Question

以下代码正在创建test.mv.db文件。它也可以正常运行并显示它已在数据库中插入数据。

架构：

create table Customer (
    id identity,
    firstname varchar(20) not null,
    lastname varchar(20) not null
);

主类：

public class App {

    public static void main(String[] args) {

        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);

        CustomerRepository repo = ctx.getBean(CustomerRepository.class);

        Customer c1 = new Customer("John", "Doe");
        Customer c2 = new Customer("Jane", "Doe");

        // insert
        c1 = repo.save(c1);
        c2 = repo.save(c2);

        for(Customer t : repo.findAll()) {
            System.out.println(t.getFirstName()+", "+t.getLastName());
        }
        ctx.close();
    }

}

配置：

@Configuration
@ComponentScan
public class Config {

    @Bean
    public DataSource datasource() {
        DriverManagerDataSource ds = new DriverManagerDataSource();

        ds.setDriverClassName("org.h2.Driver");
        ds.setUrl("jdbc:h2:~/test;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE");

        Resource schema = new ClassPathResource("schema.sql");
        ResourceDatabasePopulator dbp = new ResourceDatabasePopulator();
        dbp.addScript(schema);
        DatabasePopulatorUtils.execute(dbp, ds);

        return ds;
    }

    @Bean
    public JdbcOperations jdbcTemplate(DataSource ds) {
        return new JdbcTemplate(ds);        
    }

}

客户类：

public class Customer {

    private Long id;
    private String firstName;
    private String lastName;

    public Customer() {}

    public Customer(Long id, String firstName, String lastName) {
        super();
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public Customer(String firstName, String lastName) {
        super();
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public Long getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }



}

CustomerRepository Interface：

public interface CustomerRepository {

    Customer findOne(long id);

    Customer save(Customer cust);

    List<Customer> findAll();

    int update(Customer cust);

    int delete (Customer cust);

}

CustomerRepositoryImpl：

@Repository
public class CustomerRepositoryImpl implements CustomerRepository {

    @Autowired
    private JdbcOperations jdbc;

    private static final String SQL_INSERT = "insert into customer (firstname, lastname) values (?, ?)";
    private static final String SQL_UPDATE = "update customer set firstname=?, lastname=? where id=?";
    private static final String SQL_FIND_ONE = "select * from customer where id = ?";
    private static final String SQL_FIND_ALL = "select * from customer order by lastname";
    private static final String SQL_DELETE_ONE = "delete from customer where id = ?";


    public Customer findOne(long id) {
        return jdbc.queryForObject(SQL_FIND_ONE, new CustomerRowMapper(), id);
    }

    public Customer save(final Customer cust) {

        KeyHolder holder = new GeneratedKeyHolder();

        int rows = jdbc.update(new PreparedStatementCreator() {

            public PreparedStatement createPreparedStatement(Connection conn) throws SQLException {
                PreparedStatement ps = conn.prepareStatement(SQL_INSERT, new String[]{"id"});

                ps.setString(1,  cust.getFirstName());
                ps.setString(2, cust.getLastName());

                return ps;
            }
        }, holder);

        if(rows == 1) { // success, so apply ID to the customer object
            cust.setId((Long)holder.getKey());
            return cust;
        }

        return null;

    }

    public List<Customer> findAll() {
        return jdbc.query(SQL_FIND_ALL, new CustomerRowMapper());
    }

    public int update(Customer cust) {
        return jdbc.update(SQL_UPDATE, cust.getFirstName(), cust.getLastName(), cust.getId());
    }

    public int delete(Customer cust) {
        return jdbc.update(SQL_DELETE_ONE, cust.getId());
    }

    private class CustomerRowMapper implements RowMapper<Customer> {

        public Customer mapRow(ResultSet rs, int row) throws SQLException {

            return new Customer(rs.getLong("id"), rs.getString("firstname"), rs.getString("lastname")); 

        }

    }
}

堆栈跟踪：

Aug 14, 2017 9:45:42 PM org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@b81eda8: startup date [Mon Aug 14 21:45:42 BDT 2017]; root of context hierarchy
Aug 14, 2017 9:45:43 PM org.springframework.jdbc.datasource.DriverManagerDataSource setDriverClassName
INFO: Loaded JDBC driver: org.h2.Driver
Aug 14, 2017 9:45:43 PM org.springframework.jdbc.datasource.init.ScriptUtils executeSqlScript
INFO: Executing SQL script from class path resource [schema.sql]
Aug 14, 2017 9:45:43 PM org.springframework.jdbc.datasource.init.ScriptUtils executeSqlScript
INFO: Executed SQL script from class path resource [schema.sql] in 28 ms.
Aug 14, 2017 9:45:43 PM org.springframework.context.annotation.AnnotationConfigApplicationContext doClose
INFO: Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@b81eda8: startup date [Mon Aug 14 21:45:42 BDT 2017]; root of context hierarchy
John, Doe
Jane, Doe

问题

但是在第二次运行时，先前保存的数据不再存在。首先我用dbeaver检查，如果数据库中有任何名为Customer的表。我找不到任何。

然后我评论了以下几行 -

c1 = repo.save(c1);
c2 = repo.save(c2);

来自App.java的

但是，如果有任何数据，它将从那里用

读取它

for(Customer t : repo.findAll()) {
    System.out.println(t.getFirstName()+", "+t.getLastName());
}

但这里也没有运气。

请问有什么问题？

在数据库保存在PC中的情况下，也欢迎使用derby的工作解决方案。

Spring H2数据库，不在数据库中创建表

0 个答案: