1.Xstream介紹
(1)Xstream介紹
Xstream是一種OXMapping 技術，是用來處理XML文件序列化的框架,在將JavaBean序列化，或將XML文件反序列化的時候，不需要其它輔助類和映射文件，使得XML序列化不再繁索。Xstream也可以將JavaBean序列化成Json或反序列化，使用非常方便。
(2)Xstream的簡單例子
class Person//JavaBean實體類{ private String name; private int age; public Person(String name,int age) { this.name=name; this.age=age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; }}public class Test{ public static void main(String[] args) { Person bean=new Person("張三",19); XStream xstream = new XStream(); //XML序列化 String xml = xstream.toXML(bean); System.out.println(xml); //XML反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); xstream = new XStream(new JettisonMappedXmlDriver()); xstream.setMode(XStream.NO_REFERENCES); //Json序列化 String json=xstream.toXML(bean); System.out.println(json); //Json反序列 bean=(Person)xstream.fromXML(json); System.out.println(bean); }}
程序運行結果：
<test.Person> <name>張三</name> <age>19</age></test.Person>Person [name=張三, age=19]{"test.Person":{"name":"張三","age":19}}Person [name=張三, age=19
注意：Xstream序列化XML時需要引用的jar包：xstream-[version].jar、xpp3-[version].jar、xmlpull-[version].jar。Xstream序列化Json需要引用的jar包：jettison-[version].jar。
使用Xstream序列化時，對JavaBean沒有任何限制。JavaBean的字段可以是私有的，也可以沒有getter或setter方法，還可以沒有默認的構造函數。
2.Xstream的基本使用
(1)Xstream序列化XML
Xstream序列化XML時可以允許用戶使用不同的XML解析器，用戶可以使用一個標准的JAXP DOM解析器或自Java6集成StAX解析器。這樣用戶就不需要依賴xpp3-[version].jar。
Xstream序列化XML時，也可以對XML節點重命名。
public class Test{ public static void main(String[] args) { Person bean=new Person("張三",19); //XStream xstream = new XStream();//需要XPP3庫 //XStream xstream = new XStream(new DomDriver());//不需要XPP3庫 XStream xstream = new XStream(new StaxDriver());//不需要XPP3庫開始使用Java6 xstream.alias("人",Person.class);//為類名節點重命名 //XML序列化 String xml = xstream.toXML(bean); System.out.println(xml); //XML反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<?xml version="1.0" ?><人><name>張三</name><age>19</age></人>Person [name=張三, age=19]
(2)Xstream序列化Json
Xstream序列化Json與序列化XML類似，例如：
public class Test{ public static void main(String[] args) { Person bean=new Person("張三",19); XStream xstream = new XStream(new JettisonMappedXmlDriver());//設置Json解析器 xstream.setMode(XStream.NO_REFERENCES);//設置reference模型,不引用 xstream.alias("人",Person.class);//為類名節點重命名 //Json序列化 String xml = xstream.toXML(bean); System.out.println(xml); //Json反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
{"人":{"name":"張三","age":19}}Person [name=張三, age=19]
3.Xstream序列化重命名
(1)為包重命名：Xstream.aliasPackage()方法
public class Test{ public static void main(String[] args) { Person bean=new Person("張三",19); XStream xstream = new XStream(); xstream.aliasPackage("com.lzw", "test");//為包名稱重命名 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<com.lzw.Person> <name>張三</name> <age>19</age></com.lzw.Person>Person [name=張三, age=19]
(2)為類重命名：Xstream.alias()方法
public class Test{ public static void main(String[] args) { Person bean=new Person("張三",19); XStream xstream = new XStream(); xstream.alias("人", Person.class);//為類名節點重命名 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<人> <name>張三</name> <age>19</age></人>Person [name=張三, age=19]
(3)為字段重命名：Xstream.aliasField()方法
public class Test{ public static void main(String[] args) { Person bean=new Person("張三",19); XStream xstream = new XStream(); xstream.aliasField("姓名", Person.class,"name");//為類的字段節點重命名 xstream.aliasField("年齡", Person.class,"age");//為類的字段節點重命名 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<test.Person> <姓名>張三</姓名> <年齡>19</年齡></test.Person>Person [name=張三, age=19]
(4)省略集合根節點：Xstream.addImplicitCollection()方法
class Person{ private String name; private int age; private List friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; }}public class Test{ public static void main(String[] args) { Person bean =new Person("張三",19,"李四","王五","趙六"); XStream xstream = new XStream(); xstream.addImplicitCollection(Person.class, "friends");//省略集合根節點 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<test.Person> <name>張三</name> <age>19</age> <string>李四</string> <string>王五</string> <string>趙六</string></test.Person>Person [name=張三, age=19, friends=[李四, 王五, 趙六]]
(5)把字段節點設置成屬性：Xstream.useAttributeFor()方法
