黑马学习连接池 druid JdbcTemplate c3p0 池技术

 package cn.itcast.jdbctemplate;

 import org.junit.Test;
 import org.springframework.jdbc.core.BeanPropertyRowMapper;
 import org.springframework.jdbc.core.JdbcTemplate;

 import java.math.BigDecimal;
 import java.util.Date;
 import java.util.List;
 import java.util.Map;

 /*
  * 1. 要求 JdbcTemplate
  * 2. jdbcUtils工具类直接拿来用（druid.properties）
  * 3. 插入员工数据（完整的）
  * 4. 删除员工数据（按照员工编号删除）
  * 5. 修改员工数据（修改李逵的工资、奖金、部门）
  * 6. 查询所有工资大于20000万的员工， 按工资降序排列
  * 7. 查询所有在 2007-5-1 之后入职的员工
  * 8. 按部门分组，统计每组的人数
  *
  * 分析：
  *  1.使用jdbctemplate+druid来进行测试，准备一个DataSource对象，来创建JdbcTemplate对象
  *
  * */
 public class JdbcTemplate_Test {
     private JdbcTemplate jdbcTemplate = new JdbcTemplate(DruidJdbcUtils.getDataSource());
     /**
      * 插入员工数据（完整的）
      */
     @Test
     public void test1(){
         Employee emp = new Employee();
         emp.setId(1015);
         emp.setEname("小白龙");
         emp.setJobId(4);
         emp.setMgr(1004);
         emp.setJoindate(new Date());
         emp.setSalary(new BigDecimal(3000));
         emp.setBonus(new BigDecimal(8000));
         emp.setDeptId(20);

         String sql = "insert into emp(id, ename, job_id, mgr, joindate, salary, bonus, dept_id) values(?,?,?,?,?,?,?,?)";

         int rows = jdbcTemplate.update(sql, emp.getId(), emp.getEname(), emp.getJobId(), emp.getMgr(),
                 emp.getJoindate(), emp.getSalary(), emp.getBonus(), emp.getDeptId());
         System.out.println(rows);
     }

     /**
      * 删除员工数据（按照员工编号删除）
      */
     @Test
     public void test2(){
         String sql = "delete from emp where id = ?";
         int rows = jdbcTemplate.update(sql, 1015);
         System.out.println(rows);
     }

     /**
      * 修改员工数据（修改李逵的工资、奖金、部门）
      */
     @Test
     public void test3(){
         String sql = "update emp set salary = ?, bonus = ?, dept_id = ? where ename = ? ";
         int rows = jdbcTemplate.update(sql, 2000, 2000, 20, "李逵");
         System.out.println(rows);
     }

     /**
      * 查询所有工资大于20000万的员工， 按工资降序排列
      */
     @Test
     public void test4(){
 //        TimeZone.setDefault(TimeZone.getTimeZone("GMT+10:00"));数据库是Date类型的，这里修改默认时区根本不影响结果。
         String sql = "select id, ename, job_id as jobId, mgr, joindate, salary, bonus, dept_id as deptId from emp where salary > ? ";
         List<Employee> employeeList = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Employee.class), 20000);
         employeeList.forEach(System.out::println);
     }

     /**
      * 按部门分组，统计每组的人数
      */
     @Test
     public void test5(){
         String sql = "select\n" +
                 "\tcount(t1.id) as employee_num, t2.id as id, t2.dname as dname\n" +
                 "FROM\n" +
                 "emp as t1\n" +
                 "right join \n" +
                 "dept as t2\n" +
                 "on \n" +
                 "t1.dept_id = t2.id\n" +
                 "GROUP BY\n" +
                 "t2.id";
         List<Map<String, Object>> mapList = jdbcTemplate.queryForList(sql);
         mapList.forEach(System.out::println);
     }
 }

JdbcTemplate操作员工表

 package cn.itcast.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;

 public class DruidJdbcUtils {
     //DataSource对象
     private static DataSource dataSource;

     static {
         try {
             //加载配置
             Properties props = new Properties();
             props.load(DruidJdbcUtils.class.getClassLoader().getResourceAsStream("druid.properties"));

