记录注解@MappedSuperclass和@XmlAccessorType

默认情况下，只有public 属性才会绑定到xml元素

package com.test;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="MyRootElement")
public class AccessorType {
    
    public String name;
    private String address;
    
    public void setName(String name) {
        this.name = name;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public static void main(String[] args) throws Exception {
        AccessorType root = new AccessorType();
        root.setName("ROSS");
        root.setAddress("GZ");
        
        JAXBContext context = JAXBContext.newInstance(AccessorType.class);
        Marshaller m = context.createMarshaller();
        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        m.marshal(root, System.out);
    }   
}

输出如下，可以看到只有public的name被绑定了，而private的address没有。

    ROSS

使用@XmlAccessorType(XmlAccessType.FIELD)可以让所有member都被绑定

package com.test;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="MyRootElement")
@XmlAccessorType(XmlAccessType.FIELD)
public class AccessorType {
    
    public String name;
    private String address;
    
    public void setName(String name) {
        this.name = name;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public static void main(String[] args) throws Exception {
        AccessorType root = new AccessorType();
        root.setName("ROSS");
        root.setAddress("GZ");
        
        JAXBContext context = JAXBContext.newInstance(AccessorType.class);
        Marshaller m = context.createMarshaller();
        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        m.marshal(root, System.out);
    }
}

输出

    ROSS
    
GZ

除了绑定member，还可以用@XmlAccessorType(XmlAccessType.PROPERTY)绑定getter/setter 对

package com.test;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="MyRootElement")
@XmlAccessorType(XmlAccessType.PROPERTY)
public class AccessorType {
    
    public String name;
    private String address;
    
    public void setName(String name) {
        this.name = name;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public static void main(String[] args) throws Exception {
        AccessorType root = new AccessorType();
        root.setName("ROSS");
        root.setAddress("GZ");
        
        JAXBContext context = JAXBContext.newInstance(AccessorType.class);
        Marshaller m = context.createMarshaller();
        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
        m.marshal(root, System.out);
    }
    public String getNameAddress() {
        return name + " " + address;
    }
    public void setNameAddress(String nameAddress) {}
}

输出

    ROSS GZ

1.@MappedSuperclass注解使用在父类上面，是用来标识父类的

2.@MappedSuperclass标识的类表示其不能映射到数据库表，因为其不是一个完整的实体类，但是它所拥有的属性能够隐射在其子类对用的数据库表中

3.@MappedSuperclass标识得嘞不能再有@Entity或@Table注解