Java 中的提供者 getProperty()方法,示例
原文:https://www . geesforgeks . org/provider-getproperty-method-in-Java-with-examples/
java.security.Provider 类的 getProperty() 方法用于在该属性列表中搜索具有指定关键字的属性。如果在该属性列表中找不到该键,则递归地检查默认属性列表及其默认值。如果找不到属性,方法将返回 null。
语法:
public String getProperty(String key)
参数:该方法以属性键为参数。
返回值:该方法返回该属性列表中带有指定键值的值,如果没有找到该属性则返回空值。
以下是说明 getProperty() 方法的示例:
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);
}
}
}
Output:
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);
}
}
}
Output:
Trying to search for unspecified key
value is : null
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