单例模式 - 程序实现（Java）

我们知道单例模式，其实就是返回一个被调用类的实例。

在频繁的进行实例（Instance）创建过程，难免过多的进行new InstanceName()；我们可以只通过调用一个方法解决。

在进行设计模式的程序实现中xiaobin使用已编写的SSL程序做演示。

------------------------------------------------------------------------------------------tdtc tech-----------------------------------------------------

目的：建立SSL连接

类图：

源码：

[java]
public class ConnectionSSL {

    private final int DEFAULT_PORT = 7000;
    public final String algorithm = "SSL";
    private int port;
    private String propertyPath;
    private String keyPath;

    private static ConnectionSSL conn = new ConnectionSSL();

    private ConnectionSSL() {
        // TODO Auto-generated constructor stub
        propertyPath = getPropertyPath();

        port = getPort(propertyPath);
        if(port == 0) {
            port = DEFAULT_PORT;
        }
        keyPath = getKeyPath(propertyPath);
    }

    public static ConnectionSSL getInstance() {
        return conn;
    }

    private String getPropertyPath() {
        String path = System.getProperty("user.dir")
            + File.separator + "port.properties";
        return path;
    }

    private String getKeyPath(String filePath) {
        Properties p = new Properties();
        try {
            p.load(new FileInputStream(filePath));
        } catch (Exception e) {
            // TODO: handle exception
        }
        String path = p.getProperty("key");

        return path;
    }

    private int getPort(String filePath) {
        Properties p = new Properties();
        try {
            p.load(new FileInputStream(filePath));
        } catch (Exception e) {
            // TODO: handle exception
        }

        //p.clear();
        String strPort = p.getProperty("port");
        int port = Integer.parseInt(strPort);

        return port;
    }
}

public class ConnectionSSL {

private final int DEFAULT_PORT = 7000;
public final String algorithm = "SSL";
private int port;
private String propertyPath;
private String keyPath;

private static ConnectionSSL conn = new ConnectionSSL();

private ConnectionSSL() {
  // TODO Auto-generated constructor stub
  propertyPath = getPropertyPath();

  port = getPort(propertyPath);
  if(port == 0) {
   port = DEFAULT_PORT;
  }
  keyPath = getKeyPath(propertyPath);
}

public static ConnectionSSL getInstance() {
  return conn;
}

private String getPropertyPath() {
  String path = System.getProperty("user.dir")
   + File.separator + "port.properties";
  return path;
}

private String getKeyPath(String filePath) {
  Properties p = new Properties();
  try {
   p.load(new FileInputStream(filePath));
  } catch (Exception e) {
   // TODO: handle exception
  }
  String path = p.getProperty("key");

  return path;
}

private int getPort(String filePath) {
  Properties p = new Properties();
  try {
   p.load(new FileInputStream(filePath));
  } catch (Exception e) {
   // TODO: handle exception
  }

  //p.clear();
  String strPort = p.getProperty("port");
  int port = Integer.parseInt(strPort);

  return port;
}
}

补充：软件开发 , Java ,