JDBC java语言连接数据库

JDBC

JDBC（Java DataBase Connectivity,java数据库连接）是一种用于执行SQL语句的Java API，可以为多种关系数据库提供统一访问，它由一组用Java语言编写的类和接口组成。JDBC提供了一种基准，据此可以构建更高级的工具和接口，使数据库开发人员能够编写数据库应用程序，同时，JDBC也是个商标名。

JAVA连接数据库:

步骤如下：

1.首先需要导入数据库的jar包。

2.通过反射加载驱动。

3.建立数据库连接。

4.利用java代码对数据库进行操作。（用java代码对数据库进行增删改查的操作）

下面是代码:

public class BaseDao {

private static Connection connection;private static PreparedStatement ps;private ResultSet rs;public static Connection getConnection(){    try {        Class.forName(Contants.DRIVER);        connection = DriverManager.getConnection(Contants.URL, Contants.USERS, Contants.PWD);    } catch (ClassNotFoundException e) {        // TODO Auto-generated catch block        e.printStackTrace();    } catch (SQLException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }    System.out.println("数据库连接成功");    return connection;}//增加public static int insert(String sql,Object[] object){    int num = 0;    connection = getConnection();    try {        ps = connection.prepareStatement(sql);        if (object !=null&&object.length>0) {            for (int i = 0; i < object.length; i++) {                ps.setObject((i+1), object[i]);            }        }        num = ps.executeUpdate();    } catch (SQLException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }finally{        try {            ps.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    return num;}//删除public static int del(String sql,int num2){    int num = 0;    connection=getConnection();    try {        ps=connection.prepareStatement(sql);        ps.setInt(1, num2);        num = ps.executeUpdate();    } catch (SQLException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }    return num;}//修改public int update(String sql,Object[] object){    int num = 0;    connection = getConnection();    try {        ps = connection.prepareStatement(sql);        if (object !=null&&object.length>0) {            for (int i = 0; i < object.length; i++) {                ps.setObject((i+1), object[i]);            }        }        num = ps.executeUpdate();    } catch (SQLException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }finally{        try {            ps.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    return num;                                 }//查询public static ResultSet getSelect(String sql,Object[] objects){        try {                ps=getConnection().prepareStatement(sql);                if(objects!=null&& objects.length>0){                    for (int i = 0; i < objects.length; i++) {                            ps.setObject((i+1),objects[i]);                    }                }                rs=ps.executeQuery();        } catch (SQLException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        return rs;        }}//关闭public static void close(Connection con,Statement st,ResultSet rs){    if (con!=null) {        try {            con.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }if (st!=null) {        try {            st.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }if (rs!=null) {        try {            rs.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

}

public interface DeptDao {    //增加    public int insert(Dept dept);    //删除    public int delete(int did);    //修改    public int update(Dept dept);    //查询全部    public List<Dept> selectDept();}

public class Dept {
private int did;
private String dname;
private String dage;
private String desc;
public int getDid() {
return did;
}
public void setDid(int did) {
this.did = did;
}
public String getDname() {
return dname;
}
public void setDname(String dname) {
this.dname = dname;
}
public String getDage() {
return dage;
}
public void setDage(String dage) {
this.dage = dage;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
public Dept(int did, String dname, String dage, String desc) {
this.did = did;
this.dname = dname;
this.dage = dage;
this.desc = desc;
}
public Dept() {
}
@Override
public String toString() {
return “Dept [did=” + did + “, dname=” + dname + “, dage=” + dage
+ “, desc=” + desc + “]”;
}
}

public class DeptImpl implements DeptDao{
BaseDao bd = new BaseDao();
@Override
public int insert(Dept dept) {
String sql = “insert into dept values(?,?,?,?)”;
Object[] object = {dept.getDid(),dept.getDname(),dept.getDage(),dept.getDesc()};
int num = bd.insert(sql, object);
return num;
}
@Override
public int delete(int id) {
String sql = “delete from dept where did=?”;
int num = bd.del(sql, id);
return num;
}

@Overridepublic int update(Dept dept) {    String sql = "update dept set dname=? where did=?";    Object[] object ={dept.getDname(),dept.getDid()};    int num = bd.update(sql, object);    return num;}@Overridepublic List<Dept> selectDept() {    String sql="select *from stu";    ResultSet rs=bd.getSelect(sql,null);    List<Dept> list=new ArrayList<Dept>();    try {        while(rs.next()){            Dept dept=new Dept(rs.getInt("sid"),rs.getString("sname"),rs.getInt("ssex"),rs.getInt("sage"),rs.getString("shobby"));            list.add(dept);        }    } catch (SQLException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }    return list;}

}