一考润、簡述

?MyBatis 本是apache的一個開源項目iBatis, 2010年這個項目由apache software foundation 遷移到了google code刽沾，并且改名為MyBatis，實質上Mybatis對ibatis進行一些改進峭跳。 現(xiàn)在托管到gitHub上,下載:https://github.com/mybatis/mybatis-3/releases
MyBatis是一個優(yōu)秀的持久層框架膘婶，它對jdbc的操作數(shù)據(jù)庫的過程進行封裝，使開發(fā)者只需要關注 SQL 本身蛀醉，而不需要花費精力去處理例如注冊驅動悬襟、創(chuàng)建connection、創(chuàng)建statement拯刁、手動設置參數(shù)脊岳、結果集檢索等jdbc繁雜的過程代碼。
?這個demo是針對mybatis學習而進行的簡單的crud操作垛玻，并通過jsonp跨域將查詢封裝的數(shù)據(jù)發(fā)送至前臺割捅。關于mybatis這個框架的原理我就不再贅述了，上實例帚桩！

二亿驾、運行環(huán)境

2.1 軟件環(huán)境

Eclipse + Tomcat7 + Mysql

2.2 軟件架構

servlet+ mybatis框架 + html + bootstrap框架 + ajax + jsonp

2.3 數(shù)據(jù)庫表結構

CREATE TABLE `stu` (
  `sno` varchar(10) NOT NULL,
  `sname` varchar(20) NOT NULL,
  `sage` int(10) DEFAULT NULL,
  `ssex` varchar(5) DEFAULT NULL,
  PRIMARY KEY (`sno`),
  UNIQUE KEY `sno` (`sno`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

2.4 主要jar包

三、例子結構

3.1 web項目結構

3.2 前臺項目結構

四账嚎、主要實現(xiàn)代碼

4.1 mybatis.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration  
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"  
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <!-- 配置通用mapper -->
    <!-- <plugins></plugins> -->

    <!-- 給路徑取別名,放在environments前面 -->
    <!-- <typeAliases>
        <typeAlias type="dao.StudentDao" alias="stu" />
    </typeAliases> -->

    <environments default="development">
        <environment id="development">
            <!-- 事務管理 -->
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="username" value="root" />
                <property name="url" value="jdbc:mysql://localhost:3306/student" />
                <property name="password" value="123" />
                <property name="driver" value="com.mysql.jdbc.Driver" />
            </dataSource>
        </environment>

    </environments>
    <!-- 配置 映射文件 -->
    <mappers>
        <mapper resource="entity/StudentMapper.xml" />
    </mappers>
</configuration>

4.2 StudentMapper.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- namespace命名空間,作用就是對sql進行分類管理
    注意:使用mapper代理方法開發(fā)時,namespace需要特殊設置
 -->
<mapper namespace="dao.StudentDao">
    
    <!-- 查詢所有學生信息 -->
    <resultMap type="entity.Student" id="stuMap">
        <id column="sno" javaType="String" property="sno"></id>     
        <result column="sname" javaType="String" property="sname"/>
        <result column="ssex" javaType="String" property="ssex"/>
        <result column="sage" javaType="int" property="sage"/>
    </resultMap>
    
    <select id="findAllStudent" resultMap="stuMap">
        select * from stu
    </select>
    
    <!-- 實現(xiàn)分頁查詢學生信息 -->
    <select id="findPageStudent" parameterType="map" resultType="entity.Student">
        SELECT * FROM stu LIMIT #{startSize},#{pageSize}
    </select>
    
    <!-- 實現(xiàn)學生信息的添加操作 -->
    <insert id="doInsert" parameterType="entity.Student">
        INSERT INTO stu
        <include refid="columns_mysql"></include>
        VALUES
        <include refid="values_columns"></include>
    </insert>
    
    <!-- 添加的sql片段開始 -->
    <sql id = "columns_mysql">
        <trim prefix="(" suffix=")" suffixOverrides="," >
            <if test="sno!=null">
                sno,
            </if>
            <if test="sname!=null">
                sname,
            </if>
            <if test="sage!=null">
                sage,
            </if>
            <if test="ssex!=null">
                ssex,
            </if>
        </trim>
    </sql>
    
    <sql id="values_columns">
        <trim prefix="(" suffix=")" suffixOverrides="," >
            <if test="sno!=null">
                #{sno},
            </if>
            <if test="sname!=null">
                #{sname},
            </if>
            <if test="sage!=null">
                #{sage},
            </if>
            <if test="ssex!=null">
                #{ssex},
            </if>
        </trim>
    </sql>
    <!-- 添加的sql片段結束 -->
    
    <!-- 實現(xiàn)學生信息的更新操作 -->
    <update id="doUpdateStudent" parameterType="entity.Student">
        update stu 
            set sname = #{sname},
            ssex = #{ssex},
            sage = #{sage}
        where sno = #{sno}
    </update>
    
    <!-- 根據(jù)學生id進行刪除操作 -->
    <delete id="doDeleteBySno" parameterType="String">
        delete from stu where sno = #{sno}
    </delete>
    
    <!-- 查詢學生表總人數(shù) -->
    <select id="findCount" resultType="int">
        select count(*) from stu
    </select>
</mapper>

