Java Mysql 简明教程

Java & MySQL - Batching with PrepareStatement Object

以下是一些使用批处理和 PrepareStatement 对象的典型步骤：

Here is a typical sequence of steps to use Batch Processing with PrepareStatement Object −

Create SQL statements with placeholders.
Create PrepareStatement object using either prepareStatement() methods.
Set auto-commit to false using setAutoCommit().
Add as many as SQL statements you like into batch using addBatch() method on created statement object.
Execute all the SQL statements using executeBatch() method on created statement object.
Finally, commit all the changes using commit() method.

此示例代码基于先前章节中完成的环境和数据库设置编写。

This sample code has been written based on the environment and database setup done in the previous chapters.

将以下示例复制并粘贴到 TestApplication.java 中，如下进行编译和运行：

Copy and paste the following example in TestApplication.java, compile and run as follows −

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestApplication {
   static final String DB_URL = "jdbc:mysql://localhost/TUTORIALSPOINT";
   static final String USER = "guest";
   static final String PASS = "guest123";
   static final String INSERT_QUERY = "INSERT INTO Employees(first,last,age) VALUES(?, ?, ?)";

   public static void printResultSet(ResultSet rs) throws SQLException{
      // Ensure we start with first row
      rs.beforeFirst();
      while(rs.next()){
         // Display values
         System.out.print("ID: " + rs.getInt("id"));
         System.out.print(", Age: " + rs.getInt("age"));
         System.out.print(", First: " + rs.getString("first"));
         System.out.println(", Last: " + rs.getString("last"));
      }
      System.out.println();
   }

   public static void main(String[] args) {
      // Open a connection
      try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
         PreparedStatement stmt = conn.prepareStatement(INSERT_QUERY,
            ResultSet.TYPE_SCROLL_INSENSITIVE,
            ResultSet.CONCUR_UPDATABLE)
      ) {
         conn.setAutoCommit(false);

         ResultSet rs = stmt.executeQuery("Select * from Employees");
         printResultSet(rs);

         // Set the variables
         stmt.setString( 1, "Pappu" );
         stmt.setString( 2, "Singh" );
         stmt.setInt( 3, 33 );
         // Add it to the batch
         stmt.addBatch();

         // Set the variables
         stmt.setString( 1, "Pawan" );
         stmt.setString( 2, "Singh" );
         stmt.setInt( 3, 31 );
         // Add it to the batch
         stmt.addBatch();

         // Create an int[] to hold returned values
         int[] count = stmt.executeBatch();

         //Explicitly commit statements to apply changes
         conn.commit();

         rs = stmt.executeQuery("Select * from Employees");
         printResultSet(rs);

         stmt.close();
         rs.close();

      } catch (SQLException e) {
         e.printStackTrace();
      }
   }
}

现在让我们如下编译上述示例：

Now let us compile the above example as follows −

C:\>javac TestApplication.java
C:\>

运行 TestApplication 时，它会生成以下结果：

When you run TestApplication, it produces the following result −

C:\>java TestApplication
ID: 1, Age: 23, First: Zara, Last: Ali
ID: 2, Age: 30, First: Mahnaz, Last: Fatma
ID: 3, Age: 35, First: Zaid, Last: Khan
ID: 4, Age: 33, First: Sumit, Last: Mittal
ID: 5, Age: 40, First: John, Last: Paul
ID: 7, Age: 35, First: Sita, Last: Singh
ID: 8, Age: 20, First: Rita, Last: Tez
ID: 9, Age: 20, First: Sita, Last: Singh
ID: 10, Age: 30, First: Zia, Last: Ali
ID: 11, Age: 35, First: Raj, Last: Kumar

ID: 1, Age: 23, First: Zara, Last: Ali
ID: 2, Age: 30, First: Mahnaz, Last: Fatma
ID: 3, Age: 35, First: Zaid, Last: Khan
ID: 4, Age: 33, First: Sumit, Last: Mittal
ID: 5, Age: 40, First: John, Last: Paul
ID: 7, Age: 35, First: Sita, Last: Singh
ID: 8, Age: 20, First: Rita, Last: Tez
ID: 9, Age: 20, First: Sita, Last: Singh
ID: 10, Age: 30, First: Zia, Last: Ali
ID: 11, Age: 35, First: Raj, Last: Kumar
ID: 12, Age: 33, First: Pappu, Last: Singh
ID: 13, Age: 31, First: Pawan, Last: Singh
C:\>