有些時候，我們希望對某個已有的jar/war包寫入新的檔案、或覆寫已有檔案；
如果能夠像操作普通檔案系統一樣操作jar/war包裡的檔案就再好不過了，那麼下面的WarWriter.java就是這樣一個工具：
package kilim.tools;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarInputStream;
import java.util.jar.JarOutputStream;
/**
* Utility to write to a jar/war file.
*
* @author <a href="mailto:miles.wy.1@gmail.com">pf_miles</a>
*
*/
public class WarWriter {
// the war file to write at last
private File warFile;
// the temp directory to pre-write...
private File tempDir;
private static byte[] buf = new byte[1048576];// the writing buffer
/**
* create a war writer upon a war file... should also works for a jar file
*
* @param warPath
* the absolute path of the underlying war file
*/
public WarWriter(String warPath) {
File f = new File(warPath);
if (!f.exists())
throw new RuntimeException("War file does not exist: " + warPath);
// test if zip format
JarInputStream i = null;
try {
i = new JarInputStream(new FileInputStream(f));
if (i.getNextEntry() == null) {
throw new RuntimeException("Not jar/war format: " + warPath);
}
} catch (Exception e) {
throw new RuntimeException("Not jar/war format: " + warPath);
} finally {
try {
if (i != null)
i.close();
} catch (IOException e) {
}
}
this.warFile = f;
// create temp directory
this.tempDir = createTempDirectory(f.getName());
}
private static File createTempDirectory(String warName) {
final File temp;
try {
temp = File.createTempFile(warName, Long.toString(System.currentTimeMillis()));
temp.deleteOnExit();
} catch (IOException e) {
throw new RuntimeException(e);
}
if (!(temp.delete())) {
throw new RuntimeException("Could not delete temp file: " + temp.getAbsolutePath());
}
if (!(temp.mkdir())) {
throw new RuntimeException("Could not create temp directory: " + temp.getAbsolutePath());
}
return (temp);
}
/**
* Complete writing, rebuild the final result jar/war file and do cleaning.
*
* @throws IOException
*/
public void done() throws IOException {
// really writing to the war file, in fact a merging from the temp dir
// writing to war
// // listing temp dir files in jar entry naming style
Map<String, File> tempDirFiles = listFilesInJarEntryNamingStyle(this.tempDir, this.tempDir.getAbsolutePath());
// // create temp war
File tempWar = File.createTempFile(this.warFile.getName(), null);
// // merging write to the temp war
JarOutputStream jos = new JarOutputStream(new FileOutputStream(tempWar));
JarFile jf = new JarFile(this.warFile);
try {
Enumeration<JarEntry> iter = jf.entries();
while (iter.hasMoreElements()) {
JarEntry e = iter.nextElement();
String name = e.getName();
if (!e.isDirectory() && name.endsWith(".jar")) {
writeJarEntry(e, filterByDirName(tempDirFiles, name), jf, jos);
} else {
// prefer file in dir to war
InputStream fin = null;
if (tempDirFiles.containsKey(name)) {
File f = tempDirFiles.get(name);
if (!e.isDirectory())
fin = new FileInputStream(f);
addEntry(name, fin, f.lastModified(), jos);
tempDirFiles.remove(name);
} else {
if (!e.isDirectory())
fin = jf.getInputStream(e);
addEntry(name, fin, e.getTime(), jos);
}
}
}
} finally {
if (jf != null)
jf.close();
}
// // writing remained files in dir
for (Map.Entry<String, File> remain : tempDirFiles.entrySet()) {
String dirFileName = remain.getKey();
File dirFile = remain.getValue();
InputStream in = null;
if (!dirFile.isDirectory())
in = new FileInputStream(dirFile);
addEntry(dirFileName, in, dirFile.lastModified(), jos);
}
// // replace the target war using the temp war
jos.close();
moveTo(tempWar, warFile);
// clean
// // cleaning temp dir
recurDel(this.tempDir);
}
// move from to files
private void moveTo(File from, File to) throws IOException {
// try rename directly
if (!from.renameTo(to)) {
// renameTo failed, fallback to file flowing...
