如何使用 Android App 知道特定文档存在于 Cloudant 数据库中
How to know that specific document is present in Cloudant Database using Android App
我已经通过我的 Android 应用程序在 Cloudant 数据库中成功创建了文档。但是我找不到 Cloudant 数据库中存在的特定文档。我试过的如下....
TabTwo_Fragment.java
package com.example.android02.insightapp11;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import com.cloudant.sync.datastore.BasicDocumentRevision;
import com.cloudant.sync.datastore.Datastore;
import com.cloudant.sync.datastore.DatastoreManager;
import com.cloudant.sync.datastore.DatastoreNotCreatedException;
import com.cloudant.sync.datastore.DocumentBodyFactory;
import com.cloudant.sync.datastore.DocumentException;
import com.cloudant.sync.datastore.DocumentNotFoundException;
import com.cloudant.sync.datastore.DocumentRevision;
import com.cloudant.sync.datastore.MutableDocumentRevision;
import com.cloudant.sync.replication.Replicator;
import com.cloudant.sync.replication.ReplicatorBuilder;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.File;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
/**
* A simple {@link Fragment} subclass.
*/
public class TabTwo_Fragment extends Fragment implements View.OnClickListener, SharedPreferences.OnSharedPreferenceChangeListener {
private static final String DATASTORE_MANGER_DIR = "data";
private static final String TASKS_DATASTORE_NAME = "tasks";
Datastore DataStore;
private Replicator PushReplicator, PullReplicator;
DocumentRevision revision;
static final String CLOUDANT_USER = "user_default";
static final String CLOUDANT_DB = "database_name";
static final String CLOUDANT_API_KEY = "api_key";
static final String CLOUDANT_API_SECRET = "api_key_pwd";
long TWITTER_ID = MainActivity.twitterID;
String TWITTER_NAME = MainActivity.userName;
Button btn_submit;
Spinner sp1, sp2, sp3, sp4, sp5, sp6, sp7, sp8;
TextView ans_total;
String user = "old";
HashMap<String, String> qa_hashmap;
public TabTwo_Fragment() {
// Required empty public constructor
}
public static TabTwo_Fragment newInstance() {
return new TabTwo_Fragment();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.tabtwo_fragment, container, false);
try {
init(rootView);
} catch (DocumentNotFoundException e) {
} catch (DocumentException e) {
} catch (URISyntaxException e) {
}
return rootView;
}
void init(View rootView) throws DocumentException, URISyntaxException {
Log.e("init: ", "in init");
find_view_by_id(rootView);
registerClickEvents();
defaultConfig();
checkForRegisteredUser();
}
void find_view_by_id(View rootView) {
Log.e("find_view_by_id: ", "in find_view_by_id");
btn_submit = (Button) rootView.findViewById(R.id.btn_submit);
sp1 = (Spinner) rootView.findViewById(R.id.sp1);
sp2 = (Spinner) rootView.findViewById(R.id.sp2);
sp3 = (Spinner) rootView.findViewById(R.id.sp3);
sp4 = (Spinner) rootView.findViewById(R.id.sp4);
sp5 = (Spinner) rootView.findViewById(R.id.sp5);
sp6 = (Spinner) rootView.findViewById(R.id.sp6);
sp7 = (Spinner) rootView.findViewById(R.id.sp7);
sp8 = (Spinner) rootView.findViewById(R.id.sp8);
ans_total = (TextView) rootView.findViewById(R.id.ans_total);
}
void registerClickEvents() {
Log.e("registerClickEvents: ", "in registerClickEvents");
btn_submit.setOnClickListener(this);
}
void defaultConfig() {
Log.e("defaultConfig: ", "in defaultConfig");
PreferenceManager.setDefaultValues(getContext(), R.xml.preferences, false);
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
sharedPref.registerOnSharedPreferenceChangeListener(this);
File path = getContext().getDir(DATASTORE_MANGER_DIR, Context.MODE_PRIVATE);
DatastoreManager manager = new DatastoreManager(path.getAbsolutePath());
