)).orElse(FundAccountFlowConstants.TRADE_STATUS_FAIL));


data.stream()
    .filter(d -> Objects.equals(d.getOrgLevelId(), f.getBranchId()))
    .findFirst()
    .ifPresent(p -> {
        f.setBranchName(p.getOrgLevelName());
    });