A simple blog system instance based on Jsp+servlet (source code) _jsp programming

The example in this article describes a simple blog system based on jsp + servlet. Share to everyone for your reference. details as follows:

There are no small blogs written with frameworks, and the code is heavily repeated.

I personally feel that duplicate code is good for novices, and I am also a novice, forgive me.

Click here to download the complete example code.

Servlet

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package Servlet;
import blog.BlogBean;
import blog.BlogRepositoryJDBC;
import blog.PagerUtil;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import java.util.List;
import javax.enterprise.context.RequestScoped;
import javax.enterprise.context.SessionScoped;
import javax.inject.Inject;
import javax.inject.Named;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet (name = "PageListServlet", urlPatterns = {"/ page / *", ""})
public class ListAllServlet extends HttpServlet {
  @Inject
  private BlogRepositoryJDBC blogdao;
  @Inject
  private PagerUtil pagerUtil;
  protected void processRequest (HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    int pg;
    String s = request.getRequestURI ();
    String searchContent = request.getParameter ("search");
    if (s.matches (request.getContextPath () + "/ page /" + "\\ d")) {
      String pgnum = s.replaceAll (request.getContextPath () + "/ page /", "");
      pg = Integer.parseInt (pgnum);
    } else if (s.matches (request.getContextPath () + "/")) {
      pg = 1;
    } else {
      getServletContext (). getRequestDispatcher ("/ errorpage.jsp"). forward (request, response);
      return;
    }
    List <BlogBean> bloglist;
    boolean isNullRequest = (searchContent == null || "" .equals (searchContent));
    if (isNullRequest) {
      bloglist = blogdao.getBloglist ();
    } else {
      bloglist = blogdao.listBlogByKey (searchContent);
    }
    if (! pagerUtil.isValidPg (bloglist, pg)) {
      getServletContext (). getRequestDispatcher ("/ errorpage.jsp"). forward (request, response);
      return;
    }
    pagerUtil.fillValue (bloglist, pg);
    String pageURLBase = getServletContext (). GetContextPath ();
    String pageURLparam = isNullRequest? "": "? Search =" + searchContent;
    request.setAttribute ("pageURLBase", pageURLBase);
    request.setAttribute ("pageURLparam", pageURLparam);
    request.setAttribute ("bloglist", bloglist);
    getServletContext (). getRequestDispatcher ("/ blog.jsp"). forward (request, response);
  }
  @Override
  protected void doGet (HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    processRequest (request, response);
  }
  @Override
  protected void doPost (HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    processRequest (request, response);
  }
  @Override
  public String getServletInfo () {
    return "Short description";
  } // </ editor-fold>
}

