在项目中需要使用到复合主键时，通常是将主键相关的字段封装到一个单独的类中，这个类必须实现：
① 序列化接口 ② 覆盖equals和hashcode方法
例如下面这个例子：
主键类SystemPrivilegePK：
public class SystemPrivilegePK implements Serializable{
private String module;
private String privilege;
public SystemPrivilegePK(){}
public SystemPrivilegePK(String module, String privilege) {
this.module = module;
this.privilege = privilege;
}
public String getModule() {
return module;
}
public void setModule(String module) {
this.module = module;
}
public String getPrivilege() {
return privilege;
}
public void setPrivilege(String privilege) {
this.privilege = privilege;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((module == null) ? 0 : module.hashCode());
result = prime * result
+ ((privilege == null) ? 0 : privilege.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final SystemPrivilegePK other = (SystemPrivilegePK) obj;
if (module == null) {
if (other.module != null)
return false;
} else if (!module.equals(other.module))
return false;
if (privilege == null) {
if (other.privilege != null)
return false;
} else if (!privilege.equals(other.privilege))
return false;
return true;
}
}
系统权限类，使用上面的主键类作为主键：
public class SystemPrivilege {
private SystemPrivilegePK id;
private String name;
private Set<PrivilegeGroup> groups = new HashSet<PrivilegeGroup>();
public Set<PrivilegeGroup> getGroups() {
return groups;
}
public void setGroups(Set<PrivilegeGroup> groups) {
this.groups = groups;
}
public SystemPrivilege(){}
public SystemPrivilege(String module, String privilege, String name) {
this.name = name;
}
public SystemPrivilege(SystemPrivilegePK id) {
this.id = id;
}
public SystemPrivilegePK getId() {
return id;
}
public void setId(SystemPrivilegePK id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final SystemPrivilege other = (SystemPrivilege) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
}
在SystemPrivilege的映射文件中这样配置主键：
这样就映射好了复合主键。
