SpringData入门笔记(一) - 重温jdbc操做

学习Spring Data以前，咱们先经过几种基础的、常见的方式访问数据库，而后再经过Spring Data的方式访问，能够分别其中的优劣，对它们有一个更好的了解。

目标

有一个学生表，属性有id/name/age，id自增，经过spring-jdbc的方式查询全部数据，添加数据。

项目结构

maven依赖

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.38</version>
</dependency>

数据库创建

create database spring_data;

create table student(
	id int not null auto_increment,
	name varchar(20) not null,
	age int not null,
	primary key(id)
);

insert into student (name, age) values("zhangsan", 20);
insert into student (name, age) values("lisi", 21);
insert into student (name, age) values("wangwu", 22);

代码编写

开发JDBCUtil工具类

功能：获取Connection,关闭Connection、Statement、ResultSet

JDBCUtil.java

package com.dotleo.util;

import java.sql.*;

/**
 * 数据库工具类
 * @author LiuFei
 * @create 2017-11-05 21:13
 */

public class JDBCUtil {

    /**
     * 获取Connection
     * @return Connection 获取到的jdbcConnection
     */
    public static Connection getConnection() throws ClassNotFoundException, SQLException {


        /**
         * 不建议你们把配置硬编码到代码中
         *
         * 最佳实践： 配置性的建议写到.properties配置文件中
         */
        String driverClass = "com.mysql.jdbc.Driver";  //驱动类
        String url = "jdbc:mysql://localhost:3306/spring_data"; //数据库url
        String username = "root"; //数据库用户
        String password = "liufei"; //密码

        Class.forName(driverClass);
        Connection connection = DriverManager.getConnection(url, username, password);
        return connection;
    }

    /**
     * 释放db相关的资源
     * @param resultSet
     * @param statement
     * @param connection
     */
    public static void release(ResultSet resultSet, Statement statement, Connection connection) {
        if(resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if(statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if(connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

创建对象模型

Student.java

package com.dotleo.entity;

/**
 * Student 实体类
 * @author LiuFei
 * @create 2017-11-05 21:35
 */

public class Student {

    private int id; //主键

    private String name; //姓名

    private int age; //年龄

    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 int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

DAO开发

StudentDAO.java

package com.dotleo.dao;

import com.dotleo.entity.Student;

import java.util.List;

/**
 * 学生类DAO
 * @author LiuFei
 * @create 2017-11-05 21:38
 */

public interface StudentDAO {

    /**
     * 查询全部学生
     * @return 全部学生
     */
    public List<Student> query();

    /**
     * 添加一个学生
     * @param student 学生
     */
    public int save(Student student);
}

StudentDAOImpl.java

package com.dotleo.dao;

import com.dotleo.entity.Student;
import com.dotleo.util.JDBCUtil;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * Student类DAO实现类,经过最原始的jdbc方式操做
 * @author LiuFei
 * @create 2017-11-05 21:41
 */

public class StudentDAOImpl implements StudentDAO{

    public List<Student> query() {

        List<Student> students = new ArrayList<Student>();

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        String sql = "select id, name , age from student";

        try {
            connection = JDBCUtil.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();

            while (resultSet.next()) {
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                int age = resultSet.getInt("age");

                Student student = new Student();
                student.setId(id);
                student.setName(name);
                student.setAge(age);
                students.add(student);
            }

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JDBCUtil.release(resultSet, preparedStatement, connection);
        }

        return students;
    }

    public int save(Student student) {

        int result = 0;

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        String sql = "insert into student (name, age) values (?, ?)";

        try {
            connection = JDBCUtil.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1, student.getName());
            preparedStatement.setInt(2, student.getAge());
            result = preparedStatement.executeUpdate();

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JDBCUtil.release(null, preparedStatement, connection);
        }

        return result;
    }
}

测试类建立

JDBCUtilTest.java

package com.dotleo.util;

import org.junit.Assert;
import org.junit.Test;

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

/**
 * @author LiuFei
 * @create 2017-11-05 21:21
 */

public class JDBCUtilTest {

    @Test
    public void testGetConnection() throws SQLException, ClassNotFoundException {
        Connection connection = JDBCUtil.getConnection();
        Assert.assertNotNull(connection);
    }
}

StudentDAOTest

package com.dotleo.dao;

import com.dotleo.entity.Student;
import org.junit.Test;

import java.util.List;

/**
 * @author LiuFei
 * @create 2017-11-05 21:57
 */

public class StudentDAOTest {

    @Test
    public void testQuery() {
        StudentDAO studentDAO = new StudentDAOImpl();
        List<Student> studentList = studentDAO.query();
        for (Student student : studentList
             ) {
            System.out.println("id: " + student.getId()
                    + "name: " + student.getName()
                    + "age: " + student.getAge());
        }
    }

    @Test
    public void testSave() {
        StudentDAO studentDAO = new StudentDAOImpl();
        Student student = new Student();
        student.setName("maliu");
        student.setAge(23);
        int result = studentDAO.save(student);
        System.out.println(result);

    }
}