Mybatis 映射器中使用@InsertProvider,@UpdateProvider,@DeleteProvider,@SelectProvider

上一篇我们介绍了在Mybatis映射器的映射方法中使用@Param接收多个参数；本篇我们继续介绍如何在Mybatis的映射器中使用动态SQL。

如果您对Mybatis映射器的映射方法中使用@Param接收多个参数不太了解，建议您先进行了解后再阅读本篇，可以参考：

Mybatis 映射器中映射方法接受多个参数(@Param)https://blog.csdn.net/m1729339749/article/details/133063604

一、数据准备

这里我们直接使用脚本初始化数据库中的数据

-- 如果数据库不存在则创建数据库
CREATE DATABASE IF NOT EXISTS demo DEFAULT CHARSET utf8;
-- 切换数据库
USE demo;
-- 创建用户表
CREATE TABLE IF NOT EXISTS T_USER(
  ID INT PRIMARY KEY,
  USERNAME VARCHAR(32) NOT NULL,
  AGE INT NOT NULL 
);
-- 插入用户数据
INSERT INTO T_USER(ID, USERNAME, AGE)
VALUES(1, '张三', 20),(2, '李四', 22),(3, '王五', 24);

创建了一个名称为demo的数据库；并在库里创建了名称为T_USER的用户表并向表中插入了数据

二、创建实体类

在cn.horse.demo下创建UserInfo、UserInfoQuery类

UserInfo类：

package cn.horse.demo;

public class UserInfo {

    private Integer id;
    private String name;
    private Integer age;

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

    public Integer getId() {
        return id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Integer getAge() {
        return age;
    }

    @Override
    public String toString() {
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append('{');
        stringBuilder.append("id: " + this.id);
        stringBuilder.append(", ");
        stringBuilder.append("name: " + this.name);
        stringBuilder.append(", ");
        stringBuilder.append("age: " + this.age);
        stringBuilder.append('}');
        return stringBuilder.toString();
    }
}

UserInfoQuery类：

package cn.horse.demo;

public class UserInfoQuery {

    private Integer startAge;
    private Integer endAge;

    public void setStartAge(Integer startAge) {
        this.startAge = startAge;
    }

    public Integer getStartAge() {
        return startAge;
    }

    public void setEndAge(Integer endAge) {
        this.endAge = endAge;
    }

    public Integer getEndAge() {
        return endAge;
    }
}

三、创建UserInfoMapper映射器、UserInfoSqlProvider类

在cn.horse.demo下创建UserInfoMapper接口、UserInfoSqlProvider类

UserInfoMapper接口：

package cn.horse.demo;

import org.apache.ibatis.annotations.*;

import java.util.List;

public interface UserInfoMapper {
}

UserInfoSqlProvider类：

package cn.horse.demo;

import org.apache.ibatis.annotations.Param;

import java.util.*;

public class UserInfoSqlProvider {
}

四、引入配置文件

在resources下新建mybatis-config.xml配置文件，并引入UserInfoMapper映射器。

这里我们使用mapper引入映射器，只需要设置class属性为UserInfoMapper接口的全限类名。

五、启动程序配置

1、会话工具类

在cn.horse.demo包下新建SqlSessionUtils工具类

package cn.horse.demo;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.InputStream;
import java.util.Objects;

public class SqlSessionUtils {

    private static final SqlSessionFactory sqlSessionFactory;
    static {
        // 读取mybatis配置文件
        InputStream inputStream = ClassLoader.getSystemClassLoader().getResourceAsStream("mybatis-config.xml");
        // 根据配置创建SqlSession工厂
        sqlSessionFactory = new SqlSessionFactoryBuilder()
                .build(inputStream);
    }

    /**
     * 开启会话
     * @return
     */
    public static SqlSession openSession() {
        return sqlSessionFactory.openSession();
    }

    /**
     * 关闭会话
     * @param sqlSession
     */
    public static void closeSession(SqlSession sqlSession) {
        if(Objects.nonNull(sqlSession)) {
            sqlSession.close();
        }
    }
}

