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JAVA Bean和XML之間的相互轉換 - XStream簡單入門

• 背景介紹
• XStream的簡介
• 注解簡介
• 應用實例

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背景介紹

我們在工作中經常 遇到文件解析為數據或者數據轉化為xml文件的情況,之前我一直采用的方式都是手動的來解析或拼接XML文件,這個做法固然是可以的,但是代碼部分會顯得非常臃腫,所以就查找了相關的資料,發現了一個名為XStream的類庫可以做這件事,下面我們來看一下.

XStream的簡介

官網地址:http://x-stream.github.io/

從官網介紹我們能看到以下幾個特性:

• 易用
• 不需要Mapping文件
  
  不需要額外提供Mapping文件即可完成映射
• 高性能
  
  高速且低內存消耗
• 整潔的XML文件
  
  生成的XML的相當簡潔
• 不需要修改對象
  
  可以序列化private修飾的屬性,且不需要提供get/set方法
• 完整的對象結構支持
  
  支持循環引用情況下的輸出
• 兼容其他的XML API
  
  可以對任何的樹形結構進行序列化或反序列化
• 可以自定義的轉換策略
  
  可以通過策略的注冊,允許自定義特定類型的轉化為XML的樣式
• 安全的框架
  
  對未分組的類型進行精細化的控制,防止輸入錯誤而導致的安全問題
• 良好的異常反饋
  
  當XML文件格式錯誤的時候,能夠提供診斷信息幫助處理
• 多樣的輸出格式
  
  不止是XML他還支持JSON及其變種

注解簡介

從XStream的官網我們了解到,XStream不需要Mapping文件就能完成JavaBean和XML之間的轉變,但大部分時候我們需要對生成的XML文件進行定制,name我們需要了解XStream提供的注解

注解作用適用范圍

@XStreamAlias	設置別名	類或屬性
@XStreamImplicit	忽略屬性	集合類型的屬性
@XStreamAsAttribute	將JavaBean轉換成節點屬性	屬性
@XStreamOmitField	忽略屬性	屬性
@XStreamConverter	注入轉換器	類

應用實例

首先在我們的項目中加入依賴:

<dependency><groupId>com.thoughtworks.xstream</groupId><artifactId>xstream</artifactId><version>1.4.11.1</version> </dependency>

假定環境為Computer和CPU兩個類:

public class Computer implements Serializable {private static final long serialVersionUID = 567119860357020081L;private String name;private String brand;private List<CPU> processors;public Computer() {}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public List<CPU> getProcessors() {return processors;}public void setProcessors(List<CPU> processors) {this.processors = processors;} } public class CPU implements Serializable {private static final long serialVersionUID = -718438777162957779L;private String name;private String generation;public CPU() {}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getGeneration() {return generation;}public void setGeneration(String generation) {this.generation = generation;} }

寫一個測試方法:

import com.hykj.facheck.entity.CPU; import com.hykj.facheck.entity.Computer; import com.thoughtworks.xstream.XStream; import com.thoughtworks.xstream.io.xml.DomDriver;import java.util.ArrayList; import java.util.List;public class XStreamTest {public static void main(String[] args) {List<CPU> cpuList = new ArrayList<>();CPU cpu1 = new CPU();cpu1.setGeneration("8-i5-K");cpu1.setName("第一個");cpuList.add(cpu1);CPU cpu2 = new CPU();cpu2.setGeneration("8-i5-U");cpu2.setName("第二個");cpuList.add(cpu2);Computer computer = new Computer();computer.setBrand("huawei");computer.setName("wej-laptop");computer.setProcessors(cpuList);XStream xstream = new XStream(new DomDriver());xstream.ignoreUnknownElements();xstream.processAnnotations(Computer.class);//javabean to xmlString xml = xstream.toXML(computer);System.out.println(xml);//xml to javabeanComputer computerFromXml = (Computer) xstream.fromXML(xml);System.out.println(computer.getName());} }

運行程序,控制臺打結果如下:

Connected to the target VM, address: '127.0.0.1:53977', transport: 'socket' <com.hykj.facheck.entity.Computer><name>wej-laptop</name><brand>huawei</brand><processors><com.hykj.facheck.entity.CPU><name>第一個</name><generation>8-i5-K</generation></com.hykj.facheck.entity.CPU><com.hykj.facheck.entity.CPU><name>第二個</name><generation>8-i5-U</generation></com.hykj.facheck.entity.CPU></processors> </com.hykj.facheck.entity.Computer> Security framework of XStream not initialized, XStream is probably vulnerable. wej-laptop Disconnected from the target VM, address: '127.0.0.1:53977', transport: 'socket'Process finished with exit code 0

