Day63 Mybatis基于SQL动态代理的查询以及SQL语句动态拼接

基于sql动态代理的单表增删改查

  搭建mybatis运行环境
            注意：mapper扫描是包进行扫描
            <!--基于sql动态代理的配置方式  -->
        <mappers>
        <!--mapper包扫描  -->
        <package name="com.bjsxt.mapper"/>  
        </mappers>          
          创建mapper包
            创建并配置mapper.xml文件
                <!--根据产地和价格获取花卉信息  -->
        <select id="selF"  resultType="flower">
            select * from flower where production=#{0} and price>#{1}

        </select>
        注意:不用书写parameterType了
            创建和mapper.xml文件同名的接口
                在接口中声明和mapper.xml文件中标签ID相同的方法
                public interface FlowerMapper {
                    List<Flower>  selF(String production,double price);
                }
            注意：
                如果接口方法的形参类型全部为基本数据类型，则在mapper对应的标签中使用#{角标}或者#{param参数位置}进行参数占位即可。
                如果接口的方法参数类型为实体类类型或者map类型，则在mapper对应的标签中使用#{键名}进行参数占位
                如果参数为基本数据类型，但是也想使用#{键名}方式，在接口方法的形参声明中使用@Param(“别名”)方式实现
                    示例：
                    int insF(@Param("name")String name,@Param("price")double price,@Param("production")String production);
                    insert into flower values(default,#{name},#{price},#{production})
        创建SqlSession对象并获取接口的实例化对象
            //获取SqlSession对象
         InputStream is = Resources.getResourceAsStream("mybatis.xml");
         SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(is);
         SqlSession ss=factory.openSession();
            //基于Sql动态代理方式操作数据库
            //获取接口的实例化对象
            FlowerMapper fm=ss.getMapper(FlowerMapper.class);
        使用对象完成对数据库的操作
                List<Flower> lf=fm.selF("商丘",2.1);

mybatis的SQL语句的动态拼接：

标签类型：
        if
        where
        choose
            when
            otherwise
        set
        trim
        bind
        foreach
        include
        sql
-----------------------------------------------------------------------------------
<?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">
  <mapper namespace="com.bjsxt.mapper.FlowerMapper2">
    <!--
        根据花名和产地查询花卉信息
        如果没有花名和产地参数则查询所有
        如果有其中任一参数，则使用参数进行结果筛选。
      -->
      <!--
        if标签：
            test属性中书写判断条件，但是需要使用param参数位置进行参数值判断，不能使用#{角标}方式
            用来进行判断

        -->
      <select id="selF" resultType="flower">
            select * from flower where 1=1
            <if test="param1!=''">
                and name=#{param1}
            </if>
            <if test="param2!=''">
                and production=#{1}
            </if>
      </select>
      <!--
        where标签：
            自动添加where关键字，并去除第一个and关键字

        -->
        <select id="selWhere" resultType="flower">
            select * from flower 
            <where>
                <if test="param1!=''">
                    and name=#{param1}
                </if>
                <if test="param2!=''">
                    and production=#{1}
                </if>
            </where>    
      </select>
       <!-- 
            choose标签：
                when
                    tes属性：书写判断条件，使用param参数位置进行判断
                otherwise
                    如果when都不成立则执行otherwise
                注意：


        -->
        <select id="selChoose" resultType="flower">
            select * from flower 
            <where>
                <choose>
                    <when test="param1!=''">
                        and name=#{param1}
                    </when>
                    <when test="param2!=''">
                        and production=#{1}
                    </when>
                    <otherwise>
                        and price>2
                    </otherwise>
                </choose>   
            </where>
      </select>
      <!--
        set标签：
            自动创建set关键字。
            自动去除最后一个逗号。

