Question

我想在LocalDate列中存储DATE并保持不变。 DATE和LocalDate都是＆＃34;本地＆＃34;根据定义类型。因此， timezone 的概念不应以任何方式干扰。

下面的代码是一个最小的示例，它在内存数据库中创建一个带有DATE列的表。 maven工件com.h2database:h2:1.4.192必须位于类路径中。

首先，定义方法insert和retrieve：

static void insert(DataSource ds, String date) throws SQLException {
  try (Connection conn = ds.getConnection();
       Statement stmt = conn.createStatement()) {
    stmt.execute("CREATE TABLE people (id BIGINT NOT NULL AUTO_INCREMENT"
      + ", born DATE NOT NULL, PRIMARY KEY (id) );");
    stmt.execute("INSERT INTO people (born) VALUES ('" + date + "')");
  }
}

static LocalDate retrieve(DataSource ds) throws SQLException {
  try (Connection conn = ds.getConnection();
       Statement stmt = conn.createStatement();
       ResultSet rs = stmt.executeQuery("SELECT * FROM people limit 1")) {
    if (rs.next()) {
      java.sql.Date retrieved = java.sql.Date.valueOf(rs.getString("born"));
      return retrieved.toLocalDate();
    }
    throw new IllegalStateException("No data");
  }
}

请注意，insert方法在单引号中使用toString的{{1}}值，因此Java™没有机会创建时区歧义。现在拨打LocalDate一次，然后多次insert，每次都使用不同的timzone设置：

retrieve

然后打印以下内容：

Inserted:  2015-05-20
Retrieved: 2015-05-20
Retrieved: 2015-05-19
Retrieved: 2015-05-18

如何编写public static void main(String[] args) throws Exception { DataSource ds = JdbcConnectionPool.create("jdbc:h2:mem:test", "sa", "sa"); LocalDate born = LocalDate.parse("2015-05-20"); insert(ds, born.toString()); System.out.println("Inserted: " + born); for (int i : new int[]{-14, 0, 12}) { TimeZone z = TimeZone.getTimeZone(String.format("Etc/GMT%+02d", i)); TimeZone.setDefault(z); System.out.println("Retrieved: " + retrieve(ds)); } }方法，使其返回与无条件相同的值，假设数据库表没有变化？

Answer 1

我刚刚对您的retrieve方法进行了以下修改，它对我有用：

I am creating my first Django app, and I am trying to open a template using a button tag. I have something like this here:

<button type="submit" onClick="window.location.href='details'">View</button>

In my urls.py, I have:

url(r'^details/$', TemplateView.as_view(template_name='details.html'), name=""),

I am not sure how to set the URL in urls.py to be able to access the details.html page. Currently, the page does not open. Does someone know how I can open it please?

Answer 2

以下解决方案也有效。我更喜欢在接受的答案中通过String转换，因为它避免了下面显示的时区修补。然而，它可能在所有数据库上的工作方式不同，因为有些例如Oracle对DATE有不同的定义。

static LocalDate retrieve(DataSource ds) throws SQLException {
  try (Connection conn = ds.getConnection();
       Statement stmt = conn.createStatement();
       ResultSet rs = stmt.executeQuery("SELECT * FROM people limit 1")) {
    if (rs.next()) {
      ZoneId utc = ZoneId.of("UTC");
      TimeZone z = TimeZone.getTimeZone(utc);
      Calendar cal = Calendar.getInstance(z);
      java.sql.Date retrieved = rs.getDate("born", cal);
      long time = retrieved.getTime();
      java.util.Date utilDate = new java.util.Date(time);
      Instant instant = utilDate.toInstant();
      ZonedDateTime zdt = instant.atZone(utc);
      return zdt.toLocalDate();
    }
  }
  throw new IllegalStateException("No data");
}

根据用户Tunaki的建议，此问题中列出了java.util.Date转换：Missed opportunity to fix JDBC date handling in Java 8?

如何将sql DATE映射到LocalDate

2 个答案: