Mybatis连接数据库常用语句整理汇总（1）
这期博客我将会重点回顾Mybatis常用的语法，包括基本的增删查改语句的书写，当然查询SQL我们会重点突出，包含的知识点也会比较多。
我们首先进行配置文件，新建db.properties，该文件主要用于数据库连接，其代码如下：
#MYSQL config
jdbc.driver = com.mysql.jdbc.Driver
jdbc.url = jdbc:mysql://127.0.0.1:3306/db_mybatis?characterEncoding=utf-8
jdbc.username = root
jdbc.password = 123456然后我们新建sqlMapConfig.xml文件，该文件主要用于①引入db.properties文件；②别名的映射；③应用POOLED方式连接数据源；④加载包含SQL语句的xml文件。其代码如下：
然后我们引入log4j,mybatis以及mysql的jar包，这里我们为方便查看日志信息，新建log4j.properties，其代码如下：
# Global logging configuration
#\u751F\u4EA7\u73AF\u5883\u914D\u7F6Einfo ERROR
log4j.rootLogger=DEBUG,stdout
# MyBatis logging configuration...
log4j.logger.org.mybatis.example.BlogMapper=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n首先是基本增删查改语句的书写，我们新建实体类User，其代码如下：
package cn.neu.mybatis.entity;
import java.util.Date;
public class User {
private int uId;
private String uName;
private String uPwd;
private String uPhone;
private double uBalance;
private int uState;
private int uRole;
private String uImage;//用户头像
private Date uBirth;
public int getuId() {
return uId;
}
public void setuId(int uId) {
this.uId = uId;
}
public String getuName() {
return uName;
}
public void setuName(String uName) {
this.uName = uName;
}
public String getuPwd() {
return uPwd;
}
public void setuPwd(String uPwd) {
this.uPwd = uPwd;
}
public String getuPhone() {
return uPhone;
}
public void setuPhone(String uPhone) {
this.uPhone = uPhone;
}
public double getuBalance() {
return uBalance;
}
public void setuBalance(double uBalance) {
this.uBalance = uBalance;
}
public int getuState() {
return uState;
}
public void setuState(int uState) {
this.uState = uState;
}
public int getuRole() {
return uRole;
}
public void setuRole(int uRole) {
this.uRole = uRole;
}
public String getuImage() {
return uImage;
}
public void setuImage(String uImage) {
this.uImage = uImage;
}
public Date getuBirth() {
return uBirth;
}
public void setuBirth(Date uBirth) {
this.uBirth = uBirth;
}
public User(int uId, String uName, String uPwd, String uPhone, double uBalance, int uState, int uRole,String uImage,Date uBirth) {
super();
this.uId = uId;
this.uName = uName;
this.uPwd = uPwd;
this.uPhone = uPhone;
this.uBalance = uBalance;
this.uState = uState;
this.uRole = uRole;
this.uImage = uImage;
this.uBirth = uBirth;
}
public User() {
super();
}
public User(String uName, String uPwd, String uPhone) {
super();
this.uName = uName;
this.uPwd = uPwd;
this.uPhone = uPhone;
}
//添加注册信息
public User(String uName, String uPwd, String uPhone, Date uBirth) {
super();
this.uName = uName;
this.uPwd = uPwd;
this.uPhone = uPhone;
this.uBirth = uBirth;
}
public User(String uName, String uPwd, String uPhone, String uImage) {
super();
this.uName = uName;
this.uPwd = uPwd;
this.uPhone = uPhone;
this.uImage = uImage;
}
public User(String uName, String uPwd) {
super();
this.uName = uName;
this.uPwd = uPwd;
}
@Override
public String toString() {
return "User [uId=" + uId + ", uName=" + uName + ", uPwd=" + uPwd + ", uPhone=" + uPhone + ", uBalance="
+ uBalance + ", uState=" + uState + ", uRole=" + uRole + ", uImage=" + uImage + ", uBirth=" + uBirth
+ "]";
}
}
然后我们新建UserMapper接口，里面主要包含未实现的方法，其代码如下：
package cn.neu.mybatis.mapper;
import java.util.List;
import java.util.Map;
import cn.neu.mybatis.entity.User;
public interface UserMapper {
public User findUserByUid(int uId) throws Exception;
public User findUserByUid2(int uId) throws Exception;
public int deleteUserByUid(int uId) throws Exception;
public int addUser(User user) throws Exception;
public int updateUser(User user) throws Exception;
//根据用户编号查询用户信息,根据用户类别查询用户信息,根据用户状态
public List findUsersByConditions(User user) throws Exception;
//返回值为Map的查询方法
public List> findUserMap(User user) throws Exception;
//查询foreach1
public List foreachTest1(Object[] uIds) throws Exception;
//查询foreach2
public List foreachTest2(List uIds) throws Exception;
