Spring Boot Crud操作示例 | Java Code Geeks

SpringBoot · 發表 2019-01-29 19:37:00

摘要：，在本教程中，我們將探討spring框架的spring boot模組中的crud操作。簡介 Spring Boot是一個為spring框架提供快速應用程式開發功能的模組，包括自動配置，獨立程式碼和生產就緒程式碼它建立打包為jar的應用程式，並使用嵌...

，在本教程中，我們將探討spring框架的spring boot模組中的crud操作。

簡介

Spring Boot是一個為spring框架提供快速應用程式開發功能的模組，包括自動配置，獨立程式碼和生產就緒程式碼
它建立打包為jar的應用程式，並使用嵌入式servlet容器（例如Tomcat，Jetty或Undertow）直接啟動。因此，無需部署war檔案
它通過提供入門模板簡化了maven配置，並有助於解決依賴衝突。它會自動識別所需的依賴項並在應用程式中匯入它們
它有助於刪除樣板程式碼，額外註釋和xml配置
它提供強大的批處理並管理其餘端點
它提供了一個高效的jpa-starter庫，可以有效地將應用程式與關係資料庫連線起來

現在，讓我們看看如何在spring boot模組中使用jpa-starter庫與關係資料庫進行通訊來實現本教程。

建立Spring Boot應用程式

以下是開發應用程式所涉及的Maven依賴

在這裡，我們指定Spring Boot，Spring Boot JPA和MySQL聯結器的依賴項。Maven將自動解析其他依賴項。該更新檔案將具有下面的程式碼。步驟。

<!-- Spring boot web mvc jar -->
<!-- Automatically adds tomcat and jackson-databind jars -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- Spring boot jpa jar -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!-- Mysql database jar -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>

在Springbootcrudoperation/src/main/resources/建立一個新的屬性檔案application.properties：並向其中新增以下程式碼。

## Spring datasource.
spring.datasource.driver.<b>class</b>=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql:<font><i>//localhost:3306/paramount</i></font><font>
spring.datasource.username=root
spring.datasource.password=

## Hibernate properties.
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

## Show sql query.
spring.jpa.show-sql=<b>true</b>

## Hibernate ddl auto.
spring.jpa.hibernate.ddl-auto=validate
</font>

將以下程式碼新增到主類中以從main方法引導應用程式。永遠記住，spring boot應用程式的入口點是包含@SpringBootApplication註釋和靜態main方法的類。

<b>package</b> com.ducat.springboot.<b>rest</b>;

<b>import</b> org.springframework.boot.SpringApplication;
<b>import</b> org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
<b>public</b> <b>class</b> Myapplication {

<b>public</b> <b>static</b> <b>void</b> main(String[] args) {
SpringApplication.run(Myapplication.<b>class</b>, args);
}
}

將以下程式碼新增到員工模型類。

Employee.java：

<b>package</b> com.ducat.springboot.<b>rest</b>.model;

<b>import</b> javax.persistence.Entity;
<b>import</b> javax.persistence.GeneratedValue;
<b>import</b> javax.persistence.GenerationType;
<b>import</b> javax.persistence.Id;
<b>import</b> javax.persistence.Table;

<b>import</b> org.hibernate.annotations.DynamicInsert;
<b>import</b> org.hibernate.annotations.DynamicUpdate;
<b>import</b> org.springframework.stereotype.Component;

@Component

<font><i>// Spring jpa jars.</i></font><font>
@Entity
@Table(name= </font><font>"employee"</font><font>)

</font><font><i>// To increase speed and save sql statement execution time.</i></font><font>
@DynamicInsert
@DynamicUpdate
<b>public</b> <b>class</b> Employee {

@Id
@GeneratedValue(strategy= GenerationType.IDENTITY)
<b>private</b> <b>int</b> id;
<b>private</b> String name;
<b>private</b> String department;
<b>private</b> <b>double</b> salary;

