Seven Steps of JDBC Connection database code in Java development

JDBC (Java Data Base Connectivity) is a Java API for executing SQL statements that can provide unified access to a variety of relational databases It consists of a set of classes and interfaces written in the Java language.

JDBC is an interface model for Java programmers that are APIs for service providers that implement database connections. As a APIJDBC provides a standard interface for program development.

JDBC Connection Database

Creating a program that connects to a database in JDBC contains seven steps

2. Loading the JDBC Driver

   Before connecting to the database, you first load the driver of the database you want to connect to the Jvmjava virtual machine, which is implemented by the static method forname (String className) of the Java.lang.Class class.

   For example

   try{

   Class.forName ("Com.mysql.jdbc.Driver");

   }catch (ClassNotFoundException e) {

   System.out.println ("Failed to find driver class load driver");

   E.printstacktrace ();

   }

   After a successful load, an instance of the driver class is registered to the Drivermanger class.

4. Provide a URL for the JDBC connection

   The connection URL defines the protocol sub-Protocol data source identity when the database is connected.

   Written form protocol: sub-Protocol: Data source identification

   The protocol always starts with JDBC in JDBC

   The sub-protocol is the driver of the bridge connection or the name of the database management system

   The data source identification token locates the address of the database source and the connection port.

   For example, the connection URL for MySQL

   jdbc:mysql://localhost:3306/test?useunicode=true&characterencoding=gdk;

   Where Useunicode=true: Indicates the use of the Unicode character set. This parameter must be set to True if Characterencoding is set to gb2312 or GBK. CHARACTERENCODING=GBK: The character encoding method.

6. Create a database connection

   To connect to a database you want to request to Java.sql.DriverManager and get the Connection object This object represents a connection to a database.

   Use the DriverManager getconnection (string URL, string username, string password) method to obtain the user name and password for the path database of the specified database to connect to.

   For example

   String url = "Jdbc:mysql://localhost:3306/test";

   String username = "root";

   String password = "root";

   try{

   Connection con = drivermanager.getconnection (URL, username, password);

   }catch (SQLException e) {

   SYSTEM.OUT.PRINTLN ("Database connection failed");

   E.printstacktrace ();

   }

8. Create a statement

   To execute an SQL statement you must obtain the Java.sql.Statement instance statement instance into the following 3 types

   1. Execute the static SQL statement. Typically implemented through statement instances.

   2. Execute the dynamic SQL statement. Typically implemented through PreparedStatement instances.

   3. Execute the database stored procedure. Typically implemented through CallableStatement instances.

   Specific implementation methods

   Statement stmt = Con.createstatement ();

   PreparedStatement pstmt = con.preparestatement (sql);

   CallableStatement Cstmt=con.preparecall ("{Call DEMOSP (?,?)}";

10. Execute SQL statement

    The statement interface provides three ways to execute SQL statements executequery, executeupdate, and execute

    1. ResultSet executeQuery (String sqlString): The SQL statement that executes the query database returns a result set Resutltset object.

    2. int executeupdate (String sqlString): Used to perform INSERT, UPDATE or DELETE statements, and SQL DDL statements such as CREATE table and drop table.

    3. Execute (sqlString): Used to perform statements that return multiple update counts or combinations of multiple result sets.

    Implementation-specific code

    ResultSet rs = stmt.executequery ("SELECT * from ...");

    int rows = Stmt.executeupdate ("INSERT into ...");

    Boolean flag = Stmt.execute (String sql);

12. Processing results

    Two cases

    1. The update is performed to return the number of records affected by this operation.

    2. The result returned by the execution query is a ResultSet object.

    ResultSet contains all rows that conform to the conditions in the SQL statement and it provides access to the data in those rows through a set of Get methods.

    Fetching data using the result set ResultSet object access method

    while (Rs.next ()) {

    String name=rs.getstring ("name");

    String pass=rs.getstring ("1");

    }//Columns are numbered from left to right and start with column 1

14. Close the JDBC Object

    After the operation is complete, all the JDBC objects used are closed to release the JDBC resource close order and the declaration order is reversed

    1. Closing a recordset

    2. Closing the statement

    3. Close the Connection object

    if (rs!=null) {//close record set

    try{

Rs.close ();

}catch (SQLException e) {

E.printstacktrace ();

}

}

if (stmt! = null) {//Close declaration

try{

Stmt.close ();

}catch (SQLException e) {

E.printstacktrace ();

}

}

if (conn!=null) {//Close Connection object

try{

Conn.close ();

}catch (SQLException e) {

E.printstacktrace ();

}

}

Actual combat

Step1. Create a MAVEN project.

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Seven Steps of JDBC Connection database code in Java development