什麼是關於btrace代碼

Question

在下面的代碼的意思是：

import static com.sun.btrace.BTraceUtils.*; 
import com.sun.btrace.annotations.*; 
import org.jboss.deployment.DeploymentInfo; 

@BTrace public class Trace{ 
    @OnMethod(
     clazz="org.jboss.deployment.SARDeployer", 
     method="parseDocument" 
    ) 
    public static void traceExecute(DeploymentInfo di){ 
     printFields(di); 
    } 

    @OnMethod(
     clazz="java.net.URL", 
     method="openConnection", 
     location=@Location(Kind.RETURN) 
    ) 
    public static void resolveEntity(@Self Object instance){ 
    String protocol = str(get(field("java.net.URL", "protocol"),instance)); 
    String file = str(get(field("java.net.URL", "file"),instance)); 
    if(startsWith(protocol,"http") && (endsWith(file,".xsd") || endsWith(file,".dtd"))){ 
     String authority = str(get(field("java.net.URL", "authority"),instance)); 
     String path = str(get(field("java.net.URL", "path"),instance)); 
     println("====================================="); 
     print(protocol); 
     print("://"); 
     print(authority); 
     print(path); 
     println(" not found!"); 
     println("who call:"); 
     jstack(); 
    } 
    } 
} 

這是什麼意思：get(field("java.net.URL", "authority"),instance)？

請參閱我的文檔。

Answer 1

field("java.net.URL", "authority")將安全地從類檢索名爲權威領域的java.net.URL

get(field, instance)反思中獲得指定實例給定場的價值。

Javadoc for BTraceUtils是一個很好的起點。