Added usetimestamp attribute to Get so that it only downloads a file

via HTTP if the source is newer than the local file.
Submitted by:	Steve Loughran <steve_l@iseran.com>


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@267823 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/BuildException.java

@@ -132,6 +132,18 @@ public class BuildException extends RuntimeException {
 	this.location = location;
     }
 
+    /**
+     * Constructs an exception with the given exception as
+     * a root cause and a location in a file.
+     * @param cause Exception that might have cause this one.
+     * @param location Location in the project file where the error occured.
+     */
+
+    public BuildException(Throwable cause, Location location) {
+        this(cause);
+	this.location = location;
+    }
+
     /**
      * Returns the nested exception.
      */

src/main/org/apache/tools/ant/taskdefs/Expand.java

@@ -61,7 +61,7 @@ import java.util.zip.*;
  * Unzip a file. 
  *
  * @author costin@dnt.ro
- * @author Stefan Bodewig <a href="mailto:stefan.bodewig@megabit.net">stefan.bodewig@megabit.net</a>
+ * @author <a href="mailto:stefan.bodewig@megabit.net">Stefan Bodewig</a>
  */
 public class Expand extends Task {
     private String dest; // req
@@ -81,6 +81,8 @@ public class Expand extends Task {
 
         Touch touch = (Touch) project.createTask("touch");
         touch.setOwningTarget(target);
+        touch.setTaskName(getTaskName());
+        touch.setLocation(getLocation());
         
         File srcF=project.resolveFile(source);
         File dir=project.resolveFile(dest);
@@ -116,7 +118,7 @@ public class Expand extends Task {
 		    }
 
                     if (project.getJavaVersion() != Project.JAVA_1_1) {
-                        touch.setFile(f.getAbsolutePath());
+                        touch.setFile(f);
                         touch.setMillis(ze.getTime());
                         touch.touch();
                     }

src/main/org/apache/tools/ant/taskdefs/Get.java

@@ -57,40 +57,79 @@ package org.apache.tools.ant.taskdefs;
 import org.apache.tools.ant.*;
 import java.io.*;
 import java.net.*;
+import java.util.*;
+
 /**
- * Get a particular source. 
+ * Get a particular file from a URL source. 
+ * Options include verbose reporting, timestamp based fetches and controlling 
+ * actions on failures. NB: access through a firewall only works if the whole 
+ * Java runtime is correctly configured.
  *
  * @author costin@dnt.ro
  */
 public class Get extends Task {
-    private String source; // required
-    private String dest; // required
-    private String verbose = "";
-    String ignoreErrors=null;
+    private URL source; // required
+    private File dest; // required
+    private boolean verbose = false;
+    private boolean useTimestamp = false; //off by default
+    private boolean ignoreErrors = false;
     
     /**
      * Does the work.
      *
-     * @exception BuildException Thrown in unrecovrable error.
+     * @exception BuildException Thrown in unrecoverable error.
      */
     public void execute() throws BuildException {
 	try {
-            URL url = null;
-            try {
-                url = new URL(source);
-            } catch (MalformedURLException e) {
-                throw new BuildException(e.toString());
-            }
 
 	    log("Getting: " + source);
 
-	    File destF=new File(dest);
-	    FileOutputStream fos = new FileOutputStream(destF);
+	    	//set the timestamp to the file date.
+	    long timestamp=0;
+
+            boolean hasTimestamp=false;
+	    if(useTimestamp && dest.exists()) {
+	        timestamp=dest.lastModified();
+                if (verbose)  {
+                    Date t=new Date(timestamp);
+                    log("local file date : "+t.toString());
+                }
+                
+                hasTimestamp=true;
+            }
+	
+            //set up the URL connection
+            URLConnection connection=source.openConnection();
+            //modify the headers
+            //NB: things like user authentication could go in here too.
+            if(useTimestamp && hasTimestamp) {
+                connection.setIfModifiedSince(timestamp);
+            }
+
+            //connect to the remote site (may take some time)
+            connection.connect();
+            //next test for a 304 result (HTTP only)
+            if(connection instanceof HttpURLConnection)  {
+           	HttpURLConnection httpConnection=(HttpURLConnection)connection;
+                if(httpConnection.getResponseCode()==HttpURLConnection.HTTP_NOT_MODIFIED)  {
+                    //not modified so no file download. just return instead
+                    //and trace out something so the user doesn't think that the 
+                    //download happened when it didnt
+                    log("Not modified - so not downloaded");
+                    return; 
+                }
+            }
+
+            //REVISIT: at this point even non HTTP connections may support the if-modified-since
+            //behaviour -we just check the date of the content and skip the write if it is not
+            //newer. Some protocols (FTP) dont include dates, of course. 
+           	
+	    FileOutputStream fos = new FileOutputStream(dest);
 
 	    InputStream is=null;
 	    for( int i=0; i< 3 ; i++ ) {
 		try {
-		    is = url.openStream();
+		    is = connection.getInputStream();
 		    break;
 		} catch( IOException ex ) {
 		    log( "Error opening connection " + ex );
@@ -98,8 +137,10 @@ public class Get extends Task {
 	    }
 	    if( is==null ) {
 		log( "Can't get " + source + " to " + dest);
-		if( ignoreErrors != null ) return;
-		throw new BuildException( "Can't get " + source + " to " + dest);
+		if(ignoreErrors) 
+                    return;
+		throw new BuildException( "Can't get " + source + " to " + dest,
+                                          location);
 	    }
 		
 	    byte[] buffer = new byte[100 * 1024];
@@ -107,25 +148,70 @@ public class Get extends Task {
 	    