        -->
        <update id="upF">
            update flower
            <set>
                id=#{param3},
                <if test="param1!=''">
                    name=#{param1},
                </if>
                <if test="param2!=''">
                    production=#{param2},
                </if>   
            </set>
             where id=#{param3};
        </update>
      <!-- 
        trim标签：
            prefix:在内容之前添加指定的内容
            prefixOverrides：去除内容之前的指定内容
            suffix:在内容之后添加指定的内容
            suffixOverrides：去除内容之后的指定内容
            注意：
                先去后加

       -->
       <update id="upTrim">
            update flower
            <trim prefix="set" suffixOverrides=",">
                id=#{param3},
                <if test="param1!=''">
                    name=#{param1},
                </if>
                <if test="param2!=''">
                    production=#{param2},
                </if>
            </trim>
             where id=#{param3};
        </update>

      <!-- 
        bind标签：
            对实参数据在真正赋值给SQL语句之前重新进行赋值，主要结合like语句使用
       -->
       <select id="selBind" resultType="flower">
            select * from flower 
            <where>
                <if test="param1!=''">
                    <bind name="na" value="'%'+param1+'%'"/>
                    and name like #{na}
                </if>
                <if test="param2!=''">
                    <bind name="pd" value="'%'+param2+'%'"/>
                    and production like #{pd}
                </if>
            </where>
       </select>
       <!-- 
            foreach标签：
                主要结合in sql关键字使用
                collection:要遍历的类型，一般就是list
                open：遍历的内容之前添加的内容
                close：遍历的内容之后添加的内容
                separator:遍历内容间的间隔符号
                item：记录每次循环的遍历结果，#{变量名}获取
        -->
        <select id="selForeach" resultType="flower">
            select *from flower where id in
            <foreach collection="list" open="(" close=")" separator="," item="i">
                #{i}
            </foreach>
        </select>
        <!--
            include标签
            Sql标签：
          -->
          <select id="selIn" resultType="flower">
            select <include refid="ss"/> from flower f
          </select>
          <sql id="ss">
                f.id,f.name,f.price
          </sql>  
  </mapper>

SQL动态代理练习代码：

需要导入mabatis相关的jar包，和mysql数据库里的表

com.bjsxt.mapper：
FlowerMapper.java：

package com.bjsxt.mapper;

import java.util.List;

import com.bjsxt.pojo.Flower;

public interface FlowerMapper {
   //查询所有的花
    List<Flower> sel();
    //根据产地和价格获取
    List<Flower> selF(String production,double price);
    //插入一条数据
    int ins(Flower f);
    //修改一条数据
    int up(String name,int id);
    //删除一条数据
    int del(int id);
}

FlowerMapper.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">
 <mapper namespace="com.bjsxt.mapper.FlowerMapper">
 <!--获取全部信息  -->
 <select id="sel" resultType="flower">
 select * from flower
 </select>
 <!--根据产地和价格获取  -->
 <select id="selF"  resultType="flower">
 select * from flower where production=#{0} and price>#{1}
 </select>
 <!--增加一条数据  -->
 <insert id="ins">
 insert into flower values(default,#{name},#{price},#{production})
 </insert>
 <!--修改一条数据  -->
 <update id="up">
 update flower set name=#{0} where id=#{1}
 </update>
 <!--删除一条数据  -->
 <delete id="del">
 delete from flower where id=#{id}
 </delete>
 </mapper>

com.bjsxt.pojo:
Flower.java:

package com.bjsxt.pojo;

public class Flower {
  private int id;
  private String name;
  private double price;
  private String production;
public Flower() {
    super();
    // TODO Auto-generated constructor stub
}
public Flower(int id, String name, double price, String production) {
    super();
    this.id = id;
    this.name = name;
    this.price = price;
    this.production = production;
}
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public double getPrice() {
    return price;
}
public void setPrice(double price) {
    this.price = price;
}
public String getProduction() {
    return production;
}
public void setProduction(String production) {
    this.production = production;
}
@Override
public String toString() {
    return "Flower [id=" + id + ", name=" + name + ", price=" + price + ", production=" + production + "]";
}
@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + id;
    result = prime * result + ((name == null) ? 0 : name.hashCode());
    long temp;
    temp = Double.doubleToLongBits(price);
    result = prime * result + (int) (temp ^ (temp >>> 32));
    result = prime * result + ((production == null) ? 0 : production.hashCode());
    return result;
}
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Flower other = (Flower) obj;
    if (id != other.id)
        return false;
    if (name == null) {
        if (other.name != null)
            return false;
    } else if (!name.equals(other.name))
        return false;
    if (Double.doubleToLongBits(price) != Double.doubleToLongBits(other.price))
        return false;
    if (production == null) {
        if (other.production != null)
            return false;
    } else if (!production.equals(other.production))
        return false;
    return true;
}


