mybatis之多条件sql的实现的两种方式
首先稍微补充一下用注解首先sql功能（一般不用这种方法）
原理如下：
文件图
实现多条件sql的两种方式的具体实现代码：
mybatis.xml
<?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>
<properties resource="db.properties"></properties>
<typeAliases>
<typeAlias type="plus.domain.user" alias="use"></typeAlias>
</typeAliases>
<environments default="default">
<environment id="default">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${db.driverClassName}"></property>
<property name="url" value="${db.url}"></property>
<property name="username" value="${db.username}"></property>
<property name="password" value="${db.password}"></property>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="plus/domain/usermapper.xml"></mapper>
</mappers>
</configuration>
usermapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="plus.domain.usermapper">
<select id="login" resultType="use">
SELECT *FROM user WHERE username=#{username} AND password=#{password}
</select>
<select id="login1" resultType="use">
SELECT *FROM user WHERE username=#{username} AND password=#{password}
</select>
</mapper>
db.properties
db.driverClassName=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/mybatis
db.username=root
db.password=123456
log4j.properties
# Global logging configuration
log4j.rootLogger=ERROR, stdout
# MyBatis logging configuration...
log4j.logger.plus.domain.usermapper=TRACE //plus.domain.usermapper为具体操作数据库的那个xml所在的路径
# 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
mybatisutils工具类
package plus.utils;
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 java.io.IOException;
public class mybatisutils {
private SqlSessionFactory sf;
private static mybatisutils instance=new mybatisutils();
public mybatisutils(){
try {
sf= new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession opensession(){
return instance.sf.openSession();
}
}
user类
package plus.domain;
public class user {
private Long id;
private String username;
private String password;
private Integer age;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "user{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", age=" + age +
'}';
}
}
usermapper接口
package plus.domain;
import org.apache.ibatis.annotations.Param;
import java.util.List;
import java.util.Map;
public interface usermapper {
user login(Map<String,Object>map);
user login1(@Param("username")String username,@Param("password")String password);
}
test测试类
package plus.test;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import plus.domain.user;
import plus.domain.usermapper;
import plus.utils.mybatisutils;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class test {
@Test
public void testfirst(){
//第一种方法使用Map
SqlSession session= mybatisutils.opensession();
usermapper mapper=session.getMapper(usermapper.class);
Map<String,Object>map=new HashMap<>();
map.put("username","小王子");
map.put("password","23569");
user u=mapper.login(map);
System.out.println(u);
session.close();
}
@Test
public void testsecond(){
//第二种方法使用注解
System.out.println("-----------------------------------");
SqlSession session=mybatisutils.opensession();
usermapper mapper=session.getMapper(usermapper.class);
user u=mapper.login1("小王子","23569");
System.out.println(u);
session.close();
}
}
数据库
第一种方式结果
第二种方式的结果