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我找到了这个（http://code.google.com/apis/imagesearch/v1/jsondevguide.html#json_snippets_java），我已经将它包含在一个新项目中，我想知道如何从JSON对象。我试图进行搜索，但没有找到任何可以帮助我的东西（我是一个新手 - 自学 Java）。

package com.googlesearch;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {

public static String searchstring = "big bang theory";
public static URLConnection connection;
public static URL url;
public static BufferedReader reader;
public static JSONObject json;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    try {
        url = new URL("https://ajax.googleapis.com/ajax/services/search/images?v=1.0&q=" + searchstring);
    } catch (MalformedURLException e) {
    }

    try {
        connection = url.openConnection();
    } catch (IOException e) {
    }
    connection.addRequestProperty("Referer", "www.google.co.uk");
    String line;
    StringBuilder builder = new StringBuilder();

    try {
        reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
    } catch (IOException e1) {
    }
    try {
        while((line = reader.readLine()) != null) {
            builder.append(line);
        }
    } catch (IOException e) {
    }

    try {
        json = new JSONObject(builder.toString());
    } catch (JSONException e) {
    }
}
}

日志猫：

04-08 19:59:33.019: E/AndroidRuntime(4965): FATAL EXCEPTION: main
04-08 19:59:33.019: E/AndroidRuntime(4965): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bigbangtheorywallpapers/com.bigbangtheorywallpapers.MainActivity}: android.os.NetworkOnMainThreadException
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.ActivityThread.access$600(ActivityThread.java:140)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.os.Looper.loop(Looper.java:137)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.ActivityThread.main(ActivityThread.java:4898)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at java.lang.reflect.Method.invokeNative(Native Method)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at java.lang.reflect.Method.invoke(Method.java:511)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at dalvik.system.NativeStart.main(Native Method)
04-08 19:59:33.019: E/AndroidRuntime(4965): Caused by: android.os.NetworkOnMainThreadException
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:315)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.makeSslConnection(HttpsURLConnectionImpl.java:461)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.connect(HttpsURLConnectionImpl.java:433)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:289)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:239)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at libcore.net.http.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:271)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at com.bigbangtheorywallpapers.MainActivity.onCreate(MainActivity.java:43)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.Activity.performCreate(Activity.java:5206)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1083)
04-08 19:59:33.019: E/AndroidRuntime(4965):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2064)
04-08 19:59:33.019: E/AndroidRuntime(4965):     ... 11 more
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1 回答 1

1

根据评论：

我刚刚尝试测试上面的代码，但是应用程序在启动时崩溃了。

=> 当您直接在主 UI 线程上进行 Web API 调用时，它android.os.NetworkOnMainThreadException实际上是在给予。

要解决此问题，有两种解决方案：

  1. 标准方式 => 实现 AsyncTask
  2. 懒惰的解决方案 => 在拨打电话之前包括以下几行：

StrictMode.ThreadPolicy 策略 = new StrictMode.ThreadPolicy.Builder().permitAll().build(); StrictMode.setThreadPolicy(policy);

是的，不要忘记将其添加到 AndroidManifest.xml 文件中：

<uses-permission android:name="android.permission.INTERNET"/>
于 2013-04-08T19:05:30.180 回答