JSP, JavaBean, Mysql connection method

JSP, JavaBean, Mysql connection method

Use JSP to implement the connection of Web and databases:

(1). Complete environment settings, import java.sql package, command as follows: import java.sql. *

(2). Load driver

(3). Connect to the database

(4). Statement interface

(5). Get result set

1. Test environment:

WINDOWS 2003

J2SDK1.4.2_06

Tomcat 5.0

Mysql-4.0.23-win

mm.mysql-2.0.4-bin.jar

2. Establish a database and table

Built a publish database in MySQL and build a BOOK table. Add ID, Title, Price to Book

3. JavaBean code: dbconn.java

package Border; import java.sql *;. // complete environment setting, introducing the package java.sql public class dbconn {public dbconn () {} // declare variable private Connection conn = null; private ResultSet rs = null; private String server = "127.0.0.1"; // can't use localhost, you must use ip or cname private string port = "3306"; // change to your port private string db = "publish"; // change to your db name private String user = "root"; // change to your username private String pass = "root"; // change to your password private String drivername = "org.gjt.mm.mysql.Driver"; // mysql driver private String URL = "JDBC: MySQL: //" Server ":" Port "/" DB "User " & Password = " Pass;

Public connection getConn () {// get database connections Try {class.Forname (DRIVERNAME) .newinstance (); // Load Drive Conn = DriverManager.getConnection (URL); // Connect to Database} Catch (Exception E) { E.PrintStackTrace ();} Return CONN;

Public ResultSet ExecuteSQL (String Str) {Try {Stmt = Conn.createStatement (); // Statement Interface RS = Stmt.executeQuery (STR); // Get Result Set} Catch (Exception E) {E.PrintStackTrace (); } RETURN RS;}}

Compile Javac dbconn.java, put the compiled file dbconn.class to the directory "Your Project" / Web-INF / CLASSES / BORDER / 9. Test. JSP file Test.jsp of Java Bean

<% @ Page ContentType = "text / html; charset = GBK" import = "java.sql. *"%>

<% results = null; connection conn = null; conn = border.GetConn (); = border.executesql (" Select * from book ");%>

ID Title Price <% while (rs.next ()) {%> <% = Rs.getstring ("ID")%> <% = rs.getstring ("title")%> <% = rs.getstring ("Price) ")%> <%}%> <% rs.close (); conn.close ();%>

price:
	5. Update.jsp Write to the Database <% @ Page ContentType = "Text / HTML; Charset = GBK" Import = "Java.SQL. *"%> <% Request.setCharacterencoding ("GBK");%> <% Connection conn = null; conn = border.getConn (); String title ("title"); string prc = request.getParameter ("price"); statement stmt = conn.createstatement (); stmt.executeUpdate ("Insert Into Book (Title, Price) VALUES ('" TIT "','" PRC ")");%> 6. Provide several functions: (1). GetConnectionpublic static Connection getConnection (String url, String user, String password) throws SQLExceptionAttempts to establish a connection to the given database URL. The DriverManager attempts to select an appropriate driver from the set of registered JDBC drivers. Parameters: url - a database url of the form jdbc: subprotocol: subnameuser - the database user on whose behalf the connection is being madepassword - the user's password Returns: a connection to the URL Throws: SQLException - if a database access error occurs (2). CreateStatementpublic Statement createStatement () throws SQLExceptionCreates a Statement object for sending SQL statements to the database. SQL statements without parameters are normally executed using Statement objects. If the same SQL statement is executed many times, it may be more efficient to use . a PreparedStatement object Result sets created using the returned Statement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.Returns: a new default Statement object Throws: SQLException - if a database access error occurs (3). ExecuteQueryPublic ResultSet ExecuteQuery (String SQL) THROWS SQLEXCEPTIONEXECUTES The Given SQL Statement, Which Returns A Single ResultSet Object. Parameters: sql - an SQL statement to be sent to the database, typically a static SQL SELECT statement Returns: a ResultSet object that contains the data produced by the given query; never null Throws: SQLException - if a database access error occurs or the given SQL Statement Product PROduces Anything Other Than A Single ResultSet Object (4). GetStringpublic String getString (String columnName) throws SQLExceptionRetrieves the value of the designated column in the current row of this ResultSet object as a String in the Java programming language. Parameters: Columnname - The Sql Name of The Column Returns: The Column Value; if The Value Is Sql Null, The Value Returned Is Null Throws: SQLEXCEPTION - IF A DATABASE Access Error Occurs .. (5) nextpublic boolean next () throws SQLExceptionMoves the cursor down one row from its current position A ResultSet cursor is initially positioned before the first row; the first call to the method next makes the first row the current row; the second call . makes the second row the current row, and so on If an input stream is open for the current row, a call to the method next will implicitly close it A ResultSet object's warning chain is cleared when a new row is read.Returns.: True If the New Current Row Is Valid; False IF There No More Rows Throws: Sqlexception - IF A Database Access Error Occurs 7. OK! Now Game Is over ~~ 8. If you feel satisfied, or would like to reprint this article collections, I am very grateful, but please indicate the author: border (border@hacker.cn) http://blog.9cbs.net/border1985 Finally, please visit - China Safety Information Network - http://www.hacker.cn/ 转载请注明原文地址:https://www.9cbs.com/read-45595.html 9cbs New Post(0)