Spring框架針對dao層的jdbcTemplate操作crud之delete刪除數據操作

查詢目標是完成3個功能：

（1）查詢表，返回某一個值。例如查詢表中記錄的條數，返回一個int類型數據

（2）查詢表，返回結果為某一個對象。

（3）查詢表，返回結果為某一個泛型的list集合。

一、查詢表中記錄的條數，返回一個int類型數據的操作方法

使用jdbcTemplate

原理是把載入驅動Class.forName("com.mysql.jdbc.Driver");

和連接資料庫Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/sw_database?user=root&password=root");

用一個對象完成DriverManagerDataSource dataSource=new DriverManagerDataSource();

package com.swift;

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.stereotype.Component;

@Component(value="jdbcTemplateDemo")
public class JdbcTemplateDemo {
    public int queryCount() {
        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 count(*) from sw_user";
        int count=jdbcTemplate.qureyForObject(sql, Integer.class);
        return count;
        }
    
    public boolean update() {
        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="update sw_user set password=? where username=?";
        int count=jdbcTemplate.update(sql,"lunchtime","doomsday");
        if(count!=0) {
            return true;
        }
        return false;
        }
    
}

查詢資料庫操作使用JdbcTemplate對象根據數據源直接使用qureyForObject方法完成，第二個參數Integer.class為返回值類型的class。

之前完成需按下邊方法：

PreparedStatement ps=conn.prepareStatement("select count(*) from sw_user");

???ResultSet rs=ps.executeQuery();???有待驗證

上邊代碼使用Spring框架註解生成對象方法

xml配置文件代碼如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
         http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!-- 開啟註解掃描——對象和屬性 -->
    <context:component-scan base-package="com.swift"></context:component-scan>
    <!-- 開啟aop註解方法 -->
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
    
</beans>

使用Servlet類進行測試：

package com.swift;

import java.io.IOException;

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("/test")
public class ServletTest extends HttpServlet {
    private static final long serialVersionUID = 1L;
    public ServletTest() {
        super();
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().append("Served at: ").append(request.getContextPath());
        ApplicationContext context=new ClassPathXmlApplicationContext("aop.xml");
        JdbcTemplateDemo jdbcTemplateDemo=(JdbcTemplateDemo) context.getBean("jdbcTemplateDemo");
        response.getWriter().append(jdbcTemplateDemo.queryCount());
        
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

運行結果圖