JdbcTemplate中的query方法(代码)

灰太狼 2023-07-10 14:14 1阅读 0赞

User.java实体类：

package com.liu.jdbc.update;
    
    public class User { 
    	private Integer id;
    	private String username;
    	private String password;
    	
    	public Integer getId() { 
    		return id;
    	}
    	public void setId(Integer 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 + "]";
    	}
    	
    	
    
    }

UserDao.java接口：

package com.liu.jdbc.update;
    
    import java.util.List;
    
    public interface UserDao { 
    
    	//根据id查询数据
    	public User selectById(int id);
    	//查询所有数据
    	public List<User> selectAll();
    	
    }

UserDaoImpl.java实现类：

package com.liu.jdbc.update;
    
    import java.util.List;
    
    import org.springframework.jdbc.core.BeanPropertyRowMapper;
    import org.springframework.jdbc.core.JdbcTemplate;
    import org.springframework.jdbc.core.RowMapper;
    
    public class UserDaoImpl implements UserDao { 
    	//声明JdbcTemplate属性及其setter方法
    	private JdbcTemplate jdbcTemplate;
    	
    
    	public void setJdbcTemplate(JdbcTemplate jdbcTemplate) { 
    		this.jdbcTemplate = jdbcTemplate;
    	}
    
    	
    	//根据id查询数据
    	@Override
    	public User selectById(int id) { 
    		// TODO Auto-generated method stub
    		//定于SQL语句
    		String sql = "select * from user where id = ?";
    		//创建一个新的BeanPropertyRowMapper对象
    		RowMapper<User> rowMapper = new BeanPropertyRowMapper<User>(User.class);
    		//将id绑定到SQL语句中，通过rowMapper返回一个Object类型的单行记录
    		User user = this.jdbcTemplate.queryForObject(sql, rowMapper, 1);
    		return user;
    	}
    
    	//查询所有数据
    	@Override
    	public List<User> selectAll() { 
    		// TODO Auto-generated method stub
    		//定义SQL语句
    		String sql = "select * from user";
    		//创建一个新的BeanPropertyRowMapper对象
    		RowMapper<User> rowMapper = new BeanPropertyRowMapper<User>(User.class);
    		//通过rowMapper返回结果
    		List<User> list = this.jdbcTemplate.query(sql, rowMapper);
    		return list;
    	}
    
    }

ApplicationContext.xml配置文件：

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
    		
    		
    		<bean id = "dataSource" class = "org.springframework.jdbc.datasource.DriverManagerDataSource">
    			
    			<property name="driverClassName" value = "com.mysql.jdbc.Driver"></property>
    			
    			<property name="url" value = "jdbc:mysql://localhost:3306/test"></property>
    			
    			<property name="username" value = "root"></property>
    			
    			<property name="password" value = "root"></property>
    		</bean>
    		
    		<bean id = "jdbcTemplate" class = "org.springframework.jdbc.core.JdbcTemplate">
    			
    			<property name="dataSource" ref = "dataSource"></property>
    		</bean>
    
    		
    		<bean id = "userDao" class = "com.liu.jdbc.update.UserDaoImpl">
    			<property name="jdbcTemplate" ref ="jdbcTemplate"></property>
    		</bean>
    
    </beans>

Test.java测试类：

package com.liu.jdbc.update;
    
    import java.util.List;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class Test { 
    	
    	public static void main(String args[]) { 
    		Test test = new Test();
    		test.selectById();
    		//test.selectAll();
    	}
    	
    
    	//通过id查询
    	public void selectById() { 
    		String xmlpath = "com/liu/jdbc/update/ApplicationContext.xml";
    		ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlpath);
    		UserDao userDao = (UserDao) applicationContext.getBean("userDao");
    		User user = userDao.selectById(1);
    		System.out.println(user);
    	}
    
    	//查询全部数据
    	public void selectAll() { 
    		String xmlpath = "com/liu/jdbc/update/ApplicationContext.xml";
    		ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlpath);
    		UserDao userDao = (UserDao) applicationContext.getBean("userDao");
    		List<User> list = userDao.selectAll();
    		for(User li : list) { 
    			System.out.println(li);
    		}
    	}
    }