The first project

Creating a Maven project

pom


      
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>springbbot</groupId>
    <artifactId>mybatisannotation</artifactId>
    <version>1.0 the SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.2. RELEASE</version>
    </parent>

    <dependencies>

        <! --springMVC-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <! --mybatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>

        <! ---->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>


    </dependencies>

</project>
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Yml file

mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
# Development configuration
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/test3? characterEncoding=utf-8
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
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Start the class

@SpringBootApplication
// Scan the Mapper interface
@MapperScan(basePackages={"com.mapper"})
public class App {
    public static void main(String[] args) { SpringApplication.run(App.class,args); }}Copy the code

The mapper class

package com.mapper;
import org.apache.ibatis.annotations.Select;
import java.util.List;
import java.util.Map;
public interface UserMapper {
    @Select("select id,userName from user")
    public List<Map<String,Object>> getMaps();
}
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controller

package com.controller;
import com.mapper.UserMapper;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
import java.util.List;
import java.util.Map;
@RestController
public class UserController {
    @Resource
    UserMapper userMapper;
    @RequestMapping("/getUser")
    public List<Map<String,Object>> getUsers(){
        List<Map<String, Object>> maps = userMapper.getMaps();
        returnmaps; }}Copy the code

Other cases

Return Map(one parameter)

public interface UserMapper {
    // If you pass in only one argument, #{
    @Select("select id,userName,password from user where id = #{id}")
    public Map<String,Object> getMap(Integer id);
}
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@Resource
UserMapper userMapper;
@RequestMapping("/getUser")
public Map<String,Object> getUser(){
    Map<String, Object> map = userMapper.getMap(1);
    return map;
}
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Return Map(multiple parameters)

@select (" Select id,userName,password from user where id = #{id} ") and userName = #{userName}") public Map<String,Object> getMap(Integer id,String userName); }Copy the code

@Resource
UserMapper userMapper;

@RequestMapping("/getUser")
public Map<String,Object> getUser(a){
    Map<String, Object> map = userMapper.getMap(1."zhangsan");
    return map;
}
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Return List Map

@Resource
UserMapper userMapper;

@RequestMapping("/getUsers")
public List<Map<String,Object>> getUsers(){
    List<Map<String, Object>> maps = userMapper.getMaps();
    return maps;
}
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public interface UserMapper {
    @Select("select id,userName from user")
    public List<Map<String,Object>> getMaps();
}
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Returns the Entity

public interface UserMapper {
 @Select
 ("select id,userName,password from user where id = #{id} and userName = #{userName}")
 public User getUser(Integer id, String userName);
}
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@Resource
UserMapper userMapper;
@RequestMapping("/getUser")
public User getUser(a){
    User user = userMapper.getUser(1."zhangsan");
    return user;
}
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Return List Entity

public interface UserMapper {
    @Select("select id,userName from user")
    public List<User> getUsers(a);
}
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@Resource
UserMapper userMapper;

@RequestMapping("/getUsers")
public List<User> getUsers(a){
    List<User> users = userMapper.getUsers();
    return users;
}
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Resuts annotations

Pass parameters to the statement

The Map

public interface UserMapper {
    @Select("select * from user where id = #{id}")
    public User getUser(Map map);
}
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@Resource
UserMapper userMapper;
@RequestMapping("/getUser")
public User aaa(a){
    Map map = new HashMap();
    map.put("id".1);
    userMapper.getUser(map);
    return  null;
}
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The Entity

@Select("select * from user where id = #{id}")  //id
public User getUser2(User user);
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@RequestMapping("/getUser2")
public User getUser2(a){
    User user = new User();
    user.setId(1);
    User user2 = userMapper.getUser2(user);
    return  user2;
}
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To obtain parameters

Get a single parameter

public interface UserMapper {
    // If you pass in only one argument, #{
    @Select("select id,userName,password from user where id = #{id}")
    public Map<String,Object> getMap(Integer id);
}
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Get parameters by index

@Select("select * from user where id = #{param1} and userName=#{param2}")  //id
public User getUser3(Integer id,String userName);
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Get parameters with annotations (plain parameters)

@Select("select * from user where id = #{a} and userName=#{b}")  //id
public User getUser3(@Param("a") Integer id, @Param("b")String userName);
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Get parameters through annotations (object parameters)

