9、实现自定义AsyncTask

一、自定义AsyncTask。

package com.example.asynctask;import java.util.ArrayDeque;import java.util.concurrent.BlockingQueue;import java.util.concurrent.Callable;import java.util.concurrent.CancellationException;import java.util.concurrent.ExecutionException;import java.util.concurrent.Executor;import java.util.concurrent.FutureTask;import java.util.concurrent.LinkedBlockingQueue;import java.util.concurrent.ThreadFactory;import java.util.concurrent.ThreadPoolExecutor;import java.util.concurrent.TimeUnit;import java.util.concurrent.atomic.AtomicBoolean;import android.os.Handler;import android.os.Looper;import android.text.TextUtils;public abstract class CustomAsyncTask<Params, T, Result> {public static class AsyncTaskBaseParam {    public int operation;}ThreadPoolExecutor mThreadPoolExecutor;BlockingQueue<Runnable> mBlockingQueue;AtomicBoolean mTaskCancel;Handler mUIHandler;Executor mExecutor;private String mThreadName;public CustomAsyncTask() {    this(1, false);}public CustomAsyncTask(int threadCount, boolean isSerial) {    this(1,threadCount, isSerial, null);}public CustomAsyncTask(int coreThreadCount, int maxThreadCount, boolean isSerial, String poolName) {    if (TextUtils.isEmpty(poolName)) {        mThreadName = getClass().getSimpleName();    } else {        mThreadName = poolName;    }    mUIHandler = new Handler(Looper.getMainLooper());    mBlockingQueue = new LinkedBlockingQueue<Runnable>();    mThreadPoolExecutor = new ThreadPoolExecutor(coreThreadCount, maxThreadCount, 1, TimeUnit.SECONDS,     mBlockingQueue,    new CustomThreadFactory(mThreadName));     mThreadPoolExecutor.allowCoreThreadTimeOut(true);    if (isSerial) {        mExecutor = new SerialExecutor(mThreadPoolExecutor);    } else {        mExecutor = mThreadPoolExecutor;    }}public CustomAsyncTask<Params, T, Result> execute(Params... params) {     onPreExecute();    mExecutor.execute(new FutureTask<Result>(new WorkerRunnable(params)) {        @Override        protected void done() {            super.done();            try {                postResult(get());            } catch (InterruptedException e) {                e.printStackTrace();            } catch (ExecutionException e) {                throw new RuntimeException("An error occured while executing CustomAsyncTask doInBackground()",                e.getCause());            } catch (CancellationException e) {        }    }    });    return this; }protected Result postResult(final Result result) {    mUIHandler.post(new Runnable() {        @Override        public void run() {            onPostExecute(result);        }    });    return result;}protected void onPreExecute() {}protected abstract Result doInBackground(Params...params);protected void onPostExecute(Result r) {}class WorkerRunnable implements Callable<Result> {    WorkerRunnable(Params... p) {        mParams = p;    }    Params[] mParams;    @Override    public Result call() throws Exception {        android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_BACKGROUND);        final Result r = doInBackground(mParams);        return r;    }}static class CustomThreadFactory implements ThreadFactory {    private String mThreadNamePattern;    private int mThreadOrder;    public CustomThreadFactory(String name) {        mThreadNamePattern = name;        mThreadOrder = 0;    }@Overridepublic Thread newThread(Runnable runnable) {    Thread thread = new Thread(runnable, makeName());    thread.setPriority(Thread.MIN_PRIORITY);    return thread;    }    String makeName() {    StringBuilder sb = new StringBuilder();    sb.append(mThreadNamePattern);    sb.append(" ").append(mThreadOrder++);    return sb.toString();    }}static class SerialExecutor implements Executor {    final ArrayDeque<Runnable> mTasks = new ArrayDeque<Runnable>();    Runnable mActive;    Executor mRealExecutor;    SerialExecutor(Executor realExecutor) {        mRealExecutor = realExecutor;    }    public synchronized void execute(final Runnable r) {            mTasks.offer(new Runnable() {                public void run() {                    try {                        r.run();                    } finally {                        scheduleNext();                    }                }            });            if (mActive == null) {                scheduleNext();            }        }        protected synchronized void scheduleNext() {            if ((mActive = mTasks.poll()) != null) {                if (mRealExecutor != null) {                    mRealExecutor.execute(mActive);                }            }             }    }}

二、使用AsyncTask。

1、定义LoadParams,ResultParams。

class LoadParams {    int op;    ...}

class ResultParams {     int op;}

2、定义一个类继承CustomAsyncTask。

private class LoadDataTask extend CustomAsyncTask<LoadParams, Void, ResultParams> {     @Override      protected void onPreExecute() {          //主线程，在DoinBackGround之前执行。     }     @Override     protected ResultParamsdoInBackground(LoadParams... params) {         LoadParams loadParams = params[0];         ResultParams result = new ResultParams();          int op = loadParams .op;          switch(op) {              case xx:                   break;             case xx:                   break;         }          return result ;      }     @Override    protected void onPostExecute(Boolean result) {    //主线程，在DoinBackGround之后执行     }}

3、执行任务。

LoadParams parasm = new LoadParams();new LoadDataTask().excute(params);