Mybatis动态查询

需要导入的jar包：

实体类User：

package com.bjsxt.pojo;

import java.io.Serializable;

public class User implements Serializable{
	private int id;
	private String username;
	private String password;
	public int getId() {
		return id;
	}
	public void setId(int 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;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", username=" + username + ", password=" + password + "]";
	}
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + id;
		result = prime * result + ((password == null) ? 0 : password.hashCode());
		result = prime * result + ((username == null) ? 0 : username.hashCode());
		return result;
	}
	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		User other = (User) obj;
		if (id != other.id)
			return false;
		if (password == null) {
			if (other.password != null)
				return false;
		} else if (!password.equals(other.password))
			return false;
		if (username == null) {
			if (other.username != null)
				return false;
		} else if (!username.equals(other.username))
			return false;
		return true;
	}
	public User() {
		super();
	}

}

MyBatis.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>
  <!-- properties加载配置文件
   -->
  <properties resource="db.properties"></properties>
  <settings>
  	<setting name="logImpl" value="LOG4J"/>
  </settings>
  <typeAliases>
  	<package name="com.bjsxt.pojo"/>
  </typeAliases>
  	<environments default="dev">
 		<environment id="dev">
 			<transactionManager type="JDBC"/>
 			<dataSource type="POOLED">
 				<property name="driver" value="${jdbc.driver}"/>
 				<property name="url" value="${jdbc.url}"/>
 				<property name="username" value="${jdbc.username}"/>
 				<property name="password" value="${jdbc.password}"/>

 			</dataSource>
 		</environment>
  	</environments>
  	<mappers >
  		<package name="com.bjsxt.mapper"/>
  	</mappers>
  </configuration>

log4j和db文件：

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://192.168.5.129:3306/bjsxt
jdbc.username=root
jdbc.password=root

# Set root category priority to INFO and its only appender to CONSOLE.
log4j.rootCategory=info, CONSOLE
# log4j.rootCategory=DEBUG, CONSOLE, LOGFILE

# 单独设置SQL语句的输出级别为DEBUG级别
# 方法级别
# log4j.logger.com.bjsxt.mapper.UserMapper.selAll=DEBUG
# 类级别
# log4j.logger.com.bjsxt.mapper.UserMapper=DEBUG
# 包级别
log4j.logger.com.bjsxt.mapper=DEBUG

# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=- %m%l%n

# LOGFILE is set to be a File appender using a PatternLayout.
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d:/test.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=- %m %l%n

UserMapper接口（方法）：

package com.bjsxt.mapper;

import java.util.List;

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

import com.bjsxt.pojo.User;

public interface UserMapper {

	/**
	 * mysql动态查询语句
	 * @param id
	 * @param username
	 * @param password
	 * @return
	 */
	List<User> selByIUP(@Param("id") int id,@Param("username") String username,@Param("password") String password);

}

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="com.bjsxt.mapper.UserMapper">

    <!-- 动态通过用户名，密码，id来查询用户的所有信息 -->
  	<select id="selByIUP" resultType="User">
  		select * from t_user
  		<where>
  			<if test="id!=0">
  				and id=#{id}
  			</if>
  			<if test="username!=null and username!=''">
  				and username=#{username}
  			</if>
  			<if test="password!=null and password!=''">
  				and password=#{password}
  			</if>
  		</where>
  	</select>
  </mapper>

Test测试类：

package com.bjsxt.test;

import java.util.ArrayList;
import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.bjsxt.mapper.UserMapper;
import com.bjsxt.pojo.User;
import com.bjsxt.util.MyBatisUtil;

public class TestSelectDT {

	@Test
	public void SelectByIUP() {
		SqlSession session = MyBatisUtil.getSession();
		UserMapper mapper = session.getMapper(UserMapper.class);
		List<User> list = mapper.selByIUP(5, null, null);
		for (User u : list) {
			System.out.println(u);
		}
		session.close();
	}
}

测试截图：