springboot，简要记录，方便复习，

boot 笔记
第一步新建工程，导包，由于boot的数据库框架是用mybtis -paus,所以关于数据库系统那儿不用色选mybatis ,需要重新maven导包
完整导包以下人容：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.3</version>
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo_boot</artifactId>

    <properties>
    <version>0.0.1-SNAPSHOT</version>
        <java.version>1.8</java.version>
    </properties>

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

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.2</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.2.11</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.3.5.RELEASE</version>
            </plugin>
        </plugins>
    </build>

</project>

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.2</version>
</dependency>

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.11</version>
</dependency>
//下面那个组件目的是完成实体不需要set get，只需要加一个注解@data
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
</dependency>

第二步配，配置服务器端口，数据库 配置mybatis 的id 自增算法，还要配置日志系统不要显示全部信息，

server:
  port: 80
//配置数据库地址
spring:
  datasource:
    druid:
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://localhost:3306/xsytest
      username: root
      password: 142857
//配置表前缀
mybatis-plus:
  global-config:
    db-config:
      table-prefix: tbl_
//以下配配置id的自增算法
      id-type: auto
//配置日志系统的显示内容。
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
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第三步，编写dao数据库层，这儿只要写接口就好，先编写一个实体类，比如关于图书的表，就需要新建一个给数据库表相同字段的实体类，

import lombok.Data;
import lombok.Getter;

//使用lombok 就可以不在set get 设置了
@Data
public class Book {
    private Integer id;
    private String type;
    private String name;
}

传统配置方法一个方法对应一个sql查询语句;

@Mapper
public interface bookDao {
   @Select("select * from tbl_book where id = #{id}")
    Book getById(Integer id);

.........................................

传统定法太费时，mybatis-paus 为我们写好了全部方法，可能继承一个方法

@Mapper
public interface bookDao extends BaseMapper<Book> {}

这样常见的增删改方法就不用写了，可以在service层调用大部份数据库相关操作的方法.

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关于service，层取名一定要给业务相关，先定义接口，然后新建impl包，实现方法类：
举例如下：

import java.util.List;

public interface BookService {
   boolean save(Book book);
   boolean update(Book book);
   boolean delete(Integer id);
   Book getById(Integer id);
   List<Book> getAll();
  IPage<Book> getByPage(int currentPage, int pageSize);

}

++++++++++++++++++然后实现类实现上面方法：++++++++++++++++++++++++++++++++++++++++++++++++

import java.util.List;
@Service
public class BookServiceimpl2 implements BookService {

    @Autowired
    private bookDao bookDao;

    @Override
//    业务层都是逻辑规则，所以用返回布尔来判断
    public boolean save(Book book) {

        return bookDao.insert(book) > 0;
    }

    @Override
    public boolean update(Book book) {

        return bookDao.updateById(book) >0;

    }

    @Override
    public boolean delete(Integer id) {
        return bookDao.deleteById(id) > 0;
    }

    @Override
    public Book getById(Integer id) {
        return bookDao.selectById(id);
    }

    @Override
    public List<Book> getAll() {
        return bookDao.selectList(null);
    }
    @Override
    public IPage<Book> getByPage(int currentPage, int pageSize) {
        IPage page = new Page(currentPage,pageSize);
        bookDao.selectPage(page,null);
        return page;
    }
}

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由于都是操作增改，mybatis 帮我们也提供了更多方法，就边业务层都是可以不写的，但是很多方法不能解决实际场景时，可以重新写，但尽量不要改写框架也有的
以下是示例，

第一步定义业务层接口

public interface IBookService extends IService<Book> {

boolean saveBook(Book book);
boolean modify(Book book);
boolean delect(Integer id);
//Book select(Integer id);
IPage<Book> getPage(int currentpage, int pagesize) ;
}

第二步实现具体业务层

@Service
public class IbookServiceimpl extends ServiceImpl<bookDao, Book> implements IBookService {

   @Autowired
   private bookDao bookDao;

    @Override
    public boolean saveBook(Book book) {
        return bookDao.insert(book) > 0;
    }

    @Override
    public boolean modify(Book book) {
       return bookDao.updateById(book) >0;
    }

    @Override
    public boolean delect(Integer id) {
        return bookDao.deleteById(id) > 0;
    }

    @Override
    public IPage<Book> getPage(int currentpage, int pagesize) {
//        Page page = new Page(currentpage, pagesize);
//        bookDao.selectPage(page, null);
//        return page;

        IPage page = new Page(currentpage,pagesize);
        bookDao.selectPage(page,null);
        return page;
    }

