MyBatis游标Cursor的正确使用和百万数据传输的内存测试

CREATE TABLE test_table (
  id INT PRIMARY KEY,
  name VARCHAR(20),
  age INT,
    address VARCHAR(200)
);

-- 创建一个存储过程，用于插入10万测试数据
DELIMITER //
CREATE PROCEDURE insert_test_data()
BEGIN
  DECLARE i INT DEFAULT 1;
  WHILE i <= 100000 DO
    -- 随机生成姓名和年龄
    SET @name = CONCAT('name', i);
    SET @address = CONCAT('address......................', i);
    SET @age = FLOOR(RAND() * 100);
    -- 插入数据
    INSERT INTO test_table (id, name, age, address) VALUES (i, @name, @age, @address);
    -- 更新计数器
    SET i = i + 1;
  END WHILE;
END //
DELIMITER ;

-- 调用存储过程
CALL insert_test_data();

public interface TestMapper {
    class Person {
        private String name;
        private int age;
        private Integer id;
        private String address;

        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }

        public Integer getId() {
            return id;
        }

        public void setId(Integer id) {
            this.id = id;
        }

        public String getAddress() {
            return address;
        }

        public void setAddress(String address) {
            this.address = address;
        }
    }
    
    //TODO 注意sql中指定了表名 test，如果自己执行，需要按需修改
    @Select("select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table")
    @Options(fetchSize = Integer.MIN_VALUE)
    Cursor<Person> selectAll();

    @Select("select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table")
    List<Person> selectList();
}

@Test
public void testCursor() throws InterruptedException {
    //等待10秒方便jvisualVM监控
    Thread.sleep(10000);
    long start = System.currentTimeMillis();
    try (SqlSession sqlSession = getSqlSession()) {
        TestMapper testMapper = sqlSession.getMapper(TestMapper.class);
        try(Cursor<TestMapper.Person> cursor = testMapper.selectAll()){

            int total = 0;
            for (TestMapper.Person o : cursor) {
                total++;
            }
            System.out.println("总数: " + total);
        } catch (IOException ignore) {
        }
    }
    System.out.println("耗时: " + (System.currentTimeMillis() - start));
    Thread.sleep(10000);
}


@Test
public void testSelectAll() throws InterruptedException {
    //等待10秒方便jvisualVM监控
    Thread.sleep(10000);
    long start = System.currentTimeMillis();
    try (SqlSession sqlSession = getSqlSession()) {
        TestMapper testMapper = sqlSession.getMapper(TestMapper.class);
        List<TestMapper.Person> people = testMapper.selectList();
        System.out.println(people.size());
    }
    System.out.println("耗时: " + (System.currentTimeMillis() - start));
    Thread.sleep(10000);
}

private static SqlSessionFactory sqlSessionFactory;

@BeforeAll
public static void init() {
    try {
        Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        reader.close();
    } catch (IOException ignore) {
        ignore.printStackTrace();
    }
}

public SqlSession getSqlSession() {
    return sqlSessionFactory.openSession();
}

@Select("select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table union all " +
            "select * from test.test_table")
Cursor<Person> selectAll();

@Select("select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table union all " +
        "select * from test.test_table")
@Options(resultSetType = ResultSetType.FORWARD_ONLY)
Cursor<Person> selectAll();

/**
 * We only stream result sets when they are forward-only, read-only, and the
 * fetch size has been set to Integer.MIN_VALUE
 * 
 * @return true if this result set should be streamed row at-a-time, rather
 *         than read all at once.
 */
protected boolean createStreamingResultSet() {
    return ((this.query.getResultType() == Type.FORWARD_ONLY) && (this.resultSetConcurrency == java.sql.ResultSet.CONCUR_READ_ONLY)
            && (this.query.getResultFetchSize() == Integer.MIN_VALUE));
}

protected Resultset.Type resultSetType = Type.FORWARD_ONLY;

@Override
public java.sql.PreparedStatement prepareStatement(String sql) throws SQLException {
    return prepareStatement(sql, DEFAULT_RESULT_SET_TYPE, DEFAULT_RESULT_SET_CONCURRENCY);
}