赞
踩
前面我们介绍了使用Mybatis完成数据的增删改查,并且也了解了如何在Mybatis中使用JDK的日志系统打印日志;本篇我们介绍使用Mybatis的动态SQL完成查询数据、批量新增、批量修改、删除数据。
如果您对数据的增删改查操作和Mybatis集成JDK日志系统不太了解,建议您先进行了解后再阅读本篇,可以参考:
Mybatis查询数据https://blog.csdn.net/m1729339749/article/details/132469672Mybatis 日志(JDK Log)https://blog.csdn.net/m1729339749/article/details/132565362Mybatis 插入、修改、删除https://blog.csdn.net/m1729339749/article/details/132601345
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
在cn.horse.demo下创建UserInfo类
UserInfo类:
- package cn.horse.demo;
-
- public class UserInfo {
-
- private Integer id;
- private String name;
- private Integer age;
-
- public UserInfo() { }
- public UserInfo(Integer id, String name, Integer age) {
- this.id = id;
- this.name = name;
- this.age = 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();
- }
- }
在resources的目录下新建UserInfoMapper.xml配置文件
- <?xml version="1.0" encoding="UTF-8" ?>
- <!DOCTYPE mapper
- PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
- "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
- <mapper namespace="cn.horse.demo.UserInfoMapper">
-
- <select id="findAll" resultType="cn.horse.demo.UserInfo">
- SELECT
- ID,
- USERNAME name,
- AGE
- FROM T_USER
- </select>
- </mapper>
在resources下新建mybatis-config.xml配置文件,并引入UserInfoMapper.xml配置文件
- <?xml version="1.0" encoding="UTF-8" ?>
- <!DOCTYPE configuration
- PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
- "http://mybatis.org/dtd/mybatis-3-config.dtd">
- <configuration>
- <settings>
- <setting name="logImpl" value="JDK_LOGGING"/>
- </settings>
-
- <environments default="development">
- <environment id="development">
- <transactionManager type="JDBC"/>
- <dataSource type="POOLED">
- <property name="driver" value="org.gjt.mm.mysql.Driver"/>
- <property name="url" value="jdbc:mysql://localhost:3306/demo?useUnicode=true&useSSL=false&characterEncoding=utf8"/>
- <property name="username" value="root"/>
- <property name="password" value="horse"/>
- </dataSource>
- </environment>
- </environments>
-
- <mappers>
- <mapper resource="demo/UserInfoMapper.xml" />
- </mappers>
- </configuration>
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();
- }
- }
- }
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);
- }
- }
- }
- package cn.horse.demo;
-
- import org.apache.ibatis.session.SqlSession;
-
- import java.util.ArrayList;
- import java.util.List;
-
- 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");
- find("cn.horse.demo.UserInfoMapper.findAll", null);
- }
-
- private static void find(String statement, Object parameter) {
- SqlSession sqlSession = null;
- try {
- sqlSession = SqlSessionUtils.openSession();
- List<UserInfo> userInfoList = sqlSession.selectList(statement, parameter);
- for (UserInfo userInfo: userInfoList) {
- System.out.println(userInfo);
- }
- } finally {
- SqlSessionUtils.closeSession(sqlSession);
- }
- }
- }
执行后的结果如下:
foreach标签用于对数组或可迭代对象的遍历
foreach标签的格式如下:
- <foreach collection="" item="" index="" open="" separator="" close="">
-
- </foreach>
collection:数组或可迭代对象
item:数组中的元素或本次迭代的元素
index:数组中的索引或本地迭代的序号
open:指定开头的字符串
close:指定结尾的字符串
separator:迭代之间的分隔符
注意:如果可迭代对象是Map对象(或者Map.Entry对象的集合)时,index是键,item是值
在UserInfoMapper.xml配置文件中新增insert标签,并写入insert语句:
- <insert id="insert">
- INSERT INTO T_USER(ID,
- USERNAME,
- AGE)
- VALUES
- <foreach collection="list" item="userInfo" separator=",">
- (#{userInfo.id}, #{userInfo.name}, #{userInfo.age})
- </foreach>
- </insert>
在启动程序中新建batchInsert方法
- private static void batchInsert(List<UserInfo> userInfoList) {
- SqlSession sqlSession = null;
- try {
- sqlSession = SqlSessionUtils.openSession();
- sqlSession.insert("cn.horse.demo.UserInfoMapper.insert", userInfoList);
- sqlSession.commit();
- } finally {
- SqlSessionUtils.closeSession(sqlSession);
- }
- }
调用batchInsert方法插入数据,并查询
- List<UserInfo> userInfoList = new ArrayList<>();
- userInfoList.add(new UserInfo(11, "张三1", 20));
- userInfoList.add(new UserInfo(12, "李四1", 22));
- userInfoList.add(new UserInfo(13, "王五1", 24));
- batchInsert(userInfoList);
- find("cn.horse.demo.UserInfoMapper.findAll", null);
执行后的结果如下:
foreach标签常用于构建IN条件语句;
在UserInfoMapper.xml配置文件中新增select标签:
- <select id="findByIdList" resultType="cn.horse.demo.UserInfo">
- SELECT
- ID,
- USERNAME name,
- AGE
- FROM T_USER
- <where>
- ID IN
