[大数据]JavaWeb使用DataSource连接mysql(javax.sql.DataSource)

DataSource配置

在webapp下新建META-INF文件夹，在META-INF下新建context.xml文件：

根据自己的数据库信息更改context.xml：
我这是连接本地的mysql，将数据库名称改为你自己的。

<?xml version="1.0" encoding="UTF-8"?>
<Context>
    <Resource name="jdbc/MySQL" type="javax.sql.DataSource"
              maxTotal="100" maxIdle="30" maxWaitMillis="10000" initialSize="1"
              username="账户名称" password="密码"
              driverClassName="com.mysql.cj.jdbc.Driver"
              url="jdbc:mysql://localhost:3306/数据库名称?serverTimezone=Asia/Shanghai" />
</Context>

在pom.xml里加入jdbc和servlet的依赖：

 <!--Mysql依赖声明开始-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.23</version>
    </dependency>
    <!--Mysql依赖声明完成-->
    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>javax.annotation</groupId>
      <artifactId>javax.annotation-api</artifactId>
      <version>1.3.2</version>
      <scope>provided</scope>
    </dependency>

后端服务

这是后端的目录结构：

对应代码：
GetUserSrevlet:

package com.controller;

import com.entity.User;
import com.util.DataSourceUtils;

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 java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

@WebServlet("/getuser")
public class GetUserServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        User user = null;
        String sql = "select * from user where id=?";
        try (Connection conn = DataSourceUtils.getConnection();
             PreparedStatement st = conn.prepareStatement(sql)) {
            st.setString(1, req.getParameter("uid"));
            try (ResultSet rs = st.executeQuery()) {
                while (rs.next()) {
                    user = new User();
                    user.setId(rs.getInt("id"));
                    user.setName(rs.getString("name"));
                    user.setInsertTime(rs.getTimestamp("inserttime"));
                }
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        System.out.println(user.getName());
    }
}

User

package com.entity;

import java.util.Date;

public class User {
    private int id;
    private String name;
    private Date insertTime;

    public User() {
    }

    public User(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public User(int id, String name, Date insertTime) {
        this.id = id;
        this.name = name;
        this.insertTime = insertTime;
    }

    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;
    }

    public Date getInsertTime() {
        return insertTime;
    }

    public void setInsertTime(Date insertTime) {
        this.insertTime = insertTime;
    }
}

DataSourceUtils

package com.util;

import javax.annotation.Resource;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

@WebListener
public class DataSourceUtils implements ServletContextListener {
    @Resource(name = "jdbc/MySQL")
    private static DataSource dSource;
    public static Connection getConnection() throws SQLException {
        return dSource.getConnection();
    }
}

启动项目，浏览器地址访问,因为没有前端传值，这里模拟请求数据uid=1

http://localhost:8080/DataSource_war/getuser?uid=1

查看终端：

这就是javaweb利用DataSource简单的连接数据库并查询数据。