try {
DataStore = manager.openDatastore(TASKS_DATASTORE_NAME);
setUriPlusReplicators();
} catch (DatastoreNotCreatedException e) {
Toast.makeText(getContext(), "Unable to open Datastore!", Toast.LENGTH_SHORT).show();
} catch (URISyntaxException e) {
Toast.makeText(getContext(), "URI Exception!!", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
try {
setUriPlusReplicators();
} catch (URISyntaxException e) {
}
}
void setUriPlusReplicators() throws URISyntaxException {
Log.e("setUriPlusReplicators: ", "in setUriPlusReplicators");
URI uri = this.createServerUri();
Log.e("URI: ", "" + uri);
PushReplicator = ReplicatorBuilder.push().from(DataStore).to(uri).build();
PushReplicator.getEventBus().register(this);
PullReplicator = ReplicatorBuilder.pull().to(DataStore).from(uri).build();
PullReplicator.getEventBus().register(this);
}
private URI createServerUri() throws URISyntaxException {
Log.e("createServerUri: ", "in createServerUri");
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
String username = sharedPref.getString(CLOUDANT_USER, "");
String dbName = sharedPref.getString(CLOUDANT_DB, "");
String apiKey = sharedPref.getString(CLOUDANT_API_KEY, "");
String apiSecret = sharedPref.getString(CLOUDANT_API_SECRET, "");
String host = username + ".cloudant.com";
return new URI("https", apiKey + ":" + apiSecret, host, 443, "/" + dbName, null, null);
}
private URI createServerUri2(long twitterId) throws URISyntaxException {
Log.e("createServerUri2: ", "in createServerUri2");
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
String username = sharedPref.getString(CLOUDANT_USER, "");
String dbName = sharedPref.getString(CLOUDANT_DB, "");
String apiKey = sharedPref.getString(CLOUDANT_API_KEY, "");
String apiSecret = sharedPref.getString(CLOUDANT_API_SECRET, "");
String host = username + ".cloudant.com";
return new URI("https", apiKey + ":" + apiSecret, host, 443, "/" + dbName + "/_all_docs?", null, null);
}
void checkForRegisteredUser() throws DocumentNotFoundException, DocumentException, URISyntaxException {
BasicDocumentRevision retrieved = DataStore.getDocument(TWITTER_ID + "");
if (user.equals("new")) {
setQuizData(retrieved.getBody().toString());
} else {
newUser();
}
}
void setQuizData(String DataRetrieved) {
Log.e("setQuizData: ", "In setQuizData");
user = "old";
Log.e("DataRetrieved: ", "In " + DataRetrieved);
String[] ANSWERS = getResources().getStringArray(R.array.ans);
try {
JSONObject jsonObject = new JSONObject(DataRetrieved);
JSONObject jsonObject1 = jsonObject.getJSONObject("questions");
String qs1 = jsonObject1.getString("q1");
String qs2 = jsonObject1.getString("q2");
String qs3 = jsonObject1.getString("q3");
String qs4 = jsonObject1.getString("q4");
String qs5 = jsonObject1.getString("q5");
String qs6 = jsonObject1.getString("q6");
String qs7 = jsonObject1.getString("q7");
String qs8 = jsonObject1.getString("q8");
sp1.setSelection(Arrays.asList(ANSWERS).indexOf(qs1));
sp2.setSelection(Arrays.asList(ANSWERS).indexOf(qs2));
sp3.setSelection(Arrays.asList(ANSWERS).indexOf(qs3));
sp4.setSelection(Arrays.asList(ANSWERS).indexOf(qs4));
sp5.setSelection(Arrays.asList(ANSWERS).indexOf(qs5));
sp6.setSelection(Arrays.asList(ANSWERS).indexOf(qs6));
sp7.setSelection(Arrays.asList(ANSWERS).indexOf(qs7));
sp8.setSelection(Arrays.asList(ANSWERS).indexOf(qs8));
} catch (JSONException e) {
}
}
void newUser() {
Log.e("newUser: ", "In newUser");
user = "new";
}
void createDocument() throws DocumentException {
Log.e("createDocument: ", "In createDocument");
