mybatis3中注解方式使用mapper

淡淡的烟草味﹌ 2021-06-24 14:35 413阅读 0赞

mybatis3中增加了使用注解来配置Mapper的新特性，本篇文章主要介绍其中几个@Provider的使用方式，他们是：@SelectProvider、@UpdateProvider、@InsertProvider和@DeleteProvider。

DROP TABLE IF EXISTS `blog`;
 CREATE TABLE `blog` (
 	`id` int(10) NOT NULL auto_increment,
 	`title` varchar(200) NOT NULL,
 	`date` varchar(50) NOT NULL,
 	`authername` varchar(15) NOT NULL,
 	`content` varchar(500) NOT NULL,
 	PRIMARY KEY  (`id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `user`;
    CREATE TABLE `user` (
    `id` int(11) NOT NULL auto_increment,
    `userName` varchar(50) default NULL,
    `userAge` int(11) default NULL,
    `userAddress` varchar(200) default NULL,
    PRIMARY KEY  (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

第一种 映射器接口中写SQL语句，映射器接口注解：

package com.whut.inter;
 import java.util.List;
 import org.apache.ibatis.annotations.Delete;
 import org.apache.ibatis.annotations.Insert;
 import org.apache.ibatis.annotations.Param;
 import org.apache.ibatis.annotations.Select;
 import org.apache.ibatis.annotations.Update;
 import com.whut.model.User;
 //最基本的注解CRUD
 public interface IUserDAO {
 @Select("select *from User")
 public List<User> retrieveAllUsers();
 
 //注意这里只有一个参数，则#{}中的标识符可以任意取
 @Select("select *from User where id=#{idss}")
 public User retrieveUserById(int id);
 
 @Select("select *from User where id=#{id} and userName like #{name}")
 public User retrieveUserByIdAndName(@Param("id")int id,@Param("name")String names);
 
 @Insert("INSERT INTO user(userName,userAge,userAddress) VALUES(#{userName},"
 + "#{userAge},#{userAddress})")
 public void addNewUser(User user);
 
 @Delete("delete from user where id=#{id}")
 public void deleteUser(int id);
 
 @Update("update user set userName=#{userName},userAddress=#{userAddress}"
 + " where id=#{id}")
 public void updateUser(User user);
 }

测试代码：

package com.whut.test;
 import java.io.IOException;
 import java.io.Reader;
 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.whut.inter.IUserDAO;
 import com.whut.model.User;
 public class TestUser {
 private static SqlSessionFactory sqlSessionFactory;
 private static Reader reader;
 static {
 try {
 Reader reader = Resources.getResourceAsReader("mybatic-config.xml");
 sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
 // 由于使用了注解，所以在主配置文件没有mapper，需要在代码里显示注册该mapper接口
 sqlSessionFactory.getConfiguration().addMapper(IUserDAO.class);
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
 public static void main(String[] args) {
 // testSelectAll();
 // testSelectByConditions();
 //testAddUser();
 //testDeleteUser();
 
 testUpateUser();
 }
 public static void testSelectAll() {
 // sqlSessionFactory.getConfiguration().addMapper(IUserDAO.class);
 SqlSession session = sqlSessionFactory.openSession();
 try {
 IUserDAO userDAO = session.getMapper(IUserDAO.class);
 List<User> users = userDAO.retrieveAllUsers();
 System.out.println("用户编号\t" + "姓名\t" + "年龄\t住址");
 for (User u : users) {
 System.out.println(u.getId() + "\t" + u.getUserName() + "\t"
 + u.getUserAge() + "\t" + u.getUserAddress());
 }
 } finally {
 session.close();
 }
 }
 public static void testSelectByConditions() {
 SqlSession session = sqlSessionFactory.openSession();
 try {
 IUserDAO userDAO = session.getMapper(IUserDAO.class);
 User u = userDAO.retrieveUserByIdAndName(4, "%spring%");
 if (u != null) {
 System.out.println("用户编号\t" + "姓名\t" + "年龄\t住址");
 System.out.println(u.getId() + "\t" + u.getUserName() + "\t"
 + u.getUserAge() + "\t" + u.getUserAddress());
 }
 } finally {
 session.close();
 }
 }
 public static void testAddUser() {
 User u = new User();
 u.setUserName("dongtian");
 u.setUserAge(51);
 u.setUserAddress("hubeisheng");
 SqlSession session = sqlSessionFactory.openSession();
 try {
 IUserDAO userDAO = session.getMapper(IUserDAO.class);
 userDAO.addNewUser(u);
 session.commit();
 } finally {
 session.close();
 }
 }
 public static void testDeleteUser() {
 SqlSession session = sqlSessionFactory.openSession();
 try {
 IUserDAO userDAO = session.getMapper(IUserDAO.class);
 userDAO.deleteUser(7);
 session.commit();
 } finally {
 session.close();
 }
 }
 
 public static void testUpateUser() {
 User u = new User();
 u.setId(4);
 u.setUserName("dongtian");
 u.setUserAge(51);
 u.setUserAddress("hubeisheng");
 SqlSession session = sqlSessionFactory.openSession();
 try {
 IUserDAO userDAO = session.getMapper(IUserDAO.class);
 userDAO.updateUser(u);
 session.commit();
 } finally {
 session.close();
 }
 }
 }

