JDBC 驱动

用户下载 JDBC 驱动 并导入 jar 包后，即可以使用 JDBC 提供的 API。

示例

以下示例为通过 maven 工程使用 JDBC 进行简单的增删改查操作。

1. 在 pom.xml 中添加 PostgreSQL JDBC 驱动的依赖，以 postgresql-9.3-1104-jdbc41 为例

   <dependencies>
      <dependency>
          <groupId>org.postgresql</groupId>
          <artifactId>postgresql</artifactId>
          <version>9.3-1104-jdbc41</version>
      </dependency>
   </dependencies>

2. 假设本地有默认安装的 PostgreSQL 实例，连接到该实例并准备数据库 sample 和表 test，将其映射到 SequoiaDB 已存在的集合 sample.employee

   $ bin/psql -p 5432 sample
   psql (9.3.4)
   Type "help" for help.
   
   sample=# create foreign table test (name text, id numeric) server sdb_server options (collectionspace 'sample', collection 'employee', decimal 'on');
   CREATE FOREIGN TABLE
   sample=# \q

3. 在工程的 src/main/java/com/sequoiadb/sample 目录下添加 Sample.java 文件

   package com.sequoiadb.sample;
   
   import java.sql.Connection;
   import java.sql.DriverManager;
   import java.sql.PreparedStatement;
   import java.sql.ResultSet;
   import java.sql.ResultSetMetaData;
   import java.sql.SQLException;
   
   public class Sample {
      static {
          try {
              Class.forName("org.postgresql.Driver");
          } catch (ClassNotFoundException e) {
              e.printStackTrace();
          }
      }
   
      public static void main(String[] args) throws SQLException {
          String pghost = "127.0.0.1";
          String port = "5432";
          String databaseName = "sample";
          // postgresql process is running in which user
          String pgUser = "sdbadmin";
          String url = "jdbc:postgresql://" + pghost + ":" + port + "/" + databaseName;
          Connection conn = DriverManager.getConnection(url, pgUser, null);
   
          // insert
          String sql = "INSERT INTO test(name, id) VALUES(?, ?)";
          PreparedStatement pstmt = conn.prepareStatement(sql);
          for (int i = 0; i < 5; i++) {
              pstmt.setString(1, "Jim" + i);
              pstmt.setLong(2, i);
              pstmt.addBatch();
          }
          pstmt.executeBatch();
   
          // select
          sql = "SELECT * FROM test";
          pstmt = conn.prepareStatement(sql);
          ResultSet rs = pstmt.executeQuery();
          boolean isHeaderPrint = false;
          while (rs.next()) {
              ResultSetMetaData md = rs.getMetaData();
              int col_num = md.getColumnCount();
              if (!isHeaderPrint) {
                  System.out.print("|");
                  for (int i = 1; i <= col_num; i++) {
                      System.out.print(md.getColumnName(i) + "\t|");
                      isHeaderPrint = true;
                  }
                  System.out.println();
              }
              System.out.print("|");
              for (int i = 1; i <= col_num; i++) {
                  System.out.print(rs.getString(i) + "\t|");
              }
              System.out.println();
          }
          pstmt.close();
          conn.close();
      }
   }

4. 使用 maven 编译及运行

   $ mvn compile 
   $ mvn exec:java -Dexec.mainClass="com.sequoiadb.sample.Sample"

   得到运行结果如下:

   |name    |id |
   |Jim0    |0  |
   |Jim1    |1  |
   |Jim2    |2  |
   |Jim3    |3  |
   |Jim4    |4  |