2、JDK 日志系统配置

在resources的目录下新建logging.properties配置文件

handlers=java.util.logging.ConsoleHandler
.level=INFO

cn.horse.demo.UserInfoMapper.level=FINER
java.util.logging.ConsoleHandler.level=ALL
java.util.logging.ConsoleHandler.formatter=java.util.logging.SimpleFormatter
java.util.logging.SimpleFormatter.format=%1$tY-%1$tm-%1$td %1$tT.%1$tL %4$s %3$s - %5$s%6$s%n

在cn.horse.demo下创建JdkLogConfig类

JdkLogConfig类：

package cn.horse.demo;

import java.io.IOException;
import java.io.InputStream;
import java.util.logging.LogManager;

public class JdkLogConfig {

    public JdkLogConfig() {
        try {
            InputStream inputStream = ClassLoader.getSystemClassLoader().getResourceAsStream("logging.properties");
            LogManager.getLogManager().readConfiguration(inputStream);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

3、启动程序配置

package cn.horse.demo;

import org.apache.ibatis.session.SqlSession;

import java.util.List;
import java.util.function.Consumer;

public class Main {
    public static void main(String[] args) {
        // 引入JDK日志配置
        System.setProperty("java.util.logging.config.class", "cn.horse.demo.JdkLogConfig");
    }

    private static void execute(Consumer function) {
        SqlSession sqlSession = null;
        try {
            sqlSession = SqlSessionUtils.openSession();
            function.accept(sqlSession.getMapper(UserInfoMapper.class));
            sqlSession.commit();
        } finally {
            SqlSessionUtils.closeSession(sqlSession);
        }
    }
}

execute方法用于执行操作，方法中使用sqlSession.getMapper方法获取映射器对象，然后将映射器对象具体的执行操作委托给了Consumer对象。

六、查询数据

在UserInfoMapper映射器中新增find方法

@SelectProvider(type = UserInfoSqlProvider.class, method = "select")
List find(@Param("query") UserInfoQuery query);

使用SelectProvider注解，将查询语句的提供者配置成UserInfoSqlProvider的select方法，保证find方法的参数与UserInfoSqlProvider的select方法的参数保持一致(包括@Param注解)，以避免出现问题。

在UserInfoSqlProvider中新增select方法

public String select(@Param("query") UserInfoQuery query) {
    StringBuilder sqlBuilder = new StringBuilder();
    sqlBuilder.append("SELECT ID, USERNAME name, AGE FROM T_USER");
    // 获取条件语句
    List conditionStmt = fetchConditionStatement(query);
    if(!conditionStmt.isEmpty()) {
        sqlBuilder.append(" WHERE ");
        sqlBuilder.append(String.join(" AND ", conditionStmt));
    }
    return sqlBuilder.toString();
}

// 获取条件语句
private List fetchConditionStatement(UserInfoQuery query) {
    if(Objects.isNull(query)
        || (Objects.isNull(query.getStartAge()) && Objects.isNull(query.getEndAge()))) {
        return Collections.emptyList();
    }
    List conditionStmt = new ArrayList<>(2);
    if(Objects.nonNull(query.getStartAge())) {
        conditionStmt.add("AGE >= #{query.startAge}");
    }
    if(Objects.nonNull(query.getEndAge())) {
        conditionStmt.add("AGE <= #{query.endAge}");
    }
    return conditionStmt;
}

调用映射器中的find方法查询数据

// 引入JDK日志配置
System.setProperty("java.util.logging.config.class", "cn.horse.demo.JdkLogConfig");

// 查询
execute((UserInfoMapper userInfoMapper) -> {
    UserInfoQuery query = new UserInfoQuery();
    query.setEndAge(20);
    List userInfoList = userInfoMapper.find(query);
    for (UserInfo userInfo: userInfoList) {
        System.out.println(userInfo);
    }
});

