JDBC之获取插入语句返回的主键

该获取主键并不是绝对的，也和具体的数据库实现的驱动有关。

package cn.itcast.jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.junit.Test;
/**
 * 测试JDBC中的几个其他API
 */
public class OtherApi {
 /**
  * 测试create方法
  * @throws SQLException
  */
 @Test
 public void testCreate() throws SQLException {
  System.out.println(create());
 }
 /**
  * 测试从数据库读取数据
  * @throws SQLException
  * @throws InterruptedException
  */
 @Test
 public void testRead() throws SQLException, InterruptedException {
  read();
 }
 /**
  * 读取数据库中的数据
  * @throws SQLException
  * @throws InterruptedException
  */
 static void read() throws SQLException, InterruptedException {
  Connection conn = null;
  Statement st = null;
  ResultSet rs = null;
  try {
   //建立连接
   conn = JdbcUtils.getConnection();
   //创建语句
   st = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, 
     ResultSet.CONCUR_UPDATABLE);
   //执行语句
   rs = st.executeQuery("select id, name, money, birthday  from user where id < 5");
   //处理结果
   while(rs.next()) {
    int id = rs.getInt("id");
    System.out.println("show"  + id + "...");
    Thread.sleep(10000);
    System.out.println(id +"\t" + rs.getObject("name") + "\t"
      + rs.getObject("birthday") + "\t"
      + rs.getObject("money"));
   }
  } finally {
   JdbcUtils.free(rs, st, conn);
  }
 }
 /**
  * 向数据库中插入语句
  * @return
  * @throws SQLException
  */
 static int create() throws SQLException {
  Connection conn = null;
  PreparedStatement ps = null;
  ResultSet rs = null;
  try {
   //建立连接
   conn = JdbcUtils.getConnection();
   //创建语句
   String sql = "insert into user(name,birthday, money) values ('name2 gk', '1987-01-01', 400) ";
   //通过传入第二个参数,就会产生主键返回给我们
   ps = conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);
   ps.executeUpdate();
   //返回的结果集中包含主键,注意：主键还可以是UUID,
   //复合主键等,所以这里不是直接返回一个整型
   rs = ps.getGeneratedKeys();
   int id = 0;
   if(rs.next()) {
    id = rs.getInt(1);
   }
   return id;
  } finally{
   JdbcUtils.free(rs, ps, conn);
  }
 }
}