}

com.bjsxt.test:
TestDemo.java:

package com.bjsxt.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.bjsxt.mapper.FlowerMapper;
import com.bjsxt.pojo.Flower;

public class TestDemo {

    public static void main(String[] args) throws IOException {
          //获取SqlSession对象
        InputStream is = Resources.getResourceAsStream("mybatis.xml");
        SqlSessionFactory factory= new SqlSessionFactoryBuilder().build(is);
        SqlSession ss=factory.openSession();
        //使用动态代理方式
           //获取接口实例化对象
           FlowerMapper fm = ss.getMapper(FlowerMapper.class);
           List<Flower> lf = fm.sel();
           System.out.println(lf);
           List<Flower> lf2=fm.selF("巴西", 2.0);
           System.out.println(lf2);
           //插入一条数据
           Flower f=new Flower(0, "玫瑰花", 10.0, "北京");
           int i = fm.ins(f);
           System.out.println(i);

           //修改一条数据
           int i2=fm.up("鲜花", 5);
           System.out.println(i2);

           //删除一条数据
           int i3=fm.del(5);
           System.out.println(i3);
           ss.commit();
    }

}

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>
  <typeAliases>
  <package name="com.bjsxt.pojo"/>

  </typeAliases>
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
            <property name="username" value="root"/>
            <property name="password" value="root"/>
            </dataSource>
        </environment>  
    </environments>
    <!-- 扫描mapper包 -->
  <mappers>
  <package name="com.bjsxt.mapper"/>
  </mappers>
  </configuration>

小案例

需求分析：

实现：
数据库：

CREATE TABLE `user` (
  `id` int(10) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  `phone` varchar(100) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

src:
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>
  <typeAliases>
  <package name="com.bjsxt.pojo"/>
  </typeAliases>
  <environments default="mysql">
  <environment id="mysql">
  <transactionManager type="JDBC">
  </transactionManager>

  <dataSource type="POOLED">
  <property name="driver" value="com.mysql.jdbc.Driver"/>
   <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
    <property name="username" value="root"/>
     <property name="password" value="root"/>
  </dataSource>
  </environment>

  </environments>
  <mappers>
  <package name="com.bjsxt.mapper"/>
  </mappers>




  </configuration>

com.bjsxt.mapper:
UserMapper.java:

package com.bjsxt.mapper;

import java.io.IOException;
import java.util.List;

import com.bjsxt.pojo.User;

public interface UserMapper {
       //根据条件动态查询结果
        List<User> sel(String name,String phone) throws IOException;
}

UserMapper.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">
  <mapper namespace="com.bjsxt.mapper.UserMapper">
  <select id="sel"  resultType="user">
  select * from user
  <where>
   <if test="param1!=''">
   and name=#{param1}
   </if>
   <if test="param2!=''">
   and phone=#{param2}
   </if>
  </where>

