原創作品，可以轉載，但是請標註出處地址：https://www.cnblogs.com/V1haoge/p/9971036.html

SpringBoot整合Mybatis

步驟

第一步：新增必要的jar包

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.1</version>
</dependency>
 

第二步：新增必要的配置

application.properties

##配置資料來源
spring.datasource.url = jdbc:h2:mem:dbtest
spring.datasource.username = sa
spring.datasource.password = sa
spring.datasource.driverClassName =org.h2.Driver

第三步：新增配置類

// 該配置類用於配置自動掃描器，用於掃描自定義的mapper介面,MyBatis會針對這些介面生成代理來呼叫對應的XMl中的SQL
@Configuration
@MapperScan("com.example.springbootdemo.mapper")
public class MyBatisConfig {
}
 

這個註解必須手動配置是因為mapper介面的位置完全就是使用者自定義的，自動配置的時候也不可能找到還不存在的位置。

第四步：定義實體型別

@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
@EqualsAndHashCode
@Builder
@ApiModel("書籍模型")
public class Book {
    @ApiModelProperty(value = "書籍ID", notes = "書籍ID",example = "1")
    private Integer bookId;
    @ApiModelProperty(value = "書籍頁數", notes = "書籍頁數",example = "100")
    private Integer pageNum;
    @ApiModelProperty(value = "書籍名稱", notes = "書籍名稱",example = "Java程式設計思想")
    private String bookName;
    @ApiModelProperty(value = "書籍型別", notes = "書籍型別",hidden = false)
    private BookType BookType;
    @ApiModelProperty(value = "書籍簡介")
    private String bookDesc;
    @ApiModelProperty(value = "書籍價格")
    private Double bookPrice;
    @ApiModelProperty(value = "建立時間",hidden = true)
    private LocalDateTime createTime;
    @ApiModelProperty(value = "修改時間",hidden = true)
    private LocalDateTime modifyTime;
}
 

還有一個列舉型別

public enum BookType {
    TECHNOLOGY,//技術
    LITERARY,//文學
    HISTORY//歷史
    ;
}

實體類中使用了swagger2和Lombok中的註解，需要新增對應的jar包

第五步：定義mapper介面

public interface BookRepository {
    int addBook(Book book);
    int updateBook(Book book);
    int deleteBook(int id);
    Book getBook(int id);
    List<Book> getBooks(Book book);
}

第六步：定義mapper配置

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.springbootdemo.mapper.BookRepository">
    <insert id="addBook" parameterType="Book">
        INSERT INTO BOOK(
        <if test="pageNum != null">
            PAGE_NUM,
        </if>
        <if test="bookType != null">
            BOOK_TYPE,
        </if>
        <if test="bookName != null">
            BOOK_NAME,
        </if>
        <if test="bookDesc != null">
            BOOK_DESC,
        </if>
        <if test="bookPrice != null">
            BOOK_PRICE,
        </if>
            CREATE_TIME,
            MODIFY_TIME)
        VALUES (
        <if test="pageNum != null">
            #{pageNum},
        </if>
        <if test="bookType != null">
            #{bookType},
        </if>
        <if test="bookName != null">
            #{bookName},
        </if>
        <if test="bookDesc != null">
            #{bookDesc},
        </if>
        <if test="bookPrice != null">
            #{bookPrice},
        </if>
        sysdate,sysdate)
    </insert>
    <update id="updateBook" parameterType="Book">
        UPDATE BOOK SET
        <if test="pageNum != null">
            PAGE_NUM = #{pageNum},
        </if>
        <if test="bookType != null">
            BOOK_TYPE = #{bookType},
        </if>
        <if test="bookDesc != null">
            BOOK_DESC = #{bookDesc},
        </if>
        <if test="bookPrice != null">
            BOOK_PRICE = #{bookPrice},
        </if>
        <if test="bookName != null">
            BOOK_NAME = #{bookName},
        </if>
        MODIFY_TIME=sysdate
        WHERE 1=1
        <if test="bookId != null">
            and BOOK_ID = #{bookId}
        </if>
    </update>
    <delete id="deleteBook" parameterType="int">
        delete from BOOK where BOOK_id=#{bookId}
    </delete>
    <select id="getBook" parameterType="int" resultMap="bookResultMap">
        select * from BOOK where BOOK_ID=#{bookId}
    </select>
    <select id="getBooks" resultMap="bookResultMap">
        select * from BOOK WHERE 1=1
        <if test="bookId != null">
            and BOOK_ID = #{bookId}
        </if>
        <if test="pageNum != null">
            and PAGE_NUM = #{pageNum}
        </if>
        <if test="bookType != null">
            and BOOK_TYPE = #{bookType}
        </if>
        <if test="bookDesc != null">
            and BOOK_DESC = #{bookDesc}
        </if>
        <if test="bookPrice != null">
            and BOOK_PRICE = #{bookPrice}
        </if>
        <if test="bookName != null">
            and BOOK_NAME = #{bookName}
        </if>
    </select>
    <resultMap id="bookResultMap" type="Book">
        <id column="BOOK_ID" property="bookId"/>
        <result column="PAGE_NUM" property="pageNum"/>
        <result column="BOOK_NAME" property="bookName"/>
        <result column="BOOK_TYPE" property="bookType"/>
        <result column="BOOK_DESC" property="bookDesc"/>
        <result column="BOOK_PRICE" property="bookPrice"/>
        <result column="CREATE_TIME" property="createTime"/>
        <result column="MODIFY_TIME" property="modifyTime"/>
    </resultMap>
</mapper>

