JDBC操作（总结）

1.在项目中新建文件夹config（配置），在其中新建配置文件db.properties

driverName = oracle.jdbc.driver.OracleDriver
url = jdbc:oracle:thin:@localhost:1521:orcl
username = scott
password = tiger

2.创建dbutil（数据库工具类）

（1）静态创建特性对象

static Properties properties = new Properties();

（2）在静态代码块中用特性对象读取相应的配置文件，并配置所需要的数据库类

static{
        try {
            //加载数据库配置文件
            properties.load(new FileInputStream("config/db.properties"));

            //2.载入JDBC驱动程序
            Class.forName(properties.getProperty("driverName"));//驱动描述符 ,不能自定义   oracle.jdbc.driver.OracleDriver
            
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

（3）创建静态方法getConnection，用以得到数据库连接

public static Connection getConnection()
    {
            Connection conn = null;
            try {
                
                //3.定义连接URL
                String url = properties.getProperty("url");// 格式：jdbc:oracle:thin:@<主机名或IP>:1521:<数据库名>
                
                //4.建立连接
                conn = DriverManager.getConnection(url, properties.getProperty("username"), properties.getProperty("password"));
                
            } catch (SQLException e) {
                e.printStackTrace();
            }
            
            return conn;
    }

（4）创建静态方法close，用以关闭所用到的资源

public static void close(ResultSet rs,Statement stat,Connection conn)
    {
         //8.关闭连接(ResultSet,Statement,Connection)
         try {
                if(rs != null)
                {
                    rs.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
         try {
                if(stat != null)
                {
                    stat.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
         try {
                if(conn != null)
                {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
    }

3.编写与数据库结构相同的类

public class Emp {
      private int empno;
      private String ename;
      private String job;
      private int mgr;
      private Date hiredate;
      private double salary;
      private double comm;
      private int deptno;
      
      public  Emp()
      {
          
      }
      
    public Emp(int empno, String ename, String job, int mgr, Date hiredate,
            double salary, double comm, int deptno) {
        super();
        this.empno = empno;
        this.ename = ename;
        this.job = job;
        this.mgr = mgr;
        this.hiredate = hiredate;
        this.salary = salary;
        this.comm = comm;
        this.deptno = deptno;
    }

    public int getEmpno() {
        return empno;
    }
    public void setEmpno(int empno) {
        this.empno = empno;
    }
    public String getEname() {
        return ename;
    }
    public void setEname(String ename) {
        this.ename = ename;
    }
    public String getJob() {
        return job;
    }
    public void setJob(String job) {
        this.job = job;
    }
    public int getMgr() {
        return mgr;
    }
    public void setMgr(int mgr) {
        this.mgr = mgr;
    }
    public Date getHiredate() {
        return hiredate;
    }
    public void setHiredate(Date hiredate) {
        this.hiredate = hiredate;
    }
    public double getSalary() {
        return salary;
    }
    public void setSalary(double salary) {
        this.salary = salary;
    }
    public double getComm() {
        return comm;
    }
    public void setComm(double comm) {
        this.comm = comm;
    }
    public int getDeptno() {
        return deptno;
    }
    public void setDeptno(int deptno) {
        this.deptno = deptno;
    }
    @Override
    public String toString() {
        return "Emp [empno=" + empno + ", ename=" + ename + ", job=" + job
                + ", mgr=" + mgr + ", hiredate=" + hiredate + ", salary="
                + salary + ", comm=" + comm + ", deptno=" + deptno + "]";
    }
}

4.编写dao类，用以与数据库进行交互

（1）得到所有对象的方法

public List<Emp> getEmp()
          {
                try {
                    //2~4 获取数据库连接
                    conn = DBUtil.getConnection();

                    //5.创建PreparedStatement对象
                    stat = conn.prepareStatement("select * from emp e"); 

                    //6.执行查询或更新
                    rs = stat.executeQuery();
                    
                    //7.结果处理
                    List<Emp> emps = new ArrayList<Emp>();
                    while(rs.next())
                    {
                            Emp emp = new Emp();
                            
                            emp.setEmpno( rs.getInt("empno"));
                            emp.setEname(rs.getString("ename"));
                            emp.setSalary(rs.getDouble("sal"));
                            //.......此处省略N个字段
                            
                            //添加到集合
                            emps.add(emp);
                    }
                    return emps;
                } catch (SQLException e) {
                    e.printStackTrace();
                }finally{
                     //8.关闭连接(ResultSet,Statement,Connection)
                    DBUtil.close(null, stat, conn);
                }
                return null; 
          }

（2）插入数据的方法

public boolean insertEmp(Emp  emp)
          {
              try {
                    //2~4 获取数据库连接
                    conn = DBUtil.getConnection();

                    //5.创建PreparedStatement对象
                    stat = conn.prepareStatement("insert into emp (empno, ename) values (?, ?)"); 
                    //5.1绑定变量
                    stat.setInt(1, emp.getEmpno());
                    stat.setString(2, emp.getEname());

                    //6.执行更新
                    int result = stat.executeUpdate();
                    
                    //7.结果处理
                    if(result > 0)
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }catch (SQLException e) {
                    e.printStackTrace();
                }finally{
                     //8.关闭连接(ResultSet,Statement,Connection)
                    DBUtil.close(rs, stat, conn);
                }
              return false;
          }

（3）改变数据的方法

public boolean updateEmp(Emp  emp)
          {
              try {
                    //2~4 获取数据库连接
                    conn = DBUtil.getConnection();

                    //5.创建PreparedStatement对象
                    stat = conn.prepareStatement("update emp set ename= ? where empno = ?"); 
                    //5.1绑定变量
                    stat.setString(1, emp.getEname());
                    stat.setInt(2, emp.getEmpno());

                    //6.执行更新
                    int result = stat.executeUpdate();
                    
                    //7.结果处理
                    if(result > 0)
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }catch (SQLException e) {
                    e.printStackTrace();
                }finally{
                     //8.关闭连接(ResultSet,Statement,Connection)
                      DBUtil.close(null, stat, conn);
                }
              return false;
          }

（4）删除数据的方法

public boolean deleteEmp(int empno)
          {
              try {
                    //2~4 获取数据库连接
                    conn = DBUtil.getConnection();

                    //5.创建PreparedStatement对象
                    stat = conn.prepareStatement("delete from emp where empno = ? "); 
                    //5.1绑定变量
                    stat.setInt(1, empno);

                    //6.执行更新
                    int result = stat.executeUpdate();
                    
                    //7.结果处理
                    if(result > 0)
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }finally{
                     //8.关闭连接(ResultSet,Statement,Connection)
                     DBUtil.close(null, stat, conn);
                }
              return false;
          }

完成

注意：

1.获取申请时，一般获取的是prepareStatement，这样不会产生sql注入的危险（直接statement）