Android Studio：使用 Mongo Java Driver 连接到 MongoDB 服务器答案

【问题标题】：Android Studio: connecting to MongoDB server with Mongo Java DriverAndroid Studio：使用 Mongo Java Driver 连接到 MongoDB 服务器
【发布时间】：2017-03-10 01:25:51
【问题描述】：

有很多关于这个问题的帖子，但似乎没有人工作，所以可能有些事情已经改变了。

我正在尝试将我的 android 应用程序连接到位于 mLab 上的 MongoDB 服务器。我正在使用 Mongo Java Drived，并且已经将库添加到了 android studio。

可以启动应用程序，但是当我单击注册按钮时，应用程序崩溃了。

这是我的代码：

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.MongoClientURI;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

public class MainActivity extends AppCompatActivity {

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

    final EditText username = (EditText)findViewById(R.id.username);
    final Button bRegister = (Button) findViewById(R.id.bRegister);

    bRegister.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String stringUsername = username.toString();
            try {
                addToDatabase(stringUsername);
            } catch(Exception e) {
                e.printStackTrace();
            }
        }
    });
}

private static void addToDatabase(String username){
    MongoClientURI uri  = new MongoClientURI("mongodb:///*mLab database URL */");
    MongoClient client = new MongoClient(uri);
    MongoDatabase db = client.getDatabase(uri.getDatabase());
    MongoCollection<Document> coll = db.getCollection("newDB");

    Document doc = new Document("username", username);
    coll.insertOne(doc);
    client.close();
}
}

我在清单文件中也有 permision.INTERNET。

任何帮助将不胜感激！

//编辑堆栈跟踪：

03/10 02:43:09: Launching app
Cold swapped changes.
$ adb shell am start -n "com.newhdc.pedergb.mongodb_servertester/com.newhdc.pedergb.mongodb_servertester.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Client not ready yet..Waiting for process to come online
Connected to process 4752 on device emulator-5554
D/NetworkSecurityConfig: No Network Security Config specified, using platform default
W/org.bson.ObjectId: Failed to get process identifier from JMX, using random number instead
                     java.lang.NoClassDefFoundError: Failed resolution of: Ljava/lang/management/ManagementFactory;
                         at org.bson.types.ObjectId.createProcessIdentifier(ObjectId.java:533)
                         at org.bson.types.ObjectId.<clinit>(ObjectId.java:491)
                         at com.mongodb.connection.ClusterId.<init>(ClusterId.java:47)
                         at com.mongodb.connection.DefaultClusterFactory.create(DefaultClusterFactory.java:105)
                         at com.mongodb.Mongo.createCluster(Mongo.java:744)
                         at com.mongodb.Mongo.createCluster(Mongo.java:728)
                         at com.mongodb.Mongo.createCluster(Mongo.java:702)
                         at com.mongodb.Mongo.<init>(Mongo.java:310)
                         at com.mongodb.Mongo.<init>(Mongo.java:306)
                         at com.mongodb.MongoClient.<init>(MongoClient.java:284)
                         at com.newhdc.pedergb.mongodb_servertester.MainActivity.addToDatabase(MainActivity.java:39)
                         at com.newhdc.pedergb.mongodb_servertester.MainActivity.access$000(MainActivity.java:14)
                         at com.newhdc.pedergb.mongodb_servertester.MainActivity$1.onClick(MainActivity.java:29)
                         at android.view.View.performClick(View.java:5637)
                         at android.view.View$PerformClick.run(View.java:22429)
                         at android.os.Handler.handleCallback(Handler.java:751)
                         at android.os.Handler.dispatchMessage(Handler.java:95)
                         at android.os.Looper.loop(Looper.java:154)
                         at android.app.ActivityThread.main(ActivityThread.java:6119)
                         at java.lang.reflect.Method.invoke(Native Method)
                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
                      Caused by: java.lang.ClassNotFoundException: Didn't find class "java.lang.management.ManagementFactory" on path: DexPathList[[dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-support-annotations-25.1.0_11ac1b6ae4b8623fca16868c12f685674e962f99-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_9-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_8-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_7-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_6-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_5-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_4-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_3-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_2-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_1-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-slice_0-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-mongodb-driver-core-3.4.2_cf1ecbf321a58b8bf97e118b2c0ff7614ac982a5-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-mongodb-driver-3.4.2_cfefe7ed281d321e57736b38e1e68fc6160680ac-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-com.android.support-support-vector-drawable-25.1.0_3dbe341ffa762dac2cc1137bc6aae1731f3bc1c0-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-com.android.support-support-v4-25.1.0_c534a46cb17b55c593319a94e0d90e0b75103a24-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-com.android.support-support-media-compat-25.1.0_b58e3876df91b49420cb0766dd6edfdbff0dedbc-classes.dex", dex file "/data/data/com.newhdc.pedergb.mongodb_servertester/files/instant-run/dex/slice-com.android.support-support-fragment-25.1.0_d616629f11d994c207dfc4b5d01648e3194bccbc-classes.dex", dex f
I/cluster: Cluster created with settings {hosts=[ds123080.mlab.com:23080], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms', maxWaitQueueSize=500}
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: **FATAL EXCEPTION**: main
                  Process: com.newhdc.pedergb.mongodb_servertester, PID: 4752
                  java.lang.ExceptionInInitializerError
                      at com.mongodb.connection.InternalStreamConnectionFactory.<init>(InternalStreamConnectionFactory.java:41)
                      at com.mongodb.connection.DefaultClusterableServerFactory.create(DefaultClusterableServerFactory.java:68)
                      at com.mongodb.connection.BaseCluster.createServer(BaseCluster.java:360)
                      at com.mongodb.connection.SingleServerCluster.<init>(SingleServerCluster.java:54)
                      at com.mongodb.connection.DefaultClusterFactory.create(DefaultClusterFactory.java:114)
                      at com.mongodb.Mongo.createCluster(Mongo.java:744)
                      at com.mongodb.Mongo.createCluster(Mongo.java:728)
                      at com.mongodb.Mongo.createCluster(Mongo.java:702)
                      at com.mongodb.Mongo.<init>(Mongo.java:310)
                      at com.mongodb.Mongo.<init>(Mongo.java:306)
                      at com.mongodb.MongoClient.<init>(MongoClient.java:284)
                      at com.newhdc.pedergb.mongodb_servertester.MainActivity.addToDatabase(MainActivity.java:39)
                      at com.newhdc.pedergb.mongodb_servertester.MainActivity.access$000(MainActivity.java:14)
                      at com.newhdc.pedergb.mongodb_servertester.MainActivity$1.onClick(MainActivity.java:29)
                      at android.view.View.performClick(View.java:5637)
                      at android.view.View$PerformClick.run(View.java:22429)
                      at android.os.Handler.handleCallback(Handler.java:751)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:154)
                      at android.app.ActivityThread.main(ActivityThread.java:6119)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
                   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.security.CodeSource java.security.ProtectionDomain.getCodeSource()' on a null object reference
                      at com.mongodb.connection.ClientMetadataHelper.getDriverVersion(ClientMetadataHelper.java:111)
                      at com.mongodb.connection.ClientMetadataHelper.getDriverInformation(ClientMetadataHelper.java:201)
                      at com.mongodb.connection.ClientMetadataHelper.addDriverInformation(ClientMetadataHelper.java:182)
                      at com.mongodb.connection.ClientMetadataHelper.<clinit>(ClientMetadataHelper.java:64)
                      at com.mongodb.connection.InternalStreamConnectionFactory.<init>(InternalStreamConnectionFactory.java:41) 
                      at com.mongodb.connection.DefaultClusterableServerFactory.create(DefaultClusterableServerFactory.java:68) 
                      at com.mongodb.connection.BaseCluster.createServer(BaseCluster.java:360) 
                      at com.mongodb.connection.SingleServerCluster.<init>(SingleServerCluster.java:54) 
                      at com.mongodb.connection.DefaultClusterFactory.create(DefaultClusterFactory.java:114) 
                      at com.mongodb.Mongo.createCluster(Mongo.java:744) 
                      at com.mongodb.Mongo.createCluster(Mongo.java:728) 
                      at com.mongodb.Mongo.createCluster(Mongo.java:702) 
                      at com.mongodb.Mongo.<init>(Mongo.java:310) 
                      at com.mongodb.Mongo.<init>(Mongo.java:306) 
                      at com.mongodb.MongoClient.<init>(MongoClient.java:284) 
                      at com.newhdc.pedergb.mongodb_servertester.MainActivity.addToDatabase(MainActivity.java:39) 
                      at com.newhdc.pedergb.mongodb_servertester.MainActivity.access$000(MainActivity.java:14) 
                      at com.newhdc.pedergb.mongodb_servertester.MainActivity$1.onClick(MainActivity.java:29) 
                      at android.view.View.performClick(View.java:5637) 
                      at android.view.View$PerformClick.run(View.java:22429) 
                      at android.os.Handler.handleCallback(Handler.java:751) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:154) 
                      at android.app.ActivityThread.main(ActivityThread.java:6119) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Application terminated.

