小编Val*_*lva的帖子

我注意到有不同的bean范围,如:

@RequestScoped
@ViewScoped
@FlowScoped
@SessionScoped
@ApplicationScoped

每个人的目的是什么？如何为我的bean选择合适的范围？

我可以在GAE上序列化我的servlet中的List,但我不能反序列化它.我究竟做错了什么？

这是我在GAE中的视频类,它是序列化的:

package legiontube;

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 Video {

    @PrimaryKey
    private String id;

    @Persistent
    private String titulo;

    @Persistent
    private String descricao;

    @Persistent
    private Date date;

    public Video(){};

 public Video(String id, String titulo, String descricao, Date date) {
  //super();
  this.id = id;
  this.titulo = titulo;
  this.descricao = descricao;
  this.date = date;
 }

 public String getId() {
  return id;
 }

 public void setId(String id) {
  this.id = id; …

我有这个结构:

WebContent
    resources
        components
            top.xhtml

    company
        about_us.xhtml

    index.xhtml

top.xhtml是一个组件,即在使用index.xthml与about_us.xhtml太.

top.xhtml

<ul>
    <li><a href="index.xhtml">Home</a></li>
    <li><a href="company/about_us.xhtml">About us</a></li>
    ...
</ul>

所以我的问题是,当当前页面是index.xhtml组件正确生成URL时,但当当前页面时about_us.xhtml,它会生成错误的URL.我不能使用相对路径,因为它也会生成错误的URL.我认为这是因为组件基于*.xhtml页面的当前路径.

我能找到的唯一解决方案是:

<ul>
    <li><a href="${pageContext.request.contextPath}/webname/index.xhtml">Home</a></li>
    <li><a href="${pageContext.request.contextPath}/webname/about_us.xhtml">About us</a></li>
    ...
</ul>

但我认为根本不是"优雅".有任何想法吗？

即使用户知道某些页面的URL,我也想阻止访问某些页面.例如,/localhost:8080/user/home.xhtml(需要先登录)如果没有记录则重定向到/index.xhtml.

在JSF中如何做到这一点？我在Google上读到需要过滤器,但我不知道该怎么做.

我正在使用亚马逊的EC2来托管一个用JSP构建的网站:

http://ec2-50-17-144-64.compute-1.amazonaws.com:8080/p2p

我买了这个域名:www.p2pbrasil.com

如何将www.p2pbrasil.com重定向到我在Amazon EC2中的网站？

当有人输入www.p2pbrasil.com时,它会重定向到 http://ec2-50-17-144-64.compute-1.amazonaws.com:8080/p2p？

我有这些表:

我的意图是:用户可以是a company或a person但是每个人都有一些共同点,作为用户名是email和password,所以我使用JPA工具从表中生成实体,结果如下:

public class User implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;

    private String email;

    private String password;

    private int reputation;

    //bi-directional one-to-one association to Company
    @OneToOne(mappedBy="user", cascade={CascadeType.ALL})
    private Company company;

    //bi-directional many-to-one association to Location
    @OneToMany(mappedBy="user")
    private List<Location> locations;

    //bi-directional one-to-one association to Person
    @OneToOne(mappedBy="user")
    private Person person;

    //bi-directional many-to-one association to Product
    @OneToMany(mappedBy="user")
    private List<Product> products;

    //bi-directional many-to-one association to UserType
    @ManyToOne …

我希望在用户登录系统后控制访问权限.

例如:

administrator : can add, delete and give rights to employee
employee : fill forms only
...

因此,在知道用户具有哪些权限后,检查数据库,我想限制该用户可以看到和执行的操作.有一个简单的方法吗？

编辑

@WebFilter("/integra/user/*")
public class LoginFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {    
        HttpServletRequest req = (HttpServletRequest) request;
        Authorization authorization = (Authorization) req.getSession().getAttribute("authorization");

        if (authorization != null && authorization.isLoggedIn()) {
            // User is logged in, so just continue request.
            chain.doFilter(request, response);
        } else {
            // User is not logged in, so redirect to …

我正在尝试执行以下代码:

private void crop(HttpServletRequest request, HttpServletResponse response){
    int x = 100;
    int y = 100;
    int w = 3264;
    int h = 2448;

    String path = "D:images\\upload_final\\030311175258.jpg";

    BufferedImage image = ImageIO.read(new File(path));
    BufferedImage out = image.getSubimage(x, y, w, h);

    ImageIO.write(out, "jpg", new File(path));

}

但一直给我同样的错误:

java.awt.image.RasterFormatException: (x + width) is outside of Raster
sun.awt.image.ByteInterleavedRaster.createWritableChild(ByteInterleavedRaster.java:1230)
    java.awt.image.BufferedImage.getSubimage(BufferedImage.java:1156)

我的错误在哪里？

我想存储birthdate所以我选择date了MySQL,当我在我的数据库中创建我的实体时,结果如下:

import java.util.Date;

    // ..code
    @NotNull(message="fill you birthdate")
    @Temporal(TemporalType.DATE)
    private Date birthdate;

但是当我试图坚持它时,它给了我这个错误:

在回调事件上执行自动Bean验证时违反了Bean验证约束:'prePersist'.有关详细信息,请参阅嵌入式ConstraintViolations.

我在这做错了什么？我正在阅读有关谷歌定义时区的内容,我来自巴西,我应该怎么做？

编辑

package entity;

import java.io.Serializable;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

import org.hibernate.validator.constraints.Email;

import java.util.Date;
import java.util.List;


/**
 * The persistent class for the user database table.
 * 
 */
@Entity
public class User implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;

    @Temporal(TemporalType.DATE)
    private Date birthdate;

    @NotNull(message="informe seu e-mail")
    @Email(message="e-mail inválido")
    private String email;

    @NotNull(message="informe …

我试图阻止一个线程,但我不能这样做:

public class Middleware {

public void read() {
    try {
        socket = new Socket("192.168.1.8", 2001);

        // code .. 

        Scan scan = new Scan();
        thread = new Thread(scan);
        thread.start();

    } catch (UnknownHostException ex) {
        ex.printStackTrace();

    } catch (IOException ex) {
        ex.printStackTrace();
    }
}

class Scan extends Thread {

    public void run() {

        while (true) {
            try {
            // my code goes here

            } catch (IOException ex) {
                thread.currentThread().interrupt();
            }
        }
    }
}

public void stop() {
    Thread.currentThread().interrupt();
}

// get …