             //创建德鲁伊连接池
             dataSource = new DruidDataSourceFactory().createDataSource(props);
         } catch (IOException e) {
             e.printStackTrace();
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     //获取连接池
     public static DataSource getDataSource(){
         return dataSource;
     }

     //获取连接
     public static Connection getConnection() throws SQLException {
         return dataSource.getConnection();
     }

     //DML语句释放资源
     public static void release(Statement stmt, Connection conn){
       /*  if(stmt != null){
             try {
                 stmt.close();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
         if(conn != null){
             try {
                 conn.close();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }*/
       release(null, stmt, conn);
     }

     //查询语句释放资源
     public static void release(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();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
     }
 }

DruidJbctUtils数据库连接工具类

 package cn.itcast.jdbctemplate;

 import java.math.BigDecimal;
 import java.util.Date;

 /*
 CREATE TABLE emp (
   id INT PRIMARY KEY, -- 员工id
   ename VARCHAR(50), -- 员工姓名
   job_id INT, -- 职务id
   mgr INT , -- 上级领导
   joindate DATE, -- 入职日期
   salary DECIMAL(7,2), -- 工资
   bonus DECIMAL(7,2), -- 奖金
   dept_id INT, -- 所在部门编号
 );
  */
 public class Employee {
     private Integer id;
     private String ename;
     private Integer jobId;
     private Integer mgr;
     private Date joindate;
     private BigDecimal salary;
     private BigDecimal bonus;
     private Integer deptId;

     public Employee() {
     }

     public Integer getId() {
         return id;
     }

     public void setId(Integer id) {
         this.id = id;
     }

     public String getEname() {
         return ename;
     }

     public void setEname(String ename) {
         this.ename = ename;
     }

     public Integer getJobId() {
         return jobId;
     }

     public void setJobId(Integer jobId) {
         this.jobId = jobId;
     }

     public Integer getMgr() {
         return mgr;
     }

     public void setMgr(Integer mgr) {
         this.mgr = mgr;
     }

     public Date getJoindate() {
         return joindate;
     }

     public void setJoindate(Date joindate) {
         this.joindate = joindate;
     }

     public BigDecimal getSalary() {
         return salary;
     }

     public void setSalary(BigDecimal salary) {
         this.salary = salary;
     }

     public BigDecimal getBonus() {
         return bonus;
     }

     public void setBonus(BigDecimal bonus) {
         this.bonus = bonus;
     }

     public Integer getDeptId() {
         return deptId;
     }

     public void setDeptId(Integer deptId) {
         this.deptId = deptId;
     }

     @Override
     public String toString() {
         return "Employee{" +
                 "id=" + id +
                 ", ename='" + ename + '\'' +
                 ", jobId=" + jobId +
                 ", mgr=" + mgr +
                 ", joindate=" + joindate +
                 ", salary=" + salary +
                 ", bonus=" + bonus +
                 ", deptId=" + deptId +
                 '}';
     }
 }

Employee实体

 package utils;

 import java.io.FileReader;
 import java.io.IOException;
 import java.net.URL;
 import java.sql.*;
 import java.util.Properties;

 public class JDBCUtils {
     //连接参数
     private static String driver;
     private static String url;
     private static String user;
     private static String password;

     static{
         try {
             //读取配置
             Properties props = new Properties();
             //方式一
 //            props.load(JDBCUtils.class.getClassLoader().getResourceAsStream("jdbc.properties"));
             //方式二
             ClassLoader cl = JDBCUtils.class.getClassLoader();
             URL resource = cl.getResource("jdbc.properties");
             //D:/Code/IdeaProject/IdeaCode/javaweb-T1/out/production/jdbc-day01/jdbc.properties
             System.out.println(resource.getPath());
             props.load(new FileReader(resource.getPath()));

             //赋值
             driver = props.getProperty("driver");
             url = props.getProperty("url");
             user = props.getProperty("user");
             password = props.getProperty("password");

             //加载驱动
             Class.forName(driver);
         } catch (IOException e) {
             e.printStackTrace();
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         }
     }

     //获取连接
     public static Connection getConnection() throws SQLException {
         return DriverManager.getConnection(url, user, password);
     }

     //释放资源
     public static void release(Statement stmt, Connection conn){
         release(null, stmt, conn);
     }

     public static void release(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();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
     }
 }

JdbcUtils简单版工具类

 package conn;

 import utils.JDBCUtils;

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

 public class ConnAndSql {
     public static void main(String[] args) throws SQLException {
         long start = System.currentTimeMillis();
         Connection conn = JDBCUtils.getConnection();
         long end = System.currentTimeMillis();

         System.out.println("获取连接：" + (end - start));

         start = System.currentTimeMillis();
         String sql = "select * from account";
         PreparedStatement pstmt = conn.prepareStatement(sql);
         pstmt.executeQuery();
         end = System.currentTimeMillis();

         System.out.println("执行sql:" + (end - start));

         /*
         获取连接：543
         执行sql:18
          */
     }
 }

获取连接的时间花费远远超出了执行sql的时间，，需要使用池技术，管理连接。

 package pro01.service;

 import pro01.dao.EmployeeDao;
 import pro01.domain.Employee;

 import java.math.BigDecimal;
 import java.sql.SQLException;
 import java.util.List;
 import java.util.Scanner;

 public class EmployeeMain {
     private static EmployeeDao employeeDao = new EmployeeDao();

     private static final String prompt = "user>";

     public static void main(String[] args) {
         //显式主界面，并给出提示
         showMain();

         Scanner sc = new Scanner(System.in);
         while(true){

             System.out.print(prompt);

             String line = sc.nextLine();
             switch (line.trim().toLowerCase()){
                 case "1" :
                     findAllProc();break;
                 case "2" :
                     deleteProc();break;
                 case "3" :
                     insertProc();break;
                 case "4" :
                     updateProc();break;
                 case "5" :
                     showMain();break;
                 case "exit" :
                     return;
                 default:
                     System.out.println("输入有误，请重新输入！");
             }
         }
     }

     private static void showMain() {
         System.out.println("1 查询所有员工信息");
         System.out.println("2 删除员工");
         System.out.println("3 新增员工");
         System.out.println("4 修改员工信息");
         System.out.println("5 显示主界面");
         System.out.println("exit 退出程序");
     }

     private static void updateProc() {
         //请输入要修改的员工编号
         Scanner sc = new Scanner(System.in);
         System.out.println("请输入要修改的员工编号");
         System.out.print(prompt);

         //获取id
         String idStr = sc.nextLine();
         Integer id = null;
         try{
             id = Integer.parseInt(idStr);
         } catch (NumberFormatException e){
             System.out.println("输入有误");
             return;
         }

         //根据id，查找用户，判断是否存在
         Employee employee = employeeDao.findById(id);
         if(employee == null){
             System.out.println("员工不存在");
             return;
         }

         //封装修改条件
         employee = new Employee();
         employee.setId(id);

         //姓名
         System.out.println("请输入员工姓名");
         System.out.print(prompt);
         String name = sc.nextLine();
         if(!"".equals(name.trim())){
             employee.setName(name);
         }

         //薪水
         System.out.println("请输入员工薪水");
         System.out.print(prompt);
         String salaryStr = sc.nextLine();
         if(!"".equals(salaryStr.trim())){
             try{
                 BigDecimal salary = new BigDecimal(salaryStr);
                 employee.setSalary(salary);
             }catch (NumberFormatException e){
                 System.out.println("输入的薪水应该是数字");
                 return;
             }
         }

         boolean isSuccess = false;
         try {
             isSuccess = employeeDao.updateById(employee);
         } catch (SQLException e) {
             System.out.println("数据库错误");
             return;
         }
         if(isSuccess){
             System.out.println("更新成功");
         }else{
             System.out.println("更新失败");
         }
     }

     private static void insertProc() {
         Scanner sc = new Scanner(System.in);
         //员工编号
         System.out.println("请输入员工编号：");
         System.out.print(prompt);
         String idStr = sc.nextLine();
         int id;
         try{
             id = Integer.parseInt(idStr);
         } catch (NumberFormatException e) {
             System.out.println("员工编号输入错误，只能是正数");
             return;
         }
         //员工姓名
         System.out.println("请输入员工姓名：");
         System.out.print(prompt);
         String name = sc.nextLine();
         //员工薪资
         System.out.println("请输入员工薪资：");
         System.out.print(prompt);
         String salaryStr = sc.nextLine();
         BigDecimal salary = null;
         try{
             salary = new BigDecimal(salaryStr);
         }catch (NumberFormatException e){
             System.out.println("工资必须为有效的数字");
             return;
         }