【问题讨论】：

你能在 MongoClient client = new MongoClient(uri); 之后尝试打印 client.toString() 吗？看看你是否能够连接到数据库
错误似乎出现在第39行，也就是“new MongoClient(uri);”所在的行制作完成。
你得到什么错误？你可以发布堆栈跟踪吗？
感谢您的回复！抱歉，堆栈跟踪太长了。

标签： java android mongodb

【解决方案1】：

不幸的是，根据this StackOverflow post，Mongo Java 驱动程序无法在 Android 上运行，因为 Android 缺少一些 Java 类。然而，一位好心的 StackOverflow 用户已经分叉了 Mongo Java 驱动程序并解决了这个问题。您可以在 Github 上查看他们的库版本。

向下滚动到描述并下载最新的 jar 文件。现在是这个：

https://github.com/matfur92/mongo-java-driver/blob/gh-pages/JARs/mongo-java-driver-3.4.0-SNAPSHOT.jar?raw=true.

接下来，继续删除 mongo-java-driver 的 build.gradle 依赖项中的行。要删除的行应如下所示：

dependencies {
    ...
    compile 'org.mongodb:mongodb-driver:3.4.2'
    ...
}

最后，将您下载的 jar 添加到您的应用程序 (guide here)。现在您的代码无需修改即可工作。我能够很好地使用常规 MongoDB 功能，但我无法让 GridFS 工作。

【讨论】：

感谢您的回复。我实际上确实使用了您引用的分叉版本。我认为我的问题是我在主线程中运行了请求。我没有尝试过，但我猜如果我用 AsyncTask 运行它或创建一个新线程它会起作用。

【解决方案2】：

我遇到了同样的问题。确实问题是您在主线程中调用连接。将以下内容添加到 onCreate 方法中。

@Override
    protected void onCreate(Bundle savedInstanceState) {
 if (android.os.Build.VERSION.SDK_INT > 9)
        {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);
        }

希望对您有所帮助。

【讨论】：