@Select("select * from user where id = #{abc.id}")  //id
public User getUser2(@Param("abc") User user);
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Get parameters through annotations (Map parameters)

    @Select("select * from user where id = #{a.id}")
    public User getUser(@Param("a") Map map);

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@Resource
UserMapper userMapper;
@RequestMapping("/getUser")
public User aaa(a){
    Map map = new HashMap();
    map.put("id".1);
    User user = userMapper.getUser(map);
    return  user;
}
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Note the use of Results

    @Select("select id,userName,password from user where id = #{a.id}")
    @Results({ @Result(property = "id2",column = "id"), @Result(property = "userName2",column = "userName"), @Result(property = "password2",column = "passwords") })
    public User2 getUser2(Integer id);
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public class User2 {
    private Integer id2;
    private String userName2;
    private  String password2;

    public Integer getId2(a) {
        return id2;
    }
    public void setId2(Integer id2) {
        this.id2 = id2;
    }

    public String getUserName2(a) {
        return userName2;
    }

    public void setUserName2(String userName2) {
        this.userName2 = userName2;
    }

    public String getPassword2(a) {
        return password2;
    }

    public void setPassword2(String password2) {
        this.password2 = password2;
    }

    @Override
    public String toString(a) {
        return "User2{" +
                "id2=" + id2 +
                ", userName2='" + userName2 + '\' ' +
                ", password2='" + password2 + '\' ' +
                '} '; }}Copy the code

More than a pair of

sql

/*
MySQL Data Transfer
Source Host: localhost
Source Database: test3
Target Host: localhost
Target Database: test3
Date: 2020/9/30 13:53:18
*/

SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for dept
-- ----------------------------
DROP TABLE IF EXISTS `dept`;
CREATE TABLE `dept` (
  `deptno` bigint(11) NOT NULL auto_increment,
  `dname` char(255) default NULL.PRIMARY KEY  (`deptno`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Table structure for emp
-- ----------------------------
DROP TABLE IF EXISTS `emp`;
CREATE TABLE `emp` (
  `empno` bigint(11) NOT NULL,
  `ename` char(255) default NULL,
  `deptno` bigint(11) default NULL.PRIMARY KEY  (`empno`),
  KEY `deptno` (`deptno`),
  CONSTRAINT `emp_ibfk_1` FOREIGN KEY (`deptno`) REFERENCES `dept` (`deptno`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records 
-- ----------------------------
INSERT INTO `dept` VALUES ('10'.'Personnel Department');
INSERT INTO `dept` VALUES ('20'.'Finance Department');
INSERT INTO `dept` VALUES ('30'.'Technology');
INSERT INTO `dept` VALUES ('40'.Administration Department);
INSERT INTO `emp` VALUES ('7000'.'ename2'.'10');
INSERT INTO `emp` VALUES ('7039'.'ename2'.'10');
INSERT INTO `emp` VALUES ('7051'.'123123'.'20');
INSERT INTO `emp` VALUES ('1599207548262'.'123123'.'20');
INSERT INTO `emp` VALUES ('1599633921514'.'aaa'.'20');

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Entity class

public class Emp {
    private Integer empno;
    privateString ename; Dept dept; . }Copy the code

public class Dept {
    private  Integer deptno;
    private String dname;
    List<Emp> emps;
}
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mapper

public interface EmpMapper {
    @Select("SELECT * FROM emp WHERE empno = #{empno}")
    @Results({ @Result(property = "dept", column = "deptno", one = @One(select = "com.mapper.DeptMapper.getDept")) })
    Emp getEmp(Integer empno);


    @Select("SELECT * FROM emp WHERE deptno = #{deptno}")
    List<Emp> getEmps(Integer deptno);

    / * * *@Results({
     @Result(property = "dept", column = "deptno",
     one = @One(select = "com.mapper.DeptMapper.getDept"))
     */
}

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public interface DeptMapper {
    @Select("SELECT * FROM dept where deptno = #{deptno}")
    Dept getDept(Integer deptno);


