Mapper中的使用

在insert中增加下面两个属性，useGeneratedKeys和keyProperty

useGeneratedKeys="true" keyProperty="id"

如果数据库支持自增主键，这样就可以了。如果不行，需要自己创建序列，然后通过序列获取主键值(使用的是postgresql中的函数，其他数据库视具体情况而定)：

	<insert id="insertValue" parameterType="map"
            useGeneratedKeys="true" keyProperty="id">
        <selectKey keyProperty="id" resultType="java.lang.Long" order="BEFORE">
            SELECT nextval('sequence_name'::regclass) as id
        </selectKey>
        insert into table_name
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="id != null">
                id,
            </if>
            ...
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="id != null">
                #{id,jdbcType=BIGINT},
            </if>
            ...
        </trim>
    </insert>

当然你也可以这样使用

	<insert id="insertValue" parameterType="map" useGeneratedKeys="true" keyProperty="id">
        insert into table_name
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="id != null">
                id,
            </if>
            ...
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="id != null">
                (SELECT nextval('sequence_name'::regclass) as id),
            </if>
            ...
        </trim>
    </insert>

这种使用方法也适用于批量执行插入的时候

	<insert id="insertBatch" parameterType="java.util.List">
        insert into table_name (
    		id,
    		...
    	) values
        <foreach collection="list" item="item" index="index" separator=",">
            ((SELECT nextval('sequence_name'::regclass) as id), 
            ...)
        </foreach>
    </insert>