Java 使用POJO类在GreenDao中自定义类型
这是我的JSON示例:Java 使用POJO类在GreenDao中自定义类型,java,android,json,pojo,greendao,Java,Android,Json,Pojo,Greendao,这是我的JSON示例: { "open":true, "total_products":100, "product":[ { "p_id":1, "price":"5.00", "name":"blah one" }, { "p_id":2, "price":"15.00", "name":"blah two"
{
"open":true,
"total_products":100,
"product":[
{
"p_id":1,
"price":"5.00",
"name":"blah one"
},
{
"p_id":2,
"price":"15.00",
"name":"blah two"
},
...
]
}
这是我的POJO课程:
@Entity(nameInDb = "products")
public class ProductsPOJO {
@SerializedName("open")
@Property(nameInDb = "open")
private boolean open;
@SerializedName("total_products")
@Property(nameInDb = "total_products")
private Long total_products;
@Convert(converter = ProductConverter.class, columnType = String.class)
@SerializedName("product")
@Property(nameInDb = "product")
private Product product;
public static class productConverter implements PropertyConverter<Product, String> {
//What shoudl I write in convert part?!
@Override
public Product convertToEntityProperty(String databaseValue) {
if (databaseValue == null) {
return null;
}
for (Product p : Product.values()) {
if (p.id == databaseValue) {
return p;
}
}
return Product.DEFAULT;
}
@Override
public String convertToDatabaseValue(Product entityProperty) {
return entityProperty == null ? null : entityProperty.;
}
//
/*@Override
public Product convertToEntityProperty(String databaseValue) {
return Product.valueOf(databaseValue);
}
@Override
public String convertToDatabaseValue(Product entityProperty) {
return entityProperty.name();
}*/
}
public static class Product{
@Id
@SerializedName("p_id")
private Long p_id;
@SerializedName("price")
@Property(nameInDb = "price")
private String price;
@SerializedName("name")
@Property(nameInDb = "name")
private String name;
//Getters & Setters
}
public Product getProduct() {
return product;
}
public void setProduct(Product data) {
this.product = product;
}
//open & total_products Getters & Setters
}
但我不知道我应该为productConverter写些什么。
另一方面,Product类中的字段有多种类型。字符串和整数。
我读到:
编辑::/我在这里还混淆了两件事,GreenRobotObjectBox和greendao。。。很抱歉,但答案不变,只需将objectbox替换为greendao:
在我看来,你把GSON和ObjectBox GreenDao搞混了
您看起来像一个服务器响应者。但在数据库中,您通常只想保存产品实体,而不是答案。因此,最好只有一个ServerResultPOJO来用GSON解析您的答案,就像下面的代码没有经过测试,可能包含一些小错误,这只是为了让您走上正确的道路
public class ServerResultPOJO {
@SerializedName("open")
private boolean open;
@SerializedName("total_products")
private Long total_products;
@SerializedName("product")
private List<Product> products;
}
[Id最好不要将服务器Id用作数据库实体Id。请分别保存Id和服务器Id。自动递增和其他内容不会混淆]
然后,你不需要任何转换器,只需要一些方法将答案中的所有产品放入数据库-在放入新实体之前,你可以搜索p_id,以检查在放入之前是否需要同步到数据库
因此,首先解析您的答案,然后执行数据库操作
如果确实希望响应作为数据库实体,则需要一对多关系。但是,您不能使用相同的类进行实体和GSON解析,或者使用一些@transient字段,使事情变得更加复杂。这是因为
GSON应为BEGIN\u数组,但为BEGIN\u对象
应该这样做:
JsonParser parser = new JsonParser();
JsonObject rootObject = parser.parse(JSON_STRING).getAsJsonObject();
//You can get the "open" and "total_products" here too.//
JsonElement productElement = rootObject.get("product");
Gson gson = new Gson();
List<Product> productList = new ArrayList<>();
//Check if "data" element is an array or an object and parse accordingly...
if (productElement.isJsonObject()) {
//The returned list has only 1 element
Product p = gson.fromJson(productElement, Product.class);
productList.add(p);
}
else if (productElement.isJsonArray()) {
//The returned list has >1 elements
Type productListType = new TypeToken<List<Product>>() {}.getType();
productList = gson.fromJson(productElement, productListType);
}
[来源:]
JsonParser parser = new JsonParser();
JsonObject rootObject = parser.parse(JSON_STRING).getAsJsonObject();
//You can get the "open" and "total_products" here too.//
JsonElement productElement = rootObject.get("product");
Gson gson = new Gson();
List<Product> productList = new ArrayList<>();
//Check if "data" element is an array or an object and parse accordingly...
if (productElement.isJsonObject()) {
//The returned list has only 1 element
Product p = gson.fromJson(productElement, Product.class);
productList.add(p);
}
else if (productElement.isJsonArray()) {
//The returned list has >1 elements
Type productListType = new TypeToken<List<Product>>() {}.getType();
productList = gson.fromJson(productElement, productListType);
}