Question

在docker文件中，像这样命名图像有什么用...

FROM <image> [AS <name>]

我从文档中发现的一种用途是-


 - Optionally a name can be given to a new build stage by adding 
AS name to the FROM instruction. The name can be used in subsequent
FROM and COPY --from=<name|index> instructions to refer to the image 
built in this stage.

还有其他用途吗？

一个简单的示例-https://medium.com/thepeaklab/how-to-deploy-a-react-application-to-production-with-docker-multi-stage-builds-4da347f2d681

Answer 1

名称/别名只是在另一个阶段中引用特定阶段的一种方式。因此，如果您使用的是普通版本，则无需使用它。否则，您将使用索引号，例如：

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    RecyclerviewAdapter.updateActivity(this);
    imageEmptyLayout = findViewById(R.id.empty_img_layout);
    context = getApplicationContext();
    uContext = this;
    getSupportActionBar().setTitle("Kitchen Display");
    handler = new Handler();

    db=new DbHelper(context);
    createList();
   runnableCode.run();
    db.InsertDataViaSocket(uContext);
    isEmpty(imageEmptyLayout);

}

Runnable runnableCode = new Runnable() {
    @Override
    public void run() {
        expandableListView=findViewById(R.id.expandable_lv);
        // listAdapter=new ExpandableListAdapter(context,listDataHeader,listHashMap,null,i);
        for(int i=0;i<kotNeeds.size();i++){
            kotNeeds.get(i).setWaitingTime(calWaitingTime(kotNeeds.get(i).getDate_time()));

            // listAdapter=new ExpandableListAdapter(context,kotNeeds.get(i).getListKey_id(),kotNeeds.get(i).getExp_item(),kotNeeds,i);
        }
        // listAdapter.notifyDataSetChanged();

        myadapter.notifyDataSetChanged();
        handler.postDelayed(this, 1000);

    }
};


public void createList(){
    reobj=new RecyclerviewObjectPass(context);
    kotItems=new ArrayList<>();
    kotNeeds=new ArrayList<>();
    hashMap1=new HashMap<>();
    kotItems=db.getNeedsItems();



    for(i=0;i<kotItems.size();i++){
        KotNeeds kotNeeds1=new KotNeeds();
        kotNeeds1.kotNo=kotItems.get(i).getKotNo();
        kotNeeds1.inv_no=kotItems.get(i).getInv_no();
        kotNeeds1.listHeader=kotItems.get(i).getItem_name();
        //kotNeeds1.date_time=kotItems.get(i).getDate_time();
        kotNeeds1.date_time=kotItems.get(i).getDate_time();
        System.out.println("g9g9 "+calWaitingTime(kotItems.get(i).getDate_time()));
        kotNeeds1.setNewItem(kotItems.get(i).getNewItem());
        kotNeeds1.setCancelItem(kotItems.get(i).getCancelItem());
        kotNeeds1.listKey_id=kotItems.get(i).getItem_key_val();
        System.out.println("dfdf "+kotItems.get(i).getNewItem() + " "+ kotItems.get(i).getCancelItem());

        System.out.println( kotNeeds1.listHeader+"dsssssssssssss"+i);
        List<String> comments=kotItems.get(i).getComment_b();
        System.out.println( comments+"dsssssssssssss"+i);


        for(int j=0;j<kotNeeds1.listKey_id.size();j++){
                if(comments.get(j)!=null){
                String comment=comments.get(j);
                System.out.println(comment+"dsssssssssssss"+j);
                String[] allIdsArray = TextUtils.split(comment, ",");
                ArrayList<String> idsList = new ArrayList<String>(Arrays.asList(allIdsArray));
                hashMap1.put(kotNeeds1.listKey_id.get(j),idsList);
            }
        }


        kotNeeds1.exp_item=hashMap1;
        kotNeeds.add(kotNeeds1);
        System.out.println("QWQW " + calWaitingTime(kotItems.get(i).getDate_time())+" "+i);

    }


    LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
    myrv = findViewById(R.id.recyclerview_id);
    reobj.setMyrvobj(myrv);
    myrv.setLayoutManager(layoutManager);
    myadapter = new RecyclerviewAdapter(this, kotNeeds);
    //myrv.setLayoutManager(new GridLayoutManager(this, setColumn()));
    myrv.setAdapter(myadapter);
    myadapter.notifyDataSetChanged();

}

public void updateTime(){
    for(int i = 0; i<kotNeeds.size();i++){
        KotNeeds kot = new KotNeeds();
        System.out.println("s8s8 "+calWaitingTime(kotNeeds.get(i).date_time));
        kotNeeds.set(i,kot);
    }
}

@Override
protected void onResume() {
    super.onResume();

}



public void isEmpty(RelativeLayout view){
    if(db.getNeedsItems().size()>0){
        view.setVisibility(View.GONE);
       // handler.post(runnableCode);
    }
}

public String calWaitingTime(String dateStart) {


    long diffSeconds = 0,diffMinutes = 0,diffHours = 0,diffDays = 0;
    String fTime = "";
    //String dateStart = "08/11/2016 09:29:58";
    //String dateStop = "08/12/2016 10:31:48";

    //HH converts hour in 24 hours format (0-23), day calculation
    SimpleDateFormat format = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");

    Date d1 = null;
    Date d2 = null;

    try {
        d1 = format.parse(dateStart);
        d2 = new Date();
        //in milliseconds
        long diff = d2.getTime() - d1.getTime();

        diffSeconds = diff / 1000 % 60;
        diffMinutes = diff / (60 * 1000) % 60;
        diffHours = diff / (60 * 60 * 1000) % 24;
        diffDays = diff / (24 * 60 * 60 * 1000);

        if(diffMinutes<=0){
            fTime = diffSeconds+"";
        }else if(diffHours<=0){
            fTime = diffMinutes+" : "+diffSeconds;
        }else{
            fTime = diffHours+" : "+diffMinutes+" : "+diffSeconds;
        }

        System.out.println(diffDays + " days, ");
        System.out.println(diffHours + " hours, ");
        System.out.println(diffMinutes + " minutes, ");
        System.out.println(diffSeconds + " seconds. pppp");

    } catch (Exception e) {
        e.printStackTrace();
        System.out.print(e + " seconds. pppp");

    }

    return fTime;

}

该名称也可以与with cte ( SELECT e.Fname, e.Lname, AVG(Hours) AS avgHours, d.Dnumber as department FROM EMPLOYEE AS e INNER JOIN DEPARTMENT AS d ON e.Dno = d.Dnumber INNER JOIN Project AS p ON p.Dnum = d.Dnumber INNER JOIN WORKS_ON AS w ON w.Pno = p.Pnumber GROUP BY e.Fname, e.Lname ) select max(avgHours) from cte group by department option to the build command结合使用，例如：

FROM <image_image>
RUN <do_something>
...

FROM <image_name>
COPY --from=0 <files_to_copy> <destination>
...

--target

在Dockerfile中命名映像有什么用

1 个答案: