SSM-MyBatis-14：Mybatis中智能标签

------------吾亦无他,唯手熟尔，谦卑若愚，好学若饥-------------

谈论到智能，有什么要想的没有？

我下面放张图

相信都见过这个吧，你在之前没有学习过框架的时候怎么写的，动态sql？还是。。。

智能标签可以解决类似问题

它可以在sql语句中随传入参数是否为null甚至其他来自行加where或者and，或者其他等等用法

他分为 where ,if ,choose ,foreach的array方式 ,foreach的list方式 ,foreach的list自定义类型方式

我一块放在下面，对照着看吧

实体类

public class Book {
    private Integer bookID;
    private String bookName;
    private String bookAuthor;
    private Integer bookPrice;

    public Book() {
    }

    public Integer getBookID() {
        return this.bookID;
    }

    public void setBookID(Integer bookID) {
        this.bookID = bookID;
    }

    public String getBookName() {
        return this.bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public String getBookAuthor() {
        return this.bookAuthor;
    }

    public void setBookAuthor(String bookAuthor) {
        this.bookAuthor = bookAuthor;
    }

    public Integer getBookPrice() {
        return this.bookPrice;
    }

    public void setBookPrice(Integer bookPrice) {
        this.bookPrice = bookPrice;
    }
}

接口中的方法

//智能标签where if
    public List<Book> findtrueBookByIf(String bookName,Integer bookPrice);
    //智能标签where choose
    public List<Book> findtrueBookByChoose(Integer bookPrice);
    //智能标签where foreach array
    public List<Book> findtrueBookByForeachArray(int [] array);
    //智能标签where foreach list
    public List<Book> findtrueBookByForeachList(List<Integer> list);
    //智能标签where foreach list
    public List<Book> findtrueBookByForeachListBook(List<Book> list);

小配置中

<!--智能标签，where if-->
    <select id="findtrueBookByIf" resultType="Book">
        select * from book
        <where>
            <if test="#{0}!=null">
                AND bookName LIKE '%' #{} '%'
            </if>
            <if test="#{0}!=null">
                AND bookPrice>#{}
            </if>
        </where>
    </select>
    <!--智能标签，where choose-->
    <select id="findtrueBookByChoose" resultType="Book">
        select * from book
        <where>
            <choose>
                <when test="#{0}!=null">
                    AND bookPrice>#{}
                </when>
                <otherwise>=</otherwise>
            </choose>
        </where>
    </select>
    <!--智能标签，where foreach array-->
    <select id="findtrueBookByForeachArray" resultType="Book">
        select * from book
        <where>
            bookID IN
            <foreach collection="array" open="(" close=")" separator="," item="myid">
                #{myid}
            </foreach>
        </where>
    </select>
    <!--智能标签，where foreach list-->
    <select id="findtrueBookByForeachList" resultType="Book">
        select * from book
        <where>
            bookID IN
            <foreach collection="list" open="(" close=")" separator="," item="myid">
                #{myid}
            </foreach>
        </where>
    </select>
    <!--智能标签，where foreach list book-->
    <select id="findtrueBookByForeachListBook" resultType="Book">
        select * from book
        <where>
            bookID IN
            <foreach collection="list" open="(" close=")" separator="," item="book">
                #{book.bookID}
            </foreach>
        </where>
    </select>

测试类中

///智能标签where + foreach list Book自定义list 进行多条件查询
    @Test
    public void t9selectZhiNengByForeachListBook(){
        SqlSession session= MyBatisUtils.getSession();

        IBookDAO mapper = session.getMapper(IBookDAO.class);
        List<Book> list=new ArrayList<Book>();
        Book b1=new Book();
        b1.setBookID();
        Book b2=new Book();
        b2.setBookID();
        list.add(b1);
        list.add(b2);
        List<Book> books = mapper.findtrueBookByForeachListBook(list);
        for (Book items:books) {
            System.out.println(items.getBookName());
        }

        session.close();

    }

    ///智能标签where + foreach list 进行多条件查询
    @Test
    public void t8selectZhiNengByForeachList(){
        SqlSession session= MyBatisUtils.getSession();

        IBookDAO mapper = session.getMapper(IBookDAO.class);
        List<Integer> list=new ArrayList<Integer>();
        list.add();
        list.add();
        List<Book> books = mapper.findtrueBookByForeachList(list);
        for (Book items:books) {
            System.out.println(items.getBookName());
        }

        session.close();

    }

    ///智能标签where + foreach array 进行多条件查询
    @Test
    public void t7selectZhiNengByForeachArray(){
        SqlSession session= MyBatisUtils.getSession();

        IBookDAO mapper = session.getMapper(IBookDAO.class);
        int[] array={,};
        List<Book> books = mapper.findtrueBookByForeachArray(array);
        for (Book items:books) {
            System.out.println(items.getBookName());
        }

        session.close();

    }

    ///智能标签where + choose进行多条件查询
    @Test
    public void t6selectZhiNengByChoose(){
        SqlSession session= MyBatisUtils.getSession();

        IBookDAO mapper = session.getMapper(IBookDAO.class);
        List<Book> books = mapper.findtrueBookByChoose();
        for (Book items:books) {
            System.out.println(items.getBookName());
        }

        session.close();

    }

    ///智能标签where + if 进行多条件查询
    @Test
    public void t5selectZhiNengByIf(){
        SqlSession session= MyBatisUtils.getSession();

        IBookDAO mapper = session.getMapper(IBookDAO.class);
        List<Book> books = mapper.findtrueBookByIf("心",);
        for (Book items:books) {
            System.out.println(items.getBookName());
        }

        session.close();

    }

打完收工