java.security.Provider类的get()方法用于返回指定键所映射的值;如果此映射不包含该键的映射,则返回null。
更正式地说,如果此映射包含从键k到值v的映射,使得(key.equals(k)),则此方法返回v;否则,此方法返回v。否则返回null。 (最多可以有一个这样的映射。)
用法:
public Object get(Object key)
参数:此方法将键作为要返回其关联值的参数。
返回值:此方法返回指定键映射到的值;如果此映射不包含键的映射,则返回null。
下面是说明get()方法的示例:
示例1:
// Java program to demonstrate
// get() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
// Declaring int values
int i = 10, j = 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 get() method
Object element = provider.get(iter.next());
// printing the mapped value
System.out.println("value is : " + element);
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
示例2:
// Java program to demonstrate
// get() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
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 get() method
System.out.println("Trying to get the value of an unmapped key");
Object element = provider.get("geeks");
// printing the mapped value
System.out.println("value is : " + element);
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Trying to get the value of an unmapped key value is : null
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注:本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 Provider get() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。