    @Select("SELECT * FROM dept where deptno = #{deptno}")
    @Results({ @Result(property = "emps", column = "deptno", many = @Many(select = "com.mapper.EmpMapper.getEmps",fetchType = FetchType.EAGER)) })
    Dept getDept2(Integer deptno);
}
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Many to many

Table SQL

/*
MySQL Data Transfer
Source Host: localhost
Source Database: test8
Target Host: localhost
Target Database: test8
Date: 2020/9/30 13:44:55
*/

SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for course
-- ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
  `couId` int(11) NOT NULL auto_increment,
  `couName` varchar(255) default NULL.PRIMARY KEY  (`couId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Table structure for stucou
-- ----------------------------
DROP TABLE IF EXISTS `stucou`;
CREATE TABLE `stucou` (
  `stuId` int(11) default NULL,
  `couId` int(11) default NULL,
  KEY `stuId` (`stuId`),
  KEY `couId` (`couId`),
  CONSTRAINT `stucou_ibfk_2` FOREIGN KEY (`couId`) REFERENCES `course` (`couId`),
  CONSTRAINT `stucou_ibfk_1` FOREIGN KEY (`stuId`) REFERENCES `student` (`stuId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
  `stuId` int(11) NOT NULL auto_increment,
  `stuName` varchar(255) default NULL.PRIMARY KEY  (`stuId`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records 
-- ----------------------------
INSERT INTO `course` VALUES ('1'.'courseName1');
INSERT INTO `course` VALUES ('2'.'courseName2');
INSERT INTO `course` VALUES ('3'.'courseName3');
INSERT INTO `course` VALUES ('4'.'courseName4');
INSERT INTO `course` VALUES ('5'.'courseName5');
INSERT INTO `course` VALUES ('6'.'courseName6');
INSERT INTO `stucou` VALUES ('1'.'1');
INSERT INTO `stucou` VALUES ('1'.'2');
INSERT INTO `stucou` VALUES ('1'.'3');
INSERT INTO `stucou` VALUES ('2'.'1');
INSERT INTO `stucou` VALUES ('2'.'2');
INSERT INTO `stucou` VALUES ('3'.'1');
INSERT INTO `student` VALUES ('1'.'StudentName1');
INSERT INTO `student` VALUES ('2'.'StudentName2');
INSERT INTO `student` VALUES ('3'.'StudentName3');
INSERT INTO `student` VALUES ('4'.'StudentName4');
INSERT INTO `student` VALUES ('5'.'StudentName5');
INSERT INTO `student` VALUES ('6'.'StudentName6');

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Entity class

public class Student {
    private int stuId;
    private String stuName;
    privateList<Course> courses; . }Copy the code

public class Course {
    private int couId;
    private String couName;
    privateList<Student> students; . }Copy the code

Mapper interfaces

public interface CourseMapper {
    @Select("select * from Course where couId in(select couId from stuCou where stuId=#{stuId})")
    public List<Course> selectCourseBy(int stuId);

    @Select("select * from Course")
    @Results({ @Result(id = true,property = "couId",column = "couId"), @Result(property = "students",column = "couId",many = @Many (select = "com.mapper.StudentMapper.selectStudentBy")) })
    public List<Course> allCourse(a);

}
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public interface StudentMapper {

    @Select("select * from Student")
    @Results({ @Result(id = true,property = "stuId",column = "stuId"), @Result(property = "courses",column = "stuId",many = @Many (select = "com.mapper.CourseMapper.selectCourseBy")) })
    public List<Student> allStudent(a);

    @Select
     ("select * from student where stuId in(select stuId from stuCou where couId=#{couId})")
    public List<Student> selectStudentBy(int couId);

}
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test

@Resource
CourseMapper courseMapper;
@Resource
StudentMapper studentMapper;
@RequestMapping("/testCourse")
public void testCourse(a) {
    for (Course course : courseMapper.allCourse()) {
        System.out.println(course.getCouId() + "\t" + course.getCouName());
        for (Student student : course.getStudents()) {
            System.out.println(student.getStuId() + "\t"+ student.getStuName()); } System.out.println(); }}@RequestMapping("/testStudent")
public void testStudent(a) {

    for (Student student : studentMapper.allStudent()) {
        System.out.println(student.getStuId() + "\t" + student.getStuName());
        for (Course course : student.getCourses()) {
            System.out.println(course.getCouId() + "\t"+ course.getCouName()); } System.out.println(); }}Copy the code

