Android AsyncTask
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重写AsyncTask
public class MyAsyncTask extends AsyncTask<String, Integer, Object> { private Object appDatas; private String url; onDataFinishedListener onDataFinishedListener; public MyAsyncTask(String address) { this.url = address; } //设置监听，从而可以获取AsyncTask返回的数据 public void setOnDataFinishedListener(onDataFinishedListener onDataFinishedListener) { this.onDataFinishedListener = onDataFinishedListener; } //onPreExecute方法用于在执行后台任务前做一些UI操作 @Override protected void onPreExecute() { } //doInBackground方法内部执行后台任务,不可在此方法内修改UI @Override protected Object doInBackground(String... address) { try { if (address[0] == "string") { appDatas = okHttp.getAppData(url); } else if (address[0] == "bitmap") { appDatas = okHttp.getBitmap(url); } return appDatas; // Log.i("MyappDatas", appDatas); } catch (Exception e) { e.printStackTrace(); return null; } } //onProgressUpdate方法用于更新进度信息 @Override protected void onProgressUpdate(Integer... progress) { } //onPostExecute方法用于在执行完后台任务后更新UI,显示结果 @Override protected void onPostExecute(Object result) { if (result != null) { onDataFinishedListener.onDataSuccessfully(result); } } } -
定义接口
public interface onDataFinishedListener { public void onDataSuccessfully(Object data); } -
在Activity中调用，引用的是实际项目中的代码段
try { MyAsyncTask mTask = new MyAsyncTask(baseUrl); mTask.setOnDataFinishedListener(new onDataFinishedListener() { @Override public void onDataSuccessfully(Object data) { ViewPager pager = (ViewPager) findViewById(R.id.viewPager); String account_data = data.toString(); try { // Log.i("account_data", account_data); accounts = new ArrayList<Account>(); JSONObject jsonObject = new JSONObject(account_data); jsonAccounts = jsonObject.getJSONObject("data").getJSONArray("accounts"); for (int i = 0; i < jsonAccounts.length(); i++) { accountName = jsonAccounts.getJSONObject(i).getString("a_name"); accountWxNo = jsonAccounts.getJSONObject(i).getString("a_wx_no"); accountId = jsonAccounts.getJSONObject(i).getString("a_id"); accountLogoLink = jsonAccounts.getJSONObject(i).getString("a_logo"); accountDesc = jsonAccounts.getJSONObject(i).getString("a_desc"); accountValidReason = jsonAccounts.getJSONObject(i).getString("a_valid_reason"); accountScore = Integer.valueOf(jsonAccounts.getJSONObject(i).getString("a_rank")); Account account = new Account(accountName, accountWxNo, accountId, accountDesc, accountLogoLink, accountScore, accountValidReason); accounts.add(account); } fragment = new AccountFragment(accounts, ChildCatsActivity.this); fragments.add(fragment); pager.setAdapter(new myPagerAdapter(getSupportFragmentManager(), fragments, titles)); pager.setCurrentItem(0); tabs.setViewPager(pager); // Log.i("accounts", accounts.toString()); } catch (Exception e) { e.printStackTrace(); } } }); mTask.execute("string"); } catch (Exception e) { e.printStackTrace(); }
带post请求和get请求的AsyncTask
private void connect(final String url, final Map<String, String> params, final int request_type, final byte[] imageData, final String imagePrefix){
//params是参数列表，imageData是Bitmap转换成的字节数组，imagePrefix是图片后缀，如png、jpg等
new AsyncTask<String, Void, String>() {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected String doInBackground(String... param) {
OkHttpClient client = new OkHttpClient(); //OkHttp3
Request request = null;
if(request_type==GET){
request = new Request.Builder()
.url(url)
.build();
}else if(request_type==POST){
MultipartBody.Builder bodyBuilder = new MultipartBody.Builder();
bodyBuilder.setType(MultipartBody.FORM);
for (Map.Entry<String, String> entry : params.entrySet()) {
bodyBuilder.addFormDataPart(entry.getKey(),entry.getValue());
}
if(imageData!=null && imageData.length>0){
String prefix = imagePrefix;
String mimeType = "image/png";
if("png".equals(prefix)){
mimeType = "image/png";
}else if("jpg".equals(prefix)||"jpeg".equals(prefix)){
mimeType = "image/jpeg";
}else if("gif".equals(prefix)){
mimeType = "image/gif";
}
bodyBuilder.addFormDataPart("myfile", "temp."+prefix, RequestBody.create(MediaType.parse(mimeType), imageData));
}
RequestBody formBody = bodyBuilder.build();
request = new Request.Builder()
.url(url)
.post(formBody)
.build();
// FormBody.Builder bodyBuilder = new FormBody.Builder();
// for (Map.Entry<String, String> entry : params.entrySet()) {
// bodyBuilder.add(entry.getKey(),entry.getValue());
// }
// RequestBody formBody = bodyBuilder.build();
// request = new Request.Builder()
// .url(url)
// .post(formBody)
// .build();
}else{
return null;
}
Response response = null;
String result = null;
try {
response = client.newCall(request).execute();
if(response!=null && response.isSuccessful()) {
result = response.body().string();
}else {
return "0";
}
}catch (Exception e){
e.printStackTrace();
}
return result;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if("0".equals(result)) {
if(delegate!=null){
delegate.receiveFail(DataUtil.this, "网络链接失败，请稍后重试");
}
}else if(result==null) {
if(delegate!=null){
delegate.receiveFail(DataUtil.this, "数据请求有误，请重试");
}
}else{
if (delegate != null) {
delegate.receiveSuccess(DataUtil.this, result);
}
}
}
}.execute();
}
//将Bitmap转换成字节数组
public static byte[] Bitmap2Bytes(Bitmap bm) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
return baos.toByteArray();
}
参考文章：
结语：
坚持每天进步一点点…