MutableDocumentRevision rev = new MutableDocumentRevision();
rev.docId = TWITTER_ID + "";
gatherQAData();
/*HashMap<String, Object> map_main = new HashMap<String, Object>();*/
HashMap<String, Object> map = new HashMap<String, Object>();
ArrayList<HashMap<String, Object>> arrayTeachers = new ArrayList<>();
map.put("twitter_id", TWITTER_ID + "");
map.put("twitter_name", TWITTER_NAME);
map.put("questions", qa_hashmap);
/*arrayTeachers.add(map);*/
/*map_main.put("user", arrayTeachers);*/
rev.body = DocumentBodyFactory.create(map);
revision = DataStore.createDocumentFromRevision(rev);
PushReplicator.start();
}
void updateDocument() {
Log.e("updateDocument: ", "In updateDocument");
}
void gatherQAData() {
Log.e("gatherQAData: ", "In gatherQAData");
qa_hashmap = new HashMap<String, String>();
String a1, a2, a3, a4, a5, a6, a7, a8;
a1 = sp1.getSelectedItem().toString();
a2 = sp2.getSelectedItem().toString();
a3 = sp3.getSelectedItem().toString();
a4 = sp4.getSelectedItem().toString();
a5 = sp5.getSelectedItem().toString();
a6 = sp6.getSelectedItem().toString();
a7 = sp7.getSelectedItem().toString();
a8 = sp8.getSelectedItem().toString();
qa_hashmap.put("q1", a1);
qa_hashmap.put("q2", a2);
qa_hashmap.put("q3", a3);
qa_hashmap.put("q4", a4);
qa_hashmap.put("q5", a5);
qa_hashmap.put("q6", a6);
qa_hashmap.put("q7", a7);
qa_hashmap.put("q8", a8);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_submit:
if (user.equals("new")) {
try {
createDocument();
} catch (DocumentException e) {
}
} else {
updateDocument();
}
break;
default:
}
}
}
我可以获取存储在 DataStore 中的文档。但是我无法将文档存储在 Cloudant 数据库中。
仅供参考：我正在 checkForRegisteredUser 方法中查找文档。
是的，我做到了。下面是我的 checkForRegisteredUser 方法 TabTwo_Fragment.java
的代码
void checkForRegisteredUser() {
String url = "https://your_cloudant_user_name.cloudant.com/" + DB_NAME + "/" + DOC_ID;
RequestQueue requestQueue = Volley.newRequestQueue(getContext());
JsonObjectRequest jor = new JsonObjectRequest(Request.Method.GET, url, (String) null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
if (response.toString().length() > 0) {
setQuizData(response.toString());
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
newUser();
}
});
requestQueue.add(jor);
这是官方文档LINK。
这里DOC_ID是你要查看的文档id。希望这会对某人有所帮助。
Cloudant 中发生的事情是，默认情况下，cloudant 已经为每个文档提供了两个字段，即 _id 和 _rev，其中 _id 充当索引的主键。所以在 _id 字段上会有一个由 cloudant 创建的默认索引。如果您的文档中已有这些字段，那么 cloudant 将不会插入额外的 _id 和 _rev。
现在你可以在你的文档中有这个 _id 字段并根据你自己设置它或者让 cloudant 设置它。但是当您不设置它时，您将无法在主索引上查询 Cloudant，因为您不知道文档的 _id。
因此，要在存储的 twitter_id 等其他字段的基础上进行搜索或查找，您必须创建一个比 search/find 所能创建的索引更多的索引。
我们可以使用 cloudant api
提供的函数在 java 中创建索引
public void createIndex(java.lang.String indexName,
java.lang.String designDocName,
java.lang.String indexType,
IndexField[] fields)
或者如果你在你的函数中分配 _id 而不是你可以简单地调用一个函数
db.contains(doc_id);
这要容易得多，因为您不需要创建任何索引并使用默认索引。
编辑-1
所以这里的db就是你获取的数据库实例。
Database db=client.database(db_name,create_flag);
其中 create_flag 是一个 布尔值 表示如果数据库不存在则应创建所以 true 表示是 create false意思是不存在就不要创建。
客户端是 CloudantClient 对象。
但是，如果您知道数据库不存在，您也可以调用 createDB。您可以按照以下方式进行
Database db=client.createDB("DBNAME");
如何获取 CloudantClient 取决于您使用的 cloudant api 版本。对于 ex 1.0.1 与最新版本不同。
在版本 1.0.1 中，您可以按照以下方式进行操作
CloudantClient client=new CloudantClient(URL_OF_YOUR_CLOUDANT,USERNAME,PASSWORD);
但在最新版本中他们使用
CloudantClient client=ClientBuilder.url(new URL("your url")).username("your username string").password("your password").build();
所以我不知道您为什么找不到 createIndex。我想您无法找到 Cloudant-api javadocs 。只需 google for Cloudant javadocs 或检查此 github
GitHub link
我已经通过我的 Android 应用程序在 Cloudant 数据库中成功创建了文档。但是我找不到 Cloudant 数据库中存在的特定文档。我试过的如下....
