Question

我正在尝试编译我正在编写的Java Web应用程序，并且我遇到编译错误，我不知道该怎么做。从谷歌搜索我发现，我发现{{3问题，但提问者正在使用EJB，而我的错误是在JPA实体类中。

这是maven构建错误。

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3.988s
[INFO] Finished at: Mon Jun 24 02:39:51 UTC 2013
[INFO] Final Memory: 15M/247M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.3.2:compile (default-compile) on project donebox: Compilation failure: Compilation failure:
[ERROR] /home/cl-server/builder/tomcat-ide-builder/temp/build-1236514164814552082/src/main/java/net/donebox/accounts/User.java:[50,4] error: annotation type not applicable to this kind of declaration
[ERROR] /home/cl-server/builder/tomcat-ide-builder/temp/build-1236514164814552082/src/main/java/net/donebox/accounts/User.java:[60,4] error: annotation type not applicable to this kind of declaration
[ERROR] /home/cl-server/builder/tomcat-ide-builder/temp/build-1236514164814552082/src/main/java/net/donebox/accounts/Role.java:[53,4] error: annotation type not applicable to this kind of declaration
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

这是我的用户类文件。

package net.donebox.accounts;
import java.io.Serializable;
import java.util.UUID;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.Basic;
import javax.persistence.Cacheable;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.GeneratedValue;
import javax.persistence.Table;
import javax.persistence.Column;
import javax.persistence.Index;
import javax.persistence.ManyToMany;
import javax.persistence.JoinTable;

import org.apache.shiro.crypto.hash.Sha256Hash;
import org.apache.shiro.crypto.RandomNumberGenerator;
import org.apache.shiro.crypto.SecureRandomNumberGenerator;

@Entity
@Table(name="users")
public class User {

    private UUID id;
    private String username;
    private String email;
    private String password;
    private Set<Role> roles = new HashSet<Role>();


    @Id
    @GeneratedValue
    public UUID getId() {
        return id;
    }

    public void setId() {
        this.id = UUID.randomUUID();
    }

    /**
     * Returns the username associated with this user account;
     *
     * @return the username associated with this user account;
     */
    @Basic
    @Column(length=100)
    @Index(name="idx_users_username", columnList="username") //Error here.
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @Basic
    @Index(name="idx_users_email", columnList="email") // And here.
    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    /**
     * Returns the password for this user.
     *
     * @return this user's password
     */
    @Basic(optional=false)
    @Column(length=255)
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }


    @ManyToMany
    @JoinTable(name="users_roles")
    public Set<Role> getRoles() {
        return roles;
    }

    public void setRoles(Set<Role> roles) {
        this.roles = roles;
    }

}

我查看了javax.persistence.Index JavaDoc，我的声明正确，所以我很难过，有人知道我做错了什么吗？感谢您的时间和考虑。

Answer 1

从这里的JavaDoc：http://docs.oracle.com/javaee/7/api/javax/persistence/Index.html，似乎索引注释有@Target(value={})，这意味着它应该被用作复杂注释的一部分，不能直接使用。

从https://blogs.oracle.com/arungupta/entry/jpa_2_1_schema_generation引用，它似乎只能作为JPA注释的一部分使用：“ @Index - 默认情况下会在数据库中生成主键的索引。这个新的注释将会允许在单个或多个列上定义其他索引以获得更好的性能。这被指定为@Table，@ SecondaryTable，@ COLLableTable，@ JoinTable和@TableGenerator 的一部分“

错误：注释类型不适用于此类声明

1 个答案: