mybatis foreach使用

一:三种参数格式 List Array Map

1.单参数List的类型：

    <select id="dynamicForeachTest" resultType="Blog">
        select * from t_blog where id in
        <foreach collection="list" index="index" item="item" open="(" separator="," close=")">
            #{item}
        </foreach>
    </select>
上述collection的值为list，对应的Mapper是这样的
public List<Blog> dynamicForeachTest(List<Integer> ids);
测试代码：
    @Test
    public void dynamicForeachTest() {
        SqlSession session = Util.getSqlSessionFactory().openSession();
        BlogMapper blogMapper = session.getMapper(BlogMapper.class);
        List<Integer> ids = new ArrayList<Integer>();
        ids.add(1);
        ids.add(3);
        ids.add(6);
        List<Blog> blogs = blogMapper.dynamicForeachTest(ids);
        for (Blog blog : blogs)
            System.out.println(blog);
        session.close();
    }
2.单参数array数组的类型：
    <select id="dynamicForeach2Test" resultType="Blog">
        select * from t_blog where id in
        <foreach collection="array" index="index" item="item" open="(" separator="," close=")">
            #{item}
        </foreach>
    </select>
上述collection为array，对应的Mapper代码：
public List<Blog> dynamicForeach2Test(int[] ids);
对应的测试代码：
    @Test
    public void dynamicForeach2Test() {
        SqlSession session = Util.getSqlSessionFactory().openSession();
        BlogMapper blogMapper = session.getMapper(BlogMapper.class);
        int[] ids = new int[] {1,3,6,9};
        List<Blog> blogs = blogMapper.dynamicForeach2Test(ids);
        for (Blog blog : blogs)
            System.out.println(blog);
        session.close();
    }
3.自己把参数封装成Map的类型
    <select id="dynamicForeach3Test" resultType="Blog">
        select * from t_blog where title like "%"#{title}"%" and id in
        <foreach collection="ids" index="index" item="item" open="(" separator="," close=")">
            #{item}
        </foreach>
    </select>
上述collection的值为ids，是传入的参数Map的key，对应的Mapper代码：
public List<Blog> dynamicForeach3Test(Map<String, Object> params);
对应测试代码：
    @Test
    public void dynamicForeach3Test() {
        SqlSession session = Util.getSqlSessionFactory().openSession();
        BlogMapper blogMapper = session.getMapper(BlogMapper.class);
        final List<Integer> ids = new ArrayList<Integer>();
        ids.add(1);
        ids.add(2);
        ids.add(3);
        ids.add(6);
        ids.add(7);
        ids.add(9);
        Map<String, Object> params = new HashMap<String, Object>();
        params.put("ids", ids);
        params.put("title", "中国");
        List<Blog> blogs = blogMapper.dynamicForeach3Test(params);
        for (Blog blog : blogs)
            System.out.println(blog);
        session.close();
    }