MyBatis框架（三）动态SQL，分页，二进制存入数据库图片

1, <if>条件
　　<if test="key!=null">
　　拼接sql语句
　　</if>

2, <choose><when><otherwise>

注意：只能执行一个分支
　　<choose>
　　<when test="key==‘value‘">
　　拼接sql语句
　　</when>
　　<when test="key==‘value‘">
　　拼接sql语句
　　</when>
　　<otherwise>
　　前两者都不符合时执行
　　</otherwise>
　　</choose>
3, <where>
　　自动添加where关键字
　　如果where子句第一句中有 or 或者 and 则删除第一个
4, <trim>
　　功能与<where>类似, 并且提供了前缀, 后缀的添加, 更加灵活
5, <foreach>
　　用来遍历传入的集合参数
　　item(定义集合中每个对象的名字),
　　collection(集合的对象的名字),
　　open(定义开始的字符),
　　close(定义结束的字符),
　　separator(定义分割的字符)

　　index(定义元素的索引)

6, <set>
　　主要用于update
　　自动加上set关键字
　　自动剔除最后一个 ","
7, <sql>
　　经常用于一些常用或者固定的语句, 在外面定义一个语句, 在各种标签中引入
　　使用include, 相当于直接写在上面
8, <selectKey>
　　用于不支持自增长主键的数据库, 尽量避免写这个东西

符号：

&lt; < 小于号
&gt; > 大于号
&amp; & 和
&apos; ’ 单引号
&quot; " 双引号

<![CDATA[]]>

例子：

model：

  1 package model;
  2 
  3 import java.util.Date;
  4 
  5 public class Emp {
  6     private Integer empno;
  7     private String ename;
  8     private String job;
  9     private Integer mgr;
 10     private Date hiredate;
 11     private Integer sal;
 12     private Integer comm;
 13     private Integer deptno;
 14     private Integer sex;
 15     private Dept dept;
 16     public Emp() {
 17         super();
 18         // TODO Auto-generated constructor stub
 19     }
 20     public Emp(Integer empno, String ename, String job, Integer mgr, Date hiredate, Integer sal, Integer comm, Integer deptno, Integer sex,
 21             Dept dept) {
 22         super();
 23         this.empno = empno;
 24         this.ename = ename;
 25         this.job = job;
 26         this.mgr = mgr;
 27         this.hiredate = hiredate;
 28         this.sal = sal;
 29         this.comm = comm;
 30         this.deptno = deptno;
 31         this.sex = sex;
 32         this.dept = dept;
 33     }
 34     public Integer getEmpno() {
 35         return empno;
 36     }
 37     public void setEmpno(Integer empno) {
 38         this.empno = empno;
 39     }
 40     public String getEname() {
 41         return ename;
 42     }
 43     public void setEname(String ename) {
 44         this.ename = ename;
 45     }
 46     public String getJob() {
 47         return job;
 48     }
 49     public void setJob(String job) {
 50         this.job = job;
 51     }
 52     public Integer getMgr() {
 53         return mgr;
 54     }
 55     public void setMgr(Integer mgr) {
 56         this.mgr = mgr;
 57     }
 58     public Date getHiredate() {
 59         return hiredate;
 60     }
 61     public void setHiredate(Date hiredate) {
 62         this.hiredate = hiredate;
 63     }
 64     public Integer getSal() {
 65         return sal;
 66     }
 67     public void setSal(Integer sal) {
 68         this.sal = sal;
 69     }
 70     public Integer getComm() {
 71         return comm;
 72     }
 73     public void setComm(Integer comm) {
 74         this.comm = comm;
 75     }
 76     public Integer getDeptno() {
 77         return deptno;
 78     }
 79     public void setDeptno(Integer deptno) {
 80         this.deptno = deptno;
 81     }
 82     public Integer getSex() {
 83         return sex;
 84     }
 85     public void setSex(Integer sex) {
 86         this.sex = sex;
 87     }
 88     public Dept getDept() {
 89         return dept;
 90     }
 91     public void setDept(Dept dept) {
 92         this.dept = dept;
 93     }
 94     @Override
 95     public String toString() {
 96         return "Emp [empno=" + empno + ", ename=" + ename + ", job=" + job + ", mgr=" + mgr + ", hiredate=" + hiredate
 97                 + ", sal=" + sal + ", comm=" + comm + ", deptno=" + deptno + ", sex=" + sex + ", dept=" + dept + "]";
 98     }
 99     
100     
101     
102 }

 1 package model;
 2 
 3 public class PageBean {
 4     private int page;
 5     private int rows;
 6     private int firstRow;
 7     private int maxRow;
 8     
 9     public PageBean() {
10         this.page = 1;
11         this.rows = 10;
12         this.firstRow = (page-1)*rows;
13         this.maxRow = page*rows;
14     }
15     
16     public PageBean(int page, int rows) {
17         this.page = page;
18         this.rows = rows;
19         this.firstRow = (page-1)*rows;
20         this.maxRow = page*rows;
21     }
22 
23     public int getPage() {
24         return page;
25     }
26 
27     public void setPage(int page) {
28         this.page = page;
29     }
30 
31     public int getRows() {
32         return rows;
33     }
34 
35     public void setRows(int rows) {
36         this.rows = rows;
37     }
38 
39     public int getFirstRow() {
40         return firstRow;
41     }
42 
43     public void setFirstRow(int firstRow) {
44         this.firstRow = firstRow;
45     }
46 
47     public int getMaxRow() {
48         return maxRow;
49     }
50 
51     public void setMaxRow(int maxRow) {
52         this.maxRow = maxRow;
53     }
54     
55 }

mapper：

 1 package mapper;
 2 
 3 import java.util.List;
 4 import java.util.Map;
 5 
 6 import org.apache.ibatis.session.RowBounds;
 7 
 8 import model.Emp;
 9 import model.PageBean;
10 
11 public interface EmpMapper {
12     List<Emp> selectEmpByMapParam(Map<String,Object> map);
13     List<Emp> selectEmpByChoose(Map<String ,Object> map);
14     List<Emp> selectEmpByWhere(Map<String ,Object> map);
15     List<Emp> selectEmpByTrim(Map<String ,Object> map);
16     List<Emp> selectEmpByForeachMap(Map<String ,Object> map);
17     List<Emp> selectEmpByForeachList(List<Integer> idlist);
18     List<Emp> selectEmpByForeachInteger(Integer[] array);
19     int updateEmpBySet(Emp e);
20     int insertEmp(Emp e);
21     List<Emp> selectEmp(RowBounds rbs);
22     List<Emp> selectEmpByPage(PageBean pg);
23 }

  1 <?xml version="1.0" encoding="UTF-8" ?>
  2 <!DOCTYPE mapper
  3   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  4   "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  5 <mapper namespace="mapper.EmpMapper">
  6 
  7     <select id="selectEmp" parameterType="Map" resultType="Emp">
  8         select * from p_emp e
  9     </select>
 10 
 11     <select id="selectEmpByMapParam" parameterType="Map" resultType="Emp">
 12         select * from p_emp e
 13         <if test="sex!=null">
 14             where e.sex=#{sex}
 15         </if>
 16     </select>
 17     
 18     <select id="selectEmpByChoose" parameterType="Map" resultType="Emp">
 19         select * from p_Emp e where 1=1
 20         <choose>
 21             <when test="ename!=null">
 22                 and e.ename like #{ename}
 23             </when>
 24             <when test="job!=null">
 25                 and e.job like #{job}
 26             </when>
 27             <otherwise>
 28                 and e.ssex = ‘1‘
 29             </otherwise>
 30         </choose>
 31     </select>
 32     
 33     <select id="selectEmpByWhere" parameterType="Map" resultType="Emp">
 34         select * from p_emp e
 35         <where>
 36             <if test="ename!=null">
 37                 and e.ename like #{ename}
 38             </if>
 39             <if test="job!=null">
 40                 and e.job like #{job}
 41             </if>
 42         </where>
 43     </select>
 44     
 45     <select id="selectEmpByTrim" parameterType="Map" resultType="Emp">
 46         select * from p_Emp e
 47         <trim prefix="where" prefixOverrides="and|or">
 48             <if test="ename!=null">
 49                 and e.ename like #{ename}
 50             </if>
 51             <if test="job!=null">
 52                 and e.job like #{job}
 53             </if>
 54         </trim>
 55     </select>
 56     
 57     <select id="selectEmpByForeachMap" resultType="Emp">
 58         select * from p_Emp e where e.empno in 
 59         <foreach collection="idList" item="aaa" open="(" close=")" separator=",">
 60             #{aaa}
 61         </foreach>
 62     </select>
 63     <select id="selectEmpByForeachList" resultType="Emp">
 64         select * from p_Emp e where e.empno in 
 65         <foreach collection="list" item="aaa" open="(" close=")" separator=",">
 66             #{aaa}
 67         </foreach>
 68     </select>
 69     <select id="selectEmpByForeachInteger" resultType="Emp">
 70         select * from p_Emp e where e.empno in 
 71         <foreach collection="array" item="aaa" open="(" close=")" separator=",">
 72             #{aaa}
 73         </foreach>
 74     </select>
 75     
 76         <update id="updateEmpBySet" parameterType="Emp">
 77         update p_Emp e
 78         <set>
 79             <if test="ename!=null">
 80                 e.ename=#{ename},
 81             </if>
 82             <if test="job!=null">
 83                 e.job=#{job},
 84             </if>
 85             <if test="mgr!=null">
 86                 e.mgr=#{mgr},
 87             </if>
 88             <if test="hiredate!=null">
 89                 e.hiredate=#{hiredate},
 90             </if>
 91             <if test="sal!=null">
 92                 e.sal=#{sal}
 93             </if>
 94         </set>
 95         where e.empno=#{empno}
 96     </update>
 97     
 98         <sql id="pageSqlPre">
 99         SELECT * FROM (
100     </sql>
101     <sql id="pageSqlSuf">
102         WHERE ROWNUM <![CDATA[<=]]> 9) r WHERE r.rnum>6
103     </sql>
104     
105     <select id="selectEmpBySql" resultType="Emp">
106         <include refid="pageSqlPre"></include>
107         SELECT e.*, ROWNUM rnum FROM p_Emp e
108         <include refid="pageSqlSuf"></include>
109     </select>
110     
111 <!--     不建议使用    
112         <selectKey keyProperty="empno" order="BEFORE" resultType="int">
113             select test1.nextval from dual
114         </selectKey> -->
115         
116     <sql id="pagePre">
117         SELECT * FROM (
118     </sql>
119     <sql id="pageSuf">
120         WHERE ROWNUM <![CDATA[<=]]> #{maxRow}) r 
121         WHERE r.rnum > #{firstRow}
122     </sql>
123 
124     <select id="selectEmpByPage" resultType="Emp" parameterType="PageBean">
125         <include refid="pagePre"></include>
126         select e.*, rownum rnum from p_emp e
127         <include refid="pageSuf"></include>
128     </select>
129     
130 </mapper>