<b>public</b> Employee() { }

<b>public</b> <b>int</b> getId() {
<b>return</b> id;
}
<b>public</b> <b>void</b> setId(<b>int</b> id) {
<b>this</b>.id = id;
}
<b>public</b> String getName() {
<b>return</b> name;
}
<b>public</b> <b>void</b> setName(String name) {
<b>this</b>.name = name;
}
<b>public</b> String getDepartment() {
<b>return</b> department;
}
<b>public</b> <b>void</b> setDepartment(String department) {
<b>this</b>.department = department;
}
<b>public</b> <b>double</b> getSalary() {
<b>return</b> salary;
}
<b>public</b> <b>void</b> setSalary(<b>double</b> salary) {
<b>this</b>.salary = salary;
}

@Override
<b>public</b> String toString() {
<b>return</b> </font><font>"Employee [id="</font><font> + id + </font><font>", name="</font><font> + name + </font><font>", department="</font><font> + department + </font><font>", salary="</font><font> + salary + </font><font>"]"</font><font>;
}
}
</font>

將以下程式碼新增到擴充套件JPA儲存庫的Dao介面，以自動處理crud查詢。

Mydaorepository.java

<b>package</b> com.ducat.springboot.<b>rest</b>.dao;

<b>import</b> org.springframework.data.jpa.repository.JpaRepository;
<b>import</b> org.springframework.stereotype.Repository;

<b>import</b> com.ducat.springboot.<b>rest</b>.model.Employee;

@Repository
<b>public</b> <b>interface</b> Mydaorepository <b>extends</b> JpaRepository<Employee, Integer> {

}

將以下程式碼新增到服務類中，我們將呼叫Dao介面的方法來處理sql操作。

@Service
<b>public</b> <b>class</b> Myserviceimpl implements Myservice {

@Autowired
Mydaorepository dao;

@Override
<b>public</b> List<Employee> getEmployees() {
<b>return</b> dao.findAll();
}
@Override
<b>public</b> Optional<Employee> getEmployeeById(<b>int</b> empid) {
<b>return</b> dao.findById(empid);
}
@Override
<b>public</b> Employee addNewEmployee(Employee emp) {
<b>return</b> dao.save(emp);
}
@Override
<b>public</b> Employee updateEmployee(Employee emp) {
<b>return</b> dao.save(emp);
}
@Override
<b>public</b> <b>void</b> deleteEmployeeById(<b>int</b> empid) {
dao.deleteById(empid);
}
@Override
<b>public</b> <b>void</b> deleteAllEmployees() {
dao.deleteAll();
}
}

將以下程式碼新增到旨在處理傳入請求的控制器類中。該類使用註釋進行@RestController註釋，其中每個方法都將域物件作為json響應而不是檢視返回。

<b>package</b> com.ducat.springboot.<b>rest</b>.controller;

<b>import</b> java.util.List;
<b>import</b> java.util.Optional;

<b>import</b> org.springframework.beans.factory.annotation.Autowired;
<b>import</b> org.springframework.web.bind.annotation.PathVariable;
<b>import</b> org.springframework.web.bind.annotation.RequestBody;
<b>import</b> org.springframework.web.bind.annotation.RequestMapping;
<b>import</b> org.springframework.web.bind.annotation.RequestMethod;
<b>import</b> org.springframework.web.bind.annotation.RestController;

<b>import</b> com.ducat.springboot.<b>rest</b>.model.Employee;
<b>import</b> com.ducat.springboot.<b>rest</b>.service.Myservice;

@RestController
<b>public</b> <b>class</b> Mycontroller {

@Autowired
Myservice service;

@RequestMapping(value= <font>"/employee/all"</font><font>, method= RequestMethod.GET)
<b>public</b> List<Employee> getEmployees() {
System.out.println(<b>this</b>.getClass().getSimpleName() + </font><font>" - Get all employees service is invoked."</font><font>);
<b>return</b> service.getEmployees();
}

@RequestMapping(value= </font><font>"/employee/{id}"</font><font>, method= RequestMethod.GET)
<b>public</b> Employee getEmployeeById(@PathVariable <b>int</b> id) throws Exception {
System.out.println(<b>this</b>.getClass().getSimpleName() + </font><font>" - Get employee details by id is invoked."</font><font>);

Optional<Employee> emp =service.getEmployeeById(id);
<b>if</b>(!emp.isPresent())
<b>throw</b> <b>new</b> Exception(</font><font>"Could not find employee with id- "</font><font> + id);

