在 Java 中为树结构构建一个 json

Question

我有 3 个类

• A类包含a_id , a_name
• B类包含b_id , b_name
• ClassC包含ClassA和ClassB的外键，即c_id , c_name , fk_a_id , fk_b_id

我想从ClassC创建一个树作为

a_name1        //.....parent
- b_name1
- b_name2
a_name2
- b_name1  //...... childs
- b_name2

我想要 JSON 作为

[  
{  
"id":a_id1,
"name":"a_name1",
"parent":0
},
{  
"id":b_id1",
"name":"b_name1",
"parent":a_id1
},
{  
"id":b_id1,
"name":"b_name2",
"parent":a_id1
},
{  
"id":a_id2,
"name":"a_name2",
"parent":0
},
{  
"id":b_id1,
"name":"b_name1",
"parent":a_id2
},
{  
"id":b_id1,
"name":"b_name2",
"parent":a_id2
}
]

如何使用 java 和休眠实现上述 json

我的研究

public List<ClassCTreeDto> unique() {
Session session= getSession();
Criteria crit = session.createCriteria(ClassC.class);

List<ClassCTreeDto> hierarchydto=new ArrayList<ClassCTreeDto>();
List<ClassC> cmList  = crit.list();
for(ClassCs :cmList){
ClassCTreeDto tDto= new ClassCTreeDto();
tDto.setId(s.getFkId().getId());
tDto.setName(s.getFkId().getIdName());
tDto.setParent(s.getFkId().getGradeId());
if(s.getFkId()==null)
{
tDto.setId((long) 0);
}
else
{
tDto.setId(s.getFkId().getGradeId());
}
hierarchydto.add(tDto);
}

return hierarchydto;
}

但是我正在获得 JSON 作为，

[{"id":1,"name":"X","parent":1},
{"id":1,"name":"X","parent":1},
{"id":2,"name":"IX","parent":2},
{"id":2,"name":"IX","parent":2}]

Answer 1

我刚刚解决了这个问题

public Set<ClassCTreeDto> unique() {
long parent = 0;
long div_id = 10;
List<ClassCTreeDto> treestructure = new ArrayList<ClassCTreeDto>();
List<ClassCTreeDto> treestructure2 = new ArrayList<ClassCTreeDto>();
Set<ClassCTreeDto> all = new HashSet<ClassCTreeDto>();
List<ClassC> list = getAll();
for (ClassC ClassC: list) {
ClassCTreeDto tree = new ClassCTreeDto();
tree.setParent(parent);
tree.setId(ClassC.getFkId().getId());
tree.setName(ClassC.getFkId().getIdName());
if (containsLocation(treestructure, tree.getIdName())) {
treestructure.remove(tree);
}
else {
treestructure.add(tree);
}
}
for (ClassC classC : list) {
ClassCTreeDto tree2 = new ClassCTreeDto ();
tree2.setParent(classC.getFkId().getId());
tree2.setId(div_id);
tree2.setName(classC.getFkDId().getDName());
treestructure2.add(tree2);
}
all.addAll(treestructure);
all.addAll(treestructure2);
return all;
}