传统方式和spring jdbcTemplate方式 访问数据库

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传统方式和spring jdbcTemplate方式 访问数据库

环境准备

导入依赖

<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>5.1.38</version>
</dependency>
<dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
 </dependency>

创建数据库

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)
);

开发JDBCUtil工具类

获取Connection

jdbc.url= jdbc:mysql://localhost:3306/spring_data
jdbc.user = root
jdbc.password = root
jdbc.driverClass = com.mysql.jdbc.Driver

package com.dsdj.util;

import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/**
 * @ClassName JDBCUtil
 * @Description JDBC工具类
 * @Author dsdj
 * @Date 2018/10/20 上午9:17
 * @Version 1.0
 **/
public class JDBCUtil {
    /**
     * 获取connection
     * @return
     */
    public static Connection getConnection() throws Exception {

        InputStream resourceAsStream = ClassLoader.getSystemClassLoader().getResourceAsStream("db.properties");
        Properties properties = new Properties();
        properties.load(resourceAsStream);
        String url = properties.getProperty("jdbc.url");
        String user = properties.getProperty("jdbc.user");
        String password = properties.getProperty("jdbc.password");
        String driverClass = properties.getProperty("jdbc.driverClass");
        Class.forName(driverClass);
        Connection connection = DriverManager.getConnection(url, user, password);
        return connection;

    }

    public 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();
            }
        }

    }

}

测试类

public class TestJDBCUtil {

    @Test
    public void testGetConnetion() throws Exception {
        Connection connection = JDBCUtil.getConnection();
        Assert.assertNotNull(connection);

    }

}

测试通过

数据库访问层

实体类

package com.dsdj.domain;

/**
 * @ClassName Student
 * @Description Student 实体类
 * @Author dsdj
 * @Date 2018/10/20 上午10:10
 * @Version 1.0
 **/
public class Student {
    /**
     * 主键字段
     */
    private int id;
    /**
     * 姓名
     */
    private String name;
    /**
     * 年龄
     */
    private int age;

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

    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;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

dao接口

package com.dsdj.dao;

import com.dsdj.domain.Student;

import java.util.List;

/**
 * @ClassName StudentDAO
 * @Description TODO
 * @Author dsdj
 * @Date 2018/10/20 上午10:13
 * @Version 1.0
 **/
public interface StudentDAO {

    /**
     * 查询所有学生
     * @return 所有学生
     */
    List<Student> query();

    int save(Student student);
}

package com.dsdj.dao;

import com.dsdj.domain.Student;
import com.dsdj.util.JDBCUtil;

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

/**
 * @ClassName StudentDAOImpl
 * @Description Student访问接口实现类：通过最原始的JDBC访问方式
 * @Author dsdj
 * @Date 2018/10/20 上午10:15
 * @Version 1.0
 **/
public class StudentDAOImpl implements StudentDAO {
    @Override
    public List<Student> query() {
        List<Student> students = new ArrayList<>();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        String sql = "select * from student";
        try {
            connection = JDBCUtil.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                students.add(new Student(resultSet.getInt("id"),
                        resultSet.getString("name"),
                        resultSet.getInt("age")));
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JDBCUtil.release(resultSet,preparedStatement,connection);
        }
        return students;
    }

    @Override
    public int save(Student student) {
        List<Student> students = new ArrayList<>();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        String sql = "insert into student (name,age) values (?,?)";
        int i =0;
        try {
            connection = JDBCUtil.getConnection();
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,student.getName());
            preparedStatement.setInt(2,student.getAge());
            i = preparedStatement.executeUpdate();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JDBCUtil.release(resultSet,preparedStatement,connection);
        }
        return i;
    }

}

测试类

package com.dsdj.dao;

        import com.dsdj.domain.Student;
        import org.junit.Assert;
        import org.junit.Test;

        import javax.sound.midi.Soundbank;
        import java.util.List;

/**
 * @ClassName TestStudentDAOImpl
 * @Description TODO
 * @Author dsdj
 * @Date 2018/10/20 上午10:29
 * @Version 1.0
 **/
public class TestStudentDAOImpl {

