Java基础--JDBC-JavaBean

墨蓝 2022-07-15 10:22 185阅读 0赞

Java基础--JDBC基础知识

class Dept

package fyl;
    
    public class Dept {
    	private Integer deptno;
    	private String dname;
    	private String loc;
    
    	public Integer getDeptno() {
    		return deptno;
    	}
    
    	public void setDeptno(Integer deptno) {
    		this.deptno = deptno;
    	}
    
    	public String getDname() {
    		return dname;
    	}
    
    	public void setDname(String dname) {
    		this.dname = dname;
    	}
    
    	public String getLoc() {
    		return loc;
    	}
    
    	public void setLoc(String loc) {
    		this.loc = loc;
    	}
    
    }

Java查询MySQL数据库步骤

package fyl;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.util.ArrayList;
    import java.util.List;
    
    public class ConnDemo {
    
    	public static void main(String[] args) {
    		try {
    			//jdbc访问数据库的步骤
    			//1：导入数据库的驱动包   mysql-connector-java-5.1.6-bin.jar
    			Class.forName("com.mysql.jdbc.Driver");//静态代码块实例化一个Driver对象
    			//2：建立连接对象
    			String url = "jdbc:mysql://192.168.3.159:3306/scott";
    			String user = "root";
    			String password = "root";
    			Connection connection = DriverManager.getConnection(url, user, password);
    			//3：准备sql指令
    			String sql = "SELECT deptno,dname,loc FROM dept; ";
    			//4：执行sql的预处理对象
    			PreparedStatement preparedStatement = connection.prepareStatement(sql);
    			//5：执行sql，返回结果集
    			ResultSet rs= preparedStatement.executeQuery();
    			//6：结果集的解析，放入map或bean中
    			List<Dept> depts =new ArrayList<Dept>();
    			while (rs.next()) {
    //				System.out.println(rs.getInt("deptno"));
    //				System.out.println(rs.getString("dname"));
    //				System.out.println(rs.getString("loc"));
    //				System.out.println("===================");
    				Dept dept = new Dept();
    				dept.setDeptno(rs.getInt("deptno"));
    				dept.setDname(rs.getString("dname"));
    				dept.setLoc(rs.getString("loc"));
    				depts.add(dept);
    			}
    			//7：关闭数据库连接
    			rs.close();
    			connection.close();
    			//8：测试
    			//9：返回给页面解析数据
    			for (Dept dept : depts) {
    				System.out.println("deptno="+dept.getDeptno()+"  "+"dname="+dept.getDname()+"  "+"loc="+dept.getLoc());
    			}
    		} catch (Exception e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    }

封装Util

package fyl;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.util.ArrayList;
    import java.util.List;
    
    public class ConnUtil {
    
    	private static final String url = "jdbc:mysql://192.168.3.159:3306/scott";
    	private static final String user = "root";
    	private static final String password = "root";
    	
    	/**
    	 * 得到数据库连接
    	 */
    	public static Connection getConn() {
    		try {
    			//1：导入数据库的驱动包   mysql-connector-java-5.1.6-bin.jar
    			Class.forName("com.mysql.jdbc.Driver");//静态代码块实例化一个Driver对象
    			//2：建立连接对象
    			Connection connection = DriverManager.getConnection(url, user, password);
    			return connection;
    		} catch (Exception e) {
    			e.printStackTrace();
    			return null;
    		}
    	}
    	
    	/**
    	 * 关闭数据库连接
    	 */
    	public static void CloseConn(Connection conn,PreparedStatement statement,ResultSet rs) {
    		try {
    			if(rs!=null) rs.close();
    			if(statement!=null) statement.close();
    			if(conn!=null) conn.close();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    	
    	/**
    	 * 查找数据
    	 */
    	public static List<Dept> findData() {
    		Connection connection = null;
    		PreparedStatement preparedStatement = null;
    		ResultSet rs = null;
    		List<Dept> depts = null;
    		Dept dept = null;
    		try {
    		    connection = getConn();
    			//3：准备sql指令
    			String sql = "SELECT deptno,dname,loc FROM dept; ";
    			//4：执行sql的预处理对象
    			preparedStatement = connection.prepareStatement(sql);
    			//5：执行sql，返回结果集
    			rs= preparedStatement.executeQuery();
    			//6：结果集的解析，放入map或bean中
    			depts =new ArrayList<Dept>();
    			while (rs.next()) {
    				dept = new Dept();
    				dept.setDeptno(rs.getInt("deptno"));
    				dept.setDname(rs.getString("dname"));
    				dept.setLoc(rs.getString("loc"));
    				depts.add(dept);
    			}
    			
    			return depts;
    		} catch (Exception e) {
    			e.printStackTrace();
    			return null;
    		} finally {
    			CloseConn(connection, preparedStatement, rs);
    		}
    	}
    	
    	
    	public static void main(String[] args) {
    		List<Dept> depts = findData();
    		for (Dept dept : depts) {
    			System.out.println("deptno="+dept.getDeptno()+"  "+"dname="+dept.getDname()+"  "+"loc="+dept.getLoc());
    		}
    	}
    }