在泛型类的静态类中使用泛型类型

Question

在一个restful项目中，我试图使用通用响应。在这个通用响应中，有一个静态responseBuilder。但是responseBuilder中的生成方法不能接受泛型类型。代码：

public class RestResponse<T>{
private int status;
private String message;
private T entity;
/**
* 
*/
public static class RestResponseBuilder {
private final RestResponse restResponse;
public RestResponseBuilder(RestResponse resp) {
this.restResponse = resp;
}
public static RestResponseBuilder ok() {
return status(HttpServletResponse.SC_OK).msg("ok");
}
public static RestResponseBuilder status(int status) {
final RestResponse resp = new RestResponse();
resp.setStatus(status);
return new RestResponseBuilder(resp);
}
public RestResponseBuilder msg(String msg) {
this.restResponse.setMessage(msg);
return this;
}
public RestResponseBuilder entity(Object entity) {
this.restResponse.setEntity(entity);
return this;
}
public RestResponse build() {
return restResponse;
}
}

}

当我这样使用时：RestResponseBuilder.ok((.entity(null(.build((；有一个警告：类型安全：类型RestResponse的表达式需要未经检查的转换才能符合

我的问题是，如何在RestResponseBuilder中添加泛型类型以避免此警告？感谢

Answer 1

不要使用原始类型。使你的构建器类也是通用的，它的静态方法也是通用的：

public class RestResponse<T> {
private int status;
private String message;
private T entity;
/**
*
*/
public static class RestResponseBuilder<T> {
private final RestResponse<T> restResponse;
public RestResponseBuilder(RestResponse<T> resp) {
this.restResponse = resp;
}
public static <T> RestResponseBuilder<T> ok() {
return RestResponseBuilder.<T>status(200).msg("ok");
}
public static <T> RestResponseBuilder<T> status(int status) {
final RestResponse<T> resp = new RestResponse<T>();
resp.status = status;
return new RestResponseBuilder<T>(resp);
}
public RestResponseBuilder<T> msg(String msg) {
this.restResponse.message = msg;
return this;
}
public RestResponseBuilder<T> entity(T entity) {
this.restResponse.entity = entity;
return this;
}
public RestResponse<T> build() {
return restResponse;
}
}
}