我的gitee项目地址：https://gitee.com/hgqstudy/hgqstudy.git

CSDN地址： https://blog.csdn.net/qq_38943039

我的公众号：不颓废的程序员
#### 1. 新建一个Spring Boot 项目

```java
File -> New -> Project -> Spring Initializr -> Next -> Next -> Next ->Finish
```

#### 2. 新建数据库

```my
CREATE DATABASE test;
USE test;

DROP TABLE IF EXISTS `c_user`;
CREATE TABLE `c_user`  (
  `id` int(0) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  `phone` varchar(18) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  `create_at` date NULL DEFAULT NULL,
  `update_at` datetime(0) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

DROP TABLE IF EXISTS `c_address`;
CREATE TABLE `c_address`  (
  `id` int(0) NOT NULL AUTO_INCREMENT,
  `uid` int(0) NULL DEFAULT NULL,
  `address` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  `create_at` date NULL DEFAULT NULL,
  `update_at` datetime(0) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

SET FOREIGN_KEY_CHECKS = 1;
```

#### 3. 在pom.xml文件中引入maven依赖

```xml
<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>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
	<groupId>io.springfox</groupId>
	<artifactId>springfox-swagger-ui</artifactId>
	<version>2.7.0</version>
</dependency>

<dependency>
	<groupId>io.springfox</groupId>
	<artifactId>springfox-swagger2</artifactId>
	<version>2.7.0</version>
</dependency>

<dependency>
	<groupId>com.google.code.gson</groupId>
	<artifactId>gson</artifactId>
	<version>2.8.6</version>
</dependency>

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	
</dependency>
```

#### 4. 编写application.properties文件

```properties
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2b8
spring.datasource.username=root
spring.datasource.password=123456

server.port=8081
spring.jpa.hibernate.ddl-auto=none
#是否会打印sql语句,true为打印
spring.jpa.show-sql=true
```

#### 5. 配置Swagger

```java
@Configuration
@EnableSwagger2
public class Swagger2 {

final String host = "localhost";

@Bean
    public Docket api() {
        return new Docket(DocumentationType.SWAGGER_2)
                .host(host)
                .select()
                .apis(RequestHandlerSelectors.any())
                .paths(PathSelectors.any())
                .build();
    }
}
```

#### 6. 编写Json工具类,主要是把数据转为json格式

```java
public class JsonCode<T> {

public static class ResponseBean<T>{
        private Integer status;
        private Integer error_code;
        private String error_message;
        private T data;

public Integer getStatus() {
            return status;
        }

public void setStatus(Integer status) {
            this.status = status;
        }

public Integer getError_code() {
            return error_code;
        }

public void setError_code(Integer error_code) {
            this.error_code = error_code;
        }

public String getError_message() {
            return error_message;
        }

public void setError_message(String error_message) {
            this.error_message = error_message;
        }

public T getData() {
            return data;
        }

public void setData(T data) {
            this.data = data;
        }
    }

public String ResponseFail(int ErrorCode, String ErrorMessage) {
        ResponseBean<T> responseBean = new ResponseBean<T>();
        responseBean.setError_code(ErrorCode);
        responseBean.setError_message(ErrorMessage);
        Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm").create();
        return gson.toJson(responseBean);
    }

public String ResponseSuccess(T data) {
        ResponseBean<T> responseBean = new ResponseBean<T>();
        responseBean.setData(data);
        responseBean.setError_code(0);
        responseBean.setError_message("");
        Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm").create();
        return gson.toJson(responseBean);
    }

public String ResponseSuccess() {
        ResponseBean<T> responseBean = new ResponseBean<T>();
        responseBean.setData(null);
        responseBean.setError_code(0);
        responseBean.setError_message("");
        Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm").create();
        return gson.toJson(responseBean);
    }

}
```

#### 7. 编写WebMvcConfig

```java
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

@Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("swagger-ui.html")
                .addResourceLocations("classpath:/META-INF/resources/");

registry.addResourceHandler("/webjars/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/");

}

@Bean
    public PageableHandlerMethodArgumentResolverCustomizer customize() {
        return p -> p.setOneIndexedParameters(true);
    }

static final String ORIGINS[] = new String[] { "GET", "POST", "PUT", "DELETE" };
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**").allowedOrigins("*").allowCredentials(true).allowedMethods(ORIGINS)
                .maxAge(3600);
    }
}
```

#### 8. 主启动类编写

```java
@EnableJpaAuditing
@EnableSwagger2
@SpringBootApplication
@Configuration
public class TestApplication {

public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    }
}
```

