抽取basedao类

testJDBC/JDBCDemo2/src/com/msb/dao/BaseDao.java

@@ -1,18 +1,26 @@
 package com.msb.dao;
 
 import java.lang.reflect.Field;
-import java.sql.Connection;
+import java.sql.*;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
 
 public abstract class BaseDao {
-    public List baseQuery(Connection connection, Class clazz, String sql, Object ... args) {
+    public static String driver = "com.mysql.cj.jdbc.Driver";
+    public static String url = "jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai";
+    public static String user = "root";
+    public static String password = "Fnst1234";
+
+    public List baseQuery(Class clazz, String sql, Object ... args) {
+        Connection connection = null;
+
         List list = new ArrayList();
         PreparedStatement statement = null;
         try {
+            Class.forName(driver);
+
+            connection = DriverManager.getConnection(url, user, password);
+
             statement = connection.prepareStatement(sql);
             for (int i = 0; i < args.length; i++) {
                 statement.setObject(i + 1, args[i]);
@@ -38,15 +46,31 @@ public abstract class BaseDao {
             } catch (SQLException e) {
                 e.printStackTrace();
             }
+
+            try {
+                if (connection != null) {
+                    connection.close();
+                }
+            }
+            catch (SQLException e) {
+                e.printStackTrace();
+            }
         }
         return list;
     }
 
-    public int baseUpdate(Connection connection, String sql,Object ... args){
+    public int baseUpdate(String sql,Object ... args) {
+        Connection connection = null;
         PreparedStatement preparedStatement=null;
         int rows=0;
 
         try{
+            // 选择数据库
+            Class.forName(driver);
+
+            // 建立连接
+            connection = DriverManager.getConnection(url, user, password);
+
             preparedStatement = connection.prepareStatement(sql);
             //设置参数
             for (int i = 0; i <args.length ; i++) {
@@ -65,6 +89,15 @@ public abstract class BaseDao {
                     e.printStackTrace();
                 }
             }
+
+            try {
+                if (connection != null) {
+                    connection.close();
+                }
+            }
+            catch (SQLException e) {
+                e.printStackTrace();
+            }
         }
         return rows;
     }

testJDBC/JDBCDemo2/src/com/msb/dao/imp/DeptDaoImp.java

@@ -4,48 +4,13 @@ import com.msb.bean.Dept;
 import com.msb.dao.BaseDao;
 import com.msb.dao.DeptDao;
 
-import java.sql.*;
-import java.util.ArrayList;
 import java.util.List;
 
 public class DeptDaoImp extends BaseDao implements DeptDao {
-    public static String driver = "com.mysql.cj.jdbc.Driver";
-    public static String url = "jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai";
-    public static String user = "root";
-    public static String password = "Fnst1234";
-
     @Override
     public List<Dept> findAll() {
-        Connection connection = null;
+        String sql = "select * from dept";
-
+        return baseQuery(Dept.class, sql);
-        List<Dept> list =null;
-
-        try {
-            // 选择数据库
-            Class.forName(driver);
-
-            // 建立连接
-            connection = DriverManager.getConnection(url, user, password);
-
-            // 执行sql
-            String sql = "select * from dept";
-            list = baseQuery(connection, Dept.class, sql);
-        }
-        catch (Exception e) {
-            e.printStackTrace();
-        }
-        finally {
-            try {
-                if (connection != null) {
-                    connection.close();
-                }
-            }
-            catch (SQLException e) {
-                e.printStackTrace();
-            }
-        }
-
-        return list;
     }
 
     @Override

testJDBC/JDBCDemo2/src/com/msb/dao/imp/EmpDaoImp.java

@@ -4,81 +4,19 @@ import com.msb.bean.Emp;
 import com.msb.dao.BaseDao;
 import com.msb.dao.EmpDao;
 
-import java.sql.*;
-import java.util.ArrayList;
 import java.util.List;
 
 public class EmpDaoImp extends BaseDao implements EmpDao {
-    public static String driver = "com.mysql.cj.jdbc.Driver";
-    public static String url = "jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai";
-    public static String user = "root";
-    public static String password = "Fnst1234";
-
     @Override
     public List<Emp> findAll() {
-        Connection connection = null;
+        String sql = "select * from emp";
-
+        return baseQuery(Emp.class, sql);
-        List<Emp> list =null;
-
-        try {
-            // 选择数据库
-            Class.forName(driver);
-
-            // 建立连接
-            connection = DriverManager.getConnection(url, user, password);
-
-            // 执行sql
-            String sql = "select * from emp";
-            list = baseQuery(connection, Emp.class, sql);
-        }
-        catch (Exception e) {
-            e.printStackTrace();
-        }
-        finally {
-            try {
-                if (connection != null) {
-                    connection.close();
-                }
-            }
-            catch (SQLException e) {
-                e.printStackTrace();
-            }
-        }
-
-        return list;
     }
 
     @Override
     public int deleteByEmpno(int empno) {
-        Connection connection = null;
+        String sql = "delete from emp where empno = ?";
-
+        return baseUpdate(sql, empno);
-        int rows = 0;
-
-        try {
-            // 选择数据库
-            Class.forName(driver);
-
-            // 建立连接
-            connection = DriverManager.getConnection(url, user, password);
-
-            // 执行sql
-            String sql = "delete from emp where empno = ?";
-            rows = baseUpdate(connection, sql, empno);
-        }
-        catch (Exception e) {
-            e.printStackTrace();
-        }
-        finally {
-            try {
-                if (connection != null) {
-                    connection.close();
-                }
-            }
-            catch (SQLException e) {
-                e.printStackTrace();
-            }
-        }
-        return rows;
     }
 
     @Override
@@ -88,34 +26,7 @@ public class EmpDaoImp extends BaseDao implements EmpDao {
 
     @Override
     public int addEmp(Emp emp) {
-        Connection connection = null;
+        String sql = "insert into emp values(?,?,?,?,?,?,?,?)";
-
+        return baseUpdate(sql, emp.getEmpno(), emp.getEname(), emp.getJob(),emp.getMgr(),emp.getHiredate(),emp.getSal(),emp.getComm(),emp.getDeptno());
-        int rows = 0;
-
-        try {
-            // 选择数据库
-            Class.forName(driver);
-
-            // 建立连接
-            connection = DriverManager.getConnection(url, user, password);
-
-            // 执行sql
-            String sql = "insert into emp values(?,?,?,?,?,?,?,?)";
-            rows = baseUpdate(connection, sql, emp.getEmpno(), emp.getEname(), emp.getJob(),emp.getMgr(),emp.getHiredate(),emp.getSal(),emp.getComm(),emp.getDeptno());
-        }
-        catch (Exception e) {
-            e.printStackTrace();
-        }
-        finally {
-            try {
-                if (connection != null) {
-                    connection.close();
-                }
-            }
-            catch (SQLException e) {
-                e.printStackTrace();
-            }
-        }
-        return rows;
     }
 }