Java Database Development (3) - Supplement

1. SQL injection and prevention

Use PreparedStatement instead of Statement object, which provides a way to parameterize SQL

2. Affairs

definition

Transaction is the basic unit of concurrency control and satisfies ACID characteristics

• Atomicity: atomicity
• Consistency: consistency
• Isolation: isolation

• Persistence: durability

  transaction control

  Connection

  • .setAutoCommit() : start a transaction
  • .commit() : commit the transaction
  • .rollback() : rollback the transaction
  • .setSavepoint() : set a breakpoint

  3. Cursor

  The cursor provides a mechanism for the client to read part of the server-side result set. Use useCursorFetch=true to open the setFetchSize() method of the PreparedStatement interface to set the number of reads.

  Four, stream read

  Read large objects (large fields) in binary stream mode

  while (rs.next()) {
  //获取对象流
  InputStream in = rs.getBinaryStream("blog");
  //将对象流写入文件
  File f = new File(FILE_URL);
  OutputStream out = null;
  out = new FileOutputStream(f);
  int temp = 0;
  while ((temp = in.read()) != -1){
      //边读边写
      out.write(temp);
  }
  in.close();
  out.close();
  }

  5. Batch processing