         Employee employee = new Employee();
         employee.setId(id);
         employee.setName(name);
         employee.setSalary(salary);

         boolean isSuccess = false;
         try {
             isSuccess = employeeDao.add(employee);
         } catch (SQLException e) {
             System.out.println("数据库错误");
             return;
         }
         if(isSuccess){
             System.out.println("添加成功");
         }else{
             System.out.println("添加失败");
         }
     }

     private static void deleteProc() {
         //请输入要删除的员工编号
         Scanner sc = new Scanner(System.in);
         System.out.println("请输入要删除的员工编号");
         System.out.print(prompt);

         //获取id
         String idStr = sc.nextLine();
         int id;
         try{
             id = Integer.parseInt(idStr);
         } catch (NumberFormatException e){
             System.out.println("输入有误");
             return;
         }

         //根据id，查找用户，判断是否存在
         Employee employee = employeeDao.findById(id);
         if(employee == null){
             System.out.println("员工不存在");
             return;
         }

         //如果用户存在，则删除用户
         boolean isSuccess = employeeDao.deleteById(id);
         if(isSuccess){
             System.out.println("删除成功");
         }else{
             System.out.println("删除失败");
         }
     }

     private static void findAllProc() {
        List<Employee> list =  employeeDao.findAll();

         System.out.println("员工编号\t员工姓名\t员工薪资");
         list.forEach(e->{
             System.out.println(e.getId() + "\t\t" + e.getName() + "\t\t" + e.getSalary());
         });
     }
 }

cmdCRUD 主界面

 package pro01.domain;

 import java.math.BigDecimal;

 /*
 create table employee(
 id int primary key auto_increment,
 name varchar(50),
 salary DECIMAL
 );
  */
 public class Employee {
     private Integer id;
     private String name;
     private BigDecimal salary;

     public Employee() {
     }

     public Integer getId() {
         return id;
     }

     public void setId(Integer id) {
         this.id = id;
     }

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public BigDecimal getSalary() {
         return salary;
     }

     public void setSalary(BigDecimal salary) {
         this.salary = salary;
     }
 }

cmdCRUD 员工类

 package pro01.dao;

 import pro01.domain.Employee;

 import java.sql.*;
 import java.util.ArrayList;
 import java.util.List;

 public class EmployeeDao {
     /**
      * 查询全部员工信息
      * @return
      */
     public List<Employee> findAll() {
         String driver = "com.mysql.jdbc.Driver";
         String url = "jdbc:mysql://localhost:3307/jdbc_db";
         String user = "root";
         String password = "root";

         Connection conn = null;
         PreparedStatement pstmt = null;
         ResultSet rs = null;

         List<Employee> employeeList = new ArrayList<>();
         try {
             //连接
            conn = DriverManager.getConnection(url, user, password);
             //语句
             String sql = "select * from employee";
             pstmt = conn.prepareStatement(sql);
             //执行
             rs = pstmt.executeQuery();
             while(rs.next()){
                 //读取记录数据，封装为Employee对象
                 Employee emp = new Employee();
                 emp.setId(rs.getInt("eid"));
                 emp.setName(rs.getString("ename"));
                 emp.setSalary(rs.getBigDecimal("salary"));

                 //将员工添加到集合
                 employeeList.add(emp);
             }
         } catch (SQLException e) {
             e.printStackTrace();
         } finally{
             if(rs != null) {
                 try {
                     rs.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if(pstmt != null) {
                 try {
                     pstmt.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if(conn != null) {
                 try {
                     conn.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
         }
         return employeeList;
     }

     public Employee findById(int id) {
         String driver = "com.mysql.jdbc.Driver";
         String url = "jdbc:mysql://localhost:3307/jdbc_db";
         String user = "root";
         String password = "root";

         Connection conn = null;
         PreparedStatement pstmt = null;
         ResultSet rs = null;

