摘要：測(cè)試程序首先看到頂層服務(wù)使用格式進(jìn)行輸出。的列舉包括以下值默認(rèn)，公開所有公開和注解的，除非設(shè)置為暴露所有修飾的創(chuàng)建配置類測(cè)試分頁(yè)和排序分頁(yè)是一個(gè)由定義的接口，它擁有一個(gè)實(shí)現(xiàn)。排序提供一個(gè)對(duì)象提供排序機(jī)制。
使用 JPA 訪問數(shù)據(jù)
創(chuàng)建項(xiàng)目
打開IDEA -> Create New Project
創(chuàng)建目錄
創(chuàng)建實(shí)體
package com.example.demo.entity;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class Customer {
@Id
@GeneratedValue
private Long id;
private String firstName;
private String lastName;
protected Customer() {
}
public Customer(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
@Override
public String toString() {
return "Customer{" +
"id=" + id +
", firstName=" + firstName +
", lastName=" + lastName +
"}";
}
}
創(chuàng)建 repository
創(chuàng)建與實(shí)體對(duì)應(yīng)的Repository
package com.example.demo.repository;
import com.example.demo.entity.Customer;
import org.springframework.data.repository.CrudRepository;
import java.util.List;
public interface CustomerRepository extends CrudRepository {
List findByLastName(String lastName);
}
通過繼承CrudRepository繼承幾種增刪改查方法，也可以通過方法名支定義其他查詢方法。
添加啟動(dòng)加載類 CommandLineRunner 測(cè)試
package com.example.demo;
import com.example.demo.entity.Customer;
import com.example.demo.repository.CustomerRepository;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class SpringDataJpaDemoApplication {
public static final Logger log = LoggerFactory.getLogger(SpringDataJpaDemoApplication.class);
public static void main(String[] args) {
SpringApplication.run(SpringDataJpaDemoApplication.class, args);
}
@Bean
public CommandLineRunner demo(CustomerRepository repository) {
return (args -> {
repository.save(new Customer("Jack", "Bauer"));
repository.save(new Customer("Chloe", "Brian"));
repository.save(new Customer("Kim", "Bauer"));
repository.save(new Customer("David", "Palmer"));
repository.save(new Customer("Michelle", "Dessler"));
log.info("Customer found with save() finish");
log.info("Customer found with findAll()");
log.info("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
for (Customer customer : repository.findAll()) {
log.info(customer.toString());
}
log.info("");
repository.findById(1L).ifPresent(customer -> {
log.info("Customer found with findById()");
log.info("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
log.info(customer.toString());
log.info("");
});
log.info("Customer found with findByLastName("findByLastName")");
log.info("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
repository.findByLastName("Bauer").forEach(bauer -> {
log.info(bauer.toString());
});
log.info("");
});
}
}
運(yùn)行程序，通過 log 查看效果
使用 REST 訪問 JPA 數(shù)據(jù)
pom.xml 添加依賴
org.springframework.boot
spring-boot-starter-data-rest
創(chuàng)建實(shí)體
package com.example.demo.entity;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
private String firstName;
private String lastName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
創(chuàng)建 repository
package com.example.demo.repository;
import com.example.demo.entity.Person;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.data.rest.core.annotation.RepositoryRestResource;
import java.util.List;
@RepositoryRestResource
public interface PersonRepository extends PagingAndSortingRepository {
List findPersonByLastName(@Param("name") String name);
}
此repository是一個(gè)接口，允許您執(zhí)行涉及Person對(duì)象的各種操作。它通過繼承Spring Data Commons中定義的PagingAndSortingRepository接口來獲取這些操作