 	    while ((length = is.read(buffer)) >= 0) {
 		fos.write(buffer, 0, length);
-		if ("true".equals(verbose)) System.out.print(".");
+		if (verbose) System.out.print(".");
 	    }
-	    if( "true".equals(verbose)) System.out.println();
+	    if(verbose) System.out.println();
 	    fos.close();
 	    is.close();
+           
+            //if (and only if) the use file time option is set, then the 
+            //saved file now has its timestamp set to that of the downloaded file
+            if(useTimestamp)  {
+           	long remoteTimestamp=connection.getLastModified();
+                if (verbose)  {
+                    Date t=new Date(remoteTimestamp);
+                    log("last modified = "+t.toString()
+                   	+((remoteTimestamp==0)?" - using current time instead":""));
+                }
+                if(remoteTimestamp!=0)
+                    touchFile(dest,remoteTimestamp);
+            }
+
+           
+
 	} catch (IOException ioe) {
 	    log("Error getting " + source + " to " + dest );
-	    if( ignoreErrors != null ) return;
-	    throw new BuildException(ioe.toString());
+	    if(ignoreErrors) 
+                return;
+	    throw new BuildException(ioe, location);
 	}
     }
+    
+    /** 
+     * set the timestamp of a named file to a specified time.
+     *
+     * @param filename
+     * @param time in milliseconds since the start of the era
+     * @return true if it succeeded. False means that this is a
+     * java1.1 system and that file times can not be set
+     *@exception BuildException Thrown in unrecoverable error. Likely
+     *this comes from file access failures.
+     */
+    protected boolean touchFile(File file, long timemillis) 
+        throws BuildException  {
+
+        if (project.getJavaVersion() != Project.JAVA_1_1) {
+            Touch touch = (Touch) project.createTask("touch");
+            touch.setOwningTarget(target);
+            touch.setTaskName(getTaskName());
+            touch.setLocation(getLocation());
+            touch.setFile(file);
+            touch.setMillis(timemillis);
+            touch.touch();
+            return true;
+            
+        } else {
+            return false;
+        }
+    }	
 
     /**
      * Set the URL.
      *
-     * @param d URL for the file.
+     * @param u URL for the file.
      */
-    public void setSrc(String d) {
-	this.source=d;
+    public void setSrc(URL u) {
+	this.source = u;
     }
 
     /**
@@ -133,7 +219,7 @@ public class Get extends Task {
      *
      * @param dest Path to file.
      */
-    public void setDest(String dest) {
+    public void setDest(File dest) {
 	this.dest = dest;
     }
 
@@ -142,16 +228,38 @@ public class Get extends Task {
      *
      * @param v if "true" then be verbose
      */
-    public void setVerbose(String v) {
+    public void setVerbose(boolean v) {
 	verbose = v;
     }
 
     /**
      * Don't stop if get fails if set to "<CODE>true</CODE>".
      *
-     * @param v if "true" then be verbose
+     * @param v if "true" then don't report download errors up to ant
      */
-    public void setIgnoreErrors(String v) {
+    public void setIgnoreErrors(boolean v) {
 	ignoreErrors = v;
     }
+
+    /**
+     * Use timestamps, if set to "<CODE>true</CODE>".
+     *
+     * <p>In this situation, the if-modified-since header is set so that the file is
+     * only fetched if it is newer than the local file (or there is no local file)
+     * This flag is only valid on HTTP connections, it is ignored in other cases.
+     * When the flag is set, the local copy of the downloaded file will also 
+     * have its timestamp set to the remote file time. 
+     * <br>
+     * Note that remote files of date 1/1/1970 (GMT) are treated as 'no timestamp', and
+     * web servers often serve files with a timestamp in the future by replacing their timestamp
+     * with that of the current time. Also, inter-computer clock differences can cause no end of 
+     * grief. 
+     * @param v "true" to enable file time fetching
+     */
+    public void setUseTimestamp(boolean v) {
+        if (project.getJavaVersion() != Project.JAVA_1_1) {
+            useTimestamp = v;
+        }
+    }
+
 }

src/main/org/apache/tools/ant/taskdefs/Touch.java

@@ -73,7 +73,7 @@ import java.util.Locale;
  * created. Setting the modification time of files is not supported in
  * JDK 1.1.
  *
- * @author Stefan Bodewig <a href="mailto:stefan.bodewig@megabit.net">stefan.bodewig@megabit.net</a> 
+ * @author <a href="mailto:stefan.bodewig@megabit.net">Stefan Bodewig</a> 
  */
 public class Touch extends Task {
 
@@ -87,8 +87,8 @@ public class Touch extends Task {
     /**
      * The name of the file to touch.
      */
-    public void setFile(String name) {
-        file = project.resolveFile(name);
+    public void setFile(File file) {
+        this.file = file;
     }
 
     /**

src/main/org/apache/tools/ant/taskdefs/Untar.java

@@ -63,7 +63,7 @@ import java.io.*;
  *
  * Heavily based on the Expand task.
  *
- * @author Stefan Bodewig <a href="mailto:stefan.bodewig@megabit.net">stefan.bodewig@megabit.net</a>
+ * @author <a href="mailto:stefan.bodewig@megabit.net">Stefan Bodewig</a>
  */
 public class Untar extends Task {
     private String dest; // req
@@ -78,6 +78,8 @@ public class Untar extends Task {
 
         Touch touch = (Touch) project.createTask("touch");
         touch.setOwningTarget(target);
+        touch.setTaskName(getTaskName());
+        touch.setLocation(getLocation());
                     
         File srcF=project.resolveFile(source);
 
@@ -123,7 +125,7 @@ public class Untar extends Task {
                     }
 
                     if (project.getJavaVersion() != Project.JAVA_1_1) {
-                        touch.setFile(f.getAbsolutePath());
+                        touch.setFile(f);
                         touch.setMillis(te.getModTime().getTime());
                         touch.touch();
                     }