在這個配置檔案中我們使用了MyBatis的動態SQL和引數對映

第七步：再次新增必要的配置

application.properties

#配置Xml配置的位置
mybatis.mapper-locations=classpath*:/mapper/*.xml
#配置實體類型別名
mybatis.type-aliases-package=com.example.springbootdemo.entity

這裡的兩個配置也和之前的掃描器註解一樣，都是自動配置時未知的，需要手動配置，當然可能會存在預設的位置，但是一旦我們自定義了，就必須手動新增配置

第八步：定義service和controller

@Service
@Log4j2
public class BookService {
    
    @Autowired
    private BookRepository bookRepository;
    
    public ResponseEntity<Book> addBook(final Book book) {
        int num = bookRepository.addBook(book);
        return ResponseEntity.ok(book);
    }
    
    public ResponseEntity<Integer> updateBook(final Book book){
        return ResponseEntity.ok(bookRepository.updateBook(book));
    }
    
    public ResponseEntity<Integer> deleteBook(final int bookId){
        return ResponseEntity.ok(bookRepository.deleteBook(bookId));
    }
    
    public ResponseEntity<Book> getBook(final int bookId) {
        Book book = bookRepository.getBook(bookId);
        return ResponseEntity.ok(book);
    }
    
    public ResponseEntity<List<Book>> getBooks(final Book book){
        return ResponseEntity.ok(bookRepository.getBooks(book));
    }
    
}

@RestController
@RequestMapping("/book")
@Api(description = "書籍介面")
@Log4j2
public class BookApi {
    @Autowired
    private BookService bookService;
    
    @RequestMapping(value = "/addBook", method = RequestMethod.PUT)
    @ApiOperation(value = "新增書籍", notes = "新增一本新書籍", httpMethod = "PUT")
    public ResponseEntity<Book> addBook(final Book book){
        return bookService.addBook(book);
    }
    
    @RequestMapping(value = "/updateBook", method = RequestMethod.POST)
    @ApiOperation(value = "更新書籍", notes = "根據條件更新書籍資訊", httpMethod = "POST")
    public ResponseEntity<Integer> updateBook(final Book book){
        return bookService.updateBook(book);
    }
    
    @RequestMapping(value = "/deleteBook", method = RequestMethod.DELETE)
    @ApiOperation(value = "獲取一本書籍", notes = "根據ID獲取書籍", httpMethod = "DELETE")
    public ResponseEntity<Integer> deleteBook(final int bookId){
        return bookService.deleteBook(bookId);
    }
    
    @RequestMapping(value = "/getBook", method = RequestMethod.GET)
    @ApiOperation(value = "獲取一本書籍", notes = "根據ID獲取書籍", httpMethod = "GET")
    public ResponseEntity<Book> getBook(final int bookId){
        return bookService.getBook(bookId);
    }
    