2.dao

package blog;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.inject.Named;
import javax.sql.DataSource;
@ApplicationScoped
@Named
public class BlogRepositoryJDBC implements BlogRepository {
  @Resource (lookup = "jdbc / sample")
  private DataSource ds;
  private ArrayList <BlogBean> bloglist;
  private Set <String> tagSet;
  private Set <String> categorySet;
  private Map <String, Integer> dateMap;
  @PostConstruct
  private void init () {
    refreshCache ();
  }
  @Override
  public int addBlog (BlogBean blogi) {
    String sql = "INSERT INTO POSTS VALUES (?,?,?,?,?)";
    Connection conn = null;
    PreparedStatement ps = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, blogi.getBlogTitle ());
      ps.setString (2, blogi.getCategory ());
      ps.setString (3, blogi.getTag ());
      ps.setDate (4, new java.sql.Date (blogi.getPostDate (). getTime ()));
      ps.setString (5, blogi.getContent ());
      out = ps.executeUpdate ();
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, null);
    }
    refreshCache ();
    return out;
  }
  @Override
  public int deleteBlog (String blogName) {
    String sql = "DELETE FROM POSTS WHERE HEAD =?";
    Connection conn = null;
    PreparedStatement ps = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, blogName);
      out = ps.executeUpdate ();
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, null);
    }
    refreshCache ();
    return out;
  }
  @Override
  public int updateBlog (BlogBean blog, String oldhead) {
    String sql = "UPDATE POSTS SET HEAD = ?, CATEGORY = ?, TAG = ?, POSTDATE = ?, CONTENT =? WHERE HEAD =?";
    PreparedStatement ps = null;
    Connection conn = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, blog.getBlogTitle ());
      ps.setString (2, blog.getCategory ());
      ps.setString (3, blog.getTag ());
      ps.setDate (4, new java.sql.Date (blog.getPostDate (). getTime ()));
      ps.setString (5, blog.getContent ());
      ps.setString (6, oldhead);
      out = ps.executeUpdate ();
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, null);
    }
    refreshCache ();
    return out;
  }
  @Override
  public List <BlogBean> ListAllBlog () {
    bloglist = new ArrayList <BlogBean> ();
    BlogBean blog;
    String sql = "SELECT * FROM POSTS ORDER BY POSTDATE DESC";
    Connection conn = null;
    Statement ss = null;
    ResultSet rs = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ss = conn.createStatement ();
      rs = ss.executeQuery (sql);
      while (rs.next ()) {
        blog = new BlogBean ();
        blog.setBlogTitle (rs.getString (1));
        blog.setCategory (rs.getString (2));
        blog.setTag (rs.getString (3));
        blog.setPostDate (rs.getDate (4));
        blog.setContent (rs.getString (5));
        bloglist.add (blog);
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ss, rs);
    }
    return bloglist;
  }
  @Override
  public List listBlogByKey (String keyword) {
    List <BlogBean> list = new ArrayList <BlogBean> ();
    BlogBean blog;
    String sql = "SELECT * FROM POSTS WHERE HEAD LIKE? ORDER BY POSTDATE DESC";
    Connection conn = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, "%" + keyword + "%");
      rs = ps.executeQuery ();
      while (rs.next ()) {
        blog = new BlogBean ();
        blog.setBlogTitle (rs.getString (1));
        blog.setCategory (rs.getString (2));
        blog.setTag (rs.getString (3));
        blog.setPostDate (rs.getDate (4));
        blog.setContent (rs.getString (5));
        list.add (blog);
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, rs);
    }
    return list;
  }
  @Override
  public List listBlogByContent (String keyword) {
    List <BlogBean> list = new ArrayList <BlogBean> ();
    BlogBean blog;
    String sql = "SELECT * FROM POSTS WHERE CONTENT LIKE? ORDER BY POSTDATE DESC";
    PreparedStatement ps = null;
    ResultSet rs = null;
    Connection conn = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, "%" + keyword + "%");
      rs = ps.executeQuery ();
      while (rs.next ()) {
        blog = new BlogBean ();
        blog.setBlogTitle (rs.getString (1));
        blog.setCategory (rs.getString (2));
        blog.setTag (rs.getString (3));
        blog.setPostDate (rs.getDate (4));
        blog.setContent (rs.getString (5));
        list.add (blog);
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, rs);
    }
    return list;
  }
  public Set listAllTags () {
    tagSet = new HashSet <String> ();
    String sql = "SELECT TAG FROM POSTS";
    Connection conn = null;
    Statement ss = null;
    ResultSet rs = null;
    try {
      conn = ds.getConnection ();
      ss = conn.createStatement ();
      rs = ss.executeQuery (sql);
