Android Priority Job Queue (Job Manager)：后台线程任务结果传回前台（三）

刺骨的言语ヽ痛彻心扉 2023-10-17 08:59 92阅读 0赞

**Android Priority Job Queue (Job Manager)：后台线程任务结果传回前台（三）**

在附录文章4,5的基础上改造MainActivity.java和MyJob.java，改造后的代码，将使MyJob在后台完成线程任务后返回数据给前台。  
实现的技术路线：  
（1） 首先需要在MyJob里面定义一个结果值，假设这个值就是打算盛放后台线程计算结果的容器bean等等，然后当线程在后台计算完成后赋值。同时写一个public公共的get方法，这个get操作暴露给其他代码使用。

package zhangphil.app;
    
    import android.os.SystemClock;
    import android.support.annotation.NonNull;
    import android.support.annotation.Nullable;
    import android.util.Log;
    
    import com.birbit.android.jobqueue.Job;
    import com.birbit.android.jobqueue.Params;
    import com.birbit.android.jobqueue.RetryConstraint;
    
    /**
     * Created by Phil on 2016/10/10.
     */
    public class MyJob extends Job{
    
        private String tag;
    
        //此处的结果将传回给发起线程的上层代码
        //比如经过一个耗时的长期后台线程完成后，一个结果获得，然后传回给需求方
        private String result;
    
        public MyJob(String tag) {
            super(new Params(500).requireNetwork().persist().groupBy(tag));
            this.tag = tag;
            Log.d(tag, "初始化");
        }
    
        public String getResult(){
            return result;
        }
    
        @Override
        public void onAdded() {
            Log.d(tag, "添加任务");
        }
    
        //在这里面放置耗时的后台线程化任务
        @Override
        public void onRun() throws Throwable {
            Log.d(tag, "开始运行...");
    
            SystemClock.sleep(10000);
    
            //此处抛出异常后，jobqueue将立即自动进入shouldReRunOnThrowable
            //throw new Exception();
    
            result="任务完成！";
    
            Log.d(tag,"完成");
        }
    
        @Override
        protected RetryConstraint shouldReRunOnThrowable(@NonNull Throwable throwable, int runCount, int maxRunCount) {
            // An error occurred in onRun.
            // Return value determines whether this job should retry or cancel. You can further
            // specify a backoff strategy or change the job's priority. You can also apply the
            // delay to the whole group to preserve jobs' running order.
    
            Log.d(tag, "runCount: " + runCount + " maxRunCount: " + maxRunCount);
    
            //这样的返回将导致onRun方法的再次执行，重启线程,重启将导致代码再次进入onRun。同时，runCount自加1
            return RetryConstraint.RETRY;
        }
    
        //如果重试超过限定次数，将onCancel.
        //如果用户主动放弃删掉这个任务，也一样进入onCancel
        @Override
        protected void onCancel(int cancelReason, @Nullable Throwable throwable) {
            Log.d(tag, "放弃：" + cancelReason);
        }
    
        @Override
        protected int getRetryLimit() {
            //仅仅重启5次次，超过5次则放弃任务。
            return 5;
        }
    }

（2） JobManager添加后台线程任务时候，重写回调方法，在回调里面等待结果。

package zhangphil.app;
    
    import android.support.annotation.NonNull;
    import android.support.annotation.Nullable;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.util.Log;
    
    import com.birbit.android.jobqueue.Job;
    import com.birbit.android.jobqueue.JobManager;
    import com.birbit.android.jobqueue.callback.JobManagerCallback;
    
    public class MainActivity extends AppCompatActivity {
    
        private JobManager jobManager;
        private String tag=this.getClass().getName();
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            //setContentView(R.layout.activity_main);
    
            jobManager=MyApplication.getInstance().getJobManager();
    
            MyJob job=new MyJob("任务1");
            jobManager.addJobInBackground(job);
    
            jobManager.addCallback(new JobManagerCallback() {
                @Override
                public void onJobAdded(@NonNull Job job) {
    
                }
    
                @Override
                public void onJobRun(@NonNull Job job, int resultCode) {
    
                }
    
                @Override
                public void onJobCancelled(@NonNull Job job, boolean byCancelRequest, @Nullable Throwable throwable) {
    
                }
    
                @Override
                public void onDone(@NonNull Job job) {
                    MyJob myJob= (MyJob) job;
                    Log.d(tag,job.getId()+" onDone : "+myJob.getResult());
                }
    
                @Override
                public void onAfterJobRun(@NonNull Job job, int resultCode) {
    
                }
            });
        }
    }

代码运行结果：

![Center][]

附录：  
【1】《Java线程池：ExecutorService，Executors》链接地址：[http://blog.csdn.net/zhangphil/article/details/43898637][http_blog.csdn.net_zhangphil_article_details_43898637]  
【2】《Java线程池及Future、Callable获得线程返回结果【Java线程池系列2】》链接地址：[http://blog.csdn.net/zhangphil/article/details/49701219][http_blog.csdn.net_zhangphil_article_details_49701219]  
【3】《Java线程池之FutureTask【Java线程池系列3】》链接地址：[http://blog.csdn.net/zhangphil/article/details/49702751][http_blog.csdn.net_zhangphil_article_details_49702751]  
【4】《Android Priority Job Queue (Job Manager)（一）》链接地址：[http://blog.csdn.net/zhangphil/article/details/52777196][http_blog.csdn.net_zhangphil_article_details_52777196]  
【5】《Android Priority Job Queue (Job Manager)：线程任务的容错重启机制（二）》链接地址：[http://blog.csdn.net/zhangphil/article/details/52778525][http_blog.csdn.net_zhangphil_article_details_52778525]

[Center]: https://img-blog.csdn.net/20161011140917812?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[http_blog.csdn.net_zhangphil_article_details_43898637]: http://blog.csdn.net/zhangphil/article/details/43898637
[http_blog.csdn.net_zhangphil_article_details_49701219]: http://blog.csdn.net/zhangphil/article/details/49701219
[http_blog.csdn.net_zhangphil_article_details_49702751]: http://blog.csdn.net/zhangphil/article/details/49702751
[http_blog.csdn.net_zhangphil_article_details_52777196]: http://blog.csdn.net/zhangphil/article/details/52777196
[http_blog.csdn.net_zhangphil_article_details_52778525]: http://blog.csdn.net/zhangphil/article/details/52778525