前文展示了使用别名更改XML展示内容，在这一节，可以使用注解更简单的更改XML展示。

（1）最简单的注解示例

1. 输出响应消息

package com.favccxx.favsoft.pojo;
public class ResponseMessage {private int messageType;private String messageContent;public ResponseMessage(int messageType, String messageContent){this.messageType = messageType;this.messageContent = messageContent;}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public String getMessageContent() {return messageContent;}public void setMessageContent(String messageContent) {this.messageContent = messageContent;}
}

2. 开始测试

package com.favccxx.favsoft.main;
import com.favccxx.favsoft.pojo.ResponseMessage;
import com.thoughtworks.xstream.XStream;
public class MainAnnotations {public static void main(String[] args) {XStream stream = new XStream();ResponseMessage msg = new ResponseMessage(200, "成功");System.out.println(stream.toXML(msg));}
}

3. 测试结果

<com.favccxx.favsoft.pojo.ResponseMessage><messageType>200</messageType><messageContent>成功</messageContent>
</com.favccxx.favsoft.pojo.ResponseMessage>

4. 使用注解后的输出内容

package com.favccxx.favsoft.pojo;
import com.thoughtworks.xstream.annotations.XStreamAlias;
@XStreamAlias("message")
public class ResponseMessage {@XStreamAlias("type")private int messageType;@XStreamAlias("content")private String messageContent;public ResponseMessage(int messageType, String messageContent){this.messageType = messageType;this.messageContent = messageContent;}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public String getMessageContent() {return messageContent;}public void setMessageContent(String messageContent) {this.messageContent = messageContent;}
}

xstream.processAnnotations(ResponseMessage.class);

<message><type>200</type><content>成功</content>
</message>

（2）使用集合注解

2.1 响应消息对象

package com.favccxx.favsoft.pojo;
import java.util.Arrays;
import java.util.List;
import com.thoughtworks.xstream.annotations.XStreamAlias;
@XStreamAlias("message")
public class ResponseMessage {@XStreamAlias("type")private int messageType;@XStreamAlias("content")private List<String> messageContent;public ResponseMessage(int messageType, String ... messageContent){this.messageType = messageType;this.messageContent = Arrays.asList(messageContent);}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public List<String> getMessageContent() {return messageContent;}public void setMessageContent(List<String> messageContent) {this.messageContent = messageContent;}
}

2.2 开始测试

package com.favccxx.favsoft.main;
import com.favccxx.favsoft.pojo.ResponseMessage;
import com.thoughtworks.xstream.XStream;
public class MainAnnotations {public static void main(String[] args) {XStream xstream = new XStream();xstream.processAnnotations(ResponseMessage.class);ResponseMessage msg = new ResponseMessage(28, "终于爬上来了！","我忘带钥匙了！！！");System.out.println(xstream.toXML(msg));}
}

2.3 输出结果

<message><type>28</type><content class="java.util.Arrays$ArrayList"><a class="string-array"><string>终于爬上来了！</string><string>我忘带钥匙了！！！</string></a></content>
</message>

2.4使用@XStreamImplicit注解将集合标记为隐式集合

package com.favccxx.favsoft.pojo;
import java.util.Arrays;
import java.util.List;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamImplicit;
@XStreamAlias("message")
public class ResponseMessage {@XStreamAlias("type")private int messageType;@XStreamImplicitprivate List<String> messageContent;public ResponseMessage(int messageType, String... messageContent) {this.messageType = messageType;this.messageContent = Arrays.asList(messageContent);}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public List<String> getMessageContent() {return messageContent;}public void setMessageContent(List<String> messageContent) {this.messageContent = messageContent;}
}

2.5 输出结果

<message><type>28</type><string>终于爬上来了！</string><string>我忘带钥匙了！！！</string>
</message>

2.6 在原有注解对象上，对字段进行别名

package com.favccxx.favsoft.pojo;
import java.util.Arrays;
import java.util.List;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamImplicit;
@XStreamAlias("message")
public class ResponseMessage {@XStreamAlias("type")private int messageType;@XStreamImplicit(itemFieldName="dialog")private List<String> messageContent;public ResponseMessage(int messageType, String... messageContent) {this.messageType = messageType;this.messageContent = Arrays.asList(messageContent);}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public List<String> getMessageContent() {return messageContent;}public void setMessageContent(List<String> messageContent) {this.messageContent = messageContent;}
}

