小编Bij*_*jou的帖子

那是什么意思？

在一个项目的说明中,它说"冻结Rails宝石".这与冻结Rails版本有什么不同？

什么是冷冻的？

我还不清楚Java中注释的目的.最初我认为他们只是作为文档.但是从Google App Engine数据存储区查看此文档,我不太确定.@PersistenceCapable(identityType = IdentityType.APPLICATION)看起来更像是方法签名.

这种注释的目的是什么？它有什么作用？

import java.util.Date;
import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.IdentityType;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Employee {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Long id;

    @Persistent
    private String firstName;

    @Persistent
    private String lastName;

    @Persistent
    private Date hireDate;

    public Employee(String firstName, String lastName, Date hireDate) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.hireDate = hireDate;
    }

    // Accessors for the fields.  JDO doesn't use these, but your application does.

    public …