测试：

  1 package test;
  2 
  3 import static org.junit.Assert.*;
  4 
  5 import java.util.ArrayList;
  6 import java.util.Date;
  7 import java.util.HashMap;
  8 import java.util.List;
  9 import java.util.Map;
 10 
 11 import org.apache.ibatis.session.RowBounds;
 12 import org.apache.ibatis.session.SqlSession;
 13 import org.junit.After;
 14 import org.junit.Before;
 15 import org.junit.Test;
 16 
 17 import mapper.DeptMapper;
 18 import mapper.EmpMapper;
 19 import model.Dept;
 20 import model.Emp;
 21 import model.PageBean;
 22 import oracle.net.aso.e;
 23 import util.MyBatisUtil;
 24 
 25 public class JUTest {
 26     private SqlSession ss;
 27     private EmpMapper em;
 28     private DeptMapper dm;
 29 
 30     @Before
 31     public void setUp() throws Exception {
 32         ss = MyBatisUtil.getSession();
 33         em = ss.getMapper(EmpMapper.class);
 34         dm = ss.getMapper(DeptMapper.class);
 35     }
 36 
 37     @After
 38     public void tearDown() throws Exception {
 39         MyBatisUtil.destory(ss);
 40     }
 41 
 42     @Test
 43     public void test() {
 44         Map map=new HashMap();
 45         //map.put("sex", "1");
 46 //        List<Emp> elist = em.selectEmpByMapParam(map);
 47 //        for(Emp e:elist){
 48 //            System.out.println(e);
 49 //        }
 50         
 51         //map.put("ename", "T%");
 52 //        map.put("job", "推销员");
 53 //        List<Emp> elist=em.selectEmpByChoose(map);
 54 //        for(Emp e:elist){
 55 //            System.out.println(e);
 56 //        }
 57         
 58 //        map.put("ename", "T%");
 59 //        map.put("job", "推销员");
 60 //        List<Emp> elist =em.selectEmpByWhere(map);
 61 //        for(Emp e:elist){
 62 //            System.out.println(e);
 63 //        }
 64         
 65 //        map.put("ename", "T%");
 66 //        map.put("job", "推销员");
 67 //        List<Emp> elist =em.selectEmpByTrim(map);
 68 //        for(Emp e:elist){
 69 //            System.out.println(e);
 70 //        }
 71         
 72 //        List<Integer> idlist=new ArrayList<Integer>();
 73 //        idlist.add(7369);
 74 //        idlist.add(7521);
 75 //        idlist.add(7782);
 76 //        //直接传list集合，xml中collection属性为传入类型
 77 //        //List<Emp> elist=em.selectEmpByForeachList(idlist);
 78 //        map.put("idList", idlist);
 79 //        //将集合加到map中，传map，xml中collection属性为map的键
 80 //        //List<Emp> elist=em.selectEmpByForeachMap(map);
 81 //        //传集合，xml中collection属性为传入类型
 82 //        Integer[] ia={7369,7521};
 83 //        List<Emp> elist=em.selectEmpByForeachInteger(ia);
 84 //        for(Emp e:elist){
 85 //            System.out.println(e);
 86 //        }
 87         
 88 //        Emp e=new Emp();
 89 //        e.setEmpno(7010);
 90 //        e.setEname("修改");
 91 //        e.setSal(999);
 92 //        int ea=em.updateEmpBySet(e);
 93 //        System.out.println(ea);
 94         
 95         //分页1 设置RowBounds，然后传入，自动分页
 96 //        int page = 2;
 97 //        int rows = 5;
 98 //        
 99 //        int limit = (page-1)*rows;
100 //        int offset = rows;
101 //        
102 //        
103 //        RowBounds rbs = new RowBounds(limit, offset);
104 //        List<Emp> elist = em.selectEmp(rbs);
105 //        for(Emp e:elist){
106 //            System.out.println(e);
107 //        }
108         
109         //分页2 利用实体类，sql引入等
110         PageBean pb = new PageBean(1, 5);
111         
112         List<Emp> elist = em.selectEmpByPage(pb);
113         
114         for(Emp f : elist) {
115             System.out.println(f);
116         }

                        

                            

                                
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