  </select>
  </mapper>

com.bjsxt.pojo:
User.java:

package com.bjsxt.pojo;

import java.util.List;

public class User {
  private int id;
  private String name;
  private String phone;
public User() {
    super();
    // TODO Auto-generated constructor stub
}
public User(int id, String name, String phone) {
    super();
    this.id = id;
    this.name = name;
    this.phone = phone;
}
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getPhone() {
    return phone;
}
public void setPhone(String phone) {
    this.phone = phone;
}
@Override
public String toString() {
    return "User [id=" + id + ", name=" + name + ", phone=" + phone + "]";
}
@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + id;
    result = prime * result + ((name == null) ? 0 : name.hashCode());
    result = prime * result + ((phone == null) ? 0 : phone.hashCode());
    return result;
}
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    User other = (User) obj;
    if (id != other.id)
        return false;
    if (name == null) {
        if (other.name != null)
            return false;
    } else if (!name.equals(other.name))
        return false;
    if (phone == null) {
        if (other.phone != null)
            return false;
    } else if (!phone.equals(other.phone))
        return false;
    return true;
}


}

com.bjsxt.service:
UserService.java:

package com.bjsxt.service;

import java.io.IOException;
import java.util.List;

import com.bjsxt.pojo.User;

public interface UserService {
       //根据条件动态查询结果
    List<User> selService(String name,String phone) throws IOException;
}

com.bjsxt.serviceImpl:
UserServiceImpl.java:

package com.bjsxt.serviceImpl;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.bjsxt.mapper.UserMapper;
import com.bjsxt.pojo.User;
import com.bjsxt.service.UserService;

public class UserServiceImpl implements UserService{

    @Override
    public List<User> selService(String name, String phone) throws IOException {
        //创建SqlSession对象
                InputStream is=Resources.getResourceAsStream("mybatis.xml");
                SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(is);
                SqlSession ss=factory.openSession();
                //获取接口的实例化对象
                UserMapper um=ss.getMapper(UserMapper.class);
                List<User> lu=um.sel(name, phone);
                return lu;
    }


}

com.bjsxt.servlet:
UserServlet.java:

package com.bjsxt.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.bjsxt.pojo.User;
import com.bjsxt.service.UserService;
import com.bjsxt.serviceImpl.UserServiceImpl;
import com.google.gson.Gson;

/**
 * Servlet implementation class UserServlet
 */
@WebServlet("/user")
public class UserServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置请求编码格式
                req.setCharacterEncoding("utf-8");
                //设置响应编码格式
                resp.setCharacterEncoding("utf-8");
                resp.setContentType("text/html;charset=utf-8");
                //获取请求信息
                String name=req.getParameter("name");
                String phone=req.getParameter("phone");
                //处理请求信息
                UserService us=new UserServiceImpl();
                List<User> lu=us.selService(name, phone);
                //响应处理结果
                resp.getWriter().write(new Gson().toJson(lu));
    }
}

webContext:
js文件夹有 j.js（也就是js.1.9版本）
show.jsp:

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/j.js"></script>
<script type="text/javascript">
$(function(){
    $("#btn").click(function(){
        var name=$("#name").val();
        var phone=$("#phone").val();
        $.get("user",{name:name,phone:phone},function(data){
            eval("var obj="+data);
            var ta=$("#t1");
            ta.empty();
            ta.append("<tr height='40px'>"+
                    "<td width='200px'>编号</td>"+
                    "<td width='200px'>姓名</td>"+
                    "<td width='200px'>手机号</td>"+
                "</tr>");
            for(var i=0;i<=obj.length;i++){
                ta.append("<tr height='40px'>"+
                "<td width='200px'>"+obj[i].id+"</td>"+
                "<td width='200px'>"+obj[i].name+"</td>"+
                "<td width='200px'>"+obj[i].phone+"</td>"+
            "</tr>");
            }
        })
    })


})
</script>
</head>
<body>
 姓名：<input type="text" id="name" name="name"  value=""/>  电话 <input type="text" id="phone" name="phone" value=""/>
 <input  id="btn" type="button" value="查询"  />
 <table id="t1" cellpadding="0" cellspacing="0" border="solid:1px">
 </table>
</body>
</html>

源码地址：
链接：https://pan.baidu.com/s/1uUsxY0PqVivB14hVhlscJQ 密码：d0o6

小结：

基于sql动态代理的单表增删改查
mybatis的SQL语句的动态拼接
练习
小案例