      while (rs.next ()) {
        String tags = rs.getString (1);
        String [] Arraytags = tags.split (",");
        tagSet.addAll (Arrays.asList (Arraytags));
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ss, rs);
    }
    return tagSet;
  }
  public List listBlogByTag (String keyword) {
    List <BlogBean> list = new ArrayList <BlogBean> ();
    BlogBean blog;
    String sql = "SELECT * FROM POSTS WHERE TAG LIKE? ORDER BY POSTDATE DESC";
    Connection conn = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, "%" + keyword + "%");
      rs = ps.executeQuery ();
      while (rs.next ()) {
        blog = new BlogBean ();
        blog.setBlogTitle (rs.getString (1));
        blog.setCategory (rs.getString (2));
        blog.setTag (rs.getString (3));
        blog.setPostDate (rs.getDate (4));
        blog.setContent (rs.getString (5));
        list.add (blog);
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, rs);
    }
    return list;
  }
    public List listBlogByDate (String keyword) {
    List <BlogBean> list = new ArrayList <BlogBean> ();
    BlogBean blog;
    String sql = "SELECT * FROM POSTS WHERE POSTDATE =? ORDER BY POSTDATE DESC";
    Connection conn = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, keyword);
      rs = ps.executeQuery ();
      while (rs.next ()) {
        blog = new BlogBean ();
        blog.setBlogTitle (rs.getString (1));
        blog.setCategory (rs.getString (2));
        blog.setTag (rs.getString (3));
        blog.setPostDate (rs.getDate (4));
        blog.setContent (rs.getString (5));
        list.add (blog);
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, rs);
    }
    return list;
  }
  public Set listAllCategory () {
    categorySet = new HashSet <String> ();
    String sql = "SELECT CATEGORY FROM POSTS";
    Connection conn = null;
    Statement ss = null;
    ResultSet rs = null;
    try {
      conn = ds.getConnection ();
      ss = conn.createStatement ();
      rs = ss.executeQuery (sql);
      while (rs.next ()) {
        String category = rs.getString (1);
        categorySet.add (category);
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ss, rs);
    }
    return categorySet;
  }
  public List listBlogByCategory (String keyword) {
    List <BlogBean> list = new ArrayList <BlogBean> ();
    BlogBean blog;
    String sql = "SELECT * FROM POSTS WHERE CATEGORY LIKE?";
    Connection conn = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    int out = 0;
    try {
      conn = ds.getConnection ();
      ps = conn.prepareStatement (sql);
      ps.setString (1, "%" + keyword + "%");
      rs = ps.executeQuery ();
      while (rs.next ()) {
        blog = new BlogBean ();
        blog.setBlogTitle (rs.getString (1));
        blog.setCategory (rs.getString (2));
        blog.setTag (rs.getString (3));
        blog.setPostDate (rs.getDate (4));
        blog.setContent (rs.getString (5));
        list.add (blog);
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ps, rs);
    }
    return list;
  }
  private void fillDateMap () {
    String sql = "SELECT POSTDATE, COUNT (POSTDATE) FROM POSTS GROUP BY POSTDATE";
     Connection conn = null;
    Statement ss = null;
    ResultSet rs = null;
    dateMap = new HashMap <String, Integer> ();
    try {
      conn = ds.getConnection ();
      ss = conn.createStatement ();
       rs = ss.executeQuery (sql);
      while (rs.next ()) {
        dateMap.put (rs.getString (1), rs.getInt (2));
      }
    } catch (SQLException ex) {
      Logger.getLogger (BlogRepositoryJDBC.class.getName ()). Log (Level.SEVERE, null, ex);
    } finally {
      closeEverything (conn, ss, rs);
    }
  }
  public void test () {
        for (Map.Entry <String, Integer> dd: dateMap.entrySet ()) {
           dd.getKey ();
           dd.getValue ();
        }
  }
  public void refreshCache () {
    ListAllBlog ();
    listAllTags ();
    listAllCategory ();
    fillDateMap ();
  }
  public ArrayList <BlogBean> getBloglist () {
    return bloglist;
  }
  public Set <String> getTagSet () {
    return tagSet;
  }
  public Set <String> getCategorySet () {
    return categorySet;
  }
  public Map <String, Integer> getDateMap () {
    return dateMap;
  }
  private void closeEverything (Connection conn, Statement ps, ResultSet rs) {
    if (rs! = null) {
      try {
        rs.close ();
      } catch (SQLException ex) {
      }
    }
    if (ps! = null) {
      try {
        ps.close ();
      } catch (SQLException ex) {
      }
    }
    if (conn! = null) {
      try {
        conn.close ();
      } catch (SQLException ex) {
      }
    }
  }
}

3. Run effect screenshot:



I hope this article is helpful to everyone's JSP programming.