JDBC连接数据库

public class DBHelper {//定义四个属性: username, password, url, driverclassname
        private static final String USERNAME = "TEST";   //final ,变量不能改,不能重写,不能继承,变量名要大写
        private static final String PASSWORD = "TEST";
        private static final String URL = "jdbc:oracle:thin:@localhost:1521:orcl";
        private static final String DIVERCLASSNAME = "oracle.jdbc.OracleDriver";
       // Connection接口是jdk中定义好的一个数据库连接的接口
      
        public static Connection getConnection () {  //返回型
        	Connection cn = null;  
        	   try {
				Class.forName(DIVERCLASSNAME); //类加载器去加载数据库的驱动程序
				   cn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
				   //DriverManager:驱动程序管理类, 由这个类来获取Connection接口的实例
   //直接调用DriverManager的静态方法getConnection()获取连接
			} catch (ClassNotFoundException e) {
				e.printStackTrace();
			} catch (SQLException e) {
				e.printStackTrace();
			}
        	
        	return cn;
        }
       public static void main(String[] args) {   //目的是用来测试数据库是否引入成功,可以不用来写
			   Connection c = getConnection ();
			   System.out.println(c);
			   destroy(c,null,null);
		}    
        public static void destroy ( Connection c , Statement sm , ResultSet r) { //释放资源 
        	  if (c != null) {
        		  try {
					c.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
        		  c = null;
			}
        	  if (sm != null) {
        		  try {
					sm.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
        		  sm = null;
			}
        	  if (r != null) {
        		  try {
					r.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
        		  r = null;
			}
        }
}

以上是连接数据库

以下是从数据库里取的连接之后进行增.删.改.查的 操作

public class Student {    //将数据库里面的内容分装成一个类,就是一个数据模型
       private  Integer id;
       private String name;
       private String code;
       private Integer sex;
       private  Date birth;
	public Student() {
		super();
	}
	
	public Student(Integer id, String name, String code, Integer sex, Date birth) {
		super();
		this.id = id;
		this.name = name;
		this.code = code;
		this.sex = sex;
		this.birth = birth;
	}

	public Student(String name, String code, Integer sex, Date birth) { //如果ID不用传参数,采取序列生成
		super();
		this.name = name;
		this.code = code;
		this.sex = sex;
		this.birth = birth;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getCode() {
		return code;
	}
	public void setCode(String code) {
		this.code = code;
	}
	public Integer getSex() {
		return sex;
	}
	public void setSex(Integer sex) {
		this.sex = sex;
	}
	public Date getBirth() {
		return birth;
	}
	
	public String  setTime() {  //为了获取日期的格式而构造的方法
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		  return sdf.format(this.birth);
	}
	
	public void setBirth(Date birth) {
		this.birth = birth;
	}
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", code=" + code + ", sex=" + sex + ", birth=" + birth + "]";
	}
	
	
	
       
}

public class DatabaceMethodDal {   //dal结尾的包为一个处理数据的包,test结尾的包为一个测试是否添加进数据的包,
	//until结尾的包为一个工具的包
     private   Connection coon; 
	 private   Statement sm;
	 private  PreparedStatement  ps; 
	 private ResultSet rs;
	//添加一条数据
       public   int  insertstudent () {
    	   init();  //调用那个初始化的方法
    	   String sql = "insert into student st" +
      " values(sq_test.nextval,'张华','stu-1070','1',sysdate,'LAU-100','2')";   //nexttval为序列生成
    	   int num = -1;
    	     try {
				   num = sm.executeUpdate(sql);
			} catch (SQLException e) {
				e.printStackTrace();
			}
			close();
    	     return num;
       }
       //更新数据,用参数来实现,解决SQL注入的问题,防止后面的参数被随意更改
       public int UpdateStudent (Integer id, String name) {
    	     String sql = "update student s set s.birthday = sysdate "
    	     		+ "where s.id = ? and s.name = ?";
    	     init(sql);
    	     int p = -1;
    	     try {
				ps.setInt(1, id);  //占位符索引值, 第几个 ? , 就写几, 从1开始数
				 ps.setString(2, name);
				 p =  ps.executeUpdate(); //用于增删改的语句
			} catch (SQLException e) {
				e.printStackTrace();
			} 
    	     close();//关闭资源
    	     return p;
       }
       //批量处理  添加数据,直接通过Statement来实现的
       public int[]  InsertStudent (List<Student> list) {
    	   int[] num = null; 
    		init();
    	   try {
				for (Student st : list) {
					init();
					
