【翻译】spring-data 之JdbcTemplate 使用

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发布于 2019-08-18 22:53:58

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发布于 2019-08-18 22:53:58

文章被收录于专栏：dotnet & java

Jdbc的使用

基础的代码结构:

一个Application作为入口。IUserRepository和UserRepository作为具体的实现。applicationContext.xml定义spring的配置。db.properties保存数据库相关的信息。

环境搭建步骤

新建项目

新建一个maven项目，编辑pom.xml文件，如下。除了mysql的驱动，其他是必须的。

<?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>com.lou.spring.demo5.tx</groupId>
    <artifactId>lou-spring-demo5-tx</artifactId>
    <version>1.0-SNAPSHOT</version>
  
    <dependencies>
        <!--spring的核心-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.25.RELEASE</version>
        </dependency>
        <!--orm相关，比如jdbctemplate-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>4.3.25.RELEASE</version>
        </dependency>
        <!--mysql数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.6</version>
        </dependency>
        <!-- datasource 数据源 -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-dbcp2</artifactId>
            <version>2.7.0</version>
        </dependency>
    </dependencies>
</project>

applicationContext.xml

在resources下面添加spring的配置文件applicationContext.xml

内容:

<?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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

<!--    1.无需定义repository注解，通过属性设置的方式进行-->
    <bean id="userRepository1" class="com.lou.spring.demo5.tx.UserRepository">
        <property name="jdbcTemplate" ref="dataSource"></property>
    </bean>

<!--    2.使用Component-scan的方式配合@repository注解-->
<!--    <context:component-scan base-package="com.lou.spring.demo5.tx"></context:component-scan>-->

    <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">
        <property name="driverClassName" value="${jdbc.dirverClassName}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>
  <!--    上面datasource用到的属性值来自这个-->
    <context:property-placeholder location="db.properties"></context:property-placeholder>
</beans>

db.properties

在resources下面添加db.properties文件

jdbc.dirverClassName=com.mysql.cj.jdbc.Driver
jdbc.username=root
jdbc.password=123456
jdbc.url=jdbc:mysql://localhost:3306/test1?useSSL=false

Repository

添加IUserRepository和UserRepository用于数据库的访问。

IUserRepository.java

package com.lou.spring.demo5.tx;

public interface IUserRepository {
    //显示总数
    void showCount();
}

UserRepository.java

package com.lou.spring.demo5.tx;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import javax.sql.DataSource;

@Repository
public class UserRepository implements IUserRepository {
    private JdbcTemplate jdbcTemplate;

    @Autowired
    public void setJdbcTemplate(DataSource dataSource) {
        this.jdbcTemplate = new JdbcTemplate(dataSource);
    }

    @Override
    public void showCount() {
        Integer count = jdbcTemplate.queryForObject("select count(*) from account", Integer.class);
        System.out.println(count);
    }
}

不使用Repository和Autowired注解方式没有开启Repository和Autowired注解，所以，需要在xml中手动配置。确保set方法的后面部分和applicationContext.xml#userRepository1#property的name字段名字是一样的。然后传入一个DataSource参数，也就是property的ref引用
开启Repository和Autowired注解方式开启了注解之后就需要定义在applicationContext.xml中定义component-scan，然后spring自己去扫描查找需要的依赖。

程序入口

新建Application.java 作为程序入口。

package com.lou.spring.demo5.tx;

import org.apache.commons.dbcp2.BasicDataSource;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Application {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        BasicDataSource dataSource = (BasicDataSource) classPathXmlApplicationContext.getBean("dataSource");
        //用来测试数据源是否通
        System.out.println(dataSource);
        //通过id的方式获取
        UserRepository userRepository = (UserRepository) classPathXmlApplicationContext.getBean("userRepository1");
        userRepository.showCount();
        //通过class的方式获取
        UserRepository userRepository1 = classPathXmlApplicationContext.getBean(UserRepository.class);
        userRepository1.showCount();
    }
}

使用demo

先定义一个User对象

User.java

package com.lou.spring.demo5.tx;

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

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

查询相关(select)

修改一下IUserRepository，增加如下内容。

public interface IUserRepository {
    //总行数查询
    Integer getTotalCount();
    //带条件的总行数查询
    Integer getTotalCount(String name);
    //查询一个String
    String getName();
    //查询一个对象
    User getUser();
    //查询对象集合
    List<User> getUsers();
}

具体实现：

@Repository
public class UserRepository implements IUserRepository {
    private JdbcTemplate jdbcTemplate;

    @Autowired
    public void setJdbcTemplate111(DataSource dataSource) {
        this.jdbcTemplate = new JdbcTemplate(dataSource);
    }

    @Override
    public Integer getTotalCount() {
        Integer userCount = jdbcTemplate.queryForObject("select count(*) from user", Integer.class);
        return userCount;
    }

    @Override
    public Integer getTotalCount(String name) {
        Integer louCount = jdbcTemplate.queryForObject("select count(*) from user where name like ?", Integer.class, name);
        return louCount;
    }

    @Override
    public String getName() {
        String name = jdbcTemplate.queryForObject("select name from user where id=?", new Object[]{1}, String.class);
        return name;
    }

    @Override
    public User getUser() {
        User user = jdbcTemplate.queryForObject("select * from user where id = ?", new Object[]{1}, new UserMapper());
        return user;
    }

    @Override
    public List<User> getUsers() {
        List<User> users = jdbcTemplate.query("select * from user", new UserMapper());
        return users;
    }

    //抽取公共的RowMapper<User>,内部私有的class，放外面的话是要public，非static
    private static final class UserMapper implements RowMapper<User> {
        @Override
        public User mapRow(ResultSet resultSet, int i) throws SQLException {
            User user = new User();
            user.setId(resultSet.getInt("id"));
            user.setName(resultSet.getString("name"));
            user.setAge(resultSet.getInt("age"));
            return user;
        }
    }
}

使用RowMapper对结果集做映射。UserMapper是一个私有的静态类。使用的时候需要new。

update相关（包括insert，update，delete）

@Override
public Integer insertUser(User u) {
    return jdbcTemplate.update("insert into user (name,age) values(?,?)", u.getName(), u.getAge());
}

@Override
public Integer updateUser(Integer userId, String name) {
    return jdbcTemplate.update("update user set name=? where id=?", name, userId);
}

@Override
public Integer deleteUser(Integer userId) {
    return jdbcTemplate.update("delete from user where id = ?", userId);
}

execute 方法

用来执行create table 或者调用存储过程之类的sql语句。

this.jdbcTemplate.execute("create table mytable (id integer, name varchar(100))");
this.jdbcTemplate.update(
        "call SUPPORT.REFRESH_ACTORS_SUMMARY(?)",
        Long.valueOf(unionId));