擁抱 NamedParameterJdbcTemplate

爲何要使用 NamedParameterJdbcTemplate

  1. 簡單sql

    • NamedParameterJdbcTemplate 支持命名參數,這是原生jdbc的一大缺點,由於jdbc是採用索引的方式設置參數,在數據庫或者sql發現變化時咱們須要修改代碼,而且這種維護成本很高,同時也很容易出錯,那命名參數能夠很好的解決這個問題。數據庫

    • NamedParameterJdbcTemplate 支持對象自動映射,以下一段代碼NamedParameterJdbcTemplate 會自動將返回結果映射爲Person對象mybatis

      Person p = new Person();
      p.setName("kevin");
      p.setAddress("Shanghai");
      p.setCountry("China");
      
      namedTemplate.update("insert into t_person(name, address, country) values(:name,:address,:country)", new BeanPropertySqlParameterSource(p))
  2. 快速,NamedParameterJdbcTemplate只是實現了命名參數及數據封裝,沒有其它任何額外的開銷,在運行效率上無限接近原生jdbcapp

接下來咱們看一下使用NamedParameterJdbcTemplate如何工做,還有相同場景下MyBatis的代碼。code

插入一條數據並返回自增主鍵

NamedParameterJdbcTemplate

String sql = "INSERT INTO `t_person` (firstName, lastName, age, gender, height, weight, address, hobby, createdTime)" +
        " VALUES (:firstName, :lastName, :age, :gender, :height, :weight, :address, :hobby, :createdTime)";

KeyHolder key = new GeneratedKeyHolder();
jdbcOperations.update(sql, new BeanPropertySqlParameterSource(p), key);
p.setId(key.getKey().longValue());

咱們能夠經過BeanPropertySqlParameterSource自動綁定SQL參數只須要屬性名稱爲命名參數相同便可,同時咱們也能夠使用MapSqlParameterSource/Map綁定SQL參數。對象

MyBatis

<insert id="insert" keyProperty="id" useGeneratedKeys="true">
    INSERT INTO `t_person` (firstName, lastName, age, gender, height, weight, address, hobby, createdTime)
    VALUES (#{firstName}, #{lastName}, #{age}, #{gender}, #{height}, #{weight}, #{address}, #{hobby}, #{createdTime})
</insert>

經過主鍵查詢對象(自動映射)

NamedParameterJdbcTemplate

String sql = "select * from t_person where id=:id";
jdbcOperations.queryForObject(sql, new MapSqlParameterSource("id", id), new BeanPropertyRowMapper<>(Person.class));

咱們能夠經過BeanPropertyRowMapper將返回結果自動映射爲對象類型,和mybatis同樣只須要返回的列名與屬性名稱相同便可索引

MyBatis

<select id="queryById" resultType="io.zhudy.namedjdbcmybatis.benchmark.Person">
    SELECT * FROM t_person WHERE id=#{value}
</select>

經過主鍵查詢對象(手動映射)

NamedParameterJdbcTemplate

String sql = "select * from t_person where id=:id";

jdbcOperations.queryForObject(sql, new MapSqlParameterSource("id", selectId()), (rs, rowNum) -> {
        Person p = new Person();
        p.setId(rs.getLong("id"));
        p.setFirstName(rs.getString("firstName"));
        p.setLastName(rs.getString("lastName"));
        p.setAge(rs.getInt("age"));
        p.setGender(rs.getInt("gender"));
        p.setHeight(rs.getInt("height"));
        p.setWeight(rs.getInt("weight"));
        p.setAddress(rs.getString("address"));
        p.setHobby(rs.getString("hobby"));
        p.setCreatedTime(rs.getLong("createdTime"));
        return p;
    });

MyBatis

<resultMap id="person" type="io.zhudy.namedjdbcmybatis.benchmark.Person">
    <result column="id" property="id"/>
    <result column="firstName" property="firstName"/>
    <result column="lastName" property="lastName"/>
    <result column="age" property="age"/>
    <result column="gender" property="gender"/>
    <result column="height" property="height"/>
    <result column="weight" property="weight"/>
    <result column="weight" property="weight"/>
    <result column="address" property="address"/>
    <result column="hobby" property="hobby"/>
    <result column="createdTime" property="createdTime"/>
</resultMap>

<select id="queryByIdForManualMap" resultMap="person">
    SELECT * FROM t_person WHERE id=#{value}
</select>

查詢多個對象

NamedParameterJdbcTemplate

String sql = "select * from t_person";
jdbcOperations.query(sql, EmptySqlParameterSource.INSTANCE, new BeanPropertyRowMapper<>(Person.class));

MyBatis

<select id="query" resultType="io.zhudy.namedjdbcmybatis.benchmark.Person">
    SELECT * FROM t_person
</select>

經過上面的代碼咱們能夠發現使用NamedParameterJdbcTemplate操做數據庫很是的容易,不會給開發帶來額外的負擔,代碼很是的簡潔,同時程序的運行效率也很是的高。開發

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