带有分页API的Spring RestTemplate

我们的REST API在Pages中返回结果.以下是一个Controller的示例

@RequestMapping(value = "/search", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE + ";charset=UTF-8")
@ResponseStatus(HttpStatus.OK)
public Page findAll(Pageable pageable) {
  ...
}

有没有一种简单的方法来使用RestTemplate使用该API？

如果我们这样做

ParameterizedTypeReference> responseType = new ParameterizedTypeReference>() { };

ResponseEntity> result = restTemplate.exchange(url, HttpMethod.GET, null/*httpEntity*/, responseType);

List searchResult = result.getBody().getContent();

它引发了一个例外

org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not construct instance of org.springframework.data.domain.Page, 
problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information at [Source: java.io.PushbackInputStream@3be1e1f2; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of org.springframework.data.domain.Page, problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information

先感谢您

从Spring Boot 1.x迁移到2.0时,将读取Rest API响应的代码更改为

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.JsonNode;

import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;

import java.util.ArrayList;
import java.util.List;

public class RestPageImpl extends PageImpl{

    @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
    public RestPageImpl(@JsonProperty("content") List content,
                        @JsonProperty("number") int number,
                        @JsonProperty("size") int size,
                        @JsonProperty("totalElements") Long totalElements,
                        @JsonProperty("pageable") JsonNode pageable,
                        @JsonProperty("last") boolean last,
                        @JsonProperty("totalPages") int totalPages,
                        @JsonProperty("sort") JsonNode sort,
                        @JsonProperty("first") boolean first,
                        @JsonProperty("numberOfElements") int numberOfElements) {

        super(content, PageRequest.of(number, size), totalElements);
    }

    public RestPageImpl(List content, Pageable pageable, long total) {
        super(content, pageable, total);
    }

    public RestPageImpl(List content) {
        super(content);
    }

    public RestPageImpl() {
        super(new ArrayList<>());
    }
}

将读取Rest API响应的代码更改为;

ParameterizedTypeReference> responseType = new ParameterizedTypeReference>() { };

ResponseEntity> result = restTemplate.exchange(url, HttpMethod.GET, null/*httpEntity*/, responseType);

List searchResult = result.getBody().getContent();

这是我为RestResponsePage创建的类

package com.basf.gb.cube.seq.vaadinui.util;

import java.util.ArrayList;
import java.util.List;

import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.Pageable;

public class RestResponsePage extends PageImpl{

  private static final long serialVersionUID = 3248189030448292002L;

  public RestResponsePage(List content, Pageable pageable, long total) {
    super(content, pageable, total);
    // TODO Auto-generated constructor stub
  }

  public RestResponsePage(List content) {
    super(content);
    // TODO Auto-generated constructor stub
  }

  /* PageImpl does not have an empty constructor and this was causing an issue for RestTemplate to cast the Rest API response
   * back to Page.
   */
  public RestResponsePage() {
    super(new ArrayList());
  }

} 

扩展上面,但不需要实现每个属性.

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;

import java.util.ArrayList;
import java.util.List;

public class RestPageImpl extends PageImpl{

    @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
    public RestPageImpl(@JsonProperty("content") List content,
                        @JsonProperty("number") int page,
                        @JsonProperty("size") int size,
                        @JsonProperty("totalElements") long total) {
        super(content, new PageRequest(page, size), total);
    }

    public RestPageImpl(List content, Pageable pageable, long total) {
        super(content, pageable, total);
    }

    public RestPageImpl(List content) {
        super(content);
    }

    public RestPageImpl() {
        super(new ArrayList());
    }
}