java实现数据源案例

短命女 2022-03-18 14:16 173阅读 0赞

1、自定义连接类

public class MyConnection implements InvocationHandler {
    
        //连接
        private Connection relConnection;
    
        //数据源
        private MyDataSource dataSource;
    
        public MyConnection(MyDataSource dataSource){
            this.dataSource = dataSource;
        }
    
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            if(method.getName().equals("close")){
                this.dataSource.pushConnection(this);
                return null;
            }
            return method.invoke(this.relConnection,args);
        }
    
        public Connection getRelConnection() {
            return relConnection;
        }
    
        public void setRelConnection(Connection relConnection) {
            this.relConnection = relConnection;
        }
    }

2、自定义数据源类

public class MyDataSource implements DataSource {
    
        //驱动类
        private String driver;
    
        //数据库地址
        private String url;
    
        //用户名
        private String userId;
    
        //密码
        private String password;
    
        //是否自动提交
        private boolean autoCommit = true;
    
        //连接池
        private final LinkedList<MyConnection> connectionPool = new LinkedList<>();
    
        //当前连接总数
        private int nowSize = 0;
    
        private int activeSize = 0;
    
        //最大连接数
        private int maxSize = 10;
    
        //最小连接数
        private int minSize = 1;
    
        //等待获取连接时间
        private long waitTime = 10000;
    
        public MyDataSource(String driver,String url,String userId,String password){
            this.driver = driver;
            this.url = url;
            this.userId = userId;
            this.password = password;
        }
    
    
    
        /**
         * 获取连接
         * @return  连接
         */
        public MyConnection  popConnection() throws InterruptedException, SQLException {
            synchronized (this.connectionPool){
    
                long waitNow = System.currentTimeMillis();
                long waitOver = waitNow + this.waitTime;
                while(this.connectionPool.isEmpty()){
    
                    if(this.nowSize < this.maxSize-1){
                        MyConnection connection = buildMyConnection();
                        this.nowSize++;
                        this.activeSize++;
                        return connection;
                    }
    
                    if(this.waitTime >0 ){
                        System.out.println("无闲置的连接，等待中……");
                        this.connectionPool.wait(waitTime);
                    }
                    waitTime = waitOver - System.currentTimeMillis();
                }
    
                this.activeSize++;
                out.println("闲置总数："+connectionPool.size()+", 活跃总数："+this.activeSize);
                return this.connectionPool.removeFirst();
            }
        }
    
    
        private MyConnection buildMyConnection() throws SQLException {
            MyConnection conn =  new MyConnection(this);
            conn.setRelConnection(getConnection());
            return conn;
        }
    
    
        public void pushConnection(MyConnection connection) throws SQLException {
            synchronized (this.connectionPool){
    
                if(this.connectionPool.size()>maxSize){
                    connection.getRelConnection().close();
                    this.activeSize--;
                }
    
                this.connectionPool.addLast(connection);
                this.activeSize--;
                this.connectionPool.notifyAll();
            }
        }
    
        @Override
        public Connection getConnection() throws SQLException {
            try {
                Class.forName(this.driver);
                Connection connection =  DriverManager.getConnection(this.url,this.userId,this.password);
                connection.setAutoCommit(this.autoCommit);
                return connection;
            } catch (ClassNotFoundException e) {
                throw new RuntimeException("get connection fail because "+e.getMessage());
            }
        }
    
        @Override
        public Connection getConnection(String username, String password) throws SQLException {
            return null;
        }
    
        @Override
        public <T> T unwrap(Class<T> iface) throws SQLException {
            return null;
        }
    
        @Override
        public boolean isWrapperFor(Class<?> iface) throws SQLException {
            return false;
        }
    
        @Override
        public PrintWriter getLogWriter() throws SQLException {
            return null;
        }
    
        @Override
        public void setLogWriter(PrintWriter out) throws SQLException {
    
        }
    
        @Override
        public void setLoginTimeout(int seconds) throws SQLException {
    
        }
    
        @Override
        public int getLoginTimeout() throws SQLException {
            return 0;
        }
    
        @Override
        public Logger getParentLogger() throws SQLFeatureNotSupportedException {
            return null;
        }
    
        public boolean isAutoCommit() {
            return autoCommit;
        }
    
        public void setAutoCommit(boolean autoCommit) {
            this.autoCommit = autoCommit;
        }
    
        public void setWaitTime(long waitTime) {
            this.waitTime = waitTime;
        }
    
        public void setMaxSize(int maxSize) {
            this.maxSize = maxSize;
        }
    
        public void setMinSize(int minSize) {
            this.minSize = minSize;
            this.nowSize = minSize;
            try {
                for (int i = 0; i < minSize; i++) {
                    MyConnection conn = buildMyConnection();
                    this.connectionPool.add(conn);
                }
            }catch (Exception e){
                throw new RuntimeException("get connection fail because "+e.getMessage());
            }
        }
    }

3、测试

public static void main(String[] args) throws InterruptedException {
        MyDataSource dataSource = new MyDataSource("org.postgresql.Driver",
                "jdbc:postgresql://127.0.0.1:5432/zflow",
                "postgres","253897");
    
        for(int i=0 ; i<200 ; i++){
            Thread.sleep(2);
            new Thread(()->{
                try {
                    MyConnection connection = dataSource.popConnection();
                    Thread.sleep(20);
                    dataSource.pushConnection(connection);
                }catch (Exception e){
                    
                }
           
            }).start();
        }
    }

执行结果打印如下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nbGVpMDgyMzE5_size_16_color_FFFFFF_t_70][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nbGVpMDgyMzE5_size_16_color_FFFFFF_t_70]: /images/20220318/7900eae8195440e0bfe06206c02b087e.png