public class Test{ public static void main(String[] args) { Person bean =new Person("張三",19,"李四","王五","趙六"); XStream xstream = new XStream(); xstream.useAttributeFor(Person.class, "name");//把字段節點設置成屬性 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<test.Person name="張三"> <age>19</age> <friends class="java.util.Arrays$ArrayList"> <a class="string-array"> <string>李四</string> <string>王五</string> <string>趙六</string> </a> </friends></test.Person>Person [name=張三, age=19, friends=[李四, 王五, 趙六]]
(6)隱藏字段：xstream.omitField()方法
public class Test{ public static void main(String[] args) { Person bean =new Person("張三",19,"李四","王五","趙六"); XStream xstream = new XStream(); xstream.omitField(Person.class, "friends");//把字段節點隱藏 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<test.Person> <name>張三</name> <age>19</age></test.Person>Person [name=張三, age=19, friends=null]
4.Xstream注解的使用
(1)設置Xstream應用注解
使用Xstream注解前需要對Xstream進行配置，可以使用兩種方式：應用某個JavaBean類的注解或自動使用JavaBean類的注解。代碼如下：
XStream xstream = new XStream();xstream.processAnnotations(Person.class);//應用Person類的注解xstream.autodetectAnnotations(true);//自動檢測注解
(2)重命名注解：@XStreamAlias()
@XStreamAlias("人")class Person{ @XStreamAlias("姓名") private String name; @XStreamAlias("年齡") private int age; @XStreamAlias("朋友") private List friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; }}
程序運行結果：
<人> <姓名>張三</姓名> <年齡>19</年齡> <朋友 class="java.util.Arrays$ArrayList"> <a class="string-array"> <string>李四</string> <string>王五</string> <string>趙六</string> </a> </朋友></人>Person [name=張三, age=19, friends=[李四, 王五, 趙六]]
(3)省略集合根節點：@XStreamImplicit
class Person{ private String name; private int age; //@XStreamImplicit//只隱藏集合根節點 @XStreamImplicit(itemFieldName="朋友")//設置重復的節點名，可能會導致無法反序列化 private List<String> friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; }}
程序運行結果：
<test.Person> <name>張三</name> <age>19</age> <朋友>李四</朋友> <朋友>王五</朋友> <朋友>趙六</朋友></test.Person>Person [name=張三, age=19, friends=[李四, 王五, 趙六]]
(4)把字段節點設置成屬性：@XStreamAsAttribute
class Person{ @XStreamAsAttribute private String name; @XStreamAsAttribute private int age; private List<String> friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; }}
程序運行結果：
<test.Person name="張三" age="19"> <friends class="java.util.Arrays$ArrayList"> <a class="string-array"> <string>李四</string> <string>王五</string> <string>趙六</string> </a> </friends></test.Person>Person [name=張三, age=19, friends=[李四, 王五, 趙六]]
(5)隱藏字段：@XStreamOmitField
class Person{ private String name; private int age; @XStreamOmitField private List<String> friends; public Person(String name, int age, String... friends) { this.name = name; this.age = age; this.friends = Arrays.asList(friends); } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", friends=" + friends + "]"; }}
程序運行結果：
<test.Person> <name>張三</name> <age>19</age></test.Person>Person [name=張三, age=19, friends=null]
(6)設置轉換器：@XStreamConverter()
class Person{ private String name; private int age; @XStreamConverter(value=BooleanConverter.class,booleans={false},strings={"男","女"}) private boolean sex; public Person(String name, int age, boolean sex) { this.name = name; this.age = age; this.sex=sex; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]"; }}
程序運行結果：
<test.Person> <name>張三</name> <age>19</age> <sex>男</sex></test.Person>Person [name=張三, age=19, sex=true]
5.Xstream自定義的轉換器
(1)Xstream自帶的轉換器
Xstream內部有許多轉換器，用於JavaBean對象到XML或Json之間的轉換。這些轉換器的詳細信息網址：http://xstream.codehaus.org/converters.html
(2)使用自定義的轉換器
class Person{ private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; }}public class PersonConverter implements Converter { @Override//定義轉換器能轉換的JavaBean類型 public boolean canConvert(Class type) { return type.equals(Person.class); } @Override//把對象序列化成XML或Json public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) { Person person = (Person) value; writer.startNode("姓名"); writer.setValue(person.getName()); writer.endNode(); writer.startNode("年齡"); writer.setValue(person.getAge()+""); writer.endNode(); writer.startNode("轉換器"); writer.setValue("自定義的轉換器"); writer.endNode(); } @Override//把XML或Json反序列化成對象 public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) { Person person = new Person("",-1); reader.moveDown(); person.setName(reader.getValue()); reader.moveUp(); reader.moveDown(); person.setAge(Integer.parseInt(reader.getValue())); reader.moveUp(); return person; }}public class Test{ public static void main(String[] args) { Person bean =new Person("張三",19); XStream xstream = new XStream(); xstream.registerConverter(new PersonConverter());//注冊轉換器 //序列化 String xml = xstream.toXML(bean); System.out.println(xml); //反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
