本文介绍了泛型与Spring REST模板的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我有这样一个类:

  public class Wrapper< T> {

私人字符串消息;
私人T数据;

public String getMessage(){
return message;
}

public void setMessage(String message){
this.message = message;
}

public T getData(){
return data;
}

public void setData(T data){
this.data = data;
}

}

我使用resttemplate如下:

  ... 
Wrapper< Model> response = restTemplate.getForObject(URL,Wrapper.class,myMap);
Model model = response.getData();
...

然而它会抛出:

  ClassCastException 

我读到:,但没有帮助。有一些话题与我的问题等有关:和



任何想法?



PS:我的错误是:

  java.lang.ClassCastException:java.util.LinkedHashMap不能转换为abcdModel 

我认为resttemplate无法理解我的泛型变量,也许它将它接受为Object而不是泛型T.因此它变成了LinkedHashMap。您可以从进行阅读它说,从什么时候解释到:


解决方案

3.2 M2中引入了ParameterizedTypeReference来解决此问题。

  Wrapper< Model> response)= restClient.exchange(loginUrl,
HttpMethod.GET,
null,
new ParameterizedTypeReference< Wrapper< Model>>(){})。getBody();

但是,postForObject / getForObject变体没有引入。


I have a class like that:

public class Wrapper<T> {

 private String message;
 private T data;

 public String getMessage() {
    return message;
 }

 public void setMessage(String message) {
    this.message = message;
 }

 public T getData() {
    return data;
 }

 public void setData(T data) {
    this.data = data;
 }

}

and I use resttemplate as follows:

...
Wrapper<Model> response = restTemplate.getForObject(URL, Wrapper.class, myMap);
Model model = response.getData();
...

However it throws a:

ClassCastException

I read that: Issue when trying to use Jackson in java but didn't help. There are some topics related to my problem etc.: https://jira.springsource.org/browse/SPR-7002 and https://jira.springsource.org/browse/SPR-7023

Any ideas?

PS: My error is that:

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to a.b.c.d.Model

I think resttemplate can not understand my generic variable and maybe it accepts it as an Object instead of generic T. So it becomes a LinkedHashMap. You can read from it here It says that when explaining from what it marshalls to:

解决方案

ParameterizedTypeReference has been introduced in 3.2 M2 to workaround this issue.

Wrapper<Model> response = restClient.exchange(loginUrl,
                          HttpMethod.GET,
                          null,
                          new ParameterizedTypeReference<Wrapper<Model>>() {}).getBody();

However, the postForObject/getForObject variant was not introduced.

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08-01 05:21