read network data
URL httpUrl = new URL(jsonUrl);//Create url http address
HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection();//Open http link
InputStream in = conn.getInputStream();//Get the input stream//This sentence blocks the single-threaded thread.
Reading network data in android must be in a child thread
httpRead(url,callback){
Handler handler=new Handler();//Use the main thread
new Thread(){
public void run(){
URL httpUrl = new URL(jsonUrl);//Create url http address
HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection();//Open http link
InputStream in = conn.getInputStream();//Get the input stream//This sentence blocks the single-threaded thread.
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When the network returns success:
String str=read data from in;
//The onSucces that executes the callback in the current child thread
callback.onSucces(str);
//Use the handler to go to the main thread to execute onSucces
handler.post(new Runnable(){
callback.onSucces(str);
});
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When the network returns a failure:
//execute callback's onError in the current child thread
callback.onError();
/Use handler to go to the main thread to execute onError
handler.post(new Runnable(){
callback.onSucces(str);/
});
}
}
}
The third-party library has encapsulated the above logic of opening up the thread and reverting to the main thread. Just pass the url and callback. Note that the callback has not fallen to the thread.
For example: the third-party network library android-async-http:
asyncHttpClient=new AsyncHttpClient();//The entire project only needs one.
asyncHttpClient.get(jsonUrl, new TextHttpResponseHandler() {
@Override
public void onSuccess(int statusCode, Header[] headers, String responseString) {
//主线程执行，responseString是网络返回的结果
}
@Override
public void onFailure(int statusCode, Header[] headers, String responseString, Throwable throwable) {
//主线程执行网络出错
}
}
例如：第三方网络库Volley：
RequestQueue requestQueue= Volley.newRequestQueue(context);
StringRequest request = new StringRequest(Request.Method.GET,
url,
new Response.Listener<String>() {
public void onResponse(String s) {
//主线程执行，s是网络返回的结果
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError volleyError) {
//主线程执行网络出错
}
});
requestQueue.add(request);
//request可以设置超时时间
request.setRetryPolicy(new DefaultRetryPolicy(
60000, //timeout时间
DefaultRetryPolicy.DEFAULT_MAX_RETRIES,//重连次数
DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
注意5.0以上需要在主模块build.gradle加
android {
useLibrary 'org.apache.http.legacy'//必须在第一行
}