JAVA8时间和Mysql时间的关系

大家知道，在实体Entity里面，可以使用Java.sql.Date、java.sql.Timestamp、java.util.Date来映射到数据库的date、timestamp、datetime等字段

但是，java.sql.Date、java.sql.Timestamp、java.util.Date这些类都不好用，很多方法都过时了。

Java8里面新出来了一些API，LocalDate、LocalTime、LocalDateTime 非常好用

如果想要在JDBC中，使用Java8的日期LocalDate、LocalDateTime，则必须要求数据库驱动的版本不能低于4.2

下面将分别演示如何在JDBC中使用Java8的日期LocalDate、LocalDateTime来操作MySQL，postgresql

一：mysql

首先创建表：

create table tb_java8date (id int not null primary key auto_increment,t_date date, t_time time, t_datetime datetime);

然后，加入mysql的驱动

<dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <version>5.1.37version>
dependency>

    mysql
    mysql-connector-java
    5.1.37

上面说了，数据库驱动的版本不能低于4.2，如何判断呢？

直接打开数据库驱动jar，里面有个META-INF/MANIFEST.MF文件

注意这里，必须要至少是4.2

JDBC代码如下：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class App {
    public static void main(String[] args) throws Exception {
        Class.forName(”com.mysql.jdbc.Driver”);
        Connection conn = DriverManager.getConnection(”jdbc:mysql://192.168.1.100:3306/db_java8”,“root”,“root123”);
        PreparedStatement st = conn.prepareStatement(”insert into tb_java8date (t_date,t_time,t_datetime)values(?,?,?)”);
        st.setObject(1, LocalDate.now());
        st.setObject(2, LocalTime.now());
        st.setObject(3, LocalDateTime.now());
        st.execute();
        st.close();
        conn.close();
    }
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class App {
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://192.168.1.100:3306/db_java8","root","root123");
        PreparedStatement st = conn.prepareStatement("insert into tb_java8date (t_date,t_time,t_datetime)values(?,?,?)");
        st.setObject(1, LocalDate.now());
        st.setObject(2, LocalTime.now());
        st.setObject(3, LocalDateTime.now());
        st.execute();
        st.close();
        conn.close();
    }
}

运行，查询数据库

mysql> select * from tb_java8date;
+—-+————+———-+———————+
| id | t_date     | t_time   | t_datetime          |
+—-+————+———-+———————+
|  1 | 2016-11-13 | 11:34:31 | 2016-11-13 11:34:31 |
+—-+————+———-+———————+
1 row in set (0.00 sec)

看到已经成功插入到数据库中去了

如果你使用的mysql-connector-java版本低于5.1.37，则数据库的驱动版本低于4.2，运行会报如下错误：

Exception in thread “main” com.mysql.jdbc.MysqlDataTruncation: Data truncation: Incorrect date value: ’\xAC\xED\x00\x05sr\x00\x0Djava.time.Ser\x95]\x84\xBA\x1B”H\xB2\x0C\x00\x00xpw\x07\x03\x00\x00\x07\xE0\x0B\x0Dx’ for column ‘t_date’ at row 1
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3845)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3783)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2447)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2594)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1901)
    at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1193)
    at com.pp.App.main(App.java:18)

Exception in thread "main" com.mysql.jdbc.MysqlDataTruncation: Data truncation: Incorrect date value: '\xAC\xED\x00\x05sr\x00\x0Djava.time.Ser\x95]\x84\xBA\x1B"H\xB2\x0C\x00\x00xpw\x07\x03\x00\x00\x07\xE0\x0B\x0Dx' for column 't_date' at row 1
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3845)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3783)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2447)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2594)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1901)
    at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1193)
    at com.pp.App.main(App.java:18)

二：PostgreSQL

首先创建表：

create table tb_java8date (id SERIAL not null primary key,t_date date, t_time time, t_datetime timestamp);

然后，加入PostgreSQL的数据库驱动

<dependency>
    <groupId>org.postgresqlgroupId>
    <artifactId>postgresqlartifactId>
    <version>9.4.1212version>
dependency>

    org.postgresql
    postgresql
    9.4.1212

注意这里添加的数据库驱动版本最低要是4.2，检验方法和上面类似

JDBC代码如下：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class App {
    public static void main( String[] args ) throws Exception {
        Class.forName(”org.postgresql.Driver”);
        Connection conn = DriverManager.getConnection(”jdbc:postgresql://127.0.0.1:5432/pg_java8”,“admin”,“123456”);
        PreparedStatement st = conn.prepareStatement(”insert into tb_java8date (t_date,t_time,t_datetime)values(?,?,?)”);
        System.out.println(st.getClass());
        st.setObject(1, LocalDate.now());
        st.setObject(2, LocalTime.now());
        st.setObject(3, LocalDateTime.now());
        st.execute();
        st.close();
        conn.close();
    }
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

public class App {
    public static void main( String[] args ) throws Exception {
        Class.forName("org.postgresql.Driver");
        Connection conn = DriverManager.getConnection("jdbc:postgresql://127.0.0.1:5432/pg_java8","admin","123456");
        PreparedStatement st = conn.prepareStatement("insert into tb_java8date (t_date,t_time,t_datetime)values(?,?,?)");
        System.out.println(st.getClass());
        st.setObject(1, LocalDate.now());
        st.setObject(2, LocalTime.now());
        st.setObject(3, LocalDateTime.now());
        st.execute();
        st.close();
        conn.close();
    }
}

运行，然后查询数据库表

发现，已经成功执行

如果你加入的依赖，数据库的驱动版本低于4.2，运行会报如下错误：

Exception in thread “main” org.postgresql.util.PSQLException: Can’t infer the SQL type to use for an instance of java.time.LocalDate. Use setObject() with an explicit Types value to specify the type to use.
    at org.postgresql.jdbc.PgPreparedStatement.setObject(PgPreparedStatement.java:1051)
    at com.pp.App.main(App2.java:16)

Exception in thread "main" org.postgresql.util.PSQLException: Can't infer the SQL type to use for an instance of java.time.LocalDate. Use setObject() with an explicit Types value to specify the type to use.
    at org.postgresql.jdbc.PgPreparedStatement.setObject(PgPreparedStatement.java:1051)
    at com.pp.App.main(App2.java:16)

以上只是演示了mysql，postgresql两个数据库，其他的数据库，请自行测试。我这里就不演示了，方法都类似。