帶有可選引數請求的微服務通信-有解無憂

我有一個客房服務，它在請求 http://localhost:8082/room/search/byRoomChar 時回傳房間的詳細資訊

    @GetMapping(path = "/search/byRoomChar")
    public @ResponseBody List<Room> byCapacity(@RequestParam(required = false) Integer capacity,
                                               @RequestParam(required = false) Boolean isUnderMaintenance,
                                               @RequestParam(required = false) String equipment) {
        return roomRepository.findByRoomChar(capacity, isUnderMaintenance, equipment);
    }

現在我想從預訂服務請求這個@GetMapping，因為這是用戶將使用 http://localhost:8081/booking/search/byRoomChar 與之互動的應用程式網關。

    @GetMapping(path = "/search/byRoomChar")
    public @ResponseBody List<Room> byCapacity(@RequestParam(required = false) Integer capacity,
                                               @RequestParam(required = false) Boolean isUnderMaintenance,
                                               @RequestParam(required = false) String equipment) {
        ResponseEntity<Room[]> roomsResponse = restTemplate.getForEntity("http://localhost:8082/room/search/byRoomChar?capacity="   capacity   "&isUnderMaintenance="  
            isUnderMaintenance   "&equipment="   equipment, Room[].class);
        return Arrays.asList(roomsResponse.getBody());
    }

房間物體代碼：

package nl.tudelft.sem.template.entities;

import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "Room")
public class Room {
    @EmbeddedId
    private RoomId id;

    @Column(name = "capacity")
    private int capacity;

    @Column(name = "numberOfPeople")
    private int numberOfPeople;

    @Column(name = "isUnderMaintenance", nullable = false)
    private boolean isUnderMaintenance;

    @Column(name = "equipment")
    private String equipment;

    public Room() {
    }

    public Room(long roomNumber, long buildingNumber, int capacity,
                int numberOfPeople, boolean isUnderMaintenance, String equipment) {
        RoomId id = new RoomId(roomNumber, buildingNumber);
        this.id = id;
        this.capacity = capacity;
        this.numberOfPeople = numberOfPeople;
        this.isUnderMaintenance = isUnderMaintenance;
        this.equipment = equipment;
    }

    public RoomId getId() {
        return id;
    }

    public void setId(RoomId id) {
        this.id = id;
    }

    public int getCapacity() {
        return capacity;
    }

    public void setCapacity(int capacity) {
        this.capacity = capacity;
    }

    public int getNumberOfPeople() {
        return numberOfPeople;
    }

    public void setNumberOfPeople(int numberOfPeople) {
        this.numberOfPeople = numberOfPeople;
    }

    public boolean getIsUnderMaintenance() {
        return isUnderMaintenance;
    }

    public void setUnderMaintenance(boolean underMaintenance) {
        isUnderMaintenance = underMaintenance;
    }

    public String getEquipment() {
        return equipment;
    }

    public void setEquipment(String equipment) {
        this.equipment = equipment;
    }
}

房間存盤庫代碼：

package nl.tudelft.sem.template.repositories;

import java.util.List;
import nl.tudelft.sem.template.entities.Room;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

@Repository
public interface RoomRepository extends JpaRepository<Room, Integer> {
    @Query("SELECT r FROM Room r WHERE (:number is null or r.id.number = :number)"
          "and r.id.buildingNumber = :buildingNumber")
    List<Room> findByRoomNum(@Param("number") Long number,
                             @Param("buildingNumber") Long buildingNumber);

    @Query("SELECT r FROM Room r WHERE (:capacity is null or r.capacity = :capacity) and"
          "(:isUnderMaintenance is null or r.isUnderMaintenance = :isUnderMaintenance) and"
          "(:equipment is null or r.equipment = :equipment)")
    List<Room> findByRoomChar(@Param("capacity") Integer capacity,
                              @Param("isUnderMaintenance") Boolean isUnderMaintenance,
                              @Param("equipment") String equipment);

}

但是，這不起作用，因為在從預訂服務呼叫 getmapping 時省略引數時，由于 required=false，所有引數值都變為 null。這在硬編碼的 url 中被轉換為字串。

