Mybatis_简单查询

查询所有的数据xml语句：

<?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：映射文件的命名空间,内容规范就是映射文件的包名.此xml文件名 -->
<mapper namespace="xxx.x.mapper.PersonTestMapper">
    <!--
        resultMap的type是实体类（实体数据类型），id随便起是resultMap唯一标识，下面原来的resultType去掉改成resultMap，值就是这个id
        除了表里的id列用id表示外，其余都用result表示，所有属性都要写
        column表示表里的字段名，property表示实体类中属性的名
    -->
    <resultMap type="xxx.x.Person" id="BaseResultMap"> 
        <id column = "person_id" property = "personId" />
        <result column = "name" property = "name" />
        <result column = "gender" property = "gender" />
        <result column = "person_addr" property = "personAddr" />
        <result column = "birthday" property = "birthday" />
    </resultMap>
    <!-- 
        parameterType是传递参数的类型，下面为整型写法
        sql语句最后一个参数id是变量
        resultType是查询后的结果，内容是需要输出到的地址，那个Person类里需要定义好那些需要接受数据的属性
        #{}使用预编译的方式生成SQL，防止sql的注入
     -->
    <select id="selectPersonByID" parameterType="java.lang.Integer" resultMap="BaseResultMap">
        select * from person_test where id = #{id}
    </select>
    
    <select id="selectPersonCount" resultType="java.lang.Integer" >
        select count(*) from person
    </select>
    
    <select id="selectPersonAll" resultMap="BaseResultMap" >
        select * from person
    </select>
    
</mapper>

执行语句：

SqlSessionFactory sessionFactory;
    public void setUp() throws Exception {
        InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml");
        sessionFactory = new SqlSessionFactoryBuilder().build(in);
    }
    public void test() {
        //创建SqlSession
        SqlSession session = sessionFactory.openSession();
        try {
            List<Person> pList = session.selectList("xxx.x.mapper.PersonTestMapper.selectPersonAll"); //查找到要执行的sql语句，用命名空间.id  
            for(Person p : pList) {
                System.out.println(p);
            }
        }finally {
            session.close();
        }  
        
    }

按多个参数查询：

<select id="selectPersonByParams" parameterType="xxx.x.QueryCondition" resultMap="BaseResultMap" >
        <![CDATA[        
        select * from person t where t.gender = #{gender} and t.birthday < #{birthday}
        ]]>
    </select>
    <!-- 
        第二种方式：传递集合
        map.put("gender", 1);
        map.put("birthday", new Data());
        多个参数想查询也可以传递map集合，#{}中的内容map的key
     -->
    <select id="selectPersonByParams1" parameterType="java.util.Map" resultMap="BaseResultMap" >
        <![CDATA[        
        select * from person t where t.gender = #{gender} and t.birthday < #{birthday}
        ]]>
    </select>

第一种方式java语句：

SqlSessionFactory sessionFactory;
    public void setUp() throws Exception {
        InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml");
        sessionFactory = new SqlSessionFactoryBuilder().build(in);
    }

public void selectPersonByParams() {
        //创建SqlSession
        SqlSession session = sessionFactory.openSession();
        try {
            QueryCondition qc = new QueryCondition();
            qc.setGender(1);
            qc.setBirthday(new Date());
            List<Person> pList = session.selectList("xxx.x.mapper.PersonTestMapper.selectPersonParams",qc); //查找到要执行的sql语句，用命名空间.id  
            for(Person p : pList) {
                System.out.println(p);
            }
        }finally {
            session.close();
        }  
        
    }

第二种方式java语句：

SqlSessionFactory sessionFactory;
    public void setUp() throws Exception {
        InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml");
        sessionFactory = new SqlSessionFactoryBuilder().build(in);
    }

public void selectPersonByParams1() {
        //创建SqlSession
        SqlSession session = sessionFactory.openSession();
        try {
            Map<String,Object> map = new HashMap<String,Object>();
            map.put("gender", 1);
            map.put("birthday", new Data());
            List<Person> pList = session.selectList("xxx.x.mapper.PersonTestMapper.selectPersonParams1",map); //查找到要执行的sql语句，用命名空间.id  
            for(Person p : pList) {
                System.out.println(p);
            }
        }finally {
            session.close();
        }  
        
    }

模糊查询

<!-- 
        ${}:非预编译，使用直接拼接字符串的方式生成sql，{}中的内容必须要从map或者查询对象中获得
    -->
    <select id="selectPersonByName" parameterType="java.util.Map" resultMap="BaseResultMap" >
        select * from person t where t.name like ‘%${name}%’
    </select>

java语句：

SqlSessionFactory sessionFactory;
    public void setUp() throws Exception {
        InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml");
        sessionFactory = new SqlSessionFactoryBuilder().build(in);
    }
    public void selectPersonByName() {
        //创建SqlSession
        SqlSession session = sessionFactory.openSession();
        try {
            Map<String,Object> map = new HashMap<String,Object>();
            map.put("name", "张三");
            List<Person> pList = session.selectList("xxx.x.mapper.PersonTestMapper.selectPersonByName",map); //查找到要执行的sql语句，用命名空间.id  
            for(Person p : pList) {
                System.out.println(p);
            }
        }finally {
            session.close();
        }  
        
    }