#### 9. 用户实体类(CUserEntity)

```java
@Entity
@EntityListeners(AuditingEntityListener.class)
@Table(name = "c_user",schema = "",catalog =  "")
public class CUserEntity {
    private int id;
    private String username;
    private String phone;

@CreatedDate
    @DateTimeFormat(pattern = "yyyy-MM-dd HH-mm-ss")
    private Timestamp createAt;

@LastModifiedDate
    @DateTimeFormat(pattern = "yyyy-MM-dd HH-mm-ss")
    private Timestamp updateAt;

@Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public int getId() {
        return id;
    }

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

@Basic
    @Column(name = "username")
    public String getUsername() {
        return username;
    }

public void setUsername(String username) {
        this.username = username;
    }

@Basic
    @Column(name = "phone")
    public String getPhone() {
        return phone;
    }

public void setPhone(String phone) {
        this.phone = phone;
    }

@Basic
    @Column(name = "create_at")
    public Timestamp getCreateAt() {
        return createAt;
    }

public void setCreateAt(Timestamp createAt) {
        this.createAt = createAt;
    }

@Basic
    @Column(name = "update_at")
    public Timestamp getUpdateAt() {
        return updateAt;
    }

public void setUpdateAt(Timestamp updateAt) {
        this.updateAt = updateAt;
    }
}
```

#### 10. 地址实体类(CAddressEntity)

```java
@Entity
@EntityListeners(AuditingEntityListener.class)
@Table(name = "c_address")
public class CAddressEntity {

private int id;
    private int uid;
    private String address;

@CreatedDate
    @DateTimeFormat(pattern = "yyyy-MM-dd HH-mm-ss")
    private Timestamp createAt;

@LastModifiedDate
    @DateTimeFormat(pattern = "yyyy-MM-dd HH-mm-ss")
    private Timestamp updateAt;

@Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public int getId() {
        return id;
    }

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

@Basic
    @Column(name = "uid")
    public int getUid() {
        return uid;
    }

public void setUid(int uid) {
        this.uid = uid;
    }

@Basic
    @Column(name = "address")
    public String getAddress() {
        return address;
    }

public void setAddress(String address) {
        this.address = address;
    }

@Basic
    @Column(name = "create_at")
    public Timestamp getCreateAt() {
        return createAt;
    }

public void setCreateAt(Timestamp createAt) {
        this.createAt = createAt;
    }

@Basic
    @Column(name = "update_at")
    public Timestamp getUpdateAt() {
        return updateAt;
    }

public void setUpdateAt(Timestamp updateAt) {
        this.updateAt = updateAt;
    }
}
```

#### 11. 编写CUserEntityRepository

```java
public interface CUserEntityRepository extends JpaRepository<CUserEntity,Integer>, JpaSpecificationExecutor<CUserEntity> {

//简单的查询只需要根据JPA命名规则来命名方法,就可以直接使用了，不需要编写SQL语句，非常方便
    CUserEntity findFirstById(int id);
    CUserEntity findFirstByUsername(String username);
    CUserEntity findFirstByPhone(String phone);
}
```

#### 12. 编写CAddressEntityRepository

```java
public interface CAddressEntityRepository extends JpaRepository<CAddressEntity, Integer>, JpaSpecificationExecutor<CAddressEntity> {
    
    //复杂的查询则需要自己编写SQL语句
    @Query(value = "SELECT c_user.username,c_user.phone,c_address.* FROM c_address LEFT JOIN c_user ON c_user.id = c_address.uid " +
            "WHERE c_user.id = ?1",
            nativeQuery = true)
    List<Map<String,Object>> NativeFindByUserId(int id);

@Query(value = "SELECT c_user.username,c_user.phone,c_address.* FROM c_address LEFT JOIN c_user " +
            "ON c_user.id = c_address.uid WHERE IF(IFNULL(?1,'') !='',c_user.id = ?1,1 = 1) AND IF(?2 != '',c_user.username = ?2,1 = 1) AND " +
            "IF(?3 != '',c_user.phone = ?3,1 = 1) ",
    nativeQuery = true)
    Page<Map<String,Object>> NativeFindAllByUsernameOrPhone(Integer id,String username, String phone, Pageable pageable);
}
```

