非SpringBoot项目集成MyBatis-Plus

1. 引入maven依赖

        <!-- https://mvnrepository.com/artifact/com.baomidou/mybatis-plus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>3.5.6</version>
        </dependency>


        <!-- https://mvnrepository.com/artifact/com.baomidou/mybatis-plus-extension -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-extension</artifactId>
            <version>3.5.6</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.zaxxer/HikariCP -->
        <dependency>
            <groupId>com.zaxxer</groupId>
            <artifactId>HikariCP</artifactId>
            <version>4.0.3</version>
        </dependency>

         <!-- Mysql驱动包 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-nop</artifactId>
            <version>1.7.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.32</version>
            <scope>provided</scope>
        </dependency>

2. 编写初始化数据源单例 DataSourceInitializer

    private static DataSourceInitializer instance = new DataSourceInitializer();

    public static DataSourceInitializer getInstance() {
        return instance;
    }

    private SqlSession session;

    private DataSourceInitializer() {
        try {
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            //这是mybatis-plus的配置对象，对mybatis的Configuration进行增强
            MybatisConfiguration configuration = new MybatisConfiguration();
            //初始化配置
            initConfiguration(configuration);
            //这是初始化连接器，如mybatis-plus的分页插件
            configuration.addInterceptor(initInterceptor());
            //配置日志实现
            configuration.setLogImpl(Slf4jImpl.class);
            //扫描mapper接口所在包
            configuration.addMappers("com.example.mapper");
            //构建mybatis-plus需要的globalconfig
            GlobalConfig globalConfig = GlobalConfigUtils.getGlobalConfig(configuration);
            //此参数会自动生成实现baseMapper的基础方法映射
            globalConfig.setSqlInjector(new DefaultSqlInjector());
            //设置id生成器
            globalConfig.setIdentifierGenerator(new DefaultIdentifierGenerator());
            //设置超类mapper
            globalConfig.setSuperMapperClass(BaseMapper.class);
            //设置数据源
            Environment environment = new Environment("1", new JdbcTransactionFactory(), initDataSource());
            configuration.setEnvironment(environment);
            this.registryMapperXml(configuration, "mapper");
            //构建sqlSessionFactory
            SqlSessionFactory sqlSessionFactory = builder.build(configuration);
            //创建session
            this.session = sqlSessionFactory.openSession();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

3. 初始化配置方法

     /**
     * 初始化配置
     *
     * @param configuration
     */
    private void initConfiguration(MybatisConfiguration configuration) {
        //开启驼峰大小写转换
        configuration.setMapUnderscoreToCamelCase(true);
        //配置添加数据自动返回数据主键
        configuration.setUseGeneratedKeys(true);
    }

    /**
     * 初始化数据源
     *
     * @return
     */
    private DataSource initDataSource() {
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setJdbcUrl("jdbc:sqlite:db/database.db");
        dataSource.setDriverClassName("org.sqlite.JDBC");
        dataSource.setIdleTimeout(60000);
        dataSource.setAutoCommit(true);
        dataSource.setMaximumPoolSize(5);
        dataSource.setMinimumIdle(1);
        dataSource.setMaxLifetime(60000 * 10);
        dataSource.setConnectionTestQuery("SELECT 1");
        return dataSource;
    }

    /**
     * 初始化拦截器
     *
     * @return
     */
    private Interceptor initInterceptor() {
        //创建mybatis-plus插件对象
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        //构建分页插件
        PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor();
        paginationInnerInterceptor.setDbType(DbType.SQLITE);
        paginationInnerInterceptor.setOverflow(true);
        paginationInnerInterceptor.setMaxLimit(500L);
        interceptor.addInnerInterceptor(paginationInnerInterceptor);
        return interceptor;
    }

    /**
     * 解析mapper.xml文件
     *
     * @param configuration
     * @param classPath
     * @throws IOException
     */
    private void registryMapperXml(MybatisConfiguration configuration, String classPath) throws IOException {
        ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
        Enumeration<URL> mapper = contextClassLoader.getResources(classPath);
        while (mapper.hasMoreElements()) {
            URL url = mapper.nextElement();
            if (url.getProtocol().equals("file")) {
                String path = url.getPath();
                File file = new File(path);
                File[] files = file.listFiles();
                for (File f : files) {
                    FileInputStream in = new FileInputStream(f);
                    XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(in, configuration, f.getPath(), configuration.getSqlFragments());
                    xmlMapperBuilder.parse();
                    in.close();
                }
            } else {
                JarURLConnection urlConnection = (JarURLConnection) url.openConnection();
                JarFile jarFile = urlConnection.getJarFile();
                Enumeration<JarEntry> entries = jarFile.entries();
                while (entries.hasMoreElements()) {
                    JarEntry jarEntry = entries.nextElement();
                    if (jarEntry.getName().endsWith(".xml")) {
                        InputStream in = jarFile.getInputStream(jarEntry);
                        XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(in, configuration, jarEntry.getName(), configuration.getSqlFragments());
                        xmlMapperBuilder.parse();
                        in.close();
                    }
                }
            }
        }
    }

xml文件放在 resources/mapper 下面

4. 其他方法

    /**
     * 获取mapper类
     * @param type
     * @return
     * @param <T>
     */
    public <T> T getMapper(Class<T> type) {
        return this.session.getMapper(type);
    }

    /**
     * 销毁数据库连接
     */
    public void destroy() {
        this.session.commit();
        this.session.close();
    }

5. 调用Mapper

        UserMapper mapper = DataSourceInitializer.getInstance().getMapper(UserMapper .class);
        List<User> res= mapper.selectList(null);
        System.out.println(res);

原文地址：https://blog.csdn.net/guo__hang/article/details/137910439

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