为java应用程序的执行保留一个计数器

Question

以下是场景：

我正在运行一个Java应用程序，它调用REST接口，并以整数形式返回变量的一些状态（基本上是最后一次成功构建#form Teamcity）

现在，由于我正在运行Jenkins的实用程序，我想比较两个REST调用之间的LastSuccessfulBuildNumber。最好的方法是什么？以下是我的代码。

import java.io.File;
import java.io.FileInputStream;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;
import java.util.TimeZone;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.filter.HTTPBasicAuthFilter;
import org.apache.commons.configuration.PropertiesConfiguration;
import org.apache.commons.io.FileUtils;
public class LastSuccessBuildNum {
    private  final static String getDateTime()
    {
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd_hh:mm:ss");
        df.setTimeZone(TimeZone.getTimeZone("EST"));
        return df.format(new Date());
    }
    public static void main(String[] args) {
        try {
            Client client = Client.create();
            Properties properties = new Properties();
            File f = File.createTempFile("default", ".properties");
            properties.load(new FileInputStream("config.properties"));
            String currentDir = System.getProperty("user.dir");

            String username = properties.getProperty("username");
            String pass = properties.getProperty("password");
            //System.out.println(pass);
            String buildNumber = properties.getProperty("buildNumber");

            client.addFilter(new HTTPBasicAuthFilter("username", "password"));
            WebResource webResource = client
                    .resource("http://a.b.c.d/teamcity/app/rest/buildTypes/id:bt26/builds/status:SUCCESS/number");
            ClientResponse response = webResource.accept("text/plain").get(
                    ClientResponse.class);
            if (response.getStatus() != 200) {
                throw new RuntimeException("Failed : HTTP error code : "
                        + response.getStatus());
            }
            /**
             * Prepend timestamp to latestBuildNum
             */
            System.out.println(getDateTime());
            String latestBuildNum_1 = response.getEntity(String.class);
            //System.out.println("Output from Server .... n");
            /** 
             * Save latest build number to a local file
             */
            //System.out.println(latestBuildNum);
            String datelbn = (getDateTime() + "-" + latestBuildNum_1);
            //System.out.println(datelbn);
            //If latestBuildNumberLocal < latestBuildNum, then save to file latestBuildNum
            // Else do nothing
            FileUtils.writeStringToFile(new File("PreMDNSlatestSuccBuildNum.txt"), latestBuildNum_1);
            /**
             * Get Content from the file, which would be the LatestBuildNumber at LAST run.
             * SO the NEXT run, will save the number in a different file.
             * Then we compare the contents of these two files
             * using StringToInt() and compare
             */
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Answer 1

这里有一个您想要的草图。有很多库可以减少"样板文件"的数量（例如Apache Commons IO）。Java 7还整合了异常处理和资源清理。

此外，您还可以对这段代码做更多的工作，使其"为生产做好准备"（这只是一个草图）。对于初学者，我们应该使用日志库而不是STDOUT（至少是java.util.logging）。

最后，我的示例读取/写入一个基元int，但您应该能够以大致相同的方式读取/写入/解析String。

import java.io.*;
import java.util.concurrent.atomic.AtomicInteger;
public class GetLatestBuildNumber {

    private static final AtomicInteger number = new AtomicInteger();
    private static final String FILE_NAME = "latest_build_number.txt";
    public static void main(String[] args) {
        int latest = fetchLatestBuildNumber();
        writeLatestBuildNumber(latest);
        int next = fetchLatestBuildNumber();
        int previous;
        try {
            previous = readLatestBuildNumber();
            System.out.println("previous build number " + previous);
            System.out.println("current build number " + next);
        } catch (IOException ioe) {
            System.out.println("failed to read last build number " +
                        "from file " + FILE_NAME + ": " + ioe);
        } catch (NumberFormatException nfx) {
            System.out.println("failed to parse last build number: " + nfx);
        }
    }
    private static int fetchLatestBuildNumber() {
       return number.getAndIncrement();
    }
    private static void writeLatestBuildNumber(int number) {
        int latestBuildNumber = fetchLatestBuildNumber();
        FileWriter writer = null;
        try {
            writer = new FileWriter(FILE_NAME);
            writer.write(Integer.toString(latestBuildNumber));
        } catch (IOException ex) {
            System.out.println("failed to write build number "
                        + number + ", error: " + ex);
        } finally {
            try {
                if (writer != null) writer.close();
            } catch (IOException e) { /* we tried... */ }
        }
    }
    private static int readLatestBuildNumber() throws IOException  {
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new FileReader(FILE_NAME));
            String number = reader.readLine();
            return Integer.parseInt(number);
        } finally {
            try {
                if (reader != null) reader.close();
            } catch (IOException e) { /* we tried. */ }
        }
    }
}