BeanUtils使用总结（二）LazyDynaBean

LazyDynaBean   

     它实现一个动态的Bean，可以直接往里面加入属性，作为一个JavaBean一样使用，也可以用上面的BeanUtils或get/set方法进行操作，而不用事先定义一个标准的JavaBean类.
      记得在J2ee设计模式中有一种Value Object的模式，用于在MVC各层之间传递数据，避免直接传递大业务对象引起的性能问题，为了避免在项目中出现很多Bean类，在书中提供了一个动态Value Object的实现（通过扩展Map）。
      这里LazyDynaBean则可以作为一种更加成熟、稳定的实现来使用。

//这里使用LazyDynaMap，它是LazyBean的一个轻量级实现

      LazyDynaMap dynaBean1 = new LazyDynaMap();

      dynaBean1.set("foo", "bar");                  // simple

      dynaBean1.set("customer", "title", "Mr");        // mapped

      dynaBean1.set("address", 0, "address1");         // indexed

      System.out.println(dynaBean1.get("address",0));


      Map myMap = dynaBean1.getMap();           // retrieve the Map

      System.out.println(myMap.toString());

  
//这里使用LazyDynaMap，它是LazyBean的一个轻量级实现

      LazyDynaMap dynaBean1 = new LazyDynaMap(); 

      dynaBean1.set("foo", "bar");                  // simple

      dynaBean1.set("customer", "title", "Mr");        // mapped

      dynaBean1.set("address", 0, "address1");         // indexed

      System.out.println(dynaBean1.get("address",0));
 

      Map myMap = dynaBean1.getMap();           // retrieve the Map

      System.out.println(myMap.toString());

 上面的例子可以看到，它可以在set时自动增加bean的property（既赋值的同时增加Bean中的property），
  同时也支持3中类型的property，并且LazyDynaMap还可以导出为map。

 

对于这个类还有两个重要的Field要注意：

      （1） returnnull——指定在get方法使用了一个没有定义过的property时，DynaBean的行为。

            //设为ture。若Bean中没有此字段，返回null,默认为false。若Bean中没有此字段，自动增加一个

               dynaBean1.setReturnNull(true);

            System.out.println(dynaBean1.get("aaa"));//此时返回null

      （2） Restricted——指定是否允许改变这个bean的property

   //默认为false，允许增删和修改

      dynaBean1.setRestricted(true);

      dynaBean1.set("test","error");//这里会出错！

       通过设置这两个属性，可以防止意外修改DynaBean的property。在设计架构时，你可以在后台从数据表或xml文件自动产生DynaBean，在传到控制层和表示层之前设置上述属性使其Bean结构不允许修改，如此就不可能无意中修改Bean包含的属性……这样既可以享用它的便利，有可以防止由此引入的错误可能。

 

以下附上上几个 LazyDynaBean 的使用示例：

（1）普通bean

import java.util.GregorianCalendar;
import org.apache.commons.beanutils.LazyDynaBean;
import org.apache.commons.beanutils.BeanUtils;

public class BeanUtilsExample2 {
    //动态创建属性
    public static void main(String args[]) throws Exception {

        LazyDynaBean hh = new LazyDynaBean();
        hh.set("country", "中国");
        hh.set("city", "北京");
        hh.set("postCode", "100120");
        hh.set("addr", "aaaaaaa");

        LazyDynaBean bb = new LazyDynaBean();
        bb.set("phone", "home", "11011011");
        bb.set("phone", "office", "111111");
        bb.set("email", "[e-mail]");
        bb.set("address", 0, hh);
        bb.set("birthDate", new GregorianCalendar(1990, 3, 29).getTime());

        LazyDynaBean tt = new LazyDynaBean();
        tt.set("userId", new Long(8888888));
        tt.set("gggg", "施杨");
        tt.set("password", "sgsgsgsg");
        tt.set("dddd", bb);

        System.out.println(BeanUtils.getProperty(tt, "gggg"));
        System.out.println(BeanUtils.getProperty(tt, "dddd.birthDate"));
        System.out.println(BeanUtils.getProperty(tt,
                "dddd.address[0].addr"));
        System.out
                .println(BeanUtils.getProperty(tt, "dddd.phone(office)"));
    }
}

import java.util.GregorianCalendar;
import org.apache.commons.beanutils.LazyDynaBean;
import org.apache.commons.beanutils.BeanUtils;

public class BeanUtilsExample2 {
    //动态创建属性
    public static void main(String args[]) throws Exception {

        LazyDynaBean hh = new LazyDynaBean();
        hh.set("country", "中国");
        hh.set("city", "北京");
        hh.set("postCode", "100120");
        hh.set("addr", "aaaaaaa");

