[Java] bbs 中帖子的树状展现 JDBC （ArticleTree.java)

import java.sql.*;

public class ArticleTree {
public static void main(String[] args) {
new ArticleTree().show();
}

public void show() {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");

conn = DriverManager
.getConnection("jdbc:mysql://localhost/bbs?user=root&password=root");
stmt = conn.createStatement();
rs = stmt.executeQuery("select * from article where pid = 0");
while (rs.next()) {
System.out.println(rs.getString("cont"));
tree(conn, rs.getInt("id"), 1);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (rs != null) {
rs.close();
rs = null;
}
if (stmt != null) {
stmt.close();
stmt = null;
}
if (conn != null) {
conn.close();
conn = null;
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}

private void tree(Connection conn, int id, int level) {
Statement stmt = null;
ResultSet rs = null;

StringBuffer strPre = new StringBuffer("");
for (int i = 0; i < level; i++) {
strPre.append("★★★★");
}

try {
stmt = conn.createStatement();
String sql = "select * from article where pid = " + id;
rs = stmt.executeQuery(sql);
while (rs.next()) {
System.out.println(strPre + rs.getString("cont"));
if (rs.getInt("isleaf") != 0)
tree(conn, rs.getInt("id"), level + 1);
}

} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (rs != null) {
rs.close();
rs = null;
}
if (stmt != null) {
stmt.close();
stmt = null;
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}