内容简介:,在本教程中,我们将探讨spring框架的spring boot模块中的crud操作。现在,让我们看看如何在spring boot模块中使用jpa-starter库与关系数据库进行通信来实现本教程。
,在本教程中,我们将探讨spring框架的spring boot模块中的crud操作。
简介
- Spring Boot是一个为spring框架提供快速应用程序开发功能的模块,包括自动配置,独立代码和生产就绪代码
- 它创建打包为jar的应用程序,并使用嵌入式servlet容器(例如Tomcat,Jetty或Undertow)直接启动。因此,无需部署war文件
- 它通过提供入门模板简化了maven配置,并有助于解决依赖冲突。它会自动识别所需的依赖项并在应用程序中导入它们
- 它有助于删除样板代码,额外注释和xml配置
- 它提供强大的批处理并管理其余端点
- 它提供了一个高效的jpa-starter库,可以有效地将应用程序与关系数据库连接起来
现在,让我们看看如何在spring boot模块中使用jpa-starter库与关系数据库进行通信来实现本教程。
创建Spring Boot应用程序
以下是开发应用程序所涉及的Maven依赖
在这里,我们指定Spring Boot,Spring Boot JPA和 MySQL 连接器的依赖项。Maven将自动解析其他依赖项。该更新文件将具有下面的代码。步骤。
<!-- 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/创建一个新的属性文件application.properties:并向其中添加以下代码。
## 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>
将以下代码添加到主类中以从main方法引导应用程序。永远记住,spring boot应用程序的入口点是包含@SpringBootApplication注释和静态main方法的类。
<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); } }
将以下代码添加到员工模型类。
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>
将以下代码添加到扩展JPA存储库的Dao接口,以自动处理crud查询。
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> { }
将以下代码添加到服务类中,我们将调用Dao接口的方法来处理 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(); } }
将以下代码添加到旨在处理传入请求的控制器类中。该类使用注释进行@RestController注释,其中每个方法都将域对象作为json响应而不是视图返回。
<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>
运行应用程序
当我们准备好所有更改时,让我们编译spring boot项目并将应用程序作为 java 项目运行。
使用Postman测试:
<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>
这就是本教程的全部内容,我希望这篇文章能为您提供所需的一切。快乐学习,别忘了分享!
重点
- 我们指示hibernate连接到mysql数据库并使用它MySQL5Dialect来生成优化的sql查询
- spring.jpa.hibernate.ddl-auto=validate 将指示hibernate在应用程序启动时验证表模式
- spring.jpa.show-sql=true 将指示hibernate框架记录控制台上的所有SQL语句
- 开发人员可以根据需要更改数据源详细信息
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持 码农网
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