clientprovider.java

来自「Java编程精选集锦[科学出版社][2003]配套源码」· Java 代码 · 共 70 行

/**
 * Title:        JAVA对象系列化在数据库中的应用<p>
 * Description:  <p>
 * Copyright:    Copyright (c) love<p>
 * Company:      hqu<p>
 * @author love
 * @version 1.0
 */
package dbapplet;

import java.io.*;
import java.net.*;
import com.borland.dx.dataset.*;
import com.borland.dx.sql.dataset.*;

/**
*通过URL调用Servlet对象，建立流连接,
* 传递客户参数，启动doPost方法
*/
public class ClientProvider extends Provider {
  URLConnection servletcon;
  private ObjectInputStream inputFromServlet;
  public ClientProvider(String queryText) {
    String where = "http://localhost:8080/servlet/dbapplet.DBServlet";
    try{
      URL servleturl = new URL(where);
      servletcon = servleturl.openConnection();
      servletcon.setDoInput(true);
      servletcon.setDoOutput(true);
      servletcon.setUseCaches(false);
      servletcon.setDefaultUseCaches(false);
      servletcon.setAllowUserInteraction(false);

      PrintStream sqlToServlet = new PrintStream(servletcon.getOutputStream());
      sqlToServlet.println(queryText);

      sqlToServlet.flush();
      sqlToServlet.close();

    }
    catch(Exception ex){
      System.out.println(ex.getMessage());
    }
  }
/**
 * 接收Servlet传送来的数据对象，反系列化后提供给DBApplet的tableDataSet1
 */
  public void provideData(StorageDataSet dataSet, boolean toOpen) throws com.borland.dx.dataset.DataSetException {
     //TODO: implement this com.borland.dx.dataset.Provider abstract method
    try{
      inputFromServlet = new ObjectInputStream(servletcon.getInputStream());
      System.out.println("clientprovider1");

      DataSetData data = (DataSetData)inputFromServlet.readObject();
      dataSet.empty();
      data.loadDataSet(dataSet);
      inputFromServlet.close();
    }
    catch(ClassNotFoundException ex){
      System.out.println(ex.getMessage());
    }
    catch(IOException ex){
      System.out.println(ex.getMessage());
    }
    catch (DataSetException ex){
      System.out.println(ex.getMessage());
    }
  }
}