Spring框架针对dao层的jdbcTemplate操作crud之query查询数据操作 —

用JdbcTemplate的方法完成，查询数据库表，把用户表sw_user所有数据以List<User>集合返回

在JdbcTemplateDemo类中增加查询返回所有对象集合的方法queryAllObject()

数据源DriverManagerDataSource不变

jdbcTemplate的方法有所改变，使用query(sql, new MyRowMapper());

其中第二个参数是一个接口RowMapper<User>的实现类，可以使用匿名内部类，我使用的是单独的类MyRowMapper的对象

它要实现重载的方法mapRow(ResultSet rs, int num)只做两件事

一用ResultSet得到所需User对象数据

二用User进行封装得到对象并返回

浏览器得到查询效果图：

JdbcTemplateDemo类：

package com.swift;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.List;

import org.springframework.jdbc.core.JdbcTemplate;

import org.springframework.jdbc.core.RowMapper;

import org.springframework.jdbc.datasource.DriverManagerDataSource;

import org.springframework.stereotype.Component;

@Component(value="jdbcTemplateDemo")

public class JdbcTemplateDemo {

    public List<User> queryAllObject(){

        DriverManagerDataSource dataSource=new DriverManagerDataSource();

        dataSource.setDriverClassName("com.mysql.jdbc.Driver");

        dataSource.setUsername("root");

        dataSource.setPassword("root");

        dataSource.setUrl("jdbc:mysql://localhost:3306/sw_database");

        JdbcTemplate jdbcTemplate=new JdbcTemplate(dataSource);

        String sql="select * from sw_user";

        List<User> list=jdbcTemplate.query(sql, new MyRowMapper());

        return list;

    }

    public User queryOneObject() {

        DriverManagerDataSource dataSource=new DriverManagerDataSource();

        dataSource.setDriverClassName("com.mysql.jdbc.Driver");

        dataSource.setUrl("jdbc:mysql://localhost:3306/sw_database");

        dataSource.setUsername("root");

        dataSource.setPassword("root");

        JdbcTemplate jdbcTemplate=new JdbcTemplate(dataSource);

        String sql="select * from sw_user where username=? and password=?";

        User user=jdbcTemplate.queryForObject(sql, new MyRowMapper(), "zhangsan","123456");

        return user;

    }

    public boolean delete(String username) {

    DriverManagerDataSource dataSource=new DriverManagerDataSource();

    dataSource.setDriverClassName("com.mysql.jdbc.Driver");

    dataSource.setUrl("jdbc:mysql://localhost:3306/sw_database");

    dataSource.setUsername("root");

    dataSource.setPassword("root");

    JdbcTemplate jdbcTemplate=new JdbcTemplate(dataSource);

    int count=jdbcTemplate.update("delete from sw_user where username=?", username);

    if(count!=0) {

        return true;

    }

    return false;

    }

}

//没有用匿名内部类，注意MyRowMapper后没有<User>

class MyRowMapper implements RowMapper<User> {

    @Override

    public User mapRow(ResultSet rs, int num) throws SQLException {

        String username=rs.getString("username");

        String password=rs.getString("password");

        User user=new User(username,password);

        return user;

    }

}

Servlet类调用该JdbcTemplateDemo类

package com.swift;

import java.io.IOException;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

@WebServlet("/demo")

public class ServletDemo extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public ServletDemo() {

        super();

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.getWriter().append("Served at: ").append(request.getContextPath());

        //使用JdbcTemplat的queryForObject方法

        ApplicationContext context=new ClassPathXmlApplicationContext("aop.xml");

        JdbcTemplateDemo jdbcTemplateDemo=(JdbcTemplateDemo) context.getBean("jdbcTemplateDemo");

        List<User> list=jdbcTemplateDemo.queryAllObject();

        for(User user:list) {

            response.getWriter().append(user.toString());

            response.getWriter().println();

        }

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);

    }

}

所用到的xml配置文件在前面随笔中及相关包

巴特西

Spring框架针对dao层的jdbcTemplate操作crud之query查询数据操作 —— 查询表，返回结果为对象的list集合

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