也就是說這樣就可以用了,很棒棒
但是這個XML和我們的需求不太一樣,我們加上注解,代碼變成了這樣:

import com.thoughtworks.xstream.annotations.XStreamAlias;import java.io.Serializable; import java.util.List;@XStreamAlias("my") public class Computer implements Serializable {private static final long serialVersionUID = 567119860357020081L;private String name;private String brand;@XStreamAlias("cpuList")private List<CPU> processors;public Computer() {}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public List<CPU> getProcessors() {return processors;}public void setProcessors(List<CPU> processors) {this.processors = processors;} } import com.thoughtworks.xstream.annotations.XStreamAlias;import java.io.Serializable;@XStreamAlias("oneCpu") public class CPU implements Serializable {private static final long serialVersionUID = -718438777162957779L;private String name;private String generation;public CPU() {}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getGeneration() {return generation;}public void setGeneration(String generation) {this.generation = generation;} }

測試方法不變,結果如下:

Connected to the target VM, address: '127.0.0.1:54181', transport: 'socket' <my><name>wej-laptop</name><brand>huawei</brand><cpuList><oneCpu><name>第一個</name><generation>8-i5-K</generation></oneCpu><oneCpu><name>第二個</name><generation>8-i5-U</generation></oneCpu></cpuList> </my> Security framework of XStream not initialized, XStream is probably vulnerable. wej-laptop Disconnected from the target VM, address: '127.0.0.1:54181', transport: 'socket'Process finished with exit code 0

這個XML就很舒服啦.
我們載試一下循環引用的情況吧,代碼如下:

import com.thoughtworks.xstream.annotations.XStreamAlias;import java.io.Serializable; import java.util.List;@XStreamAlias("my") public class Computer implements Serializable {private static final long serialVersionUID = 567119860357020081L;private String name;private String brand;@XStreamAlias("cpuList")private List<CPU> processors;public Computer() {}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public List<CPU> getProcessors() {return processors;}public void setProcessors(List<CPU> processors) {this.processors = processors;} } import com.thoughtworks.xstream.annotations.XStreamAlias;import java.io.Serializable;@XStreamAlias("oneCpu") public class CPU implements Serializable {private static final long serialVersionUID = -718438777162957779L;private String name;private String generation;private Computer computer;public CPU() {}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getGeneration() {return generation;}public void setGeneration(String generation) {this.generation = generation;}public Computer getComputer() {return computer;}public void setComputer(Computer computer) {this.computer = computer;} } import com.thoughtworks.xstream.XStream; import com.thoughtworks.xstream.io.xml.DomDriver;import java.util.ArrayList; import java.util.List;public class XStreamTest {public static void main(String[] args) {Computer computer = new Computer();computer.setBrand("huawei");computer.setName("wej-laptop");List<CPU> cpuList = new ArrayList<>();CPU cpu1 = new CPU();cpu1.setGeneration("8-i5-K");cpu1.setName("第一個");cpu1.setComputer(computer);cpuList.add(cpu1);CPU cpu2 = new CPU();cpu2.setGeneration("8-i5-U");cpu2.setName("第二個");cpuList.add(cpu2);cpu1.setComputer(computer);computer.setProcessors(cpuList);XStream xstream = new XStream(new DomDriver());xstream.ignoreUnknownElements();xstream.processAnnotations(Computer.class);//javabean to xmlString xml = xstream.toXML(computer);System.out.println(xml);//xml to javabeanComputer computerFromXml = (Computer) xstream.fromXML(xml);System.out.println(computer.getName());} }

運行一下,先查看是否構成循環引用:

確認有循環引用,繼續運行代碼,控制臺打印如下:

Connected to the target VM, address: '127.0.0.1:54221', transport: 'socket' <my><name>wej-laptop</name><brand>huawei</brand><cpuList><oneCpu><name>第一個</name><generation>8-i5-K</generation><computer reference="../../.."/></oneCpu><oneCpu><name>第二個</name><generation>8-i5-U</generation></oneCpu></cpuList> </my> Security framework of XStream not initialized, XStream is probably vulnerable. wej-laptop Disconnected from the target VM, address: '127.0.0.1:54221', transport: 'socket'Process finished with exit code 0

可以看到生成的XML中采用類似路徑的reference屬性來標識了位置,實際上我們一般是需要忽略這個屬性的,采用@XStreamOmitField注解就好了.

轉載于:https://www.cnblogs.com/zichuanhong/p/10355066.html

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