MybatisPlus高级特性之SimpleQuery工具类

1、是很么？

SimpleQuery可以对selectList查询后的结果使用Stream流进行操作，使其可以返回指定的结果，简洁了api的调用

2、怎么玩？

案例演示

(1) list操作

/**
     * list(LambdaQueryWrapper<E> wrapper, SFunction<E, A> sFunction, Consumer<E>... peeks)
     * 参数说明：
     * param1 : 查询条件
     * param2 : SFunction类型的函数式接口；你想要做了操作
     */
    @Test
    public void testList1() {
        List<String> stringList = SimpleQuery.list(Wrappers.<Employee>lambdaQuery()
                .gt(Employee::getId, 1), Employee::getName);
        System.out.println("stringList = " + stringList);
    }

    /**
     * list(LambdaQueryWrapper<E> wrapper, SFunction<E, A> sFunction, boolean isParallel, Consumer<E>... peeks)
     * 参数说明：
     * param1 : 查询条件
     * param2 : SFunction类型的函数式接口；你想要做了操作
     * param3 : 是否并行操作
     * param4 : 转换后的后续流操作
     */
    @Test
    public void testList2() {
        List<String> stringList = SimpleQuery.list(Wrappers.<Employee>lambdaQuery()
                        .gt(Employee::getId, 1), Employee::getName,
                e -> Optional.of(e.getName()).map(String::toUpperCase).ifPresent(e::setName));
        System.out.println("stringList = " + stringList);
    }

(2) map操作

@Test
    public void testMap1(){
        Map<Integer, Employee> keyedMap = SimpleQuery.keyMap(Wrappers.<Employee>lambdaQuery()
                .gt(Employee::getId, 1), Employee::getId);
        System.out.println("keyedMap = " + keyedMap);
    }

    @Test
    public void testMap2(){
        Map<Integer, Employee> keyed = SimpleQuery.keyMap(Wrappers.<Employee>lambdaQuery()
                .gt(Employee::getId, 1), Employee::getId, Employee::getName);
        System.out.println("keyed = " + keyed);

(3) group操作

@Test
    public void testGroup(){
        Map<String, List<Employee>> map = SimpleQuery.group(Wrappers.<Employee>lambdaQuery()
                .gt(Employee::getId, 1), Employee::getSex);
        System.out.println("map = " + map);
    }