更新你的jar包

jar文件：/home/resin.jar
需更新包中com/caucho/server/port/Port.class类文件

方法1：
jar uf resin.jar com/caucho/server/port/Port.class
要求是必须知道jar包的结构要非常熟悉,可以使用:jar tf resin.jar来查看。

方法2：
解压jar xvf resin.jar->覆盖相应类文件->再打包(jar cvf resin.jar com)

假设目录结构是maven标准结构

复制代码代码如下:

-src
-target
-test.jar(你需要更新的jar包)

复制代码代码如下:

package com.foo.common.base.utils.development;

import static org.junit.Assert.*;

import java.io.File;
import java.io.IOException;
import java.util.Date;
import java.util.Properties;

import org.apache.commons.io.FileUtils;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.ClassPathResource;

public class JarUpdater {
 public static final Logger logger = LoggerFactory
   .getLogger(JarUpdater.class);

@Test
 /**
  * 更新com目录下的所有文件到jar的对应目录结构中去
  * 
  * 一次成功的代码更新，我们断言jar的大小是不一样的
  */
 public void updateClass() throws IOException, InterruptedException {

ClassPathResource myPath = new ClassPathResource(
    "jarUpdaterConfig.properties");
  Properties p = new Properties();
  p.load(myPath.getInputStream());

ClassUpdater classUpdater = new ClassUpdater().applySettings(p);

classUpdater.compileAndCopyClass();

String workingDirectory = p.getProperty("workingDirectory");
  String jar4UpdateName = p.getProperty("jar4UpdateName");
  // class compile path
  String updateSourcePath = workingDirectory + "target";
  // class root folder
  String updateSourceDir = "com";

Date startDate = new Date();

File myJar = new File(workingDirectory + jar4UpdateName);
  if (!myJar.isFile()) {
   logger.error("file with following path {} does not exist.",
     jar4UpdateName);
   return;
  }
  long oldLength = myJar.length();
  logger.info("Now ready to update jar file with name:{},size:{}",
    myJar.getName(), myJar.length());
  String myCommand = "jar uf " + workingDirectory + jar4UpdateName
    + " -C " + updateSourcePath + " " + updateSourceDir;
  logger.info("Update command【{}】", myCommand);

Runtime.getRuntime().exec(myCommand);

while (!FileUtils.isFileNewer(myJar, startDate)) {
   logger.info("sleep for two seconds,checking changes...");
   Thread.sleep(2000);
  }
  assertNotEquals(
    "jar may not be updated successfully,check the code please",
    oldLength, myJar.length());
  logger.info("Now finish update jar file with size:{}", myJar.length());
 }
}