java.io.FileNotFoundException: (系统找不到指定的路径) jar 结果

Question

您好，我在 Java 中遇到了这个 jar 问题。我设置的路径无法识别。我检查了 jar 内部，发现路径是正确的，我已经删除并在 Java 文件中添加了“/”和路径的开头，但仍然无法正常工作。还有什么我可以尝试的吗？

代码

package sample;


public class LocateMyCity {

    private String myCityLocation;

    private String country;

    public String getCountry() {
        return country;
    }

public String getmyCityLocation(){
    return myCityLocation;
}

public LocateMyCity() {
    // A File object pointing to your GeoIP2 or GeoLite2 database
    File database = new File("\\GeoLite2-City_20170502\\GeoLite2-City.mmdb");

    try {
        URL whatismyip = new URL("http://checkip.amazonaws.com");
        BufferedReader in = new BufferedReader(new InputStreamReader(
                whatismyip.openStream()));

        String ip = in.readLine(); //you get the IP as a String
        System.out.println(ip);

        // This creates the DatabaseReader object, which should be reused across
        // lookups.
        DatabaseReader reader = new DatabaseReader.Builder(database).build();

        InetAddress ipAddress = InetAddress.getByName(ip);

        // Replace "city" with the appropriate method for your database, e.g.,
        // "country".
        CityResponse response = reader.city(ipAddress);

        City city = response.getCity();
        System.out.println(city.getName()); // 'Minneapolis'
        this.myCityLocation = city.getName();

        Country country = response.getCountry();
        System.out.println(country.getIsoCode());            // 'GB'
        this.country = country.getIsoCode();

        System.out.println(country.getName());               // 'United Kindom'

    }catch (Exception e){
        e.printStackTrace();
        System.out.println("Tracing IP E");
    }
}

}

来自命令提示符的错误消息

java.io.FileNotFoundException: \GeoLite2-City_20170502\GeoLite2-City.mmdb (The system cannot find the path specified)
    at java.io.RandomAccessFile.open0(Native Method)
    at java.io.RandomAccessFile.open(Unknown Source)
    at java.io.RandomAccessFile.<init>(Unknown Source)
    at com.maxmind.db.BufferHolder.<init>(BufferHolder.java:19)
    at com.maxmind.db.Reader.<init>(Reader.java:116)
    at com.maxmind.geoip2.DatabaseReader.<init>(DatabaseReader.java:35)
    at com.maxmind.geoip2.DatabaseReader.<init>(DatabaseReader.java:23)
    at com.maxmind.geoip2.DatabaseReader$Builder.build(DatabaseReader.java:129)
    at sample.LocateMyCity.<init>(LocateMyCity.java:44)
    at sample.WeatherToday.getPersonLocationId(WeatherToday.java:102)
    at sample.WeatherToday.<init>(WeatherToday.java:126)
    at sample.Main.start(Main.java:37)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Unknown Source)

Answer 1

您指定的路径是相对的，可能起点不是您要查找的文件所在的位置。试试这样的

ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource("GeoLite2-City_20170502/GeoLite2-City.mmdb").getFile());

并将目录放在 JAR 的起始点（如果使用 src/resources/ 下的 Maven）

Answer 2

替换

File database = new File("\\GeoLite2-City_20170502\\GeoLite2-City.mmdb");

与

File file = new File(classLoader.getResource("\\GeoLite2-City_20170502\\GeoLite2-City.mmdb").getFile());