执行后的结果如下：

七、批量新增数据

在UserInfoMapper映射器中新增insert方法

@InsertProvider(type = UserInfoSqlProvider.class, method = "insert")
Integer insert(@Param("userInfoList") List userInfoList);

使用InsertProvider注解，将新增语句的提供者配置成UserInfoSqlProvider的insert方法，保证insert方法的参数与UserInfoSqlProvider的insert方法的参数保持一致(包括@Param注解)，以避免出现问题。

在UserInfoSqlProvider中新增insert方法

public String insert(@Param("userInfoList") List userInfoList) {
    StringBuilder sqlBuilder = new StringBuilder("INSERT INTO T_USER(ID, USERNAME, AGE) VALUES");
    for (int i = 0; i < userInfoList.size(); i++) {
        sqlBuilder.append('(');
        sqlBuilder.append("#{userInfoList["+ i +"].id},");
        sqlBuilder.append("#{userInfoList["+ i +"].name},");
        sqlBuilder.append("#{userInfoList["+ i +"].age}");
        sqlBuilder.append(')');
        if(i != userInfoList.size() - 1) {
            sqlBuilder.append(',');
        }
    }
    return sqlBuilder.toString();
}

调用映射器中的insert方法新增数据

// 引入JDK日志配置
System.setProperty("java.util.logging.config.class", "cn.horse.demo.JdkLogConfig");

// 插入
execute((UserInfoMapper userInfoMapper) -> {
    List userInfoList = new ArrayList<>();
    UserInfo userInfo1 = new UserInfo();
    userInfo1.setId(5);
    userInfo1.setName("王五1");
    userInfo1.setAge(5);
    userInfoList.add(userInfo1);
    UserInfo userInfo2 = new UserInfo();
    userInfo2.setId(6);
    userInfo2.setName("王五2");
    userInfo2.setAge(6);
    userInfoList.add(userInfo2);
    Integer total = userInfoMapper.insert(userInfoList);
    System.out.println("插入条数: " + total);
});

执行后的结果如下：

八、批量修改数据

在UserInfoMapper映射器中新增update方法

@UpdateProvider(type = UserInfoSqlProvider.class, method = "update")
Integer update(@Param("userInfoList") List userInfoList);

使用UpdateProvider注解，将更新语句的提供者配置成UserInfoSqlProvider的update方法，保证update方法的参数与UserInfoSqlProvider的update方法的参数保持一致(包括@Param注解)，以避免出现问题。

在UserInfoSqlProvider中新增update方法

public String update(@Param("userInfoList") List userInfoList) {
    StringBuilder sqlBuilder = new StringBuilder();

    for (int i = 0; i < userInfoList.size(); i++) {
        sqlBuilder.append("UPDATE T_USER SET ");

        // 获取条件语句
        sqlBuilder.append(String.join(", ", fetchUpdateStatement(i, userInfoList.get(i))));
        sqlBuilder.append(" WHERE ID = #{userInfoList["+ i +"].id}");
        if(i != userInfoList.size() - 1) {
            sqlBuilder.append(';');
        }
    }
    return sqlBuilder.toString();
}

private List fetchUpdateStatement(Integer i, UserInfo userInfo) {
    if(Objects.isNull(userInfo)
        || (Objects.isNull(userInfo.getName()) && Objects.isNull(userInfo.getAge()))) {
        return Arrays.asList("ID = #{userInfoList["+ i +"].id}");
    }
    List updateStmt = new ArrayList<>(2);
    if(Objects.nonNull(userInfo.getName())) {
        updateStmt.add("USERNAME = #{userInfoList["+ i +"].name}");
    }
    if(Objects.nonNull(userInfo.getAge())) {
        updateStmt.add("AGE = #{userInfoList["+ i +"].age}");
    }
    return updateStmt;
}

调用映射器中的update方法修改数据

// 引入JDK日志配置
System.setProperty("java.util.logging.config.class", "cn.horse.demo.JdkLogConfig");

