我正在使用 makeServiceCall 从 TheMovieDB API 获取 JSON 数据。
由于他们没有电影 ID 列表，我必须循环遍历 ID。
String JSONString = httpHandler.makeServiceCall("https://api.themoviedb.org/3/movie/" +
i +
"?api_key=" + API_KEY);
我=id
API_KEY = 我的 API key 。
当我循环访问 URL 时，我收到一些调用的 IOException。
I/System.out: ID: 152
I/System.out: ID: 160
I/System.out: ID: 165
I/System.out: ID: 168
I/System.out: ID: 171
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/181?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/184?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/185?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/186?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/187?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/188?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/189?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/190?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/191?api_key=b692b9da86f1cf0c1b623ea6e2770101
E/HttpHandler: IOException: https://api.themoviedb.org/3/movie/192?api_key=b692b9da86f1cf0c1b623ea6e2770101
一些 IOException 只是返回为 null 的 URL，如
{"status_code":34,"status_message":"The resource you requested could not be found."}
如何减慢 for 循环速度，使其不超过 API 调用限制？
HttpHandler:
package com.example.zdroa.yplex;
import android.util.Log;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
public class HttpHandler {
private static final String TAG = HttpHandler.class.getSimpleName();
public HttpHandler() {
}
public String makeServiceCall(String reqUrl) {
String response = null;
try {
URL url = new URL(reqUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
// read the response
InputStream in = new BufferedInputStream(conn.getInputStream());
response = convertStreamToString(in);
} catch (MalformedURLException e) {
Log.e(TAG, "MalformedURLException: " + e.getMessage());
} catch (ProtocolException e) {
Log.e(TAG, "ProtocolException: " + e.getMessage());
} catch (IOException e) {
Log.e(TAG, "IOException: " + e.getMessage());
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
}
return response;
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = reader.readLine()) != null) {
sb.append(line).append('\n');
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
}
我的调用是在 AsyncTask 内部进行的
class getWorkingIdsFromAPI extends AsyncTask<Void, Void, Void> {
ArrayList<String> alPersonType;
public getWorkingIdsFromAPI(ArrayList<String> arrayList) {
alPersonType = new ArrayList<>(arrayList);
}
@Override
protected Void doInBackground(Void... params) {
final HttpHandler httpHandler = new HttpHandler();
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
for (int i = 0; i < 200; i++) { //20000
String JSONString = httpHandler.makeServiceCall("https://api.themoviedb.org/3/movie/" + i + "?api_key=" + API_KEY);
if (JSONString != null) {
try {
JSONObject jsonObject = new JSONObject(JSONString);
JSONArray jsonArray = jsonObject.getJSONArray("genres");
boolean cont = true;
for (int a = 0; a < jsonArray.length(); a++) {
JSONObject jsonObject1 = jsonArray.getJSONObject(a);
String string = jsonObject1.getString("name");
for (int b = 0; b < alPersonType.size(); b++) {
if (string.equals(alPersonType.get(b))) {
cont = false;
}
}
}
if (cont) {
String id = String.valueOf(jsonObject.getInt("id"));
System.out.println("ID: " + id);
switch (id.length()) {
case 1:
id = "0000" + id;
break;
case 2:
id = "000" + id;
break;
case 3:
id = "00" + id;
break;
case 4:
id = "0" + id;
break;
}
switch (i) {
case 1:
STRING_LIST_OF_IDS = STRING_LIST_OF_IDS + id;
break;
default:
STRING_LIST_OF_IDS = ", " + STRING_LIST_OF_IDS + id;
break;
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
}
, 3000);
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
//add STRING_LIST_OF_IDS
getStringOfIdsFromDB();
}
}
最佳答案
您做错了，因为计时器任务将在每 3000 毫秒后重复一次，它将执行循环中的所有请求。你可以像这样改变你的代码。
ArrayList<String> alPersonType;
i=0; // initialise your variable once instead of each time in task
public getWorkingIdsFromAPI(ArrayList<String> arrayList) {
alPersonType = new ArrayList<>(arrayList);
}
@Override
protected Void doInBackground(Void... params) {
final HttpHandler httpHandler = new HttpHandler();
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
if(i < 200) { String JSONString = httpHandler.makeServiceCall("https://api.themoviedb.org/3/movie/" + i + "?api_key=" + API_KEY);
if (JSONString != null) {
try {
JSONObject jsonObject = new JSONObject(JSONString);
JSONArray jsonArray = jsonObject.getJSONArray("genres");
boolean cont = true;
for (int a = 0; a < jsonArray.length(); a++) {
JSONObject jsonObject1 = jsonArray.getJSONObject(a);
String string = jsonObject1.getString("name");
for (int b = 0; b < alPersonType.size(); b++) {
if (string.equals(alPersonType.get(b))) {
cont = false;
}
}
}
if (cont) {
String id = String.valueOf(jsonObject.getInt("id"));
System.out.println("ID: " + id);
switch (id.length()) {
case 1:
id = "0000" + id;
break;
case 2:
id = "000" + id;
break;
case 3:
id = "00" + id;
break;
case 4:
id = "0" + id;
break;
}
switch (i) {
case 1:
STRING_LIST_OF_IDS = STRING_LIST_OF_IDS + id;
break;
default:
STRING_LIST_OF_IDS = ", " + STRING_LIST_OF_IDS + id;
break;
}
}
} catch (JSONException e) {
e.printStackTrace();
}i++;//increase the counter
}
}
}
}
, 3000);return null;
}
您还可以使用 Thread.sleep() 采用不同的方法来更改您的 doin 背景，如下所示
@Override
protected Void doInBackground(Void... params) {
final HttpHandler httpHandler = new HttpHandler();
for (int i = 0; i < 200; i++) {try {
Thread.sleep(400);} catch (InterruptedException e) {
e.printStackTrace();}
String JSONString = httpHandler.makeServiceCall("https://api.themoviedb.org/3/movie/" + i + "?api_key=" + API_KEY);
if (JSONString != null) {
try {
JSONObject jsonObject = new JSONObject(JSONString);
JSONArray jsonArray = jsonObject.getJSONArray("genres");
boolean cont = true;
for (int a = 0; a < jsonArray.length(); a++) {
JSONObject jsonObject1 = jsonArray.getJSONObject(a);
String string = jsonObject1.getString("name");
for (int b = 0; b < alPersonType.size(); b++) {
if (string.equals(alPersonType.get(b))) {
cont = false;
}
}
}
if (cont) {
String id = String.valueOf(jsonObject.getInt("id"));
System.out.println("ID: " + id);
switch (id.length()) {
case 1:
id = "0000" + id;
break;
case 2:
id = "000" + id;
break;
case 3:
id = "00" + id;
break;
case 4:
id = "0" + id;
break;
}
switch (i) {
case 1:
STRING_LIST_OF_IDS = STRING_LIST_OF_IDS + id;
break;
default:
STRING_LIST_OF_IDS = ", " + STRING_LIST_OF_IDS + id;
break;
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
;
return null;
}
关于java - 如何减慢 API 请求速度？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44037732/