在運(yùn)行時(shí)，Spring Data REST將自動(dòng)創(chuàng)建此接口的實(shí)現(xiàn)。然后它將使用@RepositoryRestResource注解指導(dǎo)Spring MVC創(chuàng)建RESTful端點(diǎn)/persons。
測(cè)試程序
首先看到頂層服務(wù)
curl http://localhost:8080/
{
"_links" : {
"customers" : {
"href" : "http://localhost:8080/customers"
},
"persons" : {
"href" : "http://localhost:8080/persons{?page,size,sort}",
"templated" : true
},
"profile" : {
"href" : "http://localhost:8080/profile"
}
}
}
Spring Data REST使用HAL格式進(jìn)行JSON輸出。它非常靈活，可以方便地提供與所服務(wù)數(shù)據(jù)相鄰的鏈接。
curl http://localhost:8080/persons
{
"_embedded" : {
"persons" : [ ]
},
"_links" : {
"self" : {
"href" : "http://localhost:8080/persons{?page,size,sort}",
"templated" : true
},
"profile" : {
"href" : "http://localhost:8080/profile/persons"
},
"search" : {
"href" : "http://localhost:8080/persons/search"
}
},
"page" : {
"size" : 20,
"totalElements" : 0,
"totalPages" : 0,
"number" : 0
}
}
可以看到customers的也跟著顯示出來了，我們可以通過注釋隱藏，當(dāng)然也可以全局隱藏：
設(shè)置存儲(chǔ)庫(kù)檢測(cè)策略
Spring Data REST使用RepositoryDetectionStrategy來確定是否將存儲(chǔ)庫(kù)導(dǎo)出為REST資源。的RepositoryDiscoveryStrategies列舉包括以下值：
| Name |
Description |
| DEFAULT |
默認(rèn)，ANNOTATION + VISIBILITY |
| ALL |
公開所有Repository |
| ANNOTATION |
公開@RepositoryRestResource和@RestResource注解的Repository，除非exported設(shè)置為false |
| VISIBILITY |
暴露所有public修飾的Repository |
創(chuàng)建配置類
package com.example.demo.config;
import org.springframework.data.rest.core.config.RepositoryRestConfiguration;
import org.springframework.data.rest.core.mapping.RepositoryDetectionStrategy;
import org.springframework.data.rest.webmvc.config.RepositoryRestConfigurer;
import org.springframework.stereotype.Component;
@Component
public class RestConfigurer implements RepositoryRestConfigurer {
@Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.setRepositoryDetectionStrategy(RepositoryDetectionStrategy.RepositoryDetectionStrategies.ANNOTATED);
}
}
測(cè)試
curl http://localhost:8080/
{
"_links" : {
"persons" : {
"href" : "http://localhost:8080/persons{?page,size,sort}",
"templated" : true
},
"profile" : {
"href" : "http://localhost:8080/profile"
}
}
}
分頁(yè)和排序
分頁(yè)
Pageable 是一個(gè)由 Spring 定義的接口，它擁有一個(gè)實(shí)現(xiàn) PageRequest。讓我們看看如何創(chuàng)建一個(gè) PageRequest。
Pageable pageable = PageRequest.of(0, 10);
Page page = repository.findAll(pageable);
// 也可以簡(jiǎn)單一點(diǎn)
Page page = repository.findAll(PageRequest.of(0, 10));
表示請(qǐng)求第一頁(yè)10個(gè)數(shù)據(jù)。
如果我們要訪問下一頁(yè)，我們可以每次增加頁(yè)碼。
PageRequest.of(1, 10);
PageRequest.of(2, 10);
PageRequest.of(3, 10);
...
排序
Spring Data JPA 提供一個(gè)Sort對(duì)象提供排序機(jī)制。讓我們看一下排序的方式。
repository.findAll(Sort.by("fistName"));
repository.findAll(Sort.by("fistName").ascending().and(Sort.by("lastName").descending());
同時(shí)排序和分頁(yè)
Pageable pageable = PageRequest.of(0, 20, Sort.by("firstName"));
Pageable pageable = PageRequest.of(0, 20, Sort.by("fistName").ascending().and(Sort.by("lastName").descending());
按示例對(duì)象查詢
QueryByExampleExecutor
構(gòu)建復(fù)雜查詢
SpringData JPA 為了實(shí)現(xiàn) "Domain Driven Design" 中的規(guī)范概念，提供了一些列的 Specification 接口，其中最常用的便是 ：JpaSpecificationExecutor。
使用 SpringData JPA 構(gòu)建復(fù)雜查詢（join操作，聚集操作等等）都是依賴于 JpaSpecificationExecutor 構(gòu)建的 Specification 。
文章版權(quán)歸作者所有，未經(jīng)允許請(qǐng)勿轉(zhuǎn)載,若此文章存在違規(guī)行為，您可以聯(lián)系管理員刪除。
轉(zhuǎn)載請(qǐng)注明本文地址：http://www.ezyhdfw.cn/yun/73506.html
