Configuration

Install and configure database

Database type: MySQL
Host: localhost
Port: 3306
Database: hello_spring
Login: root
Password: root

Configure MySQL Driver

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.22</version>
</dependency>

Configure Datasource in Spring

For development purposes:

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/hello_spring"/>
    <property name="username" value="root"/>
    <property name="password" value="root"/>
</bean>

For more datasources possibilities check: Datasources

Example Model

Java model

public class Employee {
 
    private int id;
    private String name;
    private String role;
     
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getRole() {
        return role;
    }
    public void setRole(String role) {
        this.role = role;
    }
     
    @Override
    public String toString(){
        return "{ID="+id+",Name="+name+",Role="+role+"}";
    }
}

Database schema

CREATE TABLE `Employee` (
  `id` int(11) unsigned NOT NULL,
  `name` varchar(20) DEFAULT NULL,
  `role` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Pure JDBC

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
 
import javax.sql.DataSource;
 
public class EmployeeDAOImpl {
 
    private DataSource dataSource;

     public Employee getById(int id) {
         String query = "select name, role from Employee where id = ?";
         Employee emp = null;
         Connection con = null;
         PreparedStatement ps = null;
         ResultSet rs = null;
         try{
             con = dataSource.getConnection();
             ps = con.prepareStatement(query);
             ps.setInt(1, id);
             rs = ps.executeQuery();
             if(rs.next()){
                 emp = new Employee();
                 emp.setId(id);
                 emp.setName(rs.getString("name"));
                 emp.setRole(rs.getString("role"));
                 System.out.println("Employee Found::"+emp);
             }else{
                 System.out.println("No Employee found with id="+id);
             }
         }catch(SQLException e){
             e.printStackTrace();
         }finally{
             try {
                 rs.close();
                 ps.close();
                 con.close();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
         return emp;
     }

    public List<Employee> getAll() {
        String query = "select id, name, role from Employee";
        List<Employee> empList = new ArrayList<Employee>();
        Connection con = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try{
            con = dataSource.getConnection();
            ps = con.prepareStatement(query);
            rs = ps.executeQuery();
            while(rs.next()){
                Employee emp = new Employee();
                emp.setId(rs.getInt("id"));
                emp.setName(rs.getString("name"));
                emp.setRole(rs.getString("role"));
                empList.add(emp);
            }
        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            try {
                rs.close();
                ps.close();
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return empList;
    }

    public void create(Employee employee) {
        String query = "insert into Employee (id, name, role) values (?,?,?)";
        Connection con = null;
        PreparedStatement ps = null;
        try{
            con = dataSource.getConnection();
            ps = con.prepareStatement(query);
            ps.setInt(1, employee.getId());
            ps.setString(2, employee.getName());
            ps.setString(3, employee.getRole());
            int out = ps.executeUpdate();
            if(out !=0){
                System.out.println("Employee saved with id="+employee.getId());
            }else System.out.println("Employee save failed with id="+employee.getId());
        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            try {
                ps.close();
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    } 
 
    public void update(Employee employee) {
        String query = "update Employee set name=?, role=? where id=?";
        Connection con = null;
        PreparedStatement ps = null;
        try{
            con = dataSource.getConnection();
            ps = con.prepareStatement(query);
            ps.setString(1, employee.getName());
            ps.setString(2, employee.getRole());
            ps.setInt(3, employee.getId());
            int out = ps.executeUpdate();
            if(out !=0){
                System.out.println("Employee updated with id="+employee.getId());
            }else System.out.println("No Employee found with id="+employee.getId());
        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            try {
                ps.close();
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
 
    public void deleteById(int id) {
        String query = "delete from Employee where id=?";
        Connection con = null;
        PreparedStatement ps = null;
        try{
            con = dataSource.getConnection();
            ps = con.prepareStatement(query);
            ps.setInt(1, id);
            int out = ps.executeUpdate();
            if(out !=0){
                System.out.println("Employee deleted with id="+id);
            }else System.out.println("No Employee found with id="+id);
        }catch(SQLException e){
            e.printStackTrace();
        }finally{
            try {
                ps.close();
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
 
}

JDBC templates

What is it for?

Simplify DB access by removing boilerplate code and introduce higher level of abstraction. Thanks to JDBC templates we can focus on business value.

Action	Spring	You
Define connection parameters.		X
Open the connection.	X
Specify the SQL statement.		X
Declare parameters and provide parameter values		X
Prepare and execute the statement.	X
Set up the loop to iterate through the results (if any).	X
Do the work for each iteration.		X
Process any exception.	X
Handle transactions.	X
Close the connection, statement and resultset.	X

Dependencies

Add Spring dependencies in pom.xml :

<properties>
    ...
    <spring-jdbc.version>3.1.3.RELEASE</spring-jdbc.version>
</properties>

<dependencies>
    ...
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>${spring-jdbc.version}</version>
    </dependency>
</dependencies>

Logging

Dependency for Log4j:

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

Configuration for logging to console + JdbcTemplate in log4j.properties:

# Root logger option
log4j.rootLogger=INFO, stdout

# Direct log messages to stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

log4j.logger.org.springframework.jdbc.core = TRACE

DAO

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
 
import javax.sql.DataSource;
 
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
 
public class EmployeeDAOJDBCTemplateImpl {
 
    private DataSource dataSource;
 
    public Employee getById(int id) {
        String query = "select id, name, role from Employee where id = ?";
        JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
         
        Employee emp = jdbcTemplate.queryForObject(query, new Object[]{id}, new RowMapper<Employee>(){
 
            @Override
            public Employee mapRow(ResultSet rs, int rowNum)
                    throws SQLException {
                Employee emp = new Employee();
                emp.setId(rs.getInt("id"));
                emp.setName(rs.getString("name"));
                emp.setRole(rs.getString("role"));
                return emp;
            }});
         
        return emp;
    }
 
    public List<Employee> getAll() {
        String query = "select id, name, role from Employee";
        JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
        List<Employee> empList = new ArrayList<Employee>();
  
        List<Map<String,Object>> empRows = jdbcTemplate.queryForList(query);
         
        for(Map<String,Object> empRow : empRows){
            Employee emp = new Employee();
            emp.setId(Integer.parseInt(String.valueOf(empRow.get("id"))));
            emp.setName(String.valueOf(empRow.get("name")));
            emp.setRole(String.valueOf(empRow.get("role")));
            empList.add(emp);
        }
        return empList;
    }
 
    public void create(Employee employee) {
        String query = "insert into Employee (id, name, role) values (?,?,?)";
         
        JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
         
        Object[] args = new Object[] {employee.getId(), employee.getName(), employee.getRole()};
         
        int out = jdbcTemplate.update(query, args);
         
        if(out !=0){
            System.out.println("Employee saved with id="+employee.getId());
        }else System.out.println("Employee save failed with id="+employee.getId());
    }
 
    public void update(Employee employee) {
        String query = "update Employee set name=?, role=? where id=?";
        JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
        Object[] args = new Object[] {employee.getName(), employee.getRole(), employee.getId()};
         
        int out = jdbcTemplate.update(query, args);
        if(out !=0){
            System.out.println("Employee updated with id="+employee.getId());
        }else System.out.println("No Employee found with id="+employee.getId());
    }
 
    public void deleteById(int id) {
        String query = "delete from Employee where id=?";
        JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
         
        int out = jdbcTemplate.update(query, id);
        if(out !=0){
            System.out.println("Employee deleted with id="+id);
        }else System.out.println("No Employee found with id="+id);
    }
  
}