4.3 Mapper實現(xiàn)類StudentDaoImpl.java

public class StudentDaoImpl implements StudentDao {
    
    private SqlSession sqlSession;

    public List<Student> findAllStudent() {
        sqlSession = SqlSessionUtil.getSession();
        List<Student> list = sqlSession.selectList("findAllStudent");
        sqlSession.commit();
        sqlSession.close();
        
        return list;
    }

    public List<Student> findPageStudent(Integer startSize, Integer pageSize) {
        sqlSession = SqlSessionUtil.getSession();
        Map<String, Integer> map = new HashMap<String, Integer>();
        map.put("startSize", startSize);
        map.put("pageSize", pageSize);
        List<Student> list = sqlSession.selectList("findPageStudent",map);
        sqlSession.commit();
        sqlSession.close();
        return list;
    }

    public int doInsert(Student stu) {
        sqlSession = SqlSessionUtil.getSession();
        Integer result = sqlSession.insert("doInsert",stu);
        sqlSession.commit();
        sqlSession.close();
        
        return result;
    }

    public int doDeleteBySno(String sno) {
        sqlSession = SqlSessionUtil.getSession();
        Integer result = sqlSession.delete("doDeleteBySno",sno);
        sqlSession.commit();
        sqlSession.close();
        
        return result;
    }

    @Override
    public int doUpdateStudent(Student stu) {
        sqlSession = SqlSessionUtil.getSession();
        Integer result = sqlSession.update("doUpdateStudent",stu);
        sqlSession.commit();
        sqlSession.close();
        
        return result;
    }

    public int findCount() {
        sqlSession = SqlSessionUtil.getSession();
        Integer result = sqlSession.selectOne("findCount");
        sqlSession.commit();
        sqlSession.close();
        
        return result;
    }

}

4.4 StudentServiceImpl.java

private StudentDao stuDao = new StudentDaoImpl();
    
    public List<Student> findAllStudent() {
        return stuDao.findAllStudent();
    }

    public PageBean<Student> findPageStudent(Integer currentPage,
            Integer pageSize) {
        Integer count = stuDao.findCount();
        
        Integer allPages = count/pageSize == 0 ? count/pageSize 
                : count/pageSize + 1;
        
        if(currentPage > allPages){
            currentPage = allPages;
        }
        if(currentPage < 1){
            currentPage = 1;
        }
        PageBean<Student> pb = new PageBean<Student>();
        Integer startSize = (currentPage-1)*pageSize;
        List<Student> list = stuDao.findPageStudent(startSize, pageSize);
        
        pb.setAllPages(allPages);
        pb.setCount(count);
        pb.setCurrentPage(currentPage);
        pb.setCurrentCount(pageSize);
        pb.setList(list);
        
        return pb;
    }

    public int doInsert(Student stu) {
        return stuDao.doInsert(stu);
    }

    public int doDeleteBySno(String sno) {
        return stuDao.doDeleteBySno(sno);
    }

    public int doUpdateStudent(Student stu) {
        return stuDao.doUpdateStudent(stu);
    }

4.5 servlet主要操作的方法

4.5.1 分頁查詢方法

private void sendPageData(HttpServletRequest request,
            HttpServletResponse response) throws IOException{
        int pageSize = 5;
        int currentPage = 1;
        String currPage = request.getParameter("currentPage");
        if(currPage!=null){
            currentPage = Integer.parseInt(currPage);
        }
        
        PageBean<Student> pb = stuService.findPageStudent(currentPage, pageSize);
    
        JSONObject json = JSONObject.fromObject(pb);

        PrintWriter writer = response.getWriter();

        String callback = request.getParameter("callback");

        String result = callback + "(" + json.toString() + ")";
        
        writer.write(result);
    }

4.5.2 數(shù)據(jù)更新操作

private void doUpdate(HttpServletRequest request,
            HttpServletResponse response) throws IOException{
        String sno = request.getParameter("sno");
        String sname = request.getParameter("sname");
        String ssex = request.getParameter("ssex");
        Integer sage = null;
        if(request.getParameter("sage")!=null){
            sage = Integer.parseInt(request.getParameter("sage"));
        }
        
        System.out.println("姓名:"+sname+"\t性別："+ssex+"\t學號："+sno+"\t年紀："+sage);
        Student stu = new Student();
        stu.setSno(sno);
        stu.setSname(sname);
        stu.setSsex(ssex);
        stu.setSage(sage);
        JSONObject json = new JSONObject();
        
        if(stuService.doUpdateStudent(stu)==1){
            json.put("msg", "修改成功");
        }else{
            json.put("msg", "修改失敗");
        }
        
        PrintWriter writer = response.getWriter();

        String callback = request.getParameter("callback");

        String result = callback + "(" + json.toString() + ")";
        
        writer.write(result);
    }

4.5.3 通過學號刪除學生操作

private void doDeleteBySno(HttpServletRequest request,
            HttpServletResponse response) throws IOException{
        
        String sno = request.getParameter("sno");
        JSONObject json = new JSONObject();
        if(stuService.doDeleteBySno(sno)==1){
            json.put("msg", "刪除成功");
        }else{
            json.put("msg", "刪除失敗");
        }
        
        PrintWriter writer = response.getWriter();

        String callback = request.getParameter("callback");

        String result = callback + "(" + json.toString() + ")";
        
        writer.write(result);
    }

五莫瞬、總結

? 對于mybatis框架的使用，主要還是在映射文件的配置醉锄，將數(shù)據(jù)庫內所查出的數(shù)據(jù)與實體類的映射乏悄，從而實現(xiàn)數(shù)據(jù)的持久化操作。
? MyBatis是一個優(yōu)秀的持久層框架恳不，它對jdbc的操作數(shù)據(jù)庫的過程進行封裝檩小，使開發(fā)者只需要關注 SQL 本身，而不需要花費精力去處理例如注冊驅動烟勋、創(chuàng)建connection规求、創(chuàng)建statement、手動設置參數(shù)卵惦、結果集檢索等jdbc繁雜的過程代碼阻肿。

對于前臺頁面，我會在下一篇文章中寫出沮尿，如上面觀點你們有所異議丛塌，歡迎大家給我指出较解。