public int updateUser1(User user) throws Exception;
}
然后我们在相同的mapper包下新建UserMapper.xml文件，该文件主要包含拼接的SQL语句，其代码如下：
insert into tb_user(U_NAME,U_PWD,U_PHONE) values(#{uName},#{uPwd},#{uPhone})
DELETE FROM tb_user
WHERE U_ID = #{uId}
UPDATE tb_user SET
U_NAME=#{uName},U_PHONE=#{uPhone},U_IMAGE=#{uImage},U_PWD=#{uPwd}
where U_ID = #{uId}
SELECT U_ID uId,U_NAME uName,U_PWD uPwd,U_PHONE
uPhone,U_BALANCE uBalance,U_STATE uState,U_ROLE uRole,U_IMAGE
uImage,U_BIRTH uBirth FROM tb_user
AND U_ID = #{uId}
AND U_NAME = #{uName}
AND U_PWD = #{uPwd}
update tb_user
U_NAME = #{uName},
U_PWD = #{uPwd},
U_PHONE = #{uPhone},
where U_ID = #{uId}
然后我们进行单元测试，对每一个方法都要进行测试，新建的测试类名为UserMapperTest，其代码如下：
package cn.neu.mybatis.test;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;
import cn.neu.mybatis.entity.User;
import cn.neu.mybatis.mapper.UserMapper;
public class UserMapperTest {
private SqlSessionFactory sqlSessionFactory;
@Before
public void init() throws Exception {
InputStream inputStream = Resources.getResourceAsStream("config/sqlMapConfig.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testFindUserByUid() throws Exception {
//Spring可以使用自动装载,协助实例化UserMapper,直接调用即可
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = userMapper.findUserByUid(2);
System.out.println(user.toString());
session.close();
}
@Test
public void testDeleteUserByUid() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
int i = userMapper.deleteUserByUid(17);
System.out.println("删除了"+i+"条记录");
session.commit();
session.close();
}
@Test
public void testUpdateUser() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = userMapper.findUserByUid(7);
user.setuName("你好");
user.setuPwd("1234");
user.setuPhone("23156587691");
int i = userMapper.updateUser(user);
System.out.println("修改了"+i+"条记录");
session.commit();
session.close();
}
@Test
public void testaddUser() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = new User("ttd","1234","13825436380");
int i = userMapper.addUser(user);
System.out.println("添加了"+i+"条记录");
session.commit();
session.close();
}
@Test
public void testfindUsersByConditions() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = new User();
user.setuId(1);
List users = userMapper.findUsersByConditions(user);
for(User u : users) {
System.out.println(u.toString());
}
session.close();
}
@Test
public void testfindUserMap() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = new User();
user.setuId(1);
List> users = userMapper.findUserMap(user);
for(Map m : users) {
System.out.println(m.get("uId"));
System.out.println(m.get("uName"));//键的名字对应实体类的属性名
}
session.close();
}
@Test
public void foreachTest1() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
Object[] uIds = {1,2,6,7};
List users = userMapper.foreachTest1(uIds);
for(User u : users) {
System.out.println(u.toString());
}
session.close();
}
@Test
public void foreachTest2() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
List uIds = new ArrayList<>();
uIds.add(1);
uIds.add(2);
uIds.add(7);
List users = userMapper.foreachTest2(uIds);
for(User u : users) {
System.out.println(u.toString());
}
session.close();
}
@Test
public void testupdateUser1() throws Exception {
SqlSession session = sqlSessionFactory.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = new User();
user.setuId(2);
user.setuName("cpx");
int i = userMapper.updateUser1(user);
System.out.println("修改了"+i+"条记录");
session.commit();
session.close();
}
}
该测试类中首先写了init方法用作初始化，加载了sqlMapConfig.xml文件，我们对里面的方法进行解释：
①通过uid查询用户信息，这里实际上在xml文件中我们写了两种SQL语句，一种是直接写，另一种是把查询内容封装一下，写在sql标签内，然后再调用；
②修改用户信息，我们在xml文件中也是写了两种方法，一种是直接写出需要修改的内容，另一种是if标签语句进行判断，把可能修改的参数都放进去；
③通过条件进行查询用户信息，方法是findUsersByConditions，里面我们整合了where标签，它会判断第一个语句是否有and，如果有会自动删除；
④遍历查询我们写了两种方式用于对比，一种是数组，一种是列表，里面都是使用foreach标签，差别其实不算大，传入的参数是用户编号，一个是Object数组，一个是List列表。
好了，本期博客就到这里了，下期我们将继续整理一对一，一对多以及多对多Mybatis语句的写法，下期再见！