Spring JPA 用法总结

一时失言乱红尘 2024-02-19 20:52 98阅读 0赞

废话不多说，直接发送源码：

**Repository**

package test.dao;
    
    import java.util.List;
    import java.util.Map;
    
    import org.springframework.jdbc.core.JdbcTemplate;
    
    import test.bean.User;
    import test.mapper.UserRowMapper;
    
    public class UserRepositoryImpl extends JdbcDaoSupport {
    
    	// create table
    	public void createTable() {
    		String sql = "create table test(name varchar(50), id bigint(20) NOT NULL AUTO_INCREMENT)";
    		getJdbcTemplate().execute(sql);
    	}
    
    	// update insert delete
    	public void update() {
    		String sql = "update user set name = ? where id = ?";
    		String name = "张胜鸿";
    		int id = 100;
    		getJdbcTemplate().update(sql, new Object[] { name, id });
    	}
    
    	// count(*)
    	public void count() {
    		String sql = "select count(1) from user";
    		int count =getJdbcTemplate().queryForInt(sql);
    		System.out.println(count);
    	}
    
    	// select String
    	public void selectByString() {
    		String sql = "select name from user where id = ?";
    		int id = 100;
    		String name = getJdbcTemplate().queryForObject(sql,
    				new Object[] { id }, java.lang.String.class);
    		System.out.println(name);
    	}
    
    	// select object
    	public void selectByObject() {
    		String sql = "select * from user where id = ?";
    		int id = 100;
    		User user = getJdbcTemplate().queryForObject(sql, new Object[] { id },
    				new UserRowMapper());
    		System.out.println(user.getName());
    	}
    
    	// select list
    	public void selectByList() {
    		String sql = "select * from user";
    		List<User> list = getJdbcTemplate().query(sql, new UserRowMapper());
    		for (User user : list) {
    			System.out.println(user.getId() + ";" + user.getName());
    		}
    	}
    
    	// select row
    	@SuppressWarnings("unchecked")
    	public void selectByRows() {
    		String sql = "select * from user";
    		List rows = getJdbcTemplate().queryForList(sql);
    		for (int i = 0; i < rows.size(); i++) {
    			Map map = (Map) rows.get(i);
    			System.out.println(map.get("name"));
    		}
    	}
    }

**Mapper**

package test.mapper;
    
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    import org.springframework.jdbc.core.RowMapper;
    
    import test.bean.User;
    
    public class UserRowMapper implements RowMapper<User> {
    
    	public User mapRow(ResultSet rs, int index) throws SQLException {
    		User user = new User();
    		user.setId(rs.getInt("id"));
    		user.setName(rs.getString("name"));
    		return user;
    	}
    
    }

**Entity**

package test.bean;
    
    public class User {
    	private int id;
    	private String name;
    
    	public int getId() {
    		return id;
    	}
    
    	public void setId(int id) {
    		this.id = id;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    }

注意：实列化UserRepositoryImpl 对象后，需要调用 setDataSource(dataSource); // 设定数据源，如果想知道是什么原因，需要查看JdbcDaoSupport 的源码：

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