    @Test
    public void testQuery(){
        StudentDAO studentDAO = new StudentDAOImpl();
        List<Student> query = studentDAO.query();
        for (Student s:query){
            System.out.println(s.toString());
        }
        Assert.assertNotNull(query);
    }

    @Test
    public void testSave(){
        StudentDAO studentDAO = new StudentDAOImpl();
        int i = studentDAO.save(new Student(2, "zhao", 23));
        Assert.assertEquals(1,i);
    }
}

测试成功

总结

上面就是原始的JDBC数据访问的原始方法

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可以发现dao实现类存在许多重复的代码

使用原始的方法开发太慢，太繁琐了

使用Spring JdbcTemplate

搭建环境

添加依赖

		<dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>4.3.18.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.18.RELEASE</version>
        </dependency>

添加配置文件 bean.xml

<?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:tx="http://www.springframework.org/schema/tx"
       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/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd">

    <context:component-scan base-package="com.dsdj.*"></context:component-scan>
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="url" value="jdbc:mysql://localhost:3306/spring_data?useSSL=true"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>

</beans>

StudentDaoJDBCTemplateImpl类实现dao接口

package com.dsdj.dao;

import com.dsdj.domain.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowCallbackHandler;
import org.springframework.stereotype.Repository;

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

/**
 * @ClassName StudentDaoJDBCTemplateImpl
 * @Description TODO
 * @Author dsdj
 * @Date 2018/10/20 下午2:02
 * @Version 1.0
 **/
@Repository(value = "studentDaoJDBCTemplateImpl")
public class StudentDaoJDBCTemplateImpl implements StudentDAO {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public List<Student> query() {

        /**
         * 使用JDBCtemplate就不需要管理connection了
         */
        final List<Student> students = new ArrayList<>();
        String sql = "select * from student";

        jdbcTemplate.query(sql, new RowCallbackHandler() {
            @Override
            public void processRow(ResultSet resultSet) throws SQLException {
                while (resultSet.next()){
                    students.add(new Student(resultSet.getInt("id"),
                            resultSet.getString("name"),
                            resultSet.getInt("age")));
                }
            }
        });

        return students;
    }

    @Override
    public int save(Student student) {

        String sql = "insert into student(name, age) values(?,?)";
        int update = jdbcTemplate.update(sql, new Object[]{student.getName(), student.getAge()});
        return update;
    }
}

测试类

package com.dsdj;

import com.dsdj.dao.StudentDAO;
import com.dsdj.domain.Student;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.sql.DataSource;
import java.util.List;

/**
 * @ClassName TestDataSource
 * @Description TODO
 * @Author dsdj
 * @Date 2018/10/20 上午10:57
 * @Version 1.0
 **/
public class TestDataSource {

    ApplicationContext ctx = null;

    private StudentDAO studentDAO;

    @Before
    public void setUp(){
        System.out.println("setup");
        ctx = new ClassPathXmlApplicationContext("bean.xml");
        studentDAO = (StudentDAO) ctx.getBean("studentDaoJDBCTemplateImpl");

    }
    @After
    public void after(){
        ctx = null;
        System.out.println("close");

    }
    @Test
    public void testDataSource(){

        DataSource dataSource = (DataSource) ctx.getBean("dataSource");
        Assert.assertNotNull(dataSource);

    }
    @Test
    public void testJdbcTemplate(){

        JdbcTemplate jdbcTemplate = (JdbcTemplate) ctx.getBean("jdbcTemplate");
        Assert.assertNotNull(jdbcTemplate);

    }

    @Test
    public void textQuery(){
        List<Student> query = studentDAO.query();
        for (Student s:query){
            System.out.println(s.toString());
        }
    }

}

测试成功

总结

使用使用spring自带的datasource省去了对connection的管理，使用JDBCTemlate和原生的方式有一定的改进，JDBCTemlate只是对原生的方式进行了包装，但是在dao层的代码还是很多。

下篇文章将介绍spring data访问数据库的优势。