标签：Feign total return public content Returns 报错 序列化 page
自己在写项目的时候，调用JPA接口去查询数据一直报错，打断点又是可以得到数据的，只是接收不了，百度了很久，这个方法是可以进行解决的
报错：
Type definition error: [simple type, class org.springframework.data.domain.Page];
nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException:
Cannot construct instance of `org.springframework.data.domain.Page` (no Creators, like default construct, exist):
abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
at [Source: (PushbackInputStream); line: 1, column: 48] (through reference chain:
com.core.domain.dto.ResultDTO["data"]->com.trade.manager.rest.search.domain.dto.PCShopSearchProductDTO["products"]), feign.codec.DecodeException
feign.codec.DecodeException:
Type definition error:
[simple type, class org.springframework.data.domain.Page]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException:
Cannot construct instance of `org.springframework.data.domain.Page` (no Creators, like default construct, exist):
abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
at [Source: (PushbackInputStream); line: 1, column: 48] (through reference chain:
com.core.domain.dto.ResultDTO["data"]->com.trade.manager.rest.search.domain.dto.PCShopSearchProductDTO["products"])
at feign.SynchronousMethodHandler.decode(SynchronousMethodHandler.java:180) ~[feign-core-10.1.0.jar!/:na]
at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:140) ~[feign-core-10.1.0.jar!/:na]
at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:78) ~[feign-core-10.1.0.jar!/:na]
at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103) ~[feign-core-10.1.0.jar!/:na]
at com.sun.proxy.$Proxy161.searchProductShopPC(Unknown Source) ~[na:na]
该查询返回一个Page实例, 具体的实现是org.springframework.data.domain.PageImpl.spring
问题就出在这个PageImpl对象, 正常状况下没有任何问题, 可是若是这个对象经过Feign中转时, 就会出现没法反序列化的错误.app
究其缘由, 是PageImpl没有无参构造, 其超类Chunk也没有无参构造; 致使反序列化失败.
解决办法：有两种，第一种是自定义反序列化，又麻烦又不会。。。第二种就是重新写一个实现类实现Page，然后在feign的调用方（也就是API接口的地方）用这个类来接受数据，而不是用自带的Page类，这样就可以得到数据啦
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
/**
* Page operations.
*
* @auther rickgong@iteye.com on 2017/3/17.
* @see org.springframework.data.domain.Page
*/
public class Page<T> implements Iterable<T>, Serializable {
private static final long serialVersionUID = -3720998571176536865L;
private List<T> content = new ArrayList<>();
private long total;
private int pageNo;
private int pageSize;
public Page() {
}
public Page(List<T> content, long total, int pageNo, int pageSize) {
this.content = content;
this.total = total;
this.pageNo = pageNo;
this.pageSize = pageSize;
}
/**
* Returns if there is a previous page.
*
* @return if there is a previous page.
*/
public boolean hasPrevious() {
return getPageNo() > 0;
}
/**
* Returns if there is a next page.
*
* @return if there is a next page.
*/
public boolean hasNext() {
return getPageNo() + 1 < getTotalPage();
}
/**
* Returns whether the current page is the first one.
*
* @return whether the current page is the first one.
*/
public boolean isFirst() {
return !hasPrevious();
}
/**
* Returns whether the current page is the last one.
*
* @return whether the current page is the last one.
*/
boolean isLast() {
return !hasNext();
}
/**
* Returns the total amount of elements of all pages.
*
* @return the total amount of elements of all pages.
*/
public long getTotal() {
return total;
}
public void setTotal(long total) {
this.total = total;
}
/**
* Returns the number of total pages.
*
* @return the number of total pages
*/
public int getTotalPage() {
return getPageSize() == 0 ? 1 : (int) Math.ceil((double) total / (double) getPageSize());
}
/**
* Returns the page content as unmodifiable {@link List}.
*
* @return Returns the page content as unmodifiable {@link List}
*/
public List<T> getContent() {
return Collections.unmodifiableList(content);
}
public void setContent(List<T> content) {
this.content = content;
}
/**
* Returns whether the current page has content.
*
* @return whether the current page has content.
*/
public boolean hasContent() {
return getContentSize() > 0;
}
/**
* Returns the number of elements on current page.
*
* @return the number of elements on current page.
*/
public int getContentSize() {
return content.size();
}
/**
* Returns the number of items of each page.
*
* @return the number of items of each page
*/
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
/**
* Returns the number of current page. (Zero-based numbering.)
*
* @return the number of current page.
*/
public int getPageNo() {
return pageNo;
}
/**
* Set the number of current page. (Zero-based numbering.)
*/
public void setPageNo(int pageNo) {
this.pageNo = pageNo;
}
@Override
public Iterator<T> iterator() {
return getContent().iterator();
}
}
标签：Feign,total,return,public,content,Returns,报错,序列化,page 来源： https://blog.csdn.net/tznb1996/article/details/123042888
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