String sql = "insert into student values (sq_test.nextval,'"+st.getName()
+"','"+st.getCode()+"','"+st.getSex()+"',to_date('"+st.setTime()+"','yyyy-mm-dd'))";
						sm.addBatch(sql);   //prepareStatement.addBatch()-->每次处理一条sql语句
					
				}
				 num =  sm.executeBatch(); //返回int[] prepareStatement.executeBatch()-->将一批命令提交给数据库去执行
			} catch (SQLException e) {
				e.printStackTrace();
			}
    	   close();
    	 	return num;
       }
     //批量处理  插入数据,直接通过prepareStatement  
         public int[] InsertStudentByprepare (List<Student> list) {
        	 String sql = "insert into  AppUser  values(sq_test,?,?,?,?)";
        	 init(sql);
        	 int[] num = null;
        	try {
				for (Student s : list) {
					ps.setString(1,s.getName());
					ps.setString(2, s.getCode());
					ps.setInt(3, s.getSex());
					ps.setDate(4, new java.sql.Date(s.getBirth().getTime()));
					ps.addBatch();
				}
				  num  =  ps.executeBatch();
			} catch (SQLException e) { 
				e.printStackTrace();
			}
        	 close();
        	return num;
         }
       
       //查询
       public List<Student> selectStudent (Integer id,String name) {  //返回一个集合
    	   String sql = "select * from student st where st.id = ? and st.name = ?";
    	   init(sql);
    	   List<Student> list = null;   
    	   list = new ArrayList<Student> ();   
    	   try {
			ps.setInt(1, id );  
			   ps.setString(2, name);  
			    rs= ps.executeQuery();   //查询,返回一个由Statement执行查询sql之后返回的结果集
			    
			    while (rs.next()) {  //查询一条,相当于迭代器里面的指针
				    Student st = new Student(rs.getInt("id"),        //里面写的是数据库里列的字段名
				    		rs.getString("name"),rs.getString("code"),
				    		rs.getInt("sex"),rs.getDate("birthday"));
				    list.add(st);
				}
		} catch (SQLException e) {
			e.printStackTrace();
		}
    	   close();
		return list;
    	    
       }
  
       public void init () {  //初始化,连接数据库
    	    coon = DBHelper.getConnection();  
    	    try {
				sm = coon.createStatement();
			} catch (SQLException e) {
				e.printStackTrace();
			}
       }
       public void init ( String sql) {  //重载方法
   	    coon = DBHelper.getConnection();  
   	    try {
				ps = coon.prepareStatement(sql);  //连接的是sql
			} catch (SQLException e) {
				e.printStackTrace();
			}
      }
       public void close() {   //关闭资源的方法
    	   DBHelper.destroy(coon, sm, rs);
       }
}

在Tomcat上打印一下,看看有没有在数据库里面对数据处理成功

public class TestDemo {   //测试是否修改数据成功
	public static void main(String[] args) {
		DatabaceMethodDal dm = new  DatabaceMethodDal();
		//写入数据
		int i =  dm.insertstudent();
		System.out.println(i);
		
		//更新数据
		Student s = new Student();
	  int i =  dm.UpdateStudent(23, "张华");
		 System.out.println(i);
		 //批量处理    通过Statement来实现的
		 
		List<Student> list = new ArrayList<Student>();
		Student st1 = new Student("王小明","stu-1025",1,new Date());
		 Student st2 = new Student("王小花","stu-1026",2,new Date());
		 list.add(st1);
		list.add(st2);
		//int [] arr =  dm.InsertStudent(list);
		int[] arr2 = dm.InsertStudentByprepare(list);
		System.out.println(Arrays.toString(arr2));
		//查询
		 List<Student> list = dm.selectStudent(1, "陈迪");
	        System.out.println(list);
	        
	}	
	
	     
}