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Apache Commons DbUtils整合Spring框架实现简单的CRUD

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时间:2023-01-17 08:25:18 251浏览 收藏

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Commons DbUtils是Apache提供的一个对JDBC进行简单封装的开源工具类库,能够简化JDBC相关的开发。Commons DbUtils可以非常方便的整合Spring Framework,比较轻量级,执行SQL语句非常方便(特别是查询语句),可以代替Spring JdbcTemplate、MyBatis等数据库访问层技术。

配置

DbUtils通过

<bean id="dataSource" class="com.zaxxer.hikari.HikariDataSource" destroy-method="close"><property name="driverClassName" value="com.mysql.jdbc.Driver"></property><property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test_db"></property><property name="username" value="root"></property><property name="password" value="xxx"></property></bean><bean id="queryRunner" class="org.apache.commons.dbutils.QueryRunner"><constructor-arg ref="dataSource"></constructor-arg></bean>

我这里使用的连接池是HikariCP,这里可以根据需要换成其他的连接池,例如DBCP、Druid等。

由于DbUtils本身不支持Spring事务,如果想要支持事务,例如

<bean id="dataSource" class="org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy"><property name="targetDataSource"><bean class="com.zaxxer.hikari.HikariDataSource" destroy-method="close"><property name="driverClassName" value="com.mysql.jdbc.Driver"></property><property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test_db"></property><property name="username" value="root"></property><property name="password" value="xxx"></property></bean></property></bean><bean id="queryRunner" class="org.apache.commons.dbutils.QueryRunner"><constructor-arg ref="dataSource"></constructor-arg></bean>

Java代码中可以通过Autowired引入QueryRunner:

public class UserDao {

    @Autowired
    private QueryRunner queryRunner;
}

增删改

增删改操作,也就是INSERT、DELETE、UPDATE语句,都可以通过QueryRunner的execute方法来直接执行:

queryRunner.execute("delete from user_info");
queryRunner.execute("update user_info set user_name=?,user_age=? where user_id=?", "xxg", 28, 6);

由于DbUtils本身也是基于JDBC中的PreparedStatement来实现的,所以也是支持SQL中带有参数的。

查询

ResultSetHandler

List<user> list = queryRunner.query("select * from user_info limit 100", new ResultSetHandler<list>>() {
    @Override
    public List<user> handle(ResultSet rs) throws SQLException {
        List<user> l = new ArrayList<user>();
        while (rs.next()) {
            User user = new User();
            user.setUserId(rs.getInt("user_id"));
            user.setUserName(rs.getString("user_name"));
            user.setCreateTime(rs.getTimestamp("create_time"));
            l.add(user);
        }
        return l;
    }
});</user></user></user></list></user>

由于

List<user> list = queryRunner.query("select * from user_info limit 100", rs -> {
    List<user> l = new ArrayList<user>();
    while (rs.next()) {
        User user = new User();
        user.setUserId(rs.getInt("user_id"));
        user.setUserName(rs.getString("user_name"));
        user.setCreateTime(rs.getTimestamp("create_time"));
        l.add(user);
    }
    return l;
});</user></user></user>

常用ResultSetHandler实现类

DbUtils提供了一些常用的

long count = queryRunner.query("select count(*) from user_info", new ScalarHandler<long>()); // 查询count
String userName = queryRunner.query("select user_name from user_info where user_id=?", new ScalarHandler<string>(), 1); // 查询user_id=1的用户的用户名</string></long>

ColumnListHandler

返回查询结果(所有行)第一列的数据List:

List<string> userNameList = queryRunner.query("select user_name from user_info", new ColumnListHandler<string>()); // 查询所有用户的user_name</string></string>

MapHandler

返回查询结果第一行数据(所有列)并组装成Map,Map的key为列名,value为值:

Map<string object> userInfo = queryRunner.query("select user_id,user_name from user_info where user_id=1", new MapHandler());
long userId = (Long) userInfo.get("user_id");
String userName = (String) userInfo.get("user_name");</string>

MapListHandler

List<map object>> dataList = queryRunner.query("select user_id,user_name from user_info", new MapListHandler());</map>

ArrayHandler

返回查询结果第一行数据,将所有列值按顺序组成一个数据:

Object[] data = queryRunner.query("select user_id,user_name from user_info where user_id=1", new ArrayHandler());
long userId = (Long) data[0];
String userName = (String) data[1];

ArrayListHandler

List<object> list = queryRunner.query("select user_id,user_name from user_info", new ArrayListHandler());</object>

KeyedHandler

将ResultSet转为

Map<long map object>> dataMap = queryRunner.query("select user_id,user_name from user_info", new KeyedHandler<long>("user_id")); // Key指定为user_id列
Map<string object> data = dataMap.get(1L); // 获取user_id=1的一条记录
long userId = (Long) data.get("user_id");
String userName = (String) data.get("user_name");</string></long></long>

BeanHandler

public class User {

    private int userId;
    private String userName;
    private int userAge;
    private Date createTime;

    // 省略getter setter
}

执行查询:

// 查询user_id=1的用户数据并返回User对象
User user = queryRunner.query("select user_id as userId,user_name as userName,user_age as userAge,create_time as createTime from user_info where user_id=1", new BeanHandler<user>(User.class));</user>

数据库列名很多人会使用下划线作为单词间分隔符,而Java命名规范要求变量名是驼峰命名,这样会导致无法直接映射,所以上面代码中在SQL语句上通过

User user = queryRunner.query("select user_id,user_name,user_age,create_time from user_info where user_id=1",
        new BeanHandler<user>(User.class, new BasicRowProcessor(new GenerousBeanProcessor())));</user>

BeanListHandler

List<user> userList = queryRunner.query("select user_id as userId,user_name as userName,user_age as userAge,create_time as createTime from user_info",
        new BeanListHandler<user>(User.class));</user></user>

同样也可以将带有下划线分隔符的列名映射到驼峰命名的Java对象上:

List<user> userList = queryRunner.query("select user_id,user_name,user_age,create_time from user_info",
        new BeanListHandler<user>(User.class, new BasicRowProcessor(new GenerousBeanProcessor())));</user></user>

BeanMapHandler

类似于

Map<long user> users = queryRunner.query("select user_id as userId,user_name as userName,user_age as userAge,create_time as createTime from user_info",
        new BeanMapHandler<long user>(User.class, "userId")); // 使用userId列作为Map的key
User user1 = users.get(1L); // 获取user_id=1的用户</long></long>

同样也可以将带有下划线分隔符的列名映射到驼峰命名的Java对象上:

// Map的key默认使用查询语句中的第一列(即主键user_id)
Map<long user> users = queryRunner.query("select user_id,user_name,user_age,create_time from user_info",
        new BeanMapHandler<long user>(User.class, new BasicRowProcessor(new GenerousBeanProcessor())));
User user1 = users.get(1L); // 获取user_id=1的用户</long></long>

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