2.7 输出内容如下

<message><type>28</type><dialog>终于爬上来了！</dialog><dialog>我忘带钥匙了！！！</dialog>
</message>

（3）属性别名

3.1响应消息

package com.favccxx.favsoft.pojo;
import java.util.Arrays;
import java.util.List;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import com.thoughtworks.xstream.annotations.XStreamConverter;
import com.thoughtworks.xstream.annotations.XStreamImplicit;
import com.thoughtworks.xstream.converters.basic.BooleanConverter;
@XStreamAlias("message")
public class ResponseMessage {@XStreamAlias("type")@XStreamAsAttributeprivate int messageType;@XStreamImplicit(itemFieldName = "dialog")private List<String> messageContent;@XStreamAsAttribute@XStreamConverter(value = BooleanConverter.class, booleans = { false }, strings = { "yes", "no" })private boolean important;public ResponseMessage(int messageType, boolean important, String... messageContent) {this.messageType = messageType;this.messageContent = Arrays.asList(messageContent);this.important = important;}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public List<String> getMessageContent() {return messageContent;}public void setMessageContent(List<String> messageContent) {this.messageContent = messageContent;}
}

3.2输出内容

<message type="28" important="yes"><dialog>终于爬上来了！</dialog><dialog>我忘带钥匙了！！！</dialog>
</message>

（4）所有字段变为文本，值得注意的是，转换为文本的内容，只能是String类型的，因为转换器是StringValueConvertor。

package com.favccxx.favsoft.pojo;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamConverter;
import com.thoughtworks.xstream.converters.basic.BooleanConverter;
import com.thoughtworks.xstream.converters.extended.ToAttributedValueConverter;
@XStreamAlias("message")
@XStreamConverter(value = ToAttributedValueConverter.class, strings = { "messageContent" })
public class ResponseMessage {@XStreamAlias("type")private int messageType;@XStreamAlias("content")private String messageContent;@XStreamConverter(value = BooleanConverter.class, booleans = { false }, strings = { "yes", "no" })private boolean important;public ResponseMessage(int messageType, boolean important, String messageContent) {this.messageType = messageType;this.messageContent = messageContent;this.important = important;}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public String getMessageContent() {return messageContent;}public void setMessageContent(String messageContent) {this.messageContent = messageContent;}public boolean isImportant() {return important;}public void setImportant(boolean important) {this.important = important;}
}

<message type="200" important="yes">今天星期五</message>

（5）省略字段

package com.favccxx.favsoft.pojo;
import java.util.Arrays;
import java.util.List;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamConverter;
import com.thoughtworks.xstream.annotations.XStreamImplicit;
import com.thoughtworks.xstream.annotations.XStreamOmitField;
import com.thoughtworks.xstream.converters.basic.BooleanConverter;
@XStreamAlias("message")
public class ResponseMessage {@XStreamOmitFieldprivate int messageType;@XStreamImplicit(itemFieldName="content")private List<String> messageContent;@XStreamConverter(value = BooleanConverter.class, booleans = { false }, strings = { "yes", "no" })private boolean important;public ResponseMessage(int messageType, boolean important, String... messageContent) {this.messageType = messageType;this.important = important;this.messageContent = Arrays.asList(messageContent);}public int getMessageType() {return messageType;}public void setMessageType(int messageType) {this.messageType = messageType;}public List<String> getMessageContent() {return messageContent;}public void setMessageContent(List<String> messageContent) {this.messageContent = messageContent;}public boolean isImportant() {return important;}public void setImportant(boolean important) {this.important = important;}
}

<message><content>今天星期五</content><content>明天去逛街</content><important>yes</important>
</message>

（6）自动检测注解

可以使用下述方法自动检测注解，而不用每次都为每个类设置注解

xstream.autodetectAnnotations(true);
// xstream.processAnnotations(ResponseMessage.class);

总结：使用注解比别名方便易用，但是当一个类被多次重用时，使用别名会更明智些。