JDBC-DbUtils

依赖

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>yofc</groupId>
    <artifactId>jdbc</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <version>5.4.0</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.14</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-nop</artifactId>
            <version>1.7.26</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>commons-dbutils</groupId>
            <artifactId>commons-dbutils</artifactId>
            <version>1.7</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- 指定jdk -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

实体类

package com.jdbc;

public class User {
    private Integer id;
    private String name;
    private Integer age;

    public User(Integer id, String name, Integer age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    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 Integer getAge() {
        return age;
    }

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

    public User() {}

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

CURD

INSERT, UPDATE 和 DELETE

import com.alibaba.druid.pool.DruidDataSource;
import com.jdbc.User;
import org.apache.commons.dbutils.QueryLoader;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.*;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class DBUtilsTest {

    private Connection connection;

    @BeforeEach
    public void start() throws Exception {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://192.168.8.136:3306/jdbc");
        dataSource.setUsername("root");
        dataSource.setPassword("root");

        connection = dataSource.getConnection();
    }

    @AfterEach
    public void end() throws Exception {
        if (connection != null) {
            connection.close();
        }
    }

    /**
     * QueryRunner 类的 update 方法可用于 INSERT, UPDATE 和 DELETE
     */
    @Test
    public void testQueryRunnerUpdate() {
        QueryRunner queryRunner = new QueryRunner();
        String sql = "UPDATE user SET name = ? WHERE id = ?";
        try {
            queryRunner.update(connection, sql, "zhangsan",22);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

SELECT

@Test
public void testResultSetHandler() {
    String sql = "SELECT id, name, age FROM user";
    QueryRunner queryRunner = new QueryRunner();
    try {
        /**
         * ResultSetHandler : query 方法的返回值直接取决于 ResultSetHandler 的 hanlde(ResultSet rs) 是如何实现
         * QueryRunner 类的 query 方法中调用了 ResultSetHandler 的 handle() 方法作为返回值
         */
        List<User> usersRST = queryRunner.query(connection, sql,
                new ResultSetHandler<List<User>>() {
                    @Override
                    public List<User> handle(ResultSet rs) throws SQLException {
                        List<User> users = new ArrayList<>();
                        while (rs.next()) {
                            Integer id = rs.getInt(1);
                            String name = rs.getString(2);
                            Integer age = rs.getInt(3);
                            User user = new User(id, name, age);
                            users.add(user);
                        }
                        return users;
                    }
                }
        );
        System.out.println(usersRST);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

SELECT-BeanHandler

/**
 * BeanHandler: 把结果集的第一条记录转为创建 BeanHandler 对象时传入的 Class 参数对应的对象
 */
@Test
public void testBeanHanlder(){
    try {
        QueryRunner queryRunner = new QueryRunner();
        String sql = "SELECT id, name, age FROM user WHERE id >= ?";
        User user = (User) queryRunner.query(connection, sql, new BeanHandler(User.class), 5);
        System.out.println(user);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

SELECT-BeanListHandler

/**
 * BeanListHandler：ResultSetHandler 的实现类，把结果集转为一个 List, 该 List 不为 null, 无记录时为空集合
 * 有记录, List 中存放创建 BeanListHandler 传入的 Class 对象对应的对象
 */
@Test
public void testBeanListHandler() {
    String sql = "SELECT id, name, age FROM user";
    QueryRunner queryRunner = new QueryRunner();
    try {
        Object object = queryRunner.query(connection, sql, new BeanListHandler<>(User.class));
        System.out.println(object);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

SELECT-MapHandler

/**
 * MapHandler: 返回 SQL 对应的第一条记录对应的 Map 对象
 * 键: SQL 查询的列名(不是列的别名), 值: 列的值
 */
@Test
public void testMapHandler() {
    QueryRunner queryRunner = new QueryRunner();
    String sql = "SELECT id, name, age FROM user Where id > ?";
    try {
        Map<String, Object> map = queryRunner.query(connection, sql, new MapHandler(), 4);
        System.out.println(map);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

SELECT-MapListHandler

/**
 * Map 对应查询的一条记录: 键: SQL 查询的列名(不是列的别名), 值: 列的值
 * MapListHandler: 返回的多条记录对应的 Map 的集合
 */
@Test
public void testMapListHandler() {
    QueryRunner queryRunner = new QueryRunner();
    String sql = "SELECT id, name, age FROM user";
    try {
        List<Map<String, Object>> mapList = queryRunner.query(connection, sql, new MapListHandler());
        System.out.println(mapList);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

SELECT-ScalarHandler

/**
 * ScalarHandler: 把结果集的第一行第一列转为一个数值(可以是任意基本数据类型)返回
 */
@Test
public void testScalarHandler() {
    QueryRunner queryRunner = new QueryRunner();
    String sql = "SELECT id, name, age FROM user WHERE id > ?";
    try {
        Object count = queryRunner.query(connection, sql, new ScalarHandler(), 6);
        System.out.println(count);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

QueryLoader

sql.properties

QUERY_USER=SELECT id, name, age FROM user

/**
 * QueryLoader: 加载存放着 SQL 语句的资源文件，以更好的解耦
 * / 代表类路径的根目录
 */
@Test
public void testQueryLoader() throws IOException {
    Map<String, String> sqls = QueryLoader.instance().load("/sql.properties");
    String updateSql = sqls.get("QUERY_USER");
    System.out.println(updateSql);
}

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官方文档