<test.Person> <姓名>張三</姓名> <年齡>19</年齡> <轉換器>自定義的轉換器</轉換器></test.Person>Person [name=張三, age=19]
(3)常用的轉換器接口與抽象類
SingleValueConverter：單值轉換接口
AbstractSingleValueConverter：單值轉換抽象類
Converter：常規轉換器接口
6.Xstream對象流的使用
(1)Xstream對象輸出流
class Person{ private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; }}public class Test{ public static void main(String[] args) throws IOException { XStream xstream = new XStream(); ObjectOutputStream out = xstream.createObjectOutputStream(System.out); out.writeObject(new Person("張三",12)); out.writeObject(new Person("李四",19)); out.writeObject("Hello"); out.writeInt(12345); out.close(); }}
程序運行結果：
<object-stream> <test.Person> <name>張三</name> <age>12</age> </test.Person> <test.Person> <name>李四</name> <age>19</age> </test.Person> <string>Hello</string> <int>12345</int></object-stream>
注意：
XStream對象流是通過標准java.io.ObjectOutputStream和java.io.ObjectInputStream對象。
因為XML文檔只能有一個根節點,必須包裝在一個序列化的所有元素 額外的根節點。 這個根節點默認 < object-stream > 上面的例子所示。
(2)Xstream對象輸出流
class Person{ private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; }}public class Test{ public static void main(String[] args) throws IOException, ClassNotFoundException { String s="<object-stream><test.Person><name>張三</name><age>12</age></test.Person><int>12345</int></object-stream>"; StringReader reader = new StringReader(s); XStream xstream = new XStream(); ObjectInputStream in = xstream.createObjectInputStream(reader); System.out.println((Person) in.readObject()); System.out.println(in.readInt()); }}
程序運行結果：
Person [name=張三, age=12]12345
7.Xstream持久化API
(1)保存JavaBean對象
class Person{ private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; }}public class Test{ public static void main(String[] args) throws IOException, ClassNotFoundException { PersistenceStrategy strategy = new FilePersistenceStrategy(new File("D:\\tmp")); List list = new XmlArrayList(strategy); list.add(new Person("張三",13));//保存數據 list.add(new Person("李四",21)); list.add(new Person("王五",17)); }}
程序運行結果：
如果我們檢查D:\tmp目錄,有三個文件:int@0.xml、int@1.xml、int@2.xml；每個對象都被序列化到XML文件里。
(2)讀取並刪除JavaBean對象
public class Test{ public static void main(String[] args) throws IOException, ClassNotFoundException { PersistenceStrategy strategy = new FilePersistenceStrategy(new File("D:\\tmp")); List list = new XmlArrayList(strategy); for (Iterator it = list.iterator(); it.hasNext();) { System.out.println((Person) it.next()); it.remove();//刪除對象序列化文件 } }}
程序運行結果：
Person [name=張三, age=13]Person [name=李四, age=21]Person [name=王五, age=17]
8.Xstream操作Json
(1)Xstream序列化Json的重命名
@XStreamAlias("人")class Person{ @XStreamAlias("姓名") private String name; @XStreamAlias("年齡") private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; }}public class Test{ public static void main(String[] args) { Person bean=new Person("張三",19); XStream xstream = new XStream(new JettisonMappedXmlDriver());//設置Json解析器 xstream.autodetectAnnotations(true); //Json序列化 String xml = xstream.toXML(bean); System.out.println(xml); //Json反序列化 bean=(Person)xstream.fromXML(xml); System.out.println(bean); }}
程序運行結果：
{"人":{"姓名":"張三","年齡":19}}Person [name=張三, age=19]
注意：Xstream序列化Json的重命名的方式與其序列化成XML的方式一樣！
(2)去掉序列化Json的根節點
class Person{ private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person [name=" + name + ", age=" + age + "]"; }}public class Test00{ public static void main(String[] args) { Person bean=new Person("張三",19); XStream xstream = new XStream(new JsonHierarchicalStreamDriver() { public HierarchicalStreamWriter createWriter(Writer writer) { return new JsonWriter(writer, JsonWriter.DROP_ROOT_MODE); } }); //Json序列化 String xml = xstream.toXML(bean); System.out.println(xml); }}
程序運行結果：
{ "name": "張三", "age": 19 }
注意：去掉根節點后的Json串是不能反序列化的，因為XStream 不知道它的類型。
(3)Json的解析器區別
前面兩個例子使用了不同的Json解析器，這里說明他們的不同之處：
- JettisonMappedXmlDriver：是支持序列化和反序列化Json的。
- JsonHierarchicalStreamDriver：只支持序列化，不支持反序列化。
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