        LazyDynaBean bb = new LazyDynaBean();
        bb.set("phone", "home", "11011011");
        bb.set("phone", "office", "111111");
        bb.set("email", "[e-mail]");
        bb.set("address", 0, hh);
        bb.set("birthDate", new GregorianCalendar(1990, 3, 29).getTime());

        LazyDynaBean tt = new LazyDynaBean();
        tt.set("userId", new Long(8888888));
        tt.set("gggg", "施杨");
        tt.set("password", "sgsgsgsg");
        tt.set("dddd", bb);

        System.out.println(BeanUtils.getProperty(tt, "gggg"));
        System.out.println(BeanUtils.getProperty(tt, "dddd.birthDate"));
        System.out.println(BeanUtils.getProperty(tt,
                "dddd.address[0].addr"));
        System.out
                .println(BeanUtils.getProperty(tt, "dddd.phone(office)"));
    }
}

 （2）、连接Mysql数据库

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Iterator;
import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.ResultSetDynaClass;

public class BeanUtilsExample3 {
    public static void main(String args[]) throws Exception {
        Connection conn = getConnection();
        PreparedStatement ps = conn
                .prepareStatement("select id,title,time from guestbook2 order by id desc");
        ResultSet rs = ps.executeQuery();

        ResultSetDynaClass rsdc = new ResultSetDynaClass(rs);//重点，二次封装，对连接对象有依赖
        Iterator itr = rsdc.iterator();
        while (itr.hasNext()) {
            DynaBean bean = (DynaBean) itr.next();
            System.out.print(bean.get("id") + "\t");
            System.out.print(bean.get("title") + "\t");
            System.out.println(bean.get("time"));
        }
        conn.close();
    }

    private static Connection getConnection() {
        String url = "jdbc:mysql://localhost:3306/guestbook";
        String username = "root";
        String password = "hicc";
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
}

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Iterator;
import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.ResultSetDynaClass;

public class BeanUtilsExample3 {
    public static void main(String args[]) throws Exception {
        Connection conn = getConnection();
        PreparedStatement ps = conn
                .prepareStatement("select id,title,time from guestbook2 order by id desc");
        ResultSet rs = ps.executeQuery();

        ResultSetDynaClass rsdc = new ResultSetDynaClass(rs);//重点，二次封装，对连接对象有依赖
        Iterator itr = rsdc.iterator();
        while (itr.hasNext()) {
            DynaBean bean = (DynaBean) itr.next();
            System.out.print(bean.get("id") + "\t");
            System.out.print(bean.get("title") + "\t");
            System.out.println(bean.get("time"));
        }
        conn.close();
    }

    private static Connection getConnection() {
        String url = "jdbc:mysql://localhost:3306/guestbook";
        String username = "root";
        String password = "hicc";
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
}

 

 

 

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Iterator;
import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.RowSetDynaClass;

public class BeanUtilsExample4 {
    public static void main(String args[]) throws Exception {
        Connection conn = getConnection();
        PreparedStatement ps = conn
                .prepareStatement("select id,title,time from guestbook2 order by id desc");
        ResultSet rs = ps.executeQuery();

        RowSetDynaClass rsdc = new RowSetDynaClass(rs);
        //重点，与ResultSetDynaClass的区别
        conn.close();//重点，关闭连接后仍能读取
        Iterator itr = rsdc.getRows().iterator();
        while (itr.hasNext()) {
            DynaBean bean = (DynaBean) itr.next();
            System.out.print(bean.get("id") + "\t");
            System.out.print(bean.get("title") + "\t");
            System.out.println(bean.get("time"));
        }
    }

    private static Connection getConnection() {
        String url = "jdbc:mysql://localhost:3306/guestbook";
        String username = "root";
        String password = "hicc";
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Iterator;
import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.RowSetDynaClass;

public class BeanUtilsExample4 {
    public static void main(String args[]) throws Exception {
        Connection conn = getConnection();
        PreparedStatement ps = conn
                .prepareStatement("select id,title,time from guestbook2 order by id desc");
        ResultSet rs = ps.executeQuery();

        RowSetDynaClass rsdc = new RowSetDynaClass(rs);
        //重点，与ResultSetDynaClass的区别
        conn.close();//重点，关闭连接后仍能读取
        Iterator itr = rsdc.getRows().iterator();
        while (itr.hasNext()) {
            DynaBean bean = (DynaBean) itr.next();
            System.out.print(bean.get("id") + "\t");
            System.out.print(bean.get("title") + "\t");
            System.out.println(bean.get("time"));
        }
    }

    private static Connection getConnection() {
        String url = "jdbc:mysql://localhost:3306/guestbook";
        String username = "root";
        String password = "hicc";
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
}

 

评论

1 楼 a1641693970 2018-07-29  

还不错，学习了