System.out.println("File.renameTo failed, fallback to file streaming...");
if (!from.exists())
throw new IOException("From file does not exist: " + from.getAbsolutePath());
if (!to.exists() && !to.createNewFile())
throw new IOException("To from does not exist and cannot be created: " + to.getAbsolutePath());
OutputStream o = new FileOutputStream(to);
try {
flowTo(new FileInputStream(from), o);
} finally {
from.delete();
o.close();
}
System.out.println("File stream flowing moving done!");
}
}
/*
* list the files&dirs in the specified dir, in a jar entry naming style: 1)
* all file names come with no preceding `/` 2) all file names of
* directories must be suffixed by a `/`
*/
private static Map<String, File> listFilesInJarEntryNamingStyle(File f, String basePath) {
Map<String, File> ret = new HashMap<String, File>();
String name = f.getAbsolutePath().substring(basePath.length());
if (name.startsWith("/"))
name = name.substring(1);
if (f.isDirectory()) {
if (!name.endsWith("/"))
name += "/";
for (File sub : f.listFiles()) {
ret.putAll(listFilesInJarEntryNamingStyle(sub, basePath));
}
}
// add the current level directory itself except for the root dir
if (!"/".equals(name))
ret.put(name, f);
return ret;
}
private static void recurDel(File file) {
if (file.isDirectory()) {
for (File item : file.listFiles())
recurDel(item);
}
file.delete();
}
// merging write jar entry
private void writeJarEntry(JarEntry origJarEntry, Map<String, File> mergingFiles, JarFile origWar, JarOutputStream targetWarStream)
throws IOException {
// if there`s no merging file for this jar entry, write the original jar
// data directly
if (mergingFiles == null || mergingFiles.isEmpty()) {
JarEntry je = new JarEntry(origJarEntry.getName());
je.setTime(origJarEntry.getTime());
targetWarStream.putNextEntry(je);
flowTo(origWar.getInputStream(origJarEntry), targetWarStream);
targetWarStream.closeEntry();
} else {
String origJarEntryName = origJarEntry.getName();
long modTime = -1;
String mergingDirName = origJarEntryName + "/";
if (mergingFiles.containsKey(mergingDirName)) {
modTime = mergingFiles.get(mergingDirName).lastModified();
} else {
modTime = origJarEntry.getTime();
}
JarEntry je = new JarEntry(origJarEntryName);
je.setTime(modTime);
targetWarStream.putNextEntry(je);
mergingFiles.remove(mergingDirName);
// build the jar data
String jarSimpleName = origJarEntryName.contains("/") ? origJarEntryName.substring(origJarEntryName.lastIndexOf("/") + 1)
: origJarEntryName;
// // build the tmp jar file to write to
File tmpOutputJarFile = File.createTempFile(jarSimpleName, null);
JarOutputStream tmpOutputJar = new JarOutputStream(new FileOutputStream(tmpOutputJarFile));
// // dump the original jar file to iterate over
File tmpOrigJarFile = buildTempOrigJarFile(jarSimpleName + "_orig", origWar.getInputStream(origJarEntry));
JarFile tmpOrigJar = new JarFile(tmpOrigJarFile);
for (Enumeration<JarEntry> e = tmpOrigJar.entries(); e.hasMoreElements();) {
JarEntry origJarItemEntry = e.nextElement();
String origJarItemEntryName = origJarItemEntry.getName();
String mergingFileName = mergingDirName + origJarItemEntryName;
InputStream itemIn = null;
long itemModTime = -1;
// prefer dir files to origJar entries
if (mergingFiles.containsKey(mergingFileName)) {
File f = mergingFiles.get(mergingFileName);
if (!origJarItemEntry.isDirectory())
itemIn = new FileInputStream(f);
itemModTime = f.lastModified();
mergingFiles.remove(mergingFileName);
} else {
if (!origJarItemEntry.isDirectory())
