springmvc工具類封裝RowMapper

springmvc通常是先寫實體，在數據庫查詢，最后增刪改差，最感覺代碼很冗余，自己在封裝了一下。

常見的結構是：

entity：如

package com.liuxinquan.entiry;

/**
 * @author:lxq
 * @類說明: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
 * @類說明：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: @類說明：
 * 
 */
@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;
    }

}

下面是簡化的工具類

要是有很多實體，每寫一個，都要重復這3個，效率很低，其中后兩個是可以封裝工具類：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
 * @類說明：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()));
        }
    }

}

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:
 @類說明：
 * 
 */
@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亦可以簡化的，網上有很多，關于通用增刪改查，自己可以搜一下。希望能有所幫助。