BeanUtils 工具類，beanutils工具類

BeanUtils 工具類，beanutils工具類

一.BeanUtils 概述
     BeanUtils 是阿帕奇提供的一套專門用於將一些資料封裝到java對象中的工具類;
    
     名詞:javaBean:特定格式的java類稱為javaBean;
    
     要求:
         1:javaBean這個類要實現Serializable介面;(在實際開發中,通常省略了)
         2:javaBean必須有public許可權的空參數的構造方法;
         3:javaBean必須有屬性對應的getXxx與setter方法;

二.BeanUtils 的使用
     Beanutils 有2個依賴jar包;commons-beanutils-1.8.3.jar和commons-logging-1.1.1.jar;
     BeanUtils 有2個核心類:BeanUtils,ConvertUtils 類;
     使用步驟:
         1:下載解壓;
         2:複製核心jar包到工程中;(有2個)
         3:添加到本地;(add to build path)
         4:使用核心類;

三.BeanUtils 常用方法
     public static void setProperty(Object bean,String name,Object value)
                             throws IllegalAccessException,InvocationTargetException{}:向bean對象的name屬性中儲存value值;
     public static String getProperty(Object bean,String name)
                               throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{}:從bean對象中擷取name屬性的值;
     public static String[] getArrayProperty(Object bean,String name)
                                      throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{}:從bean對象中擷取name屬性的數群組類型的值;
     [注:getProperty方法就只認String類型和String[]數群組類型,其它類型它會自動幫你轉成這兩個類型,使用時需時刻想到String類型,用""包裹屬性]
     public static void populate(Object bean,Map properties)
                                     throws IllegalAccessException,InvocationTargetException{}:將properties集合中的資料,根據key與bean的屬性名稱(實際上是匹配setXxx方法)    匹配,匹配成功,則賦值,匹配失敗不操作;                                                   
代碼示範1:(以下代碼全在Eclipse中實現)

  1 //建立beanUtilsDemo01包  2 package beanUtilsDemo01;  3   4 import java.util.Arrays;  5   6 public class Person {  7      // 屬性  8     private String name;  9      private int age; 10      private String[] hobby; 11  12     // 構造方法 13     public Person() { 14         super(); 15      } 16  17     public Person(String name, int age, String[] hobby) { 18          super(); 19          this.name = name; 20          this.age = age; 21          this.hobby = hobby; 22      } 23  24     // getter/setter 25      public String getName() { 26          return name; 27      } 28  29     public void setName(String name) { 30          this.name = name; 31      } 32  33     public int getAge() { 34          return age; 35      } 36  37     public void setAge(int age) { 38          this.age = age; 39      } 40  41     public String[] getHobby() { 42          return hobby; 43      } 44  45     public void setHobby(String[] hobby) { 46          this.hobby = hobby; 47      } 48  49     // 覆寫toString/equal/hashcode 50      @Override 51      public String toString() { 52          return "Person [name=" + name + ", age=" + age + ", hobby=" 53                  + Arrays.toString(hobby) + "]"; 54      } 55  56     @Override 57      public int hashCode() { 58          final int prime = 31; 59          int result = 1; 60          result = prime * result + age; 61          result = prime * result + Arrays.hashCode(hobby); 62          result = prime * result + ((name == null) ? 0 : name.hashCode()); 63          return result; 64      } 65  66     @Override 67      public boolean equals(Object obj) { 68          if (this == obj) { 69              return true; 70          } 71          if (obj == null) { 72              return false; 73          } 74          if (!(obj instanceof Person)) { 75              return false; 76          } 77          Person other = (Person) obj; 78          if (age != other.age) { 79              return false; 80          } 81          if (!Arrays.equals(hobby, other.hobby)) { 82              return false; 83          } 84          if (name == null) { 85              if (other.name != null) { 86                  return false; 87              } 88          } else if (!name.equals(other.name)) { 89              return false; 90          } 91          return true; 92      } 93  94 } 95  //建立beanUtilsDemo01包 96 package beanUtilsDemo01; 97  98 import java.util.Arrays; 99 100 import org.apache.commons.beanutils.BeanUtils;101 102 //BeanUtils常用方法練習103 104 public class Demo01BeanUtils {105 106     public static void main(String[] args) throws Exception {107          // 執行個體化對象108         Person p = new Person();109          // 借用BeanUtils工具類向Person對象賦值110         BeanUtils.setProperty(p, "name", "Rose");111          BeanUtils.setProperty(p, "age", 22);112          BeanUtils.setProperty(p, "hobby", new String[] { "eating", "sleeping",113                  "kissing" });114          // 列印對象115         System.out.println(p);116          // 擷取各屬性值117         String[] hobby = BeanUtils.getArrayProperty(p, "hobby");118          System.out.println(Arrays.toString(hobby));119          String name = BeanUtils.getProperty(p, "name");120          System.out.println(name);121          String age = BeanUtils.getProperty(p, "age");122          System.out.println(age);123      }124 125 }126 

代碼示範2:封裝map集合中的資料

  1 package beanUtilsDemo01;  2   3 import java.lang.reflect.InvocationTargetException;  4  import java.util.HashMap;  5  import java.util.Map;  6   7 import org.apache.commons.beanutils.BeanUtils;  8   9 //借用BeanUtils將Map中的資料封裝到javabean中 10  11 public class Demo02BeanUtils { 12  13     public static void main(String[] args) throws IllegalAccessException, 14              InvocationTargetException { 15          // 執行個體化對象 16         Person p = new Person(); 17          // 準備MAP集合 18         Map<String, Object> map = new HashMap<>(); 19          // 向map中添加資料 20         map.put("name", "jack"); 21          map.put("age", 23); 22          map.put("hobbyy", new String[] { "eating", "sleeping", "painting" }); 23          // 將map集合中的資料封裝到javabean中 24         BeanUtils.populate(p, map); 25          System.out.println(p); 26      } 27  } 28 

代碼示範3:與以上利用同一個Person類????????????????????????

  1 package beanUtilsDemo01;  2   3 import java.util.HashMap;  4  import java.util.Map;  5   6 import org.apache.commons.beanutils.BeanUtils;  7   8 //利用BeanUtils工具類自訂工具類:要求傳入任一類型的位元組碼檔案 和 屬性的map集合,返回執行個體化對象  9 class MyBeanUtils { 10      public static <T> T popu(Class<T> c, Map map) throws Exception {    //泛型 11         Object obj = c.newInstance(); 12          BeanUtils.populate(obj, map); 13          return (T) obj; //向下轉型 14     } 15  } 16  17 public class MyTest { 18      public static void main(String[] args) throws Exception { 19         Map<String, Object> map = new HashMap<>(); 20          map.put("name", "rose"); 21          map.put("age", "18"); 22          Person p = MyBeanUtils.popu(Person.class, map); 23          System.out.println(p); 24      } 25  26 } 27 

代碼示範4:需準備一個User類,和以上的Person類,及data.xml檔案

  1 package beanutilcase;  2   3 import java.util.HashMap;  4  import java.util.List;  5  import java.util.Map;  6   7 import org.apache.commons.beanutils.BeanUtils;  8  import org.dom4j.Document;  9  import org.dom4j.Element; 10  import org.dom4j.io.SAXReader; 11  12 public class Demo { 13  14     public static void main(String[] args) throws Exception { 15          Person p = new Person(); 16          User u = new User(); 17          // 建立解析器對象 18         SAXReader sax = new SAXReader(); 19          // 讀取文檔,並擷取根節點 20         Document doc = sax.read("data.xml"); 21          Element root = doc.getRootElement(); 22          // 擷取根節點下的一級子項目 23         List<Element> listFirst = root.elements(); 24          // 迭代 25         for (Element e : listFirst) { 26              // 擷取一級子項目的屬性值 27             String path = e.attributeValue("className"); 28              // 根據路徑(屬性)擷取位元組碼檔案 29             Class c = Class.forName(path); 30              // 擷取二級子項目 31             List<Element> listSecond = e.elements(); 32              // 定義map集合裝屬性值 33             Map<String, Object> map = new HashMap<>(); 34              for (Element es : listSecond) { 35                  // 擷取二級子項目的兩個屬性值 36                 String name = es.attributeValue("name"); 37                  String value = es.attributeValue("value"); 38                  map.put(name, value); 39              } 40              // 利用beanutils工具類進行封裝 41             // 判斷是否為person 42              if (path.matches(".*Person$")) { 43                  BeanUtils.populate(p, map); 44              } else { 45                  BeanUtils.populate(u, map); 46              } 47          } 48          System.out.println(p); 49          System.out.println(u); 50      } 51  52 } 53