//
//    @Override
//    public Book select(Integer id) {
//        return bookDao.selectById(id);
//
//    }
}

mybatis-paus 自动构建的业务层方法操作数据库方法与dao 有点出入

到此为止，整个底层，业务层建 那了可以编写测试类，测试类的目录要和开发的目录一样
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dao测试文件

@SpringBootTest
public class bookDaotext {

    @Autowired
    private bookDao bookDao;

    @Test
void testGetById(){
//        System.out.println(bookDao.selectById(3));
//        System.out.println(bookDao.selectList(null));
    }

     @Test
    void testGetPage(){
        IPage page = new Page(1,6);
        bookDao.selectPage(page, null);
//        通过以下的方法可以获取当前页，共几页等前端需要的数据
        System.out.println(page.getCurrent());
         System.out.println(page.getSize());
         System.out.println(page.getTotal());
         System.out.println(page.getPages());
         System.out.println(page.getRecords());
    }

    @Test
//    按条析查询
    void testGetBy(){
        QueryWrapper<Book> qw = new QueryWrapper<>();
//        qw.eq,qw.??所有条件方法都在qw上
        qw.like("name", "rrrr");
        bookDao.selectList(qw);
    }
   //条件查询方法中强制指定参数的方法
    void testGetBy2(){
        LambdaQueryWrapper<Book> lqw = new LambdaQueryWrapper<Book>();
        String name = "Spring";
//        为了防止参数为空，方法一
//        if(name != null ) lqw.like(Book::getName,name);
//        方法二
       lqw.like(name !=null,Book::getName,name);
        bookDao.selectList(lqw);

    }

业务层测试文件

@SpringBootTest
public class BookServiceTest {
    @Autowired
    private BookService bookService;

    @Test
    void testGetById(){
        System.out.println( "运行结果为"+bookService.getById(4));
    }

//    测保存方法
    @Test
    void testSave(){
         Book book = new Book();
         book.setName("黄金枝");
         book.setType("name_vv");
         bookService.save(book);
    }

@Test
void testUpdate(){
        Book book = new Book();
         book.setId(16);
         book.setName("kk151515");
         book.setType("u151515");
         bookService.update(book);

}

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然后编写控制层。

import java.util.List;
@RestController
@RequestMapping("/books")
public class BookController {
    @Autowired
    private IBookService bookService;
    @GetMapping
    public List<Book> getAll(){
        return bookService.list();
    }
    @PostMapping
    public Boolean save(@RequestBody Book book){
        return bookService.save(book);
    }
    @PutMapping
    public Boolean update(@RequestBody Book book){
        return bookService.modify(book);
    }
    @DeleteMapping("{id}")
    public boolean delect(@PathVariable Integer id){
        return bookService.delect(id);
    }
    @GetMapping("{id}")
    public Book getById(@PathVariable Integer id){
        return bookService.getById(id);
    }
    @GetMapping("/{currentpage}/{pagesize}")
    public IPage<Book> getPage(@PathVariable  int currentpage,@PathVariable int pagesize){
       return bookService.getPage(currentpage, pagesize);
    }

}

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由于前端交互数据需要统一数据，这儿需要专门定义一个类用来返回数据，将数据封装后返回：
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

@Data
public class R {
    private Boolean flag;
    private Object data;
    public R(){}
    public R(Boolean flag){
        this.flag = flag;
    }
    public R(Boolean flag, Object data){
        this.flag = flag;
        this.data = data;
    }
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

@RestController
@RequestMapping("/books")
public class BookController {
    @Autowired
    private IBookService bookService;
    @GetMapping
    public R getAll(){
         return new R(true,bookService.list());
//        return bookService.list();
    }
    @PostMapping
    public R save(@RequestBody Book book){
        return new R(bookService.save(book));
    }

    @PutMapping
    public R update(@RequestBody Book book){

        return new R(bookService.modify(book));
    }
    @DeleteMapping("{id}")
    public R delect(@PathVariable Integer id){
        return new R(bookService.delect(id));
       // return bookService.delect(id);
    }
    @GetMapping("{id}")
    public R getById(@PathVariable Integer id){
         return new R(true, bookService.getById(id));
//        return bookService.getById(id);
    }
    @GetMapping("/{currentpage}/{pagesize}")
    public R getPage(@PathVariable  int currentpage,@PathVariable int pagesize){
        return new R(true, bookService.getPage(currentpage, pagesize));

        //       return bookService.getPage(currentpage, pagesize);
    }

}
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