2018/9/14
2019/01/20 (增加連結)
REST (Representational state transfer)是提供web services的一種方法，REST利用HTTP的POST,GET , PUT, DELETE來進行CRUD。
Spring framework提供不同方式來提供REST service，最新也最簡單的就是使用data rest。
pom.xml，使用spring framework提供的data rest，因為我們直接套用JPA，所以，也需要那部份的package:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-rest</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency>application.properties (詳參: Spring JPA)
#disbale Spring banner#spring.main.banner-mode=off# Loads SQL scripts? schema.sql and data.sql#spring.datasource.initialize=truespring.datasource.url=jdbc:mysql://localhost/practice?verifyServerCertificate=false&useSSL=false&requireSSL=falsespring.datasource.username=rootspring.datasource.password=1234spring.datasource.driver-class-name=com.mysql.jdbc.Driver第一、要安裝mySQL server (或其他資料庫)
第二、要啟動mySQL server (或其他資料庫) (請參考投影片)
第三、要建立資料表 (或匯入資料表) (請參考投影片) (或詳參: https://dev.mysql.com/doc/workbench/en/wb-table-editor.html)
CREATE TABLE `practice`.`customer` ( `id` INT NOT NULL AUTO_INCREMENT, `name` VARCHAR(15) NULL, `address` VARCHAR(45) NULL, `weight` INT NULL, PRIMARY KEY (`id`));Spring framework提供了RepositoryRestResource讓這件事變得非常簡單。只要寫一個CustomerDAO.java，跟CrudRepository的做法類似 (詳參: Spring JPA)，只是加上了RepositoryRestResource。
package com.example.demo.dao;import org.springframework.data.rest.core.annotation.RepositoryRestResource;import org.springframework.data.repository.CrudRepository;import com.example.demo.entity.Customer;@RepositoryRestResource(collectionResourceRel = "customer", path = "customer")public interface CustomerDAO extends CrudRepository<Customer, Long> {}可以使用PagingAndSortingRepository，當資料量大的時候，可以排序，也可以看特定的頁的資料。
package com.example.demo.dao;import org.springframework.data.repository.PagingAndSortingRepository;import org.springframework.data.rest.core.annotation.RepositoryRestResource;import com.example.demo.entity.Customer;@RepositoryRestResource(collectionResourceRel = "customer", path = "customer")public interface CustomerDAO extends PagingAndSortingRepository<Customer, Long> {}Customer.java裡利用@Entity告訴JPA這是個Entity類別，JPA會自動連接到類別名稱對應的資料表(customer)。另外，並以@Id指定一個欄位為資料表對應的主鍵(primary key)，如果這個欄位的內容是自動產生，則必須加上@GeneratedValue(strategy=GenerationType.IDENTITY) (詳參: http://www.thoughts-on-java.org/jpa-generate-primary-keys/ )。**在Hibernate 5，設為AUTO會使用一個資料表來產生序號，所以，請改為IDENTITY或SEQUENCE (詳參: Migration from Hibernate 4 to 5)。
package com.example.demo.entity;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "customer")public class Customer { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String name; @Column(name = "address") private String address; private int weight; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public int getWeight() { return weight; } public void setWeight(int weight) { this.weight = weight; }}ㄧ般而言，我們是利用RESTful web services，與其他的web site或手機交換資料。所以，下面的範例可以想像成去另外一個網站(雖然目前的url是自己)取得資料。
http://localhost:8080/customer/1 的內容類似:
{ "name" : "Ben", "address" : "新北市新莊區中正路510號", "weight" : 60, "_links" : { "self" : { "href" : "http://localhost:8080/customer/1" }, "customer" : { "href" : "http://localhost:8080/customer/1" } }}可以利用postman去進行資料的CRUD。(詳參: Postman - 測試Web Service的工具, Spring MVC RESTFul Web Service CRUD Example: Deploy and Test Spring MVC RESTFul API using Postman)
Create是利用HTTP POST
Read是利用HTTP GET
Update是利用HTTP PUT
Delete是利用HTTP DELETE
也可以用以下的jQuery去得到id = 1(如果存在的話)的customer資料。jQuery的語法請詳參jQuery。
<!DOCTYPE html><html><head><title>Hello jQuery</title><script src="https://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script><script> $(document).ready(function() { $.ajax({ url : "http://localhost:8080/customer/1", success : function(data) { $('.customer-name').append(data.name); $('.customer-address').append(data.address); }, error: function(){ $('.customer-name').append("**Not Available**"); $('.customer-address').append("**Not Available**"); } }); });</script></head><body> <div> <p class="customer-name">The Name is</p> <p class="customer-address">The Address is</p> </div></body></html>http://localhost:8080/customer 的內容類似:
{ "_embedded" : { "customer" : [ { "name" : "Ben", "address" : "新北市新莊區中正路510號", "weight" : 60, "_links" : { "self" : { "href" : "http://localhost:8080/customer/1" }, "customer" : { "href" : "http://localhost:8080/customer/1" } } }, { "name" : "Cathy", "address" : "台北市仁愛路1號", "weight" : 65, "_links" : { "self" : { "href" : "http://localhost:8080/customer/2" }, "customer" : { "href" : "http://localhost:8080/customer/2" } } } ] }, "_links" : { "self" : { "href" : "http://localhost:8080/customer{?page,size,sort}", "templated" : true }, "profile" : { "href" : "http://localhost:8080/profile/customer" } }, "page" : { "size" : 20, "totalElements" : 2, "totalPages" : 1, "number" : 0 }}以下的範例是讀取上面的資料，並將資料放到表格中。jQuery的語法請詳參jQuery。
<!DOCTYPE html><html><head><title>Hello jQuery</title><script src="https://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script><script> $(document).ready(function() { $.ajax({ url : "http://localhost:8080/customer", success : function(data) { $.each(data._embedded.customer, function(i, item) { $('#customer_tbl tbody').append("<tr><td>"); $('#customer_tbl tbody').append(item.name); $('#customer_tbl tbody').append("</td><td>"); $('#customer_tbl tbody').append(item.address); $('#customer_tbl tbody').append("</td></tr>"); }) } }); });</script></head><body> <table id="customer_tbl"> <thead> <tr> <th>Name</th> <th>Address</th> </tr> </thead> <tbody> </tbody> </table></body></html>