The use of SelectProvider

package mapper;

import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.SelectProvider;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;
import java.util.Set;

public interface AbstractMapper<T> {

    @SelectProvider(type = Sql.class, method = "getSql")
    public List<T> getEntitys(@Param("param1") T entity);



    @SelectProvider(type = Sql.class, method = "getSql")
    public T getEntity(@Param("param1") T entity);

    @SelectProvider(type = Sql.class, method = "getSql")
    public List<T> getEntitysByPageNow(@Param("param1")
                                            T entity,
                                    @Param("param2")
                                            Integer pageNow,
                                    @Param("param3")
                                            Integer pageSize);


    public class Sql {
        public String getSql(Map param) {
            // reflection gets class information
            Object entity = param.get("param1"); Class<? > entityClass = entity.getClass(); String simpleName = entityClass.getSimpleName(); String TABLENAME = simpleName.toUpperCase(); Method[] declaredMethods = entityClass.getDeclaredMethods(); String columns ="";
            String condition = "";
            String conditionValue = "";


            // Get attribute and method information
            for (Method declaredMethod : declaredMethods) {
                String methosName = declaredMethod.getName();
                System.out.println(methosName.indexOf("get"));
                if (methosName.indexOf("get") != -1) {
                    // Get the get method
                    String column = methosName.replace("get"."").toUpperCase();
                    System.out.println(column);
                    columns += column + ",";
                    Object returnValue = invodGetMethod(entity, declaredMethod);
                    if(returnValue ! =null) {
                        condition += column + "=#{param1." + getPropName(methosName) + "} and ";
                    }
                }
            }

            columns = columns.substring(0, columns.length() - 1);

            // Concatenate statements
            final String SELECT = " SELECT ";
            final String FROM = " FROM ";
            final String WHERE = " WHERE ";
            String sql = SELECT + columns + FROM + TABLENAME;


            // Check whether there is a condition
            if(! condition.equals("")){

                condition = condition.substring(0, condition.lastIndexOf("and "));

                sql +=  WHERE + condition;
            }
            // Check whether paging is available
            if (param.getOrDefault("param2".null) != null) {
                / / the current page
                int pagenow = Integer.parseInt(param.get("param2").toString());
                / / how many pages
                int pagesize = Integer.parseInt(param.get("param3").toString());

                Integer start = (pagenow-1)*pagesize;
                sql += " limit "+start+","+pagesize;

            }
            System.out.println(sql);


            return sql;
        }

        public String getPropName(String getName) {
            String get = getName.replace("get"."");
            String propName = get.replace(get.charAt(0), Character.toLowerCase(get.charAt(0)));
            return propName;
        }

        Object invodGetMethod(Object obj, Method method) {
            Object invoke = null;
            try {
                invoke = method.invoke(obj, null);
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
            returninvoke; }}}Copy the code

The cache

Mybatis cache

Level 1 cache

Session level cache

The second level cache

@CacheNamespace
public interface UserMapper {
    @Select("select id from user")
    public List<Map> getMaps(a);
}
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For additional articles please refer to juejin.cn/user/175884…

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SpringBoot integration Mybatis annotated case book

The first project

Creating a Maven project

Yml file

Start the class

The mapper class

controller

Other cases

Return Map(one parameter)

Return Map(multiple parameters)

Return List Map

Returns the Entity

Return List Entity

Resuts annotations

Pass parameters to the statement

To obtain parameters

More than a pair of

sql

Entity class

mapper

Many to many

Table SQL

Entity class

Mapper interfaces

test

The use of SelectProvider

The cache

Mybatis cache

Level 1 cache

The second level cache

SpringBoot integration Mybatis annotated case book

The first project

Creating a Maven project

Yml file

Start the class

The mapper class

controller

Other cases

Return Map(one parameter)

Return Map(multiple parameters)

Return List Map

Returns the Entity

Return List Entity

Resuts annotations

Pass parameters to the statement

To obtain parameters

More than a pair of

sql

Entity class

mapper

Many to many

Table SQL

Entity class

Mapper interfaces

test

The use of SelectProvider

The cache

Mybatis cache

Level 1 cache

The second level cache

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