SpringData

传统方式访问数据库

1：创建一个Maven web项目

2：修改pom.xml为以下内容

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.gx</groupId>
  <artifactId>SpringData</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>SpringData Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.0.1</version>
        <scope>provided</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.38</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>SpringData</finalName>
  </build>
</project>

3：创建一个数据库表User，包括id，name，age三个字段，并向其中添加数据

4：创建一个配置文件db.properties，用于存放所有和数据库有关的配置

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3307/test
jdbc.username=root
jdbc.password=root

5：开发一个JDBC相关工具类com.gx.help.JdbcUtil

package com.gx.help;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
 * 这是一个JDBC工具类
 * @author Administrator
 *
 *包含的内容
 *1：获取Connection
 *2：释放资源（关闭Connection，Statement（PrepareStatement），ResultSet）
 */
public class JdbcUtil {
    /**
     * 获取Connection
     * @return 返回所获得的JDBC的Connection
     * @throws SQLException
     * @throws ClassNotFoundException
     * @throws IOException
     */
    public static Connection getConnection() throws SQLException, ClassNotFoundException, IOException{
        //从配置文件获取数据
        InputStream inputStream = JdbcUtil.class.getClassLoader().getResourceAsStream("db.properties");
        Properties properties = new Properties();
        properties.load(inputStream);
        //驱动程序名
        String driver=properties.getProperty("jdbc.driver");
        //url指向要访问的数据库名
        String url=properties.getProperty("jdbc.url");
        //MySQL配置时的用户名和密码
        String username=properties.getProperty("jdbc.username");
        String password=properties.getProperty("jdbc.password");
        Class.forName(driver);
        Connection conn = DriverManager.getConnection(url,username,password);
        return conn;
    }
    /**
     * 释放资源（使用Statement的情况下）
     * @param resultSet
     * @param statement
     * @param connection
     */
    public static void close(ResultSet resultSet,Statement statement,Connection connection){
        if(resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if(statement!=null){
            try {
                statement.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if(connection!=null){
            try {
                connection.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
    /**
     * 释放资源（使用PrepareStatement的情况下）
     * @param resultSet
     * @param preparedStatement
     * @param connection
     */
    public static void close(ResultSet resultSet,PreparedStatement preparedStatement,Connection connection){
        if(resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if(preparedStatement!=null){
            try {
                preparedStatement.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if(connection!=null){
            try {
                connection.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

5：创建对象模型com.gx.domain.User

package com.gx.domain;

public class User {
    private int id;
    private String name;
    private int 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 "User [id=" + id + ", name=" + name + ", age=" + age + "]";
    }

}

6：创建Dao的接口com.gx.dao.UserDao

package com.gx.dao;

import java.util.List;

import com.gx.domain.User;
/**
 * UserDao访问接口
 * @author Administrator
 *
 */
public interface UserDao {
    //查询所有用户
    public List<User> finaAll();
}

7：创建Dao的实现类com.gx.dao.impl.UserDaoImpl

package com.gx.dao.impl;

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

import com.gx.dao.UserDao;
import com.gx.domain.User;
import com.gx.help.JdbcUtil;
/**
 * UserDao访问接口实现类，这个实现类通过最原始的JDBC的操作实现
 * @author Administrator
 *
 */
public class UserDaoImpl implements UserDao{
    /**
     * 查询所有学生
     */
    public List<User> finaAll(){
        List<User> users = new ArrayList<User>();
        Connection conn=null;
        PreparedStatement preparedStatement = null;
        ResultSet result = null;
        try {
            String sql = "select * from user";
            conn = JdbcUtil.getConnection();
            preparedStatement = conn.prepareStatement(sql);
            result = preparedStatement.executeQuery();
            while(result.next()){
                User user = new User();
                user.setId(result.getInt("id"));
                user.setName(result.getString("name"));
                user.setAge(result.getInt("age"));
                users.add(user);
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally{
            JdbcUtil.close(result, preparedStatement, conn);
        }
        return users;
    }
}

8：在JDBC相关工具类com.gx.help.JdbcUtil里面添加测试方法

    @Test
    public void testUserQuery(){
        UserDao udao = new UserDaoImpl();
        List<User> users = udao.finaAll();
        for(User user:users){
            System.out.println(user.toString());
        }
    }

9：运行测试类

10：添加save方法并测试

UserDao里面的代码

    //添加学生
    public void save(User user);

UserDaoImpl里面的代码

/**
     * 添加学生
     */
    public void save(User user){
        Connection conn=null;
        PreparedStatement preparedStatement = null;
        ResultSet result = null;
        try {
            String sql = "insert into user(id,name,age) value(?,?,?)";
            conn = JdbcUtil.getConnection();
            preparedStatement = conn.prepareStatement(sql);
            preparedStatement.setInt(1,user.getId());
            preparedStatement.setString(2,user.getName());
            preparedStatement.setInt(3,user.getAge());
            preparedStatement.executeUpdate();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally{
            JdbcUtil.close(result, preparedStatement, conn);
        }
    }

JdbcUtilTest里面的代码

　　@Test
    public void testUserSave(){
        UserDao udao = new UserDaoImpl();
        User user = new User();
        user.setAge(12);
        user.setId(6);
        user.setName("minuobaci");
        udao.save(user);
    }

测试结果

传统方式访问数据库的第二种方式（使用spring框架内置jdbc模板）