itemIn = tmpOrigJar.getInputStream(origJarItemEntry);
itemModTime = origJarItemEntry.getTime();
}
addEntry(origJarItemEntryName, itemIn, itemModTime, tmpOutputJar);
}
tmpOrigJar.close();
tmpOrigJarFile.delete();
// check&write remained dir files
for (Map.Entry<String, File> remain : mergingFiles.entrySet()) {
String dirFileName = remain.getKey();
File dirFile = remain.getValue();
InputStream in = null;
if (!dirFile.isDirectory())
in = new FileInputStream(dirFile);
addEntry(dirFileName.substring(mergingDirName.length()), in, dirFile.lastModified(), tmpOutputJar);
}
tmpOutputJar.close();
// write to war
InputStream jarData = new FileInputStream(tmpOutputJarFile);
flowTo(jarData, targetWarStream);
jarData.close();
tmpOutputJarFile.delete();
targetWarStream.closeEntry();
}
}
// build a temp file containing the given inputStream data
private File buildTempOrigJarFile(String name, InputStream in) throws IOException {
File f = File.createTempFile(name, null);
OutputStream out = new FileOutputStream(f);
try {
flowTo(in, out);
} finally {
out.close();
}
return f;
}
// data stream `flow` from in to out, pseudo-zero-copy
private static void flowTo(InputStream in, OutputStream out) throws IOException {
try {
for (int count = in.read(buf); count != -1; count = in.read(buf)) {
out.write(buf, 0, count);
}
} finally {
in.close();
}
}
// collect entries which contain the specified dir path segment, and also
// delete from the original map
private Map<String, File> filterByDirName(Map<String, File> nameFileMapping, String pathSegment) {
if (nameFileMapping == null || nameFileMapping.isEmpty())
return Collections.emptyMap();
Map<String, File> ret = new HashMap<String, File>();
if (!pathSegment.endsWith("/"))
pathSegment += "/";
for (Iterator<Map.Entry<String, File>> iter = nameFileMapping.entrySet().iterator(); iter.hasNext();) {
Map.Entry<String, File> e = iter.next();
if (e.getKey().contains(pathSegment)) {
ret.put(e.getKey(), e.getValue());
iter.remove();
}
}
return ret;
}
private static void addEntry(String entryName, InputStream in, long modTime, JarOutputStream target) throws IOException {
JarEntry e = new JarEntry(entryName);
e.setTime(modTime);
target.putNextEntry(e);
if (in != null) {
flowTo(in, target);
}
target.closeEntry();
}
/**
* create outputStream writing to the specified war/jar file, all paths
* specified here are relative to the root of the war/jar.
*/
public OutputStream getFileOutputStream(String relPath) throws IOException {
if (relPath.startsWith("/"))
relPath = relPath.substring(1);
if (relPath.endsWith("/"))
relPath = relPath.substring(0, relPath.length() - 1);
File f = new File(this.tempDir.getAbsolutePath() + "/" + relPath);
File p = f.getParentFile();
if (p != null && !p.exists()) {
p.mkdirs();
}
if (!f.exists())
f.createNewFile();
return new FileOutputStream(f);
}
/**
* get the temporarily pre-writing directory
*/
public String getTempPrewriteDir() {
return this.tempDir.getAbsolutePath();
}
/**
* return the current writing war file path
*/
public String getWarFilePath() {
return this.warFile.getAbsolutePath();
}
}用法很簡單：
首先使用WarWriter ww = new WarWriter(path_to_war_file);建立WarWriter物件，引數就是你想要寫入的jar/war檔案位置；
然後…直接呼叫ww.getFileOutputStream(relPath)就能夠得到war/jar檔案內部對應檔案的OutputStream了，然後就可以向該stream寫入資料了，就是這麼簡單(寫完記得關閉outputStream仍然是個好習慣)；
其中relPath是相對於jar/war包根目錄的相對路徑，比如傳入WEB-INF/web.xml的話，就會得到jar/war檔案內部WEB-INF/web.xml這個entry的輸出流； 若該entry不存在則會自動建立;
最後，當所有的寫入都完成後，記得呼叫ww.done();, 這會執行一些資料同步操作，並清理工作空間， 整個寫入才算完成。
gist地址： https://gist.github.com/pfmiles/158a805904a98944793d