第二种 映射器接口调用SqlBuilder生成的SQL进行执行

映射器接口

package com.whut.inter;
 import java.util.List;
 import org.apache.ibatis.annotations.CacheNamespace;
 import org.apache.ibatis.annotations.DeleteProvider;
 import org.apache.ibatis.annotations.InsertProvider;
 import org.apache.ibatis.annotations.Options;
 import org.apache.ibatis.annotations.Param;
 import org.apache.ibatis.annotations.Result;
 import org.apache.ibatis.annotations.ResultMap;
 import org.apache.ibatis.annotations.Results;
 import org.apache.ibatis.annotations.SelectProvider;
 import org.apache.ibatis.annotations.UpdateProvider;
 import org.apache.ibatis.type.JdbcType;
 import com.whut.model.Blog;
 import com.whut.sqlTool.BlogSqlProvider;
 @CacheNamespace(size=100)
 public interface IBlogDAO {
 @SelectProvider(type = BlogSqlProvider.class, method = "getSql") 
 @Results(value ={ 
 @Result(id=true, property="id",column="id",javaType=Integer.class,jdbcType=JdbcType.INTEGER),
 @Result(property="title",column="title",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 @Result(property="date",column="date",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 @Result(property="authername",column="authername",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 @Result(property="content",column="content",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 }) 
 public Blog getBlog(@Param("id") int id);
 
 @SelectProvider(type = BlogSqlProvider.class, method = "getAllSql") 
 @Results(value ={ 
 @Result(id=true, property="id",column="id",javaType=Integer.class,jdbcType=JdbcType.INTEGER),
 @Result(property="title",column="title",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 @Result(property="date",column="date",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 @Result(property="authername",column="authername",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 @Result(property="content",column="content",javaType=String.class,jdbcType=JdbcType.VARCHAR),
 }) 
 public List<Blog> getAllBlog();
 
 @SelectProvider(type = BlogSqlProvider.class, method = "getSqlByTitle") 
 @ResultMap(value = "sqlBlogsMap") 
 //这里调用resultMap，这个是SQL配置文件中的,必须该SQL配置文件与本接口有相同的全限定名
 //注意文件中的namespace路径必须是使用@resultMap的类路径
 public List<Blog> getBlogByTitle(@Param("title")String title);
 
 @InsertProvider(type = BlogSqlProvider.class, method = "insertSql") 
 public void insertBlog(Blog blog);
 
 @UpdateProvider(type = BlogSqlProvider.class, method = "updateSql")
 public void updateBlog(Blog blog);
 
 @DeleteProvider(type = BlogSqlProvider.class, method = "deleteSql")
 @Options(useCache = true, flushCache = false, timeout = 10000) 
 public void deleteBlog(int ids);
 
 }

SQL生成器(利用SqlBuilder生成)

package com.whut.sqlTool;
 import java.util.Map;
 import static org.apache.ibatis.jdbc.SqlBuilder.*;
 public class BlogSqlProvider {
 private final static String TABLE_NAME = "blog";
 public String getSql(Map<Integer, Object> parameter) {
 BEGIN();
 //SELECT("id,title,authername,date,content");
 SELECT("*");
 FROM(TABLE_NAME);
 //注意这里这种传递参数方式，#{}与map中的key对应，而map中的key又是注解param设置的
 WHERE("id = #{id}");
 return SQL();
 }
 public String getAllSql() {
 BEGIN();
 SELECT("*");
 FROM(TABLE_NAME);
 return SQL();
 }
 public String getSqlByTitle(Map<String, Object> parameter) {
 String title = (String) parameter.get("title");
 BEGIN();
 SELECT("*");
 FROM(TABLE_NAME);
 if (title != null)
 WHERE(" title like #{title}");
 return SQL();
 }
 public String insertSql() {
 BEGIN();
 INSERT_INTO(TABLE_NAME);
 VALUES("title", "#{title}");
 // VALUES("title", "#{tt.title}");
 //这里是传递一个Blog对象的，如果是利用上面tt.方式，则必须利用Param来设置别名
 VALUES("date", "#{date}");
 VALUES("authername", "#{authername}");
 VALUES("content", "#{content}");
 return SQL();
 }
 public String deleteSql() {
 BEGIN();
 DELETE_FROM(TABLE_NAME);
 WHERE("id = #{id}");
 return SQL();
 }
 public String updateSql() {
 BEGIN();
 UPDATE(TABLE_NAME);
 SET("content = #{content}");
 WHERE("id = #{id}");
 return SQL();
 }
 }

注意由于在映射器接口中调用了@ResultMap,该注解内容是SQL配置文件ResultMap的ID，它是允许访问SQL配置文件中的ResultMap，则需要在相应的SQL配置相应ResultMap，然后再在主配置文件加上该SQL配置的Mapper路径。并且该SQL配置文件的namespace必须与使用@ResultMap的映射器接口的全限定相同。Blog.xml如下。

