dbservlet.java

<Java编程精选集锦>随书源码

package dbapplet;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import com.borland.dx.sql.dataset.*;
import com.borland.dx.dataset.*;

public class DBServlet extends HttpServlet {


  //Initialize global variables
  public void init(ServletConfig config) throws ServletException {
    super.init(config);
  }

/**
 * 利用JDBC查询后台数据库，并将数据对象系列化
 * 返回DataSetData对象
 */
  public DataSetData provideAuthorData(String url, String username, String password, String queryText) throws DataSetException {
    Database     db   = new Database();
    QueryDataSet qds  = new QueryDataSet();
    try {
      db.setConnection(new com.borland.dx.sql.dataset.ConnectionDescriptor(url, username, password, false, "sun.jdbc.odbc.JdbcOdbcDriver"));
      qds.setQuery(new com.borland.dx.sql.dataset.QueryDescriptor(db, queryText, null, true, Load.ALL));
      qds.open();
      DataSetData  data = DataSetData.extractDataSet(qds);
      return data;
    }
    finally {
      qds.close();
      db.closeConnection();
    }
  }

  //Process the HTTP Get request
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    PrintWriter out = new PrintWriter (response.getOutputStream());
    response.setContentType("text/html");
    out.println("<FONT COLOR=GREEN>");
    out.println("祝贺你！Servlet已正常启动！");
    out.println("</FONT>");
    out.close();
  }



  //Process the HTTP Post request
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    ObjectOutputStream outputToApplet = new ObjectOutputStream(response.getOutputStream());

    String sql="", odbc="", username="", password="";

    try{
        sql = request.getParameter("sql");
        odbc = request.getParameter("odbc");
        username = request.getParameter("username");
        password = request.getParameter("password");
    }catch(Exception e){
        System.out.println("取参数失败");
    }

    System.out.println(odbc + sql);


    try{
      odbc="jdbc:odbc:" + odbc;
      DataSetData data = provideAuthorData(odbc, username, password, sql);
      outputToApplet.writeObject(data);
      outputToApplet.flush();

    }
    catch (com.borland.dx.dataset.DataSetException ex) {
     System.out.println(ex.getMessage());// new DataSetException(ex.getMessage());
    }
    finally{
      outputToApplet.close();
    }
  }

  public DBServlet() {
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }

  private void jbInit() throws Exception {

  }
}