springmvc工具类封装RowMapper

springmvc通常是先写实体，在数据库查询，最后增删改差，最感觉代码很冗余，自己在封装了一下。

常见的结构是：

entity：如

package com.liuxinquan.entiry;

/**
 * @author:lxq
 * @类说明:Book
 * 
 */
public class Book {

	private String id;
	private String user_id;
	private String item_id;
	private String prefer;

	private String time;

	public String getId() {
		return id;
	}

	public String getUser_id() {
		return user_id;
	}

	public void setUser_id(String user_id) {
		this.user_id = user_id;
	}

	public String getItem_id() {
		return item_id;
	}

	public void setItem_id(String item_id) {
		this.item_id = item_id;
	}

	public String getPrefer() {
		return prefer;
	}

	public void setPrefer(String prefer) {
		this.prefer = prefer;
	}

	public String getTime() {
		return time;
	}

	public void setTime(String time) {
		this.time = time;
	}

	public void setId(String id) {
		this.id = id;
	}

}

object：如

package com.liuxinquan.object;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.springframework.jdbc.core.RowMapper;

import com.liuxinquan.entiry.Book;

/**
 * @author:lxq
 * @类说明：bookobject
 * 
 */
public class BookObj implements RowMapper<Book> {

	@Override
	public Book mapRow(ResultSet rs, int arg1) throws SQLException {
		Book book = new Book();
		book.setId(rs.getString("id"));
		book.setItem_id(rs.getString("item_id"));
		book.setPrefer(rs.getString("prefer"));
		book.setTime(rs.getString("time"));
		book.setUser_id(rs.getString("user_id"));
		return book;
	}
	
	

}

service

package com.liuxinquan.service;

import java.util.List;

import javax.annotation.Resource;

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;

import com.liuxinquan.entiry.Book;
import com.liuxinquan.utils.CommonObj;

/**
 * @author: @类说明：
 * 
 */
@Service
public class BookService {
	@Resource(name = "jdbcTemplate")
	public JdbcTemplate jdbcTemplate;

	public List<Book> findAll() {
		String sql = "select * from recommender_prefer ";
		List<Book> books = jdbcTemplate.query(sql, new bookObj());
		return books;
	}

	public Book findbyId(String id) {
		String sql = "select * from recommender_prefer where id =" + id;
		Book book = jdbcTemplate.queryForObject(sql, new BookObj());
		return book;
	}
	
}

下面是简化的工具类

要是有很多实体，每写一个，都要重复这3个，效率很低，其中后两个是可以封装工具类：通用object

package com.liuxinquan.utils;

import java.lang.reflect.Field;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.springframework.jdbc.core.RowMapper;

/**
 * @author:lxq
 * @类说明：通用dao工具
 * 
 */
public class CommonObj implements RowMapper<Object> {

	private Class<?> cl;

	public CommonObj(Class<?> cl) {
		this.cl = cl;
	}

	@Override
	public Object mapRow(ResultSet rs, int i) throws SQLException {

		try {
			Field[] fields = cl.getDeclaredFields();
			Object entity = cl.newInstance();
			for (Field f : fields) {
				f.setAccessible(true);
				this.typeMapper(f, entity, rs);
				f.setAccessible(false);
			}
			return entity;
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;
	}

	private void typeMapper(Field field, Object obj, ResultSet rs) throws Exception {
		String type = field.getType().getName();
		if (type.equals("java.lang.String")) {
			field.set(obj, rs.getString(field.getName()));
		} else if (type.equals("int") || type.equals("java.lang.Integer")) {
			field.set(obj, rs.getInt(field.getName()));
		} else if (type.equals("long") || type.equals("java.lang.Long")) {
			field.set(obj, rs.getLong(field.getName()));
		} else if (type.equals("boolean") || type.equals("java.lang.Boolean")) {
			field.set(obj, rs.getBoolean(field.getName()));
		} else if (type.equals("java.util.Date")) {
			field.set(obj, rs.getDate(field.getName()));
		}
	}

}

这个可以放在utils中，具体用法如下：

package com.liuxinquan.service;

import java.util.List;

import javax.annotation.Resource;

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;

import com.liuxinquan.entiry.Book;
import com.liuxinquan.utils.CommonObj;

/**
 * @author:
 @类说明：
 * 
 */
@Service
public class BookService {
	@Resource(name = "jdbcTemplate")
	public JdbcTemplate jdbcTemplate;

	public List<Object> findAll() {
		String sql = "select * from recommender_prefer ";
		List<Object> books = jdbcTemplate.query(sql, new CommonObj(Book.class));
		return books;
	}

	public Object findbyId(String id) {
		String sql = "select * from recommender_prefer where id =" + id;
		Object book = jdbcTemplate.queryForObject(sql, new CommonObj(Book.class));
		return book;
	}
	
}

service亦可以简化的，网上有很多，关于通用增删改查，自己可以搜一下。希望能有所帮助。

来源：oschina

链接：https://my.oschina.net/u/2248826/blog/615922