使用getMapper方式对自定义持久层框架进行优化

1、Dao层使用持久层框架，存在代码重复，整个操作过程模板重复（加载配置文件、创建SqlSessionFactory、生产SqlSession）文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

2、存在硬编码（statementId）文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

使用代理模式生成Dao层接口的实现类文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

​文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

​文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

SqlSession接口新增getMapper方法文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

fun <T> getMapper(mapperClass: Class<*>?): T

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

public <T> T getMapper(Class<?> mapperClass);

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

DefaultSqlSession中getMapper方法的实现文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

override fun <T> getMapper(mapperClass: Class<*>): T {
    // 使用JDK动态代理为Dao接口生成代理对象
    return Proxy.newProxyInstance(
        DefaultSqlSession::class.java.classLoader,
        arrayOf(mapperClass)
    ) { proxy, method, args -> // 底层还是执行JDBC
        // 准备参数1
        // statemendid=namespace.id，获取不到
        // statemendid=接口全限定名.方法名
        val clazzName = method.declaringClass.name
        val methodName = method.name
        val statementId = "$clazzName.$methodName"

        // 准备参数2：params=args

        // 获取被调用方法的返回类型
        val genericReturnType = method.genericReturnType
        // 判断是否进行了泛型类型参数化
        if (genericReturnType is ParameterizedType) {
            selectList<Any>(statementId, *args)
        } else selectOne<Any>(statementId, *args)
    } as T
}

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

@Override
public <T> T getMapper(Class<?> mapperClass) {
    // 使用JDK动态代理为Dao接口生成代理对象
    return (T) Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            // 底层还是执行JDBC
            // 准备参数1
            // statemendid=namespace.id，获取不到
            // statemendid=接口全限定名.方法名
            String clazzName = method.getDeclaringClass().getName();
            String methodName = method.getName();
            String statementId = clazzName + "." + methodName;

            // 准备参数2：params=args

            // 获取被调用方法的返回类型
            Type genericReturnType = method.getGenericReturnType();
            // 判断是否进行了泛型类型参数化
            if (genericReturnType instanceof ParameterizedType) {
                return selectList(statementId, args);
            }

            return selectOne(statementId, args);
        }
    });
}

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

mybatis-proxy/custom-persistence文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

mybatis-normal/custom-persistence文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html

文章更新历史
2022/05/08 feat:增加Kotlin实现 文章源自浅海拾贝-https://blog.terwergreen.com/use-getmapper-to-optimize-the-custom-persistence-layer-framework.html