【MyBatis】学习笔记05：获取参数值的两种方式
作者：互联网
【MyBatis】学习笔记03：配置文件进一步解读（非常重要）
目录
MyBatis获取参数值的两种方式：
1.字符串拼接：${}
2.占位符赋值：#{}
一些准备工作
java/cc/mllt/sky/utils
resources/cc/mllt/sky/utils
封装SQLSessionUtils工具类
package cc.mllt.sky.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;
import java.io.InputStream;
public class SqlSessionUtils {
public static SqlSession getSqlSession(){
SqlSession sqlSession = null;
try{
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
sqlSession = sqlSessionFactory.openSession(true);
}catch (IOException e){
e.printStackTrace();
}
return sqlSession;
}
}
MyBatis获取参数值的各种情况
1.mapper接口方法的参数为单个的字面量类型
或者这样
总结
可以通过
${}和#{}以任意的字符串获取参数值，但是需要注意${}的单引号问题
2.mapper接口方法的参数为多个时
总结
mapper接口方法的参数为多个时，MyBatis会将这些参数放在map集合中，以两种方式进行存储，
第一种为：arg0，arg1……为键，以参数为值
第二种为：以param1，param2……为键，以参数为值
因此只需要通过
#{}和${}以键的形式访问值就可以了。
3.mapper接口方法的参数有多个时，可以手动将这些参数放在一个map中存储
4.mapper接口方法的参数是一个实体类类型的参数
实体类：属性 属性值
Map：键 值
通过#{}或${}以属性的方式访问值即可
必须是属性名字，不能乱写噢！
5.使用@Param命名参数
此时Mybatis会将这些参数放在一个Map集合中，以两种方式存储
a. 以@Param注解的值为键，以参数为值
b. 以param1，param2……为键，以参数为值
通过#{}或${}以键的方式访问值即可
源码贴贴
目录
cc.mllt.sky.utils.UserParameterMapper.java
package cc.mllt.sky.utils;
import cc.mllt.sky.jdbc.User;
import org.apache.ibatis.annotations.Param;
import java.util.Map;
public interface UserParameterMapper {
/**
* 登录验证
* @param username String 用户名
* @param password String 密码
* @return User对象
*/
User UserLogin(String username,String password);
/**
* 验证登陆
* @return User对象
*/
User UserLoginByMap(Map<String,Object> map);
/**
* 验证登陆（使用@Param注解）
* @param username 用户名
* @param password 用户密码
* @return User对象
*/
User UserLoginByParam(@Param("name") String username, @Param("password") String password);
/**
* 根据用户账号查询用户信息
* @return User对象
*/
User getUserByUserCount(String usercount);
/**
* 添加用户
* @param user 用户对象
* @return int型
*/
int UserAdd(User user);
}
cc.mllt.sky.jdbc.User.java
package cc.mllt.sky.jdbc;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.sql.Timestamp;
public class User {
private BigInteger userId;
public String userName;
private String userCount;
private String userPassword;
private int userGrade;
public Timestamp userRegDate;
private BigDecimal userBlance;
public User( String userName,String userCount,String userPassword) {
this.userName=userName;
this.userCount=userCount;
this.userPassword=userPassword;
}
//getter and setter
public BigInteger getUserId() {
return userId;
}
public void setUserId(BigInteger userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserCount() {
return userCount;
}
public void setUserCount(String userCount) {
this.userCount = userCount;
}
public String getUserPassword() {
return userPassword;
}
public void setUserPassword(String userPassword) {
this.userPassword = userPassword;
}
public int getUserGrade() {
return userGrade;
}
public void setUserGrade(int userGrade) {
this.userGrade = userGrade;
}
public Timestamp getUserRegDate() {
return userRegDate;
}
public void setUserRegDate(Timestamp userRegDate) {
this.userRegDate = userRegDate;
}
public BigDecimal getUserBlance() {
return userBlance;
}
public void setUserBlance(BigDecimal userBlance) {
this.userBlance = userBlance;
}
@Override
public String toString(){
return "User{"+
"userId='"+userId+"'"+
",userName='"+userName+"'"+
"userCount='"+userCount+"'"+
",userPassword='"+userPassword+"'"+
"userGrade='"+userGrade+"'"+
",userRegDate='"+userRegDate+"'"+
"userBlance='"+userBlance+"'}";
}
}
resources.cc.mllt.sky.utils.UserParameterMapper.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="cc.mllt.sky.utils.UserParameterMapper">
<!-- User getUserByUsedCount(String usercount);-->
<select id="getUserByUserCount" resultType="User">
<!--select * from t_users where `userCount` = #{username}-->
select * from t_users where `userCount` = '${username}'
</select>
<!-- User UserLogin(String username,String password);-->
<select id="UserLogin" resultType="User">
<!--select * from t_users where userCount=#{arg0} and userPassword=#{arg1}-->
<!--select * from t_users where userCount=#{param1} and userPassword=#{param2}-->
