springMvc 將物件json返回時自動忽略掉物件中的特定屬性的註解方式
阿新 • • 發佈:2019-01-02
1.註解使用在 類名,介面頭上
@JsonIgnoreProperties(value={"comid"}) //希望動態過濾掉的屬性
例
@JsonIgnoreProperties(value={"comid"})
public interface CompanyFilter{
}
2。該註解使用在get方法頭上
@JsonIgnore
例
@JsonIgnore public Integer getPageSize(){ return Integer.valueOf(getRows()==null?"0":getRows().toString()); }
-------------------------------
- Jackson’s
@JsonView
is supported directly on@ResponseBody
andResponseEntity
controller methods for serializing different amounts of detail for the same POJO (e.g. summary vs. detail page). This is also supported with View-based rendering by adding the serialization view type as a model attribute under a special key. See
@RestController public class UserController { @RequestMapping(path = "/user", method = RequestMethod.GET) @JsonView(User.WithoutPasswordView.class) public User getUser() { return new User("eric", "7!jd#h23"); } }
public class User {
public interface WithoutPasswordView {};
public interface WithPasswordView extends WithoutPasswordView {};
private String username;
private String password;
public User() {
}
public User(String username, String password) {
this.username = username;
this.password = password;
}
@JsonView(WithoutPasswordView.class)
public String getUsername() {
return this.username;
}
@JsonView(WithPasswordView.class)
public String getPassword() {
return this.password;
}
}
---------- 然後在把他加入到model的過程 可以這麼寫
@Controller
public class UserController extends AbstractController {
@RequestMapping(path = "/user", method = RequestMethod.GET)
public String getUser(Model model) {
model.addAttribute("user", new User("eric", "7!jd#h23"));
model.addAttribute(JsonView.class.getName(), User.WithoutPasswordView.class);
return "userView";
}
}
------ 下面是測試
public static void main(String[] args) throws IOException {
ObjectMapper objectMapper = new ObjectMapper();
//建立物件
User user = new User("user1","123456");
//序列化
ByteArrayOutputStream bos = new ByteArrayOutputStream();
objectMapper.writerWithView(User.WithoutPasswordView.class).writeValue(bos, user);
System.out.println(bos.toString());
bos.reset();
objectMapper.writerWithView(User.WithPasswordView.class).writeValue(bos, user);
System.out.println(bos.toString());
}
輸出的答案是
{"username":"user1"}
{"username":"user1","password":"123456"}
------ 當然spring也有提供基於xml的配置方法,詳情看文件的內容 http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#mvc-ann-jsonview 也有人用aop的around中去過濾結果. ------------------------------- gson 版本
GSON 是Google釋出的 JSON 序列化/反序列化工具,非常容易使用。本文簡要討論在使用GSON將Java物件轉成JSON時,如何排除某些欄位。
最簡單的用法
假設有下面這個類:
class MyObj {
public int x;
public int y;
public MyObj(int x, int y) {
this.x = x;
this.y = y;
}
}
最簡單的GSON用法如下所示:
@Test
public void gson() {
MyObj obj = new MyObj(1, 2);
String json = new Gson().toJson(obj);
Assert.assertEquals("{\"x\":1,\"y\":2}", json);
}
方法1:排除transient欄位
這個方法最簡單,給欄位加上 transient 修飾符就可以了,如下所示:
class MyObj {
public transient int x; // <---
public int y;
public MyObj(int x, int y) {
this.x = x;
this.y = y;
}
}
@Test
public void gson() {
MyObj obj = new MyObj(1, 2);
String json = new Gson().toJson(obj);
Assert.assertEquals("{\"y\":2}", json); // <---
}
方法2:排除Modifier為指定型別的欄位
這個方法需要用GsonBuilder定製一個GSON例項,如下所示:
class MyObj {
protected int x; // <---
public int y;
public MyObj(int x, int y) {
this.x = x;
this.y = y;
}
}
@Test
public void gson() {
Gson gson = new GsonBuilder()
.excludeFieldsWithModifiers(Modifier.PROTECTED) // <---
.create();
MyObj obj = new MyObj(1, 2);
String json = gson.toJson(obj); // <---
Assert.assertEquals("{\"y\":2}", json);
}
方法3:使用@Expose註解
注意,沒有被 @Expose 標註的欄位會被排除,如下所示:
class MyObj {
public int x;
@Expose public int y; // <---
public MyObj(int x, int y) {
this.x = x;
this.y = y;
}
}
@Test
public void gson() {
Gson gson = new GsonBuilder()
.excludeFieldsWithoutExposeAnnotation() // <---
.create();
MyObj obj = new MyObj(1, 2);
String json = gson.toJson(obj);
Assert.assertEquals("{\"y\":2}", json);
}
方法4:使用ExclusionStrategy定製欄位排除策略
這種方式最靈活,下面的例子把所有以下劃線開頭的欄位全部都排除掉:
class MyObj {
public int _x; // <---
public int y;
public MyObj(int x, int y) {
this._x = x;
this.y = y;
}
}
@Test
public void gson() {
ExclusionStrategy myExclusionStrategy = new ExclusionStrategy() {
@Override
public boolean shouldSkipField(FieldAttributes fa) {
return fa.getName().startsWith("_");
}
@Override
public boolean shouldSkipClass(Class<?> clazz) {
return false;
}
};
Gson gson = new GsonBuilder()
.setExclusionStrategies(myExclusionStrategy) // <---
.create();
MyObj obj = new MyObj(1, 2);
String json = gson.toJson(obj);
Assert.assertEquals("{\"y\":2}", json);
}