// 更新
execute((UserInfoMapper userInfoMapper) -> {
    List userInfoList = new ArrayList<>();
    UserInfo userInfo1 = new UserInfo();
    userInfo1.setId(5);
    userInfo1.setName("王五11");
    userInfoList.add(userInfo1);
    UserInfo userInfo2 = new UserInfo();
    userInfo2.setId(6);
    userInfo2.setAge(26);
    userInfoList.add(userInfo2);
    Integer total = userInfoMapper.update(userInfoList);
    System.out.println("更新条数: " + total);
});

执行后的结果如下：

可能出现的问题：

2023-09-15 14:18:10.601 详细 cn.horse.demo.UserInfoMapper.update - ==>  Preparing: UPDATE T_USER SET USERNAME = ? WHERE ID = ?;UPDATE T_USER SET AGE = ? WHERE ID = ? 
2023-09-15 14:18:10.641 详细 cn.horse.demo.UserInfoMapper.update - ==> Parameters: 王五11(String), 5(Integer), 26(Integer), 6(Integer)
Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException: 
### Error updating database.  Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'UPDATE T_USER SET AGE = 26 WHERE ID = 6' at line 1
### The error may involve cn.horse.demo.UserInfoMapper.update-Inline
### The error occurred while setting parameters
### SQL: UPDATE T_USER SET USERNAME = ? WHERE ID = ?;UPDATE T_USER SET AGE = ? WHERE ID = ?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'UPDATE T_USER SET AGE = 26 WHERE ID = 6' at line 1
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:200)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:62)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
	at jdk.proxy2/jdk.proxy2.$Proxy7.update(Unknown Source)
	at cn.horse.demo.Main.lambda$main$0(Main.java:59)
	at cn.horse.demo.Main.execute(Main.java:76)
	at cn.horse.demo.Main.main(Main.java:49)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'UPDATE T_USER SET AGE = 26 WHERE ID = 6' at line 1
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:403)
	at com.mysql.jdbc.Util.getInstance(Util.java:386)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3933)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3869)
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2524)
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2675)
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2465)
	at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1915)
	at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1254)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59)
	at jdk.proxy3/jdk.proxy3.$Proxy9.execute(Unknown Source)
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:46)
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74)
	at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50)
	at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)
	at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)
	... 6 more

从上面执行的情况来看，SQL执行过程中报错了，原因是我们批量更新使用的是同时执行多条更新语句，而JDBC是不支持的；

解决办法：

在JDBC连接中添加连接属性allowMultiQueries=true

修改mybatis-config.xml配置文件：

在配置文件中我们仅修改了

jdbc:mysql://localhost:3306/demo?useUnicode=true&useSSL=false&characterEncoding=utf8&allowMultiQueries=true

九、批量删除数据

在UserInfoMapper映射器中新增delete方法

@DeleteProvider(type = UserInfoSqlProvider.class, method = "delete")
Integer delete(@Param("idList") List idList);

使用DeleteProvider注解，将更新语句的提供者配置成UserInfoSqlProvider的delete方法，保证delete方法的参数与UserInfoSqlProvider的delete方法的参数保持一致(包括@Param注解)，以避免出现问题。

在UserInfoSqlProvider中新增delete方法

public String delete(@Param("idList") List idList) {
    StringBuilder sqlBuilder = new StringBuilder("DELETE FROM T_USER WHERE ID IN (");
    for (int i = 0; i < idList.size(); i++) {
        sqlBuilder.append("#{idList["+ i +"]}");
        if(i != idList.size() - 1) {
            sqlBuilder.append(',');
        }
    }
    sqlBuilder.append(')');
    return sqlBuilder.toString();
}

调用映射器中的delete方法删除数据

// 引入JDK日志配置
System.setProperty("java.util.logging.config.class", "cn.horse.demo.JdkLogConfig");

// 删除
execute((UserInfoMapper userInfoMapper) -> {
    Integer total = userInfoMapper.delete(Arrays.asList(5, 6));
    System.out.println("删除条数: " + total);
});

执行后的结果如下：