<!--select * from t_users where userCount=#{param1} and userPassword=#{arg1}}-->
select * from t_users where userCount='${param1}' and userPassword='${arg1}'
</select>
<!-- User UserLoginByMap(Map<String,Object> map);-->
<select id="UserLoginByMap" resultType="User">
select * from t_users where userCount=#{username} and userPassword=#{password}
</select>
<!-- int UserAdd(User user);-->
<insert id="UserAdd">
insert into t_users set
`userName`=#{userName},
`userCount`=#{userCount},
`UserPassword`=#{userPassword},
`userGrade`='0',
`userBlance`='0';
</insert>
<!-- User UserLoginByParam(@Param("name") String username, @Param("password") String password);-->
<select id="UserLoginByParam" resultType="User">
select * from t_users where userCount=#{name} and userPassword=#{password}
</select>
</mapper>
Test
下面有一些测试方法是以前用到的，在本次笔记中没有用到的，可以删掉
import cc.mllt.sky.jdbc.User;
import cc.mllt.sky.jdbc.UsersMapper;
import cc.mllt.sky.utils.SqlSessionUtils;
import cc.mllt.sky.utils.UserParameterMapper;
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.jupiter.api.Test;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class TestUsers {
@Test
public void UsersAdd() throws IOException {
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);
mapper.insertUser();
}
@Test
public void UsersDel() throws IOException {
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);
mapper.deleteUser();
}
@Test
public void UsersUpdate() throws IOException {
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);
mapper.updateUser();
}
@Test
public void UsersGetById() throws IOException {
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);
User user = mapper.selectUserById();
System.out.println(user);
System.out.println(user.getUserName());
}
@Test
public void UsersGetAll() throws IOException {
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession(true);
UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);
List<User> list = mapper.selectUser();
list.forEach(user -> System.out.println(user));
}
@Test
public void testJDBC() throws Exception{
String username ="xrilang";
Class.forName("");
//创建链接对象
Connection connection = DriverManager.getConnection("");
//PreparedStatement ps = connection.prepareStateme nt("selsect * from t_users where userName = '"+username+"'");//麻烦且不安全，会造成SQL注入
PreparedStatement ps = connection.prepareStatement("select * from t_users where userName= ? ");
ps.setString(1,username);
}
@Test
public void GetUserByCount(){
SqlSession sqlSession = SqlSessionUtils.getSqlSession();
UserParameterMapper mapper = sqlSession.getMapper(UserParameterMapper.class);
User user = mapper.getUserByUserCount("test001");
System.out.println(user);
}
@Test
public void CheckUserLogin(){
SqlSession sqlSession = SqlSessionUtils.getSqlSession();
UserParameterMapper mapper = sqlSession.getMapper(UserParameterMapper.class);
User user = mapper.UserLogin("test001","123456改了密码");
System.out.println(user);
}
@Test
public void CheckUserLoginByMap(){
SqlSession sqlSession = SqlSessionUtils.getSqlSession();
UserParameterMapper mapper = sqlSession.getMapper(UserParameterMapper.class);
Map<String,Object> map = new HashMap<>();
map.put("username","test001");
map.put("password","123456改了密码");
User user = mapper.UserLoginByMap(map);
System.out.println(user);
}
@Test
public void UserAdd(){
SqlSession sqlSession = SqlSessionUtils.getSqlSession();
UserParameterMapper mapper = sqlSession.getMapper(UserParameterMapper.class);
int result = mapper.UserAdd(new User("张三","mllt@xrilang.com","123"));
System.out.println(result);
}
@Test
public void CheckUserLoginByParam(){
SqlSession sqlSession = SqlSessionUtils.getSqlSession();
UserParameterMapper mapper = sqlSession.getMapper(UserParameterMapper.class);
Map<String,Object> map = new HashMap<>();
User user = mapper.UserLoginByParam("test001","123456改了密码");
System.out.println(user);
}
}
标签：mapper,String,05,参数值,sqlSession,User,MyBatis,import,public 来源： https://www.cnblogs.com/mllt/p/mybatis05.html