<b>return</b> emp.get();
}

@RequestMapping(value= </font><font>"/employee/add"</font><font>, method= RequestMethod.POST)
<b>public</b> Employee createEmployee(@RequestBody Employee newemp) {
System.out.println(<b>this</b>.getClass().getSimpleName() + </font><font>" - Create new employee method is invoked."</font><font>);
<b>return</b> service.addNewEmployee(newemp);
}

@RequestMapping(value= </font><font>"/employee/update/{id}"</font><font>, method= RequestMethod.PUT)
<b>public</b> Employee updateEmployee(@RequestBody Employee updemp, @PathVariable <b>int</b> id) throws Exception {
System.out.println(<b>this</b>.getClass().getSimpleName() + </font><font>" - Update employee details by id is invoked."</font><font>);

Optional<Employee> emp =service.getEmployeeById(id);
<b>if</b> (!emp.isPresent())
<b>throw</b> <b>new</b> Exception(</font><font>"Could not find employee with id- "</font><font> + id);

</font><font><i>/* IMPORTANT - To prevent the overriding of the existing value of the variables in the database, 
* if that variable is not coming in the @RequestBody annotation object. */</i></font><font>
<b>if</b>(updemp.getName() == <b>null</b> || updemp.getName().isEmpty())
updemp.setName(emp.get().getName());
<b>if</b>(updemp.getDepartment() == <b>null</b> || updemp.getDepartment().isEmpty())
updemp.setDepartment(emp.get().getDepartment());
<b>if</b>(updemp.getSalary() == 0)
updemp.setSalary(emp.get().getSalary());

</font><font><i>// Required for the "where" clause in the sql query template.</i></font><font>
updemp.setId(id);
<b>return</b> service.updateEmployee(updemp);
}

@RequestMapping(value= </font><font>"/employee/delete/{id}"</font><font>, method= RequestMethod.DELETE)
<b>public</b> <b>void</b> deleteEmployeeById(@PathVariable <b>int</b> id) throws Exception {
System.out.println(<b>this</b>.getClass().getSimpleName() + </font><font>" - Delete employee by id is invoked."</font><font>);

Optional<Employee> emp =service.getEmployeeById(id);
<b>if</b>(!emp.isPresent())
<b>throw</b> <b>new</b> Exception(</font><font>"Could not find employee with id- "</font><font> + id);

service.deleteEmployeeById(id);
}

@RequestMapping(value= </font><font>"/employee/deleteall"</font><font>, method= RequestMethod.DELETE)
<b>public</b> <b>void</b> deleteAll() {
System.out.println(<b>this</b>.getClass().getSimpleName() + </font><font>" - Delete all employees is invoked."</font><font>);
service.deleteAllEmployees();
}
}
</font>

執行應用程式

當我們準備好所有更改時，讓我們編譯spring boot專案並將應用程式作為java專案執行。

使用Postman測試：

<font><i>// Get all employees</i></font><font>
http:</font><font><i>//localhost:8080/employee/all</i></font><font>

</font><font><i>// Get employee by id</i></font><font>
http:</font><font><i>//localhost:8080/employee/1003</i></font><font>

</font><font><i>// Create new employee</i></font><font>
http:</font><font><i>//localhost:8080/employee/add</i></font><font>

</font><font><i>// Update existing employee by id</i></font><font>
http:</font><font><i>//localhost:8080/employee/update/1008</i></font><font>

</font><font><i>// Delete employee by id</i></font><font>
http:</font><font><i>//localhost:8080/employee/delete/1002</i></font><font>

</font><font><i>// Delete all employees</i></font><font>
http:</font><font><i>//localhost:8080/employee/deleteall</i></font><font>
</font>

這就是本教程的全部內容，我希望這篇文章能為您提供所需的一切。快樂學習，別忘了分享！

重點

我們指示hibernate連線到mysql資料庫並使用它MySQL5Dialect來生成優化的sql查詢
spring.jpa.hibernate.ddl-auto=validate 將指示hibernate在應用程式啟動時驗證表模式
spring.jpa.show-sql=true 將指示hibernate框架記錄控制檯上的所有SQL語句
開發人員可以根據需要更改資料來源詳細資訊

Springbootcrudoperation 原始碼

Spring Boot Crud操作示例 | Java Code Geeks

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