Java对象与XML文件互转的几个小技巧(使用jaxb工具类)

野性酷女 2022-07-17 02:15 251阅读 0赞

采用Jaxb工具类实现Java对象与XML文件互转时，有一些注意的地方，记录如下：

1、model类需要加注解 @XmlRootElement 否则报错；

2、如果model类的属性与XML节点名称不同，使用注解 @XmlElement(name="xxx") 指定；【注意】该注解必须加到getter方法上，加到属性上会报错！！！

3、集合类型，使用注解 @XmlElementWrapper 指定其包装类型；并建议同时使用注解 @XmlElement 显式指定其节点名称；

4、日期类型，使用注解 @XmlJavaTypeAdapter 指定日期格式，其参数为Class类型，继承 XmlAdapter 类；

5、数值类型，使用注解 @XmlJavaTypeAdapter 指定数值格式，其参数为Class类型，继承 XmlAdapter 类；

完整示例如下：

@XmlRootElement(name="request")
    public class Group {
    	private Integer groupId;
    	private String groupName;
    	private List students;
    	private Date createTime;
    	private Date endDate;
    	private Double amount;
    	
    	public Integer getGroupId() {
    		return groupId;
    	}
    	public void setGroupId(Integer groupId) {
    		this.groupId = groupId;
    	}
    	
    	@XmlElement(name="group_name")
    	public String getGroupName() {
    		return groupName;
    	}
    	public void setGroupName(String groupName) {
    		this.groupName = groupName;
    	}
    	
    	@XmlElementWrapper(name="students")
    	@XmlElement(name="student")
    	public List getStudents() {
    		return students;
    	}
    	public void setStudents(List students) {
    		this.students = students;
    	}
    	
    	@XmlJavaTypeAdapter(JaxbDateTimeAdapter.class)
    	public Date getCreateTime() {
    		return createTime;
    	}
    	public void setCreateTime(Date createTime) {
    		this.createTime = createTime;
    	}
    	
    	@XmlJavaTypeAdapter(JaxbDateAdapter.class)
    	public Date getEndDate() {
    		return endDate;
    	}
    	public void setEndDate(Date endDate) {
    		this.endDate = endDate;
    	}
    	
    	@XmlJavaTypeAdapter(JaxbNumberAdapter.class)
    	public Double getAmount() {
    		return amount;
    	}
    	public void setAmount(Double amount) {
    		this.amount = amount;
    	}
    }
    
    class JaxbDateTimeAdapter extends XmlAdapter {
    	private static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
    
    	@Override
    	public Date unmarshal(String dateStr) throws Exception {
    		if (dateStr == null) {
    			return null;
    		}
    
    		DateFormat format = new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);
    		return format.parse(dateStr);
    	}
    
    	@Override
    	public String marshal(Date date) throws Exception {
    		DateFormat format = new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT);
    		return format.format(date);
    	}
    }
    
    class JaxbDateAdapter extends XmlAdapter {
    	private static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    
    	@Override
    	public Date unmarshal(String dateStr) throws Exception {
    		if (dateStr == null) {
    			return null;
    		}
    
    		DateFormat format = new SimpleDateFormat(DEFAULT_DATE_FORMAT);
    		return format.parse(dateStr);
    	}
    
    	@Override
    	public String marshal(Date date) throws Exception {
    		DateFormat format = new SimpleDateFormat(DEFAULT_DATE_FORMAT);
    		return format.format(date);
    	}
    }
    
    class JaxbNumberAdapter extends XmlAdapter {
    	@Override
    	public Number unmarshal(String v) throws Exception {
    		if(v == null) {
    			return null;
    		}
    		
    		NumberFormat format = NumberFormat.getCurrencyInstance(Locale.CHINA);
    		return format.parse(v);
    	}
    	
    	@Override
    	public String marshal(Number v) throws Exception {
    		NumberFormat format = NumberFormat.getCurrencyInstance(Locale.CHINA);
    		return format.format(v);
    	}
    }

参考文献：

http://www.cnblogs.com/yjmyzz/p/xstream-jaxb-format-date-and-number.html