SpringBoot写接口不需要mybatis-plus
## 项目文件夹名称
新建的项目在/src/java/com.你的项目名字/新建四个Package文件夹分别叫 controller，Mapper，entry，service
controller：控制层 ，dao(mapper)：数据层，service：服务层，domin/entry：实体类
编写application
在项目文档中，打开 /src/resources/application.yml配置文件
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| server:
port: 8080
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/db1?characterEncoding=utf-8&useSSl=false&serverTimezone=UTC
username: root
password: 123456
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编写实体类
在entry文件夹下，创建一个实体类，名称为Student.java。注：名称也可以为个人所需要编写的实体类。
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| @Data
@AllArgsConstructor
@NoArgsConstructor
public class Student {
@TableId(value = "id", type = IdType.AUTO)
private Integer id;
private String username;
private String password;
private String email;
private String phone;
public Student() {
}
public Student(Integer id, String username, String password, String email, String phone) {
this.id = id;
this.username = username;
this.password = password;
this.email = email;
this.phone = phone; }
public Integer getId() {
return id;}
public void setId(Integer id) {
this.id = id;}
public String getUsername() {
return username;}
public void setUsername(String username) {
this.username = username;}
public String getPassword() {
return password;}
public void setPassword(String password) {
this.password = password;}
public String getEmail() {
return email;}
public void setEmail(String email) {
this.email = email;}
public String getPhone() {
return phone;}
public void setPhone(String phone) {
this.phone = phone;}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", email='" + email + '\'' +
", phone='" + phone + '\'' +
'}';}}
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编写Mapper/Dao接口
添加一条数据
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| @Insert("insert into student (username, password, email, phone) values(#{username}, #{password}, #{email}, #{phone})")
public int insert(Student student);
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删除一条数据
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| @Delete("delete from student where id = #{id}")
public int delete(Integer id);
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修改一条数据
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| @Update("update student set username = #{username}, password = #{password}, email = #{email}, phone = #{phone} where id = #{id}")
public int update(Student student);
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查找一条数据
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| @Select("select * from student where id = #{id}")
public Student getById(Integer id);
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查找全部数据
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| @Select("select * from student")
public List<Student> getAll();
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service
新建一个接口
我取名为StudentService
可以按照个人写接口名称
使用布尔值Boolean来进行判断是否增加、修改、删除成功
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| boolean insert(Student student);
boolean update(Student student);
boolean delete(Integer id);
Student getById(Integer id);
List<Student> getAll();
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在service文件夹下新建一个Package，名称为impl
在impl文件夹下新建一个名为StudentServiceimpl.java类 名字按个人所需要去编写
注意：千万不要忘记@Service
然后连接service 文件夹下StudentService接口
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| @Service
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentMapper studentMapper;
@Override
public boolean insert(Student student) {
return studentMapper.insert(student) > 0;
}
@Override
public boolean update(Student student) {
return studentMapper.update(student) > 0;
}
@Override
public boolean delete(Integer id) {
return studentMapper.delete(id) > 0;
}
@Override
public Student getById(Integer id) {
return studentMapper.getById(id);
}
@Override
public List<Student> getAll() {
return studentMapper.getAll();
}
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Controller
在Controller文件下创建三个.java类 分别为Code、Result、StudentController
注解：
@Autowired 可以对类成员``变量、方法及构造函数进行标注，完成自动装配的工作
@GetMapping，处理get请求
@PostMapping，处理post请求
@PutMapping，处理put请求
@DeleteMapping，处理delete请求
@RequestBody：主要用来接收前端传递给后端的json字符串中的数据的
@PathVariable ：通过 @PathVariable 可以将 URL 中占位符参数绑定到控制器处理方法的入参中:URL 中的 {xxx} 占位符可以通过
第一步：编写Result.java
以下数据给StudentController.java 用于调用
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| public class Result {
private Integer code;
private Object data;
private String msg;
public Result(Integer code, Object data) {
this.code = code;
this.data = data;
}
public Result(Integer code, Object data, String msg) {
this.code = code;
this.data = data;
this.msg = msg;
}
public Integer getCode() {
return code;
}
public void setCode(Integer code) {
this.code = code;
}
public Object getData() {
return data;
}
public void setData(Object data) {
this.data = data;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
}
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第二步：编写Code.java
什么是final？
final是java中的一个关键字，意思为恒定不变。 java中final数据具体有两个含义：1、对于基本数据类型，表示永不改变的编译时常量；2、对于普通对象，表示该引用恒定不变，不能指向另外一个对象，但是该对象本身是可以进行修改的。
以下代码用于在StudentController.java中用于输出。例如：添加成功输出20001 否则输出2002
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| public class Code {
public static final Integer INSERT_OK = 20001;
public static final Integer INSERT_ERR = 20002;
public static final Integer UPDATE_OK = 20011;
public static final Integer UPDATE_ERR = 20012;
public static final Integer DELETE_OK = 20021;
public static final Integer DELETE_ERR = 20022;
public static final Integer SELECT_OK = 20031;
public static final Integer SELECT_ERR = 20032;
}
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第三步：编写StudentController.java
注意不要在开头忘了@RestController和@RequestMapping("/路径")
添加数据
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| @PostMapping
public Result insert(@RequestBody Student student){
boolean flag = studentService.insert(student);
return new Result(flag? Code.INSERT_OK: Code.INSERT_ERR, flag);
}
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修改
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| @PutMapping
public Result update(@RequestBody Student student){
boolean flag = studentService.update(student);
return new Result(flag? Code.UPDATE_OK: Code.UPDATE_ERR, flag);
}
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删除
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| @DeleteMapping("/{id}")
public Result delete(@PathVariable Integer id){
boolean flag = studentService.delete(id);
return new Result(flag? Code.DELETE_OK: Code.DELETE_ERR, flag);
}
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查询一条数据
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| @GetMapping("/{id}")
public Result getById(@PathVariable Integer id){
Student student = studentService.getById(id);
if (student == null){
return new Result(Code.SELECT_ERR, "查询失败");
}
Integer code = student != null? Code.SELECT_OK: Code.SELECT_ERR;
String msg = student != null? "查询成功": "查询失败";
return new Result(code, student, msg);
}
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查询全部数据
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| @GetMapping
public Result getAll(){
List<Student> studentList = studentService.getAll();
Integer code = studentList != null? Code.SELECT_OK: Code.SELECT_ERR;
String msg = studentList != null? "查询成功": "查询失败";
return new Result(code, studentList, msg);
}
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