添加连接池

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

@@ -6,20 +6,12 @@ import java.util.ArrayList;
 import java.util.List;
 
 public abstract class BaseDao {
-    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);
+            connection = MyConnectionPool.getConnection();
 
             statement = connection.prepareStatement(sql);
             for (int i = 0; i < args.length; i++) {
@@ -46,15 +38,7 @@ public abstract class BaseDao {
             } catch (SQLException e) {
                 e.printStackTrace();
             }
-
-            try {
-                if (connection != null) {
-                    connection.close();
-                }
-            }
-            catch (SQLException e) {
-                e.printStackTrace();
-            }
+            MyConnectionPool.returnConnection(connection);
         }
         return list;
     }
@@ -65,11 +49,8 @@ public abstract class BaseDao {
         int rows=0;
 
         try{
-            // 选择数据库
-            Class.forName(driver);
-
             // 建立连接
-            connection = DriverManager.getConnection(url, user, password);
+            connection = MyConnectionPool.getConnection();
 
             preparedStatement = connection.prepareStatement(sql);
             //设置参数
@@ -89,15 +70,7 @@ public abstract class BaseDao {
                     e.printStackTrace();
                 }
             }
-
-            try {
-                if (connection != null) {
-                    connection.close();
-                }
-            }
-            catch (SQLException e) {
-                e.printStackTrace();
-            }
+            MyConnectionPool.returnConnection(connection);
         }
         return rows;
     }

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

@@ -0,0 +1,77 @@
+package com.msb.dao;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.LinkedList;
+import java.util.List;
+
+public class MyConnectionPool {
+
+    private static String driver = "com.mysql.cj.jdbc.Driver";
+    private static String url = "jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai";
+    private static String user = "root";
+    private static String password = "Fnst1234";
+
+    private static int initSize = 5;
+
+    private static int maxSize = 10;
+
+    private static LinkedList<Connection> pool = new LinkedList<Connection>();
+
+    static {
+        try {
+            Class.forName(driver);
+
+            for (int i = 0; i < initSize; i++) {
+                Connection connection = initConnection();
+                if (connection != null) {
+                    pool.add(connection);
+                }
+            }
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private static Connection initConnection() {
+        try {
+            return DriverManager.getConnection(url, user, password);
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    public static Connection getConnection() {
+        Connection connection =null;
+        if (pool.size() > 0) {
+            connection = pool.removeFirst();
+        }
+        else {
+            connection = initConnection();
+        }
+        return connection;
+    }
+
+    public static void returnConnection(Connection connection) {
+        if (connection == null) {
+            return;
+        }
+        try {
+            if (connection.isClosed()) {
+                return;
+            }
+            if (pool.size() < maxSize) {
+                connection.setAutoCommit(true);
+                pool.addLast(connection);
+            }
+            else {
+                connection.close();
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+}