小编Joh*_*ohn的帖子

我正在阅读有关部分和细分的内容.似乎您可以列出部分和段之间的映射,如下所示.

$ readelf -l test

Elf file type is EXEC (Executable file)
Entry point 0x8048330
There are 9 program headers, starting at offset 52

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  PHDR           0x000034 0x08048034 0x08048034 0x00120 0x00120 R E 0x4
  INTERP         0x000154 0x08048154 0x08048154 0x00013 0x00013 R   0x1
      [Requesting program interpreter: /lib/ld-linux.so.2]
  LOAD           0x000000 0x08048000 0x08048000 0x0065c 0x0065c R E 0x1000
  LOAD           0x000f14 0x08049f14 0x08049f14 0x00104 0x00110 RW  0x1000
  DYNAMIC        0x000f28 0x08049f28 0x08049f28 0x000c8 0x000c8 RW  0x4 …

我无法识别stat抛出的错误.以下程序读取目录中的所有文件并打印文件名:

DIR *dp;
struct dirent *dirp;
struct stat sb;

if((dp = opendir(argv[1]))==NULL)
{
    perror("can't open dir");
}
while((dirp = readdir(dp))!=NULL)
{
    if (stat(dirp->d_name, &sb) == -1) {
        perror("stat");
    }   
    printf("File name:               %s \n",dirp->d_name);
}

样本输出:

/home/eipe
stat error: No such file or directory
File name:               copyofsample 
File name:               a.out 
File name:               . 
stat error: No such file or directory
File name:               udpclient.c 
File name:               .. 
stat error: No such file or directory
File name:               client.c 
stat error: No such file …

我在shell中读到,true命令返回0 =>逻辑真.false命令返回1 =>逻辑错误.但是当我跑步时,我得到了惊人的结果.

if [ 0 ]
then
echo "0 is true."
else
echo "0 is false."
fi

if [ 1 ]
then
echo "1 is true."
else
echo "1 is false."
fi

if [ false ]
then
echo "false is true."
else
echo "false is false."
fi

if [ true ]
then
echo "true is true."
else
echo "true is false."
fi

我得到了这些结果.

0是真的.1是真的.错是真的.的确如此.

我做到了

a=1234 
let "a=a+1"

在命令行上,它很好.但是当我在shell脚本中执行相同操作时.它打印出一个"让:未找到"的错误.这是脚本文件.

#!/bin/sh
a=1234;
let "a=a+1";
echo "$a";

谢谢,

作为javascript的初学者,我试图从这里了解Object.create()方法

https://developer-new.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Object/create

在示例代码中,第18行.创建一个accessable属性,其writeable设置为true.我还读到可写只适用于数据描述符.

试过跑,

var o = Object.create(Object.prototype, {
  // foo is a regular "value property"
  foo: { 
    writable:true, configurable:true, value: "hello" 
  },
  // bar is a getter-and-setter (accessor) property
  bar: {
    writable: true,
    configurable: false,
    get: function() { return 10 },
    set: function(value) { console.log("Setting `o.bar` to", value) }
  }
  });
console.log(o); 

我得到invalid property error.

什么时候应该使用像这样的通用多态类型,它的含义是什么？

 1. List<? super Dog> list = new ArrayList<Animal>();
 2. List<? extends Animal> list = new ArrayList<Dog>();
 3. List<?> list = new ArrayList<Dog>();

有人会用这样的东西

List<? super Dog> list = new ArrayList<Dog>();
List<? extends Animal> list = new ArrayList<Animal>();

注意:我理解人们何时使用List<? super Dog>或List<? extends Animal>在方法定义中.但我不明白的是多态泛型类型对象创建.

我的第一个问题 - 是否可以在不使用数字证书的情况下使用https？我的第二个问题 - 我在我的网络应用程序中保护了几页.所以添加了以下内容

<security-constraint>
    <web-resource-collection>
        ......
    </web-resource-collection>
    <auth-constraint>
        ......
    </auth-constraint>
    <user-data-constraint>
        <transport-guarantee>CONFIDENTIAL</transport-guarantee>
    </user-data-constraint>
</security-constraint>

我尝试运行应用程序,并且没有加载ssl的页面.所以我继续创建证书.在server.xml中添加了以下内容？

<Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
       maxThreads="150" 
       scheme="https" 
       secure="true" 
       keystoreFile="C:\Program Files\apache-tomcat-7.0.11-windows-x86\apache-tomcat-7.0.11\.keystore" 
       keystorePass="johneipe"
       clientAuth="optional" 
       sslProtocol="TLS" />

我仍然无法访问这些页面,也无法访问https:// localhost:8443.

是否可以在不修改基类和派生类的情况下调用基类函数？

class Employee {
    public String getName() {
        return "Employee";
    }

    public int getSalary() {
        return 5000;
    }
}

class Manager extends Employee {
    public int getBonus() {
        return 1000;
    }

    public int getSalary() {
        return 6000;
    }
}

class Test {
    public static void main(String[] args) {
        Employee em = new Manager();
        System.out.println(em.getName());
        // System.out.println(em.getBonus());
        System.out.println(((Manager) em).getBonus());
        System.out.println(em.getSalary());
    }
}

输出:员工1000 6000

如何在em对象上调用Employee的getSalary()方法？

list和islice对象都是可迭代的,但为什么会产生这种差异.

r = [1, 2, 3, 4]               
i1, i2 = tee(r)
print [e for e in r if e < 3]
print [e for e in i2]
#[1, 2]
#[1, 2, 3, 4]


r = islice(count(), 1, 5)          
i1, i2 = tee(r)
print [e for e in r if e < 3]
print [e for e in i2]
#[1, 2]
#[]

似乎没有一种特定的标准方法可以让我在网上找到@DataJpaTest可以正确运行的方法。

@DataJpaTest现在没有使用并且所有测试都使用在服务或控制器级别运行是真的@SpringBootTest吗？

    @Repository
    public interface MyBeanRepository extends JpaRepository<MyBean, Long> { 
    }

    @Configuration
    @EnableJpaRepositories("com.app.repository.*")
    @ComponentScan(basePackages = { "com.app.repository.*" })
    public class ConfigurationRepository { 
    }


    @Entity
    public class MyBean {

        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        @Column(name = "id")
        private Long id;

        @Version
        @Column(name = "version")
        private Integer version;

        @NotNull
        @Size(min = 2)
        private String name;
    }

    @DataJpaTest
    public class MyBeanIntegrationTest {

        @Autowired
        MyBeanRepository myBeanRepository;

        @Test
        public void testMarkerMethod() {
        }

        @Test
        public void testCount() {
            Assertions.assertNotNull(myBeanRepository , "Data …