    @RequestMapping(value = "/getBooks", method = RequestMethod.GET)
    @ApiOperation(value = "獲取書籍", notes = "根據條件獲取書籍", httpMethod = "GET")
    public ResponseEntity<List<Book>> getBooks(final Book book){
        return bookService.getBooks(book);
    }
}

這裡使用了swagger2的註解
至此設定完畢。

第十步：瀏覽器訪問

http://localhost:8080/swagger-ui.html

通過swagger介面可以看到我們定義的介面。

高階功能

分頁（兩種，簡單分頁RowBounds和攔截器分頁，外掛）

RowBounds分頁

使用RowBounds分頁適用於小資料量的分頁查詢
使用方式是在查詢的Mapper介面上新增RowBounds引數即可，service傳參時需要指定其兩個屬性，當前頁和每頁數

1-定義分頁模型

@Data
@Builder
@ToString
@EqualsAndHashCode
@NoArgsConstructor
@AllArgsConstructor
public class MyPage<T> {
    private Integer pageId;//當前頁
    private Integer pageNum;//總頁數
    private Integer pageSize;//每頁數
    private Integer totalNum;//總數目
    private List<T> body;//分頁結果
    private Integer srartIndex;//開始索引
    private boolean isMore;//是否有下一頁
}

2-定義mapper

public interface BookRepository {
    
    // 省略多餘內容
    
    int count(Book book);
    List<Book> getBooks(Book book, RowBounds rowBounds);
}

BookRepository.xml

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.springbootdemo.mapper.BookRepository">
   
    <!--省略多餘內容-->
    
    <select id="getBooks" resultMap="bookResultMap">
        select * from BOOK WHERE 1=1
        <if test="bookId != null">
            and BOOK_ID = #{bookId}
        </if>
        <if test="pageNum != null">
            and PAGE_NUM = #{pageNum}
        </if>
        <if test="bookType != null">
            and BOOK_TYPE = #{bookType}
        </if>
        <if test="bookDesc != null">
            and BOOK_DESC = #{bookDesc}
        </if>
        <if test="bookPrice != null">
            and BOOK_PRICE = #{bookPrice}
        </if>
        <if test="bookName != null">
            and BOOK_NAME = #{bookName}
        </if>
    </select>
    <select id="count" resultType="int">
        select count(1) from BOOK WHERE 1=1
        <if test="bookId != null">
            and BOOK_ID = #{bookId}
        </if>
        <if test="pageNum != null">
            and PAGE_NUM = #{pageNum}
        </if>
        <if test="bookType != null">
            and BOOK_TYPE = #{bookType}
        </if>
        <if test="bookDesc != null">
            and BOOK_DESC = #{bookDesc}
        </if>
        <if test="bookPrice != null">
            and BOOK_PRICE = #{bookPrice}
        </if>
        <if test="bookName != null">
            and BOOK_NAME = #{bookName}
        </if>
    </select>
    <resultMap id="bookResultMap" type="Book">
        <id column="BOOK_ID" property="bookId"/>
        <result column="PAGE_NUM" property="pageNum"/>
        <result column="BOOK_NAME" property="bookName"/>
        <result column="BOOK_TYPE" property="bookType"/>
        <result column="BOOK_DESC" property="bookDesc"/>
        <result column="BOOK_PRICE" property="bookPrice"/>
        <result column="CREATE_TIME" property="createTime"/>
        <result column="MODIFY_TIME" property="modifyTime"/>
    </resultMap>
</mapper>

3-定義service

@Service
@Log4j2
public class BookService {
    
    @Autowired
    private BookRepository bookRepository;
    // 省略多餘內容
    // 使用RowBounds實現分頁
    public ResponseEntity<MyPage<Book>> getBooksByRowBounds(int pageId,int pageSize){
        MyPage<Book> myPage = new MyPage<>();
        myPage.setPageId(pageId);
        myPage.setPageSize(pageSize);
        List<Book> books = bookRepository.getBooks(Book.builder().build(), new RowBounds(pageId,pageSize));
        int totalNum = bookRepository.count(Book.builder().build());
        myPage.setBody(books);
        myPage.setTotalNum(totalNum);
        return ResponseEntity.ok(myPage);
    }
}