         Employee employee = null;
         try {
             //连接
             conn = DriverManager.getConnection(url, user, password);
             //语句
             String sql = "select * from employee where eid = ? ";
             pstmt = conn.prepareStatement(sql);
             pstmt.setInt(1, id);
             //执行
             rs = pstmt.executeQuery();
             if(rs.next()){
                 //读取记录数据，封装为Employee对象
                 employee = new Employee();
                 employee.setId(rs.getInt("eid"));
                 employee.setName(rs.getString("ename"));
                 employee.setSalary(rs.getBigDecimal("salary"));
             }
         } catch (SQLException e) {
             e.printStackTrace();
         } finally{
             if(rs != null) {
                 try {
                     rs.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if(pstmt != null) {
                 try {
                     pstmt.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if(conn != null) {
                 try {
                     conn.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
         }
         return employee;
     }

     public boolean deleteById(int id) {
         String driver = "com.mysql.jdbc.Driver";
         String url = "jdbc:mysql://localhost:3307/jdbc_db";
         String user = "root";
         String password = "root";

         Connection conn = null;
         PreparedStatement pstmt = null;
         try{
             //获取连接对象
             conn = DriverManager.getConnection(url, user, password);
             //获取语句
             String sql = "delete from employee where eid = ? ";
             pstmt = conn.prepareStatement(sql);
             pstmt.setInt(1, id);
             //执行
             int count = pstmt.executeUpdate();
             //如果条数大于0，表示删除成功
             return count > 0 ? true : false;
         } catch (SQLException e) {
             e.printStackTrace();
         } finally{
             if(pstmt != null) {
                 try {
                     pstmt.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if(conn != null) {
                 try {
                     conn.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
         }
         return false;
     }

     public boolean add(Employee employee) throws SQLException {
         String driver = "com.mysql.jdbc.Driver";
         String url = "jdbc:mysql://localhost:3307/jdbc_db";
         String user = "root";
         String password = "root";

         Connection conn = null;
         PreparedStatement pstmt = null;
         try{
             //获取连接对象
             conn = DriverManager.getConnection(url, user, password);
             //获取语句
             String sql = "insert into employee(eid, ename, salary) values(?,?,?)";
             pstmt = conn.prepareStatement(sql);
             pstmt.setInt(1, employee.getId());
             pstmt.setString(2,employee.getName());
             pstmt.setBigDecimal(3, employee.getSalary());
             //执行
             int count = pstmt.executeUpdate();
             //如果条数大于0，表示删除成功
             return count > 0 ? true : false;
         }  finally{
             if(pstmt != null) {
                 try {
                     pstmt.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if(conn != null) {
                 try {
                     conn.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
         }
     }

     public boolean updateById(Employee employee) throws SQLException {
         String driver = "com.mysql.jdbc.Driver";
         String url = "jdbc:mysql://localhost:3307/jdbc_db";
         String user = "root";
         String password = "root";

         Connection conn = null;
         PreparedStatement pstmt = null;
         try{
             //获取连接对象
             conn = DriverManager.getConnection(url, user, password);
             //获取语句
             ArrayList<Object> args = new ArrayList<>();
             StringBuilder sb = new StringBuilder();

             if(employee.getName() != null){
                 sb.append(",ename=? ");
                 args.add(employee.getName());
             }
             if(employee.getSalary() != null){
                 sb.append(",salary=? ");
                 args.add(employee.getSalary());
             }

             int argsNum = args.size();
             if(argsNum == 0){
                 return false;
             }
             String sql = "update employee set " + sb.deleteCharAt(0).toString() + "where eid=? ";

             pstmt = conn.prepareStatement(sql);

             for (int i = 0; i < argsNum; i++) {
                 pstmt.setObject(i + 1, args.get(i));
             }
             pstmt.setObject(argsNum + 1, employee.getId());
             //执行
             int count = pstmt.executeUpdate();
             //如果条数大于0，表示删除成功
             return count > 0 ? true : false;
         } finally{
             if(pstmt != null) {
                 try {
                     pstmt.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if(conn != null) {
                 try {
                     conn.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
         }
     }
 }

cmdCRUD 数据库操作类employeeDao