看到java.bean這個包的時候，覺得XMLEncoder和XMLDecoder這兩個類有點意思。前者可以直接將JavaBean輸入為XML檔案，後者可以直接將格式正確的XML檔案還原為JavaBean的物件，感覺和物件序列化有點類似，只不過這種方式我們可以清晰地看到轉換為普通檔案以後的物件的格式，這種方式也可以實現對一個遊離物件的持久化。

一.先定義兩個普通的JavaBean

程式碼如下

package com.bean.test; import java.io.Serializable; public class Role implements Serializable { private static final long serialVersionUID = -40359605540725572L; private int id; private String roleName; private String roleCode; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getRoleCode() { return roleCode; } public void setRoleCode(String roleCode) { this.roleCode = roleCode; } public String getRoleName() { return roleName; } public void setRoleName(String roleName) { this.roleName = roleName; } }

另一個javabean類如下

package com.bean.test; import java.io.Serializable; import java.util.Date; import java.util.List; public class User implements Serializable { private static final long serialVersionUID = 5076428480402933567L; private String id; private String name; private String password; private int age; private Integer score; private Date birth; private List list; public List getList() { return list; } public void setList(List list) { this.list = list; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public Date getBirth() { return birth; } public void setBirth(Date birth) { this.birth = birth; } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public Integer getScore() { return score; } public void setScore(Integer score) { this.score = score; } }

二. Encoder程式碼即序列化部分

程式碼如下，執行後在根目錄生成一個xml檔案user.xml

進一步驗證發現，如果JavaBean的屬性的值為預設初始值，那麼對應的屬性和值將不會輸出到輸出流。例如，當int=0,String=null,boolean=false,自定義型別=null的時候,將會忽略該節點。注意：String如果為空字串仍然會輸出該節點，同時在從XML檔案載入到JavaBean物件的時候，也會根據這些預設值對JavaBean進行填充。

package com.bean.test; import java.beans.XMLEncoder; import java.io.BufferedOutputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.util.ArrayList; import java.util.Date; import java.util.List; public class DudanBeanToXMLEncoder { public static void main(String[] args) { FileOutputStream fos = null; BufferedOutputStream bos = null; try { fos = new FileOutputStream("user.xml"); } catch (FileNotFoundException e) { e.printStackTrace(); } bos = new BufferedOutputStream(fos); XMLEncoder encoder = new XMLEncoder(bos); User user = new User(); user.setAge(10); user.setBirth(new Date()); user.setId("0x4535435"); user.setName("杜丹"); user.setPassword("111111"); user.setScore(98); List list = new ArrayList(); Role role = null; for (int i = 0; i < 5; i++) { role = new Role(); role.setId(i); role.setRoleName("角色" + i); role.setRoleCode(String.valueOf(10 + i)); list.add(role); } user.setList(list); encoder.writeObject(user); encoder.close(); } }

三.以下是從XML檔案載入為JavaBean物件的程式碼

程式碼如下

package com.bean.test; import java.beans.XMLDecoder; import java.io.BufferedInputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; public class DudanXMLToBeanDecoder { public static void main(String[] args) { FileInputStream fos = null; BufferedInputStream bos = null; try { fos = new FileInputStream("user.xml"); } catch (FileNotFoundException e) { e.printStackTrace(); } bos = new BufferedInputStream(fos); XMLDecoder encoder = new XMLDecoder(bos); User user = (User) encoder.readObject(); System.out.println(user.getAge()); System.out.println(user.getId()); System.out.println(user.getName()); encoder.close(); } }