尝试将java连接到sql Server

package sd;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class test {
    public static void main(String[] args) {
        try {
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");  
            Connection conn = DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=P_Cat_tweets;integratedSecurity=true");
            System.out.println("test");
            Statement sta = conn.createStatement();
            String Sql = "select * from teewts";
            ResultSet rs = sta.executeQuery(Sql);

            System.out.println(rs.next());
        } catch (Exception e){
            e.printStackTrace();
        }
    }
}

错误： com.microsoft.sqlserver.jdbc.SQLServerException: 与主机localhost，端口1433的TCP / IP连接失败 . 错误："Connection refused: connect. Verify the connection properties, check that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port, and that no firewall is blocking TCP connections to the port." .

java sql