#### 13. 编写UserMessageWebController

```java
@RestController
@RequestMapping("/api")
public class UserMessageWebController {

//用户信息
    //查看/添加/删除/修改
    
    @Autowired
    CUserEntityRepository cUserEntityRepository;

//查询用户信息
    @GetMapping(value = "/userMessage")
    public String userMessage(HttpServletRequest request,
                  @RequestParam(value = "username",required = true) String username
    ){

CUserEntity cUserEntity = cUserEntityRepository.findFirstByUsername(username);
        if(cUserEntity == null){
            return new JsonCode<>().ResponseFail(99,"log_out");
        }

return new JsonCode<>().ResponseSuccess(cUserEntity);
    }

//添加用户信息
    @PostMapping(value = "/userMessage")
    public String addUserMessage(HttpServletRequest request,
                  @RequestParam(value = "username",required = true) String username,
                  @RequestParam(value = "phone",required = true) String phone
    ){

CUserEntity cUserEntity = new CUserEntity();
        cUserEntity.setUsername(username);
        cUserEntity.setPhone(phone);
        cUserEntityRepository.saveAndFlush(cUserEntity);

return new JsonCode<>().ResponseSuccess();
    }

//修改用户信息
    @PutMapping(value = "/userMessage")
    public String changeUserMessage(HttpServletRequest request,
                  @RequestParam(value = "username",required = true) String username,
                  @RequestParam(value = "phone",required = true) String phone
    ){

CUserEntity cUserEntity = cUserEntityRepository.findFirstByUsername(username);
        if(cUserEntity == null){
            return new JsonCode<>().ResponseFail(99,"log_out");
        }

cUserEntity.setPhone(phone);
        cUserEntityRepository.save(cUserEntity);
        return new JsonCode<>().ResponseSuccess();
    }

//删除用户信息
    @DeleteMapping(value = "/userMessage")
    public String deleteUserMessage(HttpServletRequest request,
                  @RequestParam(value = "username",required = true) String username
    ){

CUserEntity cUserEntity = cUserEntityRepository.findFirstByUsername(username);
        if(cUserEntity == null){
            return new JsonCode<>().ResponseFail(99,"log_out");
        }

cUserEntityRepository.delete(cUserEntity);
        return new JsonCode<>().ResponseSuccess();
    }
}
```

#### 14. 编写UserAddressWebController

```java
@RestController
@RequestMapping("/api")
public class UserAddressWebController {

@Autowired
    CAddressEntityRepository cAddressEntityRepository;

@Autowired
    CUserEntityRepository cUserEntityRepository;

@GetMapping(value = "/userAddress1")
    public String userAddress(HttpServletRequest request,
                  @RequestParam(value = "username",required = true) String username
    ){

CUserEntity cUserEntity = cUserEntityRepository.findFirstByUsername(username);
        if(cUserEntity == null){
            return new JsonCode<>().ResponseFail(99,"log_out");
        }

List<Map<String, Object>> address = cAddressEntityRepository.NativeFindByUserId(cUserEntity.getId());
        return new JsonCode<>().ResponseSuccess(address);
    }

@GetMapping(value = "/userAddress2")
    public String userAddress(HttpServletRequest request,
                  @RequestParam(value="page", required=true) int page,
                  @RequestParam(value = "id",required = false) int id,
                  @RequestParam(value = "username",required = false) String username,
                  @RequestParam(value = "phone",required = false) String phone
   ){

Pageable firstPageWithTwoElements = PageRequest.of(page, 10);
        Page<Map<String, Object>> address = cAddressEntityRepository.NativeFindAllByUsernameOrPhone(id,username,phone,firstPageWithTwoElements);

return new JsonCode<>().ResponseSuccess(address);
    }
}
```

####  15. 最后测试一下

```java
Swagger文档的地址: http://localhost:8081/swagger-ui.html#/

测试接口地址: http://localhost:8081/api/userMessage?username=张三
```

![](https://kuangstudy.oss-cn-beijing.aliyuncs.com/bbs/2020/12/04/kuangstudy8a0efde2-17e8-4379-94f7-86afbab34714.jpg)

```json
获得数据为: {"error_code":0,"error_message":"","data":{"id":4,"username":"张三","phone":"13622808877","createAt":"2020-10-14 00:00","updateAt":"2020-10-14 17:20"} }
```

#### 16. 总结

这是一个Spring Boot + JPA + Swagger的入门项目，主要是介绍一下如何在Spring Boot中使用JPA和Swagger，如果想要更加了解JPA的使用，还是需要自己更加深入地去学习一下的，可以看看B站的有关JPA的视频。学习是自己的，别人帮不了你多少，加油吧，骚年！

使用IDEA 从零开始搭建一个 Spring Boot + JPA + Swagger入门项目

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