Facade模式的定義: 為子系統(tǒng)中的一組接口提供一個一致的界面.Facade一個典型應(yīng)用就是數(shù)據(jù)庫JDBC的應(yīng)用,如下例對數(shù)據(jù)庫的操作:
說明：這是在網(wǎng)上的一篇文章中看到的列子，上面沒有寫全，我在這里補上了，沒有用到接口。
package com.pattern.structural.facade;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/*
* 外觀模式的主要用途就是為子系統(tǒng)的復(fù)雜處理過程提供方便的調(diào)用方法，
* 使得子系統(tǒng)更加容易被使用。
* Facade對象通常屬于Singleton模式。
*/
public class Mysql {
private static Connection conn=null;
private static PreparedStatement prep=null;
public Mysql(String sql) {
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test","root","");
prep = conn.prepareStatement(sql);
} catch (Exception e) {
e.printStackTrace();
}
}
public void setString(int index, String parString) {
try {
prep.setString(index, parString);
} catch (SQLException e) {
e.printStackTrace();
}
}
public ResultSet executeQuery() {
try {
return prep.executeQuery();
} catch (SQLException e) {
e.printStackTrace();
return null;
}
}
public void close() {
try {
conn.close();
prep.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
package com.pattern.structural.facade;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class DBCompare {
public void getResultSet(String sql) {
// String sql = "SELECT * FROM bulletin WHERE id = ?";
Mysql mysql = new Mysql(sql);
try {
mysql.setString(1, "4");
ResultSet rset = mysql.executeQuery();
while (rset.next()) {
System.out.println(rset.getString("id"));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
mysql.close();
mysql = null;
}
}
}
package com.pattern.structural.facade;
import java.sql.ResultSet;
public class FacadeTest {
public static void main(String[] args) {
Mysql mysql = new Mysql("SELECT * FROM bulletin");
try {
ResultSet rset = mysql.executeQuery();
while (rset.next()) {
System.out.println(rset.getString("id"));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
mysql.close();
mysql = null;
}
}
}