morphia(3)-查询

1、查询所有

@Test
public void query() throws Exception {
    final Query<Employee> query = datastore.createQuery(Employee.class);
    final List<Employee> list = query.asList();
    list.forEach(e -> Console.log("{}", e));
}

输出：

Employee(id=5bcef23890c1d9280c07128e, name=小弟1, manager=null, directReports=[], salary=2000.0)
Employee(id=5bcef23890c1d9280c07128f, name=小弟2, manager=null, directReports=[], salary=3000.0)
Employee(id=5bcef23890c1d9280c071290, name=zuoys, manager=null, directReports=[Employee(id=5bcef23890c1d9280c07128e, name=小弟1, manager=null, directReports=[], salary=2000.0), Employee(id=5bcef23890c1d9280c07128f, name=小弟2, manager=null, directReports=[], salary=3000.0)], salary=10000.0)
Employee(id=5bcef45d90c1d91d509941cd, name=小弟3有父, manager=Employee(id=5bcef23890c1d9280c071290, name=zuoys, manager=null, directReports=[Employee(id=5bcef23890c1d9280c07128e, name=小弟1, manager=null, directReports=[], salary=2000.0), Employee(id=5bcef23890c1d9280c07128f, name=小弟2, manager=null, directReports=[], salary=3000.0)], salary=10000.0), directReports=[], salary=22.0)

使用asList()是可以的，但实际上，fetch()通常是更好的选择。

 2、条件过滤

//条件过滤-field
@Test
public void query2() throws Exception {
    List<Employee> list = datastore.createQuery(Employee.class)
            .field("salary").lessThanOrEq(22)
            .asList();
    list.forEach(e -> Console.log("{}", e));
}
//条件查询-filter
@Test
public void query3() throws Exception {
    List<Employee> list = datastore.createQuery(Employee.class)
            .filter("salary <=", 22)
            .asList();
    list.forEach(e -> Console.log("{}", e));
}

使用filter比fiele更简洁，但要注意语法。