JavaWeb - 数据库连接池、C3P0、Druid、JDBCTemplate

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
 * Druid连接池的工具类
 */
public class JDBCUtils {
    //1.定义一个成员变量 DataSource
    private static DataSource ds;

    static {
        try {
            //1.加载配置文件
            Properties pro = new Properties();
            pro.load(JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
            //2.获取DataSource 并赋值
            ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 获取连接
     */
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

    /**
     * 释放资源
     */

    public static void close(Statement stmt, Connection conn){
        close(null,stmt,conn); //直接调用三个参数的方法 简化编译
    }

    public static void close(ResultSet rs,Statement stmt, Connection conn){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if(stmt!=null){
            try {
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null){
            try {
                conn.close();//归还连接
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 获取连接池的方法
     */
    public static DataSource getDateSource(){
        return ds;
    }
}

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class druidDemo2 {
    public static void main(String[] args) {
        //完成添加操作 给account表添加一条记录
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            //1.获取连接
            conn = JDBCUtils.getConnection();
            //2.定义sql
            String sql = "insert into account values(null,?,?)";
            //3.获取pstmt对象
            pstmt = conn.prepareStatement(sql);

            //4.给问号赋值
            pstmt.setString(1,"liudanao");
            pstmt.setDouble(2,8000);

            //5.执行sql
            int count = pstmt.executeUpdate();

            System.out.println(count);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            JDBCUtils.close(pstmt,conn);
        }
    }
}

import cn.itcast.dataSource.utils.JDBCUtils;
import org.junit.Test;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

public class JdbcTemplateDemo2 {

    //Junit单元测试,可以让方法独立执行    //1.获取JdbcTemplate对象
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDateSource());
    //1.修改1号数据的salary为10000
    @Test
    public void test1(){

        //2.定义sql
        String sql = "update emp set salary = 10000 where id = ?";

        int count = template.update(sql, 1001);
        System.out.println(count);
    }

    //2.添加一条记录
    @Test
    public void test2(){
        String sql = "insert into emp(id,ename,dept_id) values(?,?,?)";
        int count = template.update(sql, 1015, "郭靖", 10);
        System.out.println(count);
    }

    //3.删除刚才添加的记录
    @Test
    public void test3(){
        String sql = "delete from emp where id = ?";
        int count = template.update(sql, 1015);
        System.out.println(count);
    }

    //4.查询id为1的记录，将其封装为map集合
    @Test
    public void test4(){
        String sql = "select * from emp where id = ?";
        Map<String, Object> map = template.queryForMap(sql, 1001);
        //注意：这个方法查询的结果集长度只能是1
        System.out.println(map);
        //{id=1001, ename=孙悟空, job_id=4, mgr=1004, joindate=2000-12-17, salary=10000.00, bonus=null, dept_id=20}
    }

    //5.查询所有记录，将其封装为list
    @Test
    public void test5(){
        String sql = "select * from emp";
        List<Map<String, Object>> list = template.queryForList(sql);
        for (Map<String, Object> result : list) {
            System.out.println(result);
        }
    }
    //6.查询所有记录，将其封装为Emp对象的list集合
    @Test
    public void test6(){
        String sql = "select * from emp";
        List<Emp> list = template.query(sql, new BeanPropertyRowMapper<Emp>(Emp.class));
        for (Emp emp : list) {
            System.out.println(emp);
        }
    }
    //7.查询总记录数
    @Test
    public void test7(){
        String sql = "select count(id) from emp";
        Long total = template.queryForObject(sql, Long.class);
        System.out.println(total);
    }
}