Java中的Provider getProperty（）方法及其示例-yiteyi-C++库

这个 getProperty（） 方法 JAVA安全供应商 类用于在此属性列表中搜索具有指定键的属性。如果在该属性列表中找不到该键，则会递归地检查默认属性列表及其默认值。如果找不到属性，该方法将返回null。

null

语法：

public String getProperty(String key)

参数： 这种方法需要 属性密钥 作为参数。

返回值： 此方法返回 此属性列表中的值 使用指定的键值或 无效的 如果找不到该属性。

下面是一些例子来说明 getProperty（） 方法：

例1：

                     // Java program to demonstrate                   
                     // getProperty() method                   
                             
                     import                               java.security.*;                   
                     import                               java.util.*;                   
                             
                     public                               class                               GFG1 {                   
                                         public                               static                               void                               main(String[] argv)                               throws                               Exception                   
                                         {                   
                                         // Declaring int values                   
                                         int                               i =                               10                               ;                   
                             
                                         try                               {                   
                                         // creating the object of  KeyPairGenerator                   
                                         KeyPairGenerator sr = KeyPairGenerator.getInstance(                               "DSA"                               ,                               "SUN"                               );                   
                             
                                         // getting the Provider of the KeyPairGenerator sr                   
                                         // by using method getProvider()                   
                                         Provider provider = sr.getProvider();                   
                             
                                         // Declaring the variable of set<Map> type                   
                                         Set<Object> set;                   
                             
                                         // getting unmodifiable Set view of the property entries                   
                                         set = provider.keySet();                   
                             
                                         // Creating the object of iterator to iterate set                   
                                         Iterator iter = set.iterator();                   
                             
                                         while                               (i >                               0                               ) {                   
                             
                                         // getting the mapped value in element                   
                                         // using getProperty() method                   
                                         String property = provider.getProperty((String)iter.next());                   
                             
                                         // printing the property of specified key                   
                                         System.out.println(                               "value is : "                               + property);                   
                                         i--;                   
                                         }                   
                                         }                   
                             
                                         catch                               (NoSuchAlgorithmException e) {                   
                             
                                         System.out.println(                               "Exception thrown : "                               + e);                   
                                         }                   
                                         }                   
                     }                   

输出：

value is : SHA1withDSA
value is : SHA1withDSA
value is : SHA1withDSA
value is : Software
value is : sun.security.provider.JavaKeyStore$DualFormatJKS
value is : SHA
value is : sun.security.provider.SHA
value is : sun.security.provider.JavaKeyStore$CaseExactJKS
value is : Software
value is : sun.security.provider.DSA$SHA256withDSA

例2：

                     // Java program to demonstrate                   
                     // getProperty() method                   
                             
                     import                               java.security.*;                   
                     import                               java.util.*;                   
                             
                     public                               class                               GFG1 {                   
                                         public                               static                               void                               main(String[] argv)                               throws                               Exception                   
                                         {                   
                                         // Declaring int values                   
                                         int                               i =                               10                               ;                   
                             
                                         try                               {                   
                                         // creating the object of  KeyPairGenerator                   
                                         KeyPairGenerator sr = KeyPairGenerator.getInstance(                               "DSA"                               ,                               "SUN"                               );                   
                             
                                         // getting the Provider of the KeyPairGenerator sr                   
                                         // by using method getProvider()                   
                                         Provider provider = sr.getProvider();                   
                             
                                         // getting the mapped value in element                   
                                         // using getProperty() method                   
                                         System.out.println(                               "Trying to search for unspecified key"                               );                   
                                         String property = provider.getProperty(                               "geeks"                               );                   
                             
                                         // printing the property of specified key                   
                                         System.out.println(                               "value is : "                               + property);                   
                                         }                   
                             
                                         catch                               (NoSuchAlgorithmException e) {                   
                             
                                         System.out.println(                               "Exception thrown : "                               + e);                   
                                         }                   
                                         }                   
                     }                   

输出：

Trying to search for unspecified key
value is : null

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