4-定義controller

@RestController
@RequestMapping("/book")
@Api(description = "書籍介面")
@Log4j2
public class BookApi {
   
    @Autowired
    private BookService bookService;
    // 省略多餘內容
    @RequestMapping(value = "/getBooksPageByRowBounds", method = RequestMethod.GET)
    @ApiOperation(value = "分頁獲取書籍", notes = "通過RowBounds分頁獲取書籍", httpMethod = "GET")
    public ResponseEntity<PageInfo<Book>> getBooksPageByRowBounds(final int pageId, final int pageNum){
        return bookService.getBooksByRowBounds(pageId, pageNum);
    }
    
}

攔截器分頁

當面對大資料量的分頁時，RowBounds就力不從心的，這時需要我們使用分頁攔截器實現分頁。
這裡其實可以直接使用外掛PageHelper，其就是以攔截器技術實現的分頁查詢外掛。
具體使用方法見SpringBoot整合MyBatis分頁外掛PageHelper

自定義型別轉換器（列舉轉換器）

public class BookTypeEnumHandler extends BaseTypeHandler<BookType> {
    /**
     * 用於定義設定引數時，該如何把Java型別的引數轉換為對應的資料庫型別
     */
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, BookType parameter, JdbcType jdbcType) throws SQLException {
        int j = 0;
        for (BookType bookType : BookType.values()){
            if(bookType.equals(parameter)){
                ps.setString(i, j +"");
                return;
            }
            j++;
        }
    }
    /**
     * 用於定義通過欄位名稱獲取欄位資料時，如何把資料庫型別轉換為對應的Java型別
     */
    @Override
    public BookType getNullableResult(ResultSet rs, String columnName) throws SQLException {
        int j = Integer.valueOf(rs.getString(columnName));
        if(j >= BookType.values().length) {
            return null;
        }
        int i = 0;
        for(BookType bookType:BookType.values()){
            if(j == i){
                return bookType;
            }
            i++;
        }
        return null;
    }
    /**
     * 用於定義通過欄位索引獲取欄位資料時，如何把資料庫型別轉換為對應的Java型別
     */
    @Override
    public BookType getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        return null;
    }
    /**
     * 用定義呼叫儲存過程後，如何把資料庫型別轉換為對應的Java型別
     */
    @Override
    public BookType getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        return null;
    }
}

使用@Mapper（不常用，可不看）

注意：使用@Mapper註解的時候是不需要新增xml配置Mapper檔案的，SQL指令碼在介面方法的註解內部定義

第一步：定義實體類

@Data
@Builder
@ToString
@EqualsAndHashCode
@NoArgsConstructor
@AllArgsConstructor
public class Tree {
    private Integer treeId;
    private String treeName;
    private Integer treeAge;
    private Double treeHight;
    private TreeType treeType;
    private TreeState treeState;
    private String treeDesc;
}

第二步：定義持久層

@Mapper
public interface TreeRepository {
    
    @Insert("INSERT INTO TREE (TREE_NAME,TREE_AGE,TREE_HIGHT,TREE_TYPE,TREE_STATE,TREE_DESC) VALUES (#{treeName},#{treeAge},#{treeHight},#{treeType},#{treeState},#{treeDesc}) ")
    int addTree(Tree tree);
    
    // 此處treeState是一個列舉，此處執行一直報錯
    @Update("UPDATE TREE SET TREE_STATE=#{treeState} WHERE TREE_ID=#{treeId}")
    int updateState(final int treeId, final TreeState treeState);
    
    @Delete("DELETE FROM TREE WHERE TREE_ID=#{treeId}")
    int deleteTree(final int treeId);
    
    @Results({
            @Result(id = true, column = "TREE_ID",property = "treeId"),
            @Result(column = "TREE_NAME",property = "treeName"),
            @Result(column = "TREE_AGE", property = "treeAge"),
            @Result(column = "TREE_HIGHT",property = "treeHight"),
            @Result(column = "TREE_TYPE",property = "treeType",typeHandler = EnumOrdinalTypeHandler.class),
            @Result(column = "TREE_STATE",property = "treeState",typeHandler = EnumOrdinalTypeHandler.class),
            @Result(column = "TREE_DESC", property = "treeDesc")
    })
    @Select("SELECT * FROM TREE WHERE TREE_ID=#{treeId}")
    Tree getTree(final int treeId);
    
    @Results({
            @Result(id = true, column = "TREE_ID",property = "treeId"),
            @Result(column = "TREE_NAME",property = "treeName"),
            @Result(column = "TREE_AGE", property = "treeAge"),
            @Result(column = "TREE_HIGHT",property = "treeHight"),
            @Result(column = "TREE_TYPE",property = "treeType",typeHandler = EnumOrdinalTypeHandler.class),
            @Result(column = "TREE_STATE",property = "treeState",typeHandler = EnumOrdinalTypeHandler.class),
            @Result(column = "TREE_DESC", property = "treeDesc")
    })
    @Select("SELECT * FROM TREE")
    List<Tree> getTrees(RowBounds rowBounds);
}

注意：重點就在這個介面中，我們新增介面註解@Mapper，表示這是一個持久層Mapper,它的例項化依靠SpringBoot自動配置完成。
在介面方法上直接新增對應的執行註解，在註解中直接定義SQL，這種SQL仍然可以使用表示式#{}來獲取引數的值。
注意@Result註解中定義的兩個關於列舉的型別處理器EnumOrdinalTypeHandler，其實其為MyBatis內部自帶的兩種列舉處理器之一，
用於儲存列舉序號，還有一個EnumTypeHandler用於儲存列舉名稱。

第三步：定義service和controller

@Service
@Log4j2
public class TreeService {
    
    @Autowired
    private TreeRepository treeRepository;
    
    public ResponseEntity<Tree> addTree(final Tree tree){
        treeRepository.addTree(tree);
        return ResponseEntity.ok(tree);
    }
    
    public ResponseEntity<Tree> updateTree(final int treeId, final TreeState treeState){
        treeRepository.updateState(treeId,treeState);
        return ResponseEntity.ok(Tree.builder().treeId(treeId).treeState(treeState).build());
    }
    
    public ResponseEntity<Integer> deleteTree(final int treeId){
        return ResponseEntity.ok(treeRepository.deleteTree(treeId));
    }
    
    public ResponseEntity<Tree> getTree(final int treeId){
        return ResponseEntity.ok(treeRepository.getTree(treeId));
    }
   
    public ResponseEntity<MyPage<Tree>> getTrees(final int pageId,final int pageSize){
        List<Tree> trees = treeRepository.getTrees(new RowBounds(pageId,pageSize));
        MyPage<Tree> treeMyPage = new MyPage<>();
        treeMyPage.setPageId(pageId);
        treeMyPage.setPageSize(pageSize);
        treeMyPage.setBody(trees);
        return ResponseEntity.ok(treeMyPage);
    }
}

@RestController
@RequestMapping("/tree")
@Api(description = "樹木介面")
public class TreeApi {
   
    @Autowired
    private TreeService treeService;
    
    @RequestMapping(value = "/addTree",method = RequestMethod.PUT)
    @ApiOperation(value = "新增樹木",notes = "新增新樹木",httpMethod = "PUT")
    public ResponseEntity<Tree> addTree(final Tree tree){
        return treeService.addTree(tree);
    }
    
    @RequestMapping(value = "/updateTree",method = RequestMethod.POST)
    @ApiOperation(value = "更新狀態",notes = "修改樹木狀態",httpMethod = "POST")
    public ResponseEntity<Tree> updateTree(final int treeId,final TreeState treeState){
        return treeService.updateTree(treeId,treeState);
    }
    
    @ApiOperation(value = "獲取樹木",notes = "根據ID獲取一棵樹",httpMethod = "GET")
    @RequestMapping(value = "/getTree",method = RequestMethod.GET)
    public ResponseEntity<Tree> getTree(final int treeId){
        return treeService.getTree(treeId);
    }
}

注意：這個例子中更新狀態的時候還是無法成功，這個狀態是列舉值