- <foreach collection="list" item="id" open="(" separator="," close=")">
- #{id}
- </foreach>
- </where>
- </select>
查询数据
find("cn.horse.demo.UserInfoMapper.findByIdList", Arrays.asList(11, 12, 13));
执行后的结果如下:
在UserInfoMapper.xml配置文件中新增update标签,并写入update语句:
- <update id="update">
- <foreach collection="list" item="userInfo" separator=";" close=";">
- UPDATE T_USER
- <set>
- <if test="null != userInfo.name and '' != userInfo.name">
- USERNAME = #{userInfo.name},
- </if>
- <if test="null != userInfo.age">
- AGE = #{userInfo.age},
- </if>
- </set>
- WHERE ID = #{userInfo.id}
- </foreach>
- </update>
在启动程序中新建batchUpdate方法:
- private static void batchUpdate(List<UserInfo> userInfoList) {
- SqlSession sqlSession = null;
- try {
- sqlSession = SqlSessionUtils.openSession();
- sqlSession.update("cn.horse.demo.UserInfoMapper.update", userInfoList);
- sqlSession.commit();
- } finally {
- SqlSessionUtils.closeSession(sqlSession);
- }
- }
调用batchUpdate方法更新数据,并查询
- List<UserInfo> userInfoList = new ArrayList<>();
- userInfoList.add(new UserInfo(11, "张三2", null));
- userInfoList.add(new UserInfo(12, "李四2", 30));
- userInfoList.add(new UserInfo(13, "王五2", null));
- batchUpdate(userInfoList);
- find("cn.horse.demo.UserInfoMapper.findByIdList", Arrays.asList(11, 12, 13));
执行后的结果如下:
- 2023-09-03 10:28:11.873 详细 cn.horse.demo.UserInfoMapper.update - ==> Preparing: UPDATE T_USER SET USERNAME = ? WHERE ID = ? ; UPDATE T_USER SET USERNAME = ?, AGE = ? WHERE ID = ? ; UPDATE T_USER SET USERNAME = ? WHERE ID = ? ;
- 2023-09-03 10:28:11.909 详细 cn.horse.demo.UserInfoMapper.update - ==> Parameters: 张三2(String), 11(Integer), 李四2(String), 30(Integer), 12(Integer), 王五2(String), 13(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 USERNAME = '李四2',
-
- ' at line 5
- ### The error may involve defaultParameterMap
- ### The error occurred while setting parameters
- ### SQL: UPDATE T_USER SET USERNAME = ? WHERE ID = ? ; UPDATE T_USER SET USERNAME = ?, AGE = ? WHERE ID = ? ; UPDATE T_USER SET USERNAME = ? 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 USERNAME = '李四2',
-
- ' at line 5
- at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
- at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:200)
- at cn.horse.demo.Main.batchUpdate(Main.java:48)
- at cn.horse.demo.Main.main(Main.java:29)
- 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 USERNAME = '李四2',
-
- ' at line 5
- 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.$Proxy3.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)
- ... 2 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;解决方式是在JDBC连接中添加连接属性allowMultiQueries=true
修改mybatis-config.xml配置文件:
- <?xml version="1.0" encoding="UTF-8" ?>
- <!DOCTYPE configuration
- PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
- "http://mybatis.org/dtd/mybatis-3-config.dtd">
- <configuration>
- <settings>
- <setting name="logImpl" value="JDK_LOGGING"/>
- </settings>
-
- <environments default="development">
- <environment id="development">
- <transactionManager type="JDBC"/>
- <dataSource type="POOLED">
- <property name="driver" value="org.gjt.mm.mysql.Driver"/>
- <property name="url" value="jdbc:mysql://localhost:3306/demo?useUnicode=true&useSSL=false&characterEncoding=utf8&allowMultiQueries=true"/>
- <property name="username" value="root"/>
- <property name="password" value="horse"/>
- </dataSource>
- </environment>
- </environments>
-
- <mappers>
- <mapper resource="demo/UserInfoMapper.xml" />
- </mappers>
- </configuration>
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
再次执行后的结果如下:
在UserInfoMapper.xml配置文件中新增delete标签,并写入delete语句:
- <delete id="delete">
- DELETE FROM T_USER
- <where>
- ID IN
- <foreach collection="list" item="id" open="(" separator="," close=")">
- #{id}
- </foreach>
- </where>
- </delete>
在启动程序中新建batchDelete方法:
- private static void batchDelete(List<Integer> idList) {
- SqlSession sqlSession = null;
- try {
- sqlSession = SqlSessionUtils.openSession();
- sqlSession.delete("cn.horse.demo.UserInfoMapper.delete", idList);
- sqlSession.commit();
- } finally {
- SqlSessionUtils.closeSession(sqlSession);
- }
- }
调用batchDelete方法更新数据,并查询
- batchDelete(Arrays.asList(11, 12, 13));
- find("cn.horse.demo.UserInfoMapper.findByIdList", Arrays.asList(11, 12, 13));
执行后的结果如下:
Copyright © 2003-2013 www.wpsshop.cn 版权所有,并保留所有权利。