<?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.whut.inter.IBlogDAO">
 <resultMap type="Blog" id="sqlBlogsMap">
 <id property="id" column="id"/>
 <result property="title" column="title"/>
 <result property="authername" column="authername"/>
 <result property="date" column="date"/>
 <result property="content" column="content"/>
 </resultMap> 
 </mapper>

再在主配置文件mybatis-config.xml加入一句mapper。

测试：

package com.whut.test;
 import java.io.IOException;
 import java.io.Reader;
 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.whut.inter.IBlogDAO;
 import com.whut.model.Blog;
 /**
 * 注意这里是一种利用SqlBuilder以及多种设置来注解使用
 * @author zxl
 *
 */
 public class TestBlog {
 private static SqlSessionFactory sqlSessionFactory;
 private static Reader reader;
 static {
 try {
 Reader reader = Resources.getResourceAsReader("mybatic-config.xml");
 sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
 // 由于使用了注解，所以在主配置文件没有mapper，需要在代码里显示注册该mapper接口
 //sqlSessionFactory.getConfiguration().addMapper(IBlogDAO.class);
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
 
 public static void main(String[] args) {
 //testOneBlog();
 //testAllBlog();
 //testBlogByTitle();
 //testAddBlog();
 //testDeleteBlog();
 
 testUpdateBlog();
 }
 
 public static void testOneBlog()
 {
 SqlSession session=sqlSessionFactory.openSession();
 try{
 IBlogDAO dao=session.getMapper(IBlogDAO.class);
 Blog blog=dao.getBlog(2);
 System.out.println(blog.getId()+"\t"+blog.getAuthername()+"\t"+blog.getTitle());
 }finally{
 session.close();
 }
 
 }
 public static void testAllBlog()
 {
 SqlSession session=sqlSessionFactory.openSession();
 try{
 IBlogDAO dao=session.getMapper(IBlogDAO.class);
 List<Blog> blogs=dao.getAllBlog();
 System.out.println("编号\t作者\t标题");
 for(Blog blog:blogs)
 System.out.println(blog.getId()+"\t"+blog.getAuthername()+"\t"+blog.getTitle());
 }finally{
 session.close();
 }
 }
 public static void testBlogByTitle()
 {
 SqlSession session=sqlSessionFactory.openSession();
 try{
 IBlogDAO dao=session.getMapper(IBlogDAO.class);
 List<Blog> blogs=dao.getBlogByTitle("%word%");
 System.out.println("编号\t作者\t标题");
 for(Blog blog:blogs)
 System.out.println(blog.getId()+"\t"+blog.getAuthername()+"\t"+blog.getTitle());
 }finally{
 session.close();
 }
 }
 
 public static void testAddBlog()
 {
 SqlSession session=sqlSessionFactory.openSession();
 Blog blog=new Blog();
 blog.setTitle("chuntian");
 blog.setAuthername("xiaohua");
 blog.setDate("2013/12/25");
 blog.setContent("bushuangyayya");
 try{
 IBlogDAO dao=session.getMapper(IBlogDAO.class);
 dao.insertBlog(blog);
 session.commit();
 }finally{
 session.close();
 }
 }
 
 public static void testDeleteBlog()
 {
 SqlSession session=sqlSessionFactory.openSession();
 try{
 IBlogDAO dao=session.getMapper(IBlogDAO.class);
 dao.deleteBlog(5);
 session.commit();
 }finally{
 session.close();
 }
 }
 
 public static void testUpdateBlog()
 {
 SqlSession session=sqlSessionFactory.openSession();
 Blog blog=new Blog();
 blog.setId(6);
 blog.setTitle("daxuexiaoyuan");
 blog.setAuthername("xiaohua");
 blog.setDate("2013/2/25");
 blog.setContent("冷死了");
 try{
 IBlogDAO dao=session.getMapper(IBlogDAO.class);
 dao.updateBlog(blog);
 session.commit();
 }finally{
 session.close();
 }
 }
 }

注意事项：  
1） 在利用注解配置映射器接口的时候，必须要通过  
sqlSessionFactory.getConfiguration().addMapper(IBlogDAO.class);来对给映射器接口注册，如果映射器接口中使用了@ResultMap注解，则由于已经在mybatis-config.xml配置了Mapper，则就不需要再次在代码中添加mapper。  
2）当方法有多个参数的时候，为了与SQL语句中的\#\{\}对应，一般可以使用@Param("")来为每个参数命别名，使得该别名与\#\{\}对应。当参数只有一个的时候，不需要别名。  
3 在进行更新删除添加的时候，如果传递的是一个实体对象，则SQL可以直接使用实体的属性。  
4）映射器接口调用SqlBuilder中的方法，都是将参数转换为Map中的key，可以在SqlBuilder的方法中利用Map来获取传递的参数值，进而进行逻辑操作判断。  
5）注解中对于返回多条记录的查询可以直接利用@Results和@Result来配置映射，或者利用@ResultMap来调用SQL配置文件中的ResultMap。