2021-12-04 17:13:03.883  WARN 16920 --- [nio-8082-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.method.annotation.MethodArgumentTypeMismatchException: Failed to convert value of type 'java.lang.String' to required type 'java.lang.Boolean'; nested exception is java.lang.IllegalArgumentException: Invalid boolean value [null]]

如何從代碼中使用可選引數發出 get http 請求？

uj5u.com熱心網友回復：

UriComponentsBuilder可以幫助構建 URI。它正確處理可為空的查詢引數。

String uri = UriComponentsBuilder.fromHttpUrl("http://localhost:8082/room/search/byRoomChar")
            .queryParam("capacity", capacity)
            .queryParam("isUnderMaintenance", isUnderMaintenance)
            .queryParam("equipment", equipment)
            .encode().toUriString();
ResponseEntity<Room[]> roomsResponse = restTemplate.getForEntity(uri, Room[].class);

此外，以下答案可能會有所幫助：https : //stackoverflow.com/a/25434451/5990117

uj5u.com熱心網友回復：

如果這些引數在您的 Room API 中不是強制性的，但您仍然在呼叫資料庫時使用它們，或者您有合理的默認值，如果它們實際上不是由用戶提供的。遵循以下幾點（在這種情況下，您實際上不需要明確定義required = false）：

@GetMapping(path = "/search/byRoomChar")
public @ResponseBody List<Room> byCapacity(@RequestParam(defaultValue = "10") Integer capacity,
                                           @RequestParam(defaultValue = "false") Boolean isUnderMaintenance,
                                           @RequestParam(defaultValue = "default-equipment") String equipment) {
    return roomRepository.findByRoomChar(capacity, isUnderMaintenance, equipment);
}

或者您定義一個沒有附加引數的 Repository 方法，但這可能會更棘手，因為您基本上需要 null 和非 null 引數的所有可能性。

uj5u.com熱心網友回復：

這是因為在引數為 null 時構建的 URI 字串如下所示：

http://localhost:8082/room/search/byRoomChar?isUnderMaintenance=null

由于“null”作為引數的值被附加，房間服務器無法嘗試將其反序列化為不同的型別。例如，在您給出的錯誤訊息中，“isUnderMaintenance”應該是布林值，但是是“null”字串。

為了解決這個問題，我建議使用UriComponentBuilder.

@Test
fun constructUriWithQueryParameter() {
    val uri = UriComponentsBuilder.newInstance()
        .scheme("http")
        .host("localhost")
        .port(8082)
        .path("/room/search/byRoomChar")
        .query("capacity={capa}")
        .query("isUnderMaintenance={isUnderMaintenance}")
        .query("equipment={equip}")
        .buildAndExpand(null, null, null)
        .toUriString()
    assertEquals(
        "http://localhost:8082/room/search/byRoomChar 
             capacity=&isUnderMaintenance=&equipment=",
        uri
    )
}

uj5u.com熱心網友回復：

我試過彼得亞歷山德羅夫的回答。看起來很干凈，這很可能是要走的路，但我得到了一個“不是絕對的 uri”例外。

沒有時間尋找答案，所以我創建了我的解決方法代碼。凌亂，但它的作業。

    @GetMapping(path = "/search/byRoomChar")
    public @ResponseBody List<Room> byCapacity(@RequestParam(required = false) Integer capacity,
                                               @RequestParam(required = false) Boolean isUnderMaintenance,
                                               @RequestParam(required = false) String equipment) {
        if(capacity == null && isUnderMaintenance == null && equipment == null) {
            ResponseEntity<Room[]> roomsResponse = restTemplate.getForEntity("http://localhost:8082/room/search/byRoomChar", Room[].class);
            return Arrays.asList(roomsResponse.getBody());
        }
        String url = "http://localhost:8082/room/search/byRoomChar?";
        if(capacity != null) {
            url  = "capacity="   capacity   "&";
        }
        if(isUnderMaintenance != null) {
            url  = "isUnderMaintenance="   isUnderMaintenance   "";
        }
        if(equipment != null) {
            url  = "equipment="   equipment;
        }
        ResponseEntity<Room[]> roomsResponse = restTemplate.getForEntity(url, Room[].class);
        return Arrays.asList(roomsResponse.getBody());

    }

轉載請註明出處，本文鏈接：https://www.uj5u.com/ruanti/373296.html

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