TabTwo_Fragment.java
package com.example.android02.insightapp11;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import com.cloudant.sync.datastore.BasicDocumentRevision;
import com.cloudant.sync.datastore.Datastore;
import com.cloudant.sync.datastore.DatastoreManager;
import com.cloudant.sync.datastore.DatastoreNotCreatedException;
import com.cloudant.sync.datastore.DocumentBodyFactory;
import com.cloudant.sync.datastore.DocumentException;
import com.cloudant.sync.datastore.DocumentNotFoundException;
import com.cloudant.sync.datastore.DocumentRevision;
import com.cloudant.sync.datastore.MutableDocumentRevision;
import com.cloudant.sync.replication.Replicator;
import com.cloudant.sync.replication.ReplicatorBuilder;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.File;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
/**
* A simple {@link Fragment} subclass.
*/
public class TabTwo_Fragment extends Fragment implements View.OnClickListener, SharedPreferences.OnSharedPreferenceChangeListener {
private static final String DATASTORE_MANGER_DIR = "data";
private static final String TASKS_DATASTORE_NAME = "tasks";
Datastore DataStore;
private Replicator PushReplicator, PullReplicator;
DocumentRevision revision;
static final String CLOUDANT_USER = "user_default";
static final String CLOUDANT_DB = "database_name";
static final String CLOUDANT_API_KEY = "api_key";
static final String CLOUDANT_API_SECRET = "api_key_pwd";
long TWITTER_ID = MainActivity.twitterID;
String TWITTER_NAME = MainActivity.userName;
Button btn_submit;
Spinner sp1, sp2, sp3, sp4, sp5, sp6, sp7, sp8;
TextView ans_total;
String user = "old";
HashMap<String, String> qa_hashmap;
public TabTwo_Fragment() {
// Required empty public constructor
}
public static TabTwo_Fragment newInstance() {
return new TabTwo_Fragment();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.tabtwo_fragment, container, false);
try {
init(rootView);
} catch (DocumentNotFoundException e) {
} catch (DocumentException e) {
} catch (URISyntaxException e) {
}
return rootView;
}
void init(View rootView) throws DocumentException, URISyntaxException {
Log.e("init: ", "in init");
find_view_by_id(rootView);
registerClickEvents();
defaultConfig();
checkForRegisteredUser();
}
void find_view_by_id(View rootView) {
Log.e("find_view_by_id: ", "in find_view_by_id");
btn_submit = (Button) rootView.findViewById(R.id.btn_submit);
sp1 = (Spinner) rootView.findViewById(R.id.sp1);
sp2 = (Spinner) rootView.findViewById(R.id.sp2);
sp3 = (Spinner) rootView.findViewById(R.id.sp3);
sp4 = (Spinner) rootView.findViewById(R.id.sp4);
sp5 = (Spinner) rootView.findViewById(R.id.sp5);
sp6 = (Spinner) rootView.findViewById(R.id.sp6);
sp7 = (Spinner) rootView.findViewById(R.id.sp7);
sp8 = (Spinner) rootView.findViewById(R.id.sp8);
ans_total = (TextView) rootView.findViewById(R.id.ans_total);
}
void registerClickEvents() {
Log.e("registerClickEvents: ", "in registerClickEvents");
btn_submit.setOnClickListener(this);
}
void defaultConfig() {
Log.e("defaultConfig: ", "in defaultConfig");
PreferenceManager.setDefaultValues(getContext(), R.xml.preferences, false);
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
sharedPref.registerOnSharedPreferenceChangeListener(this);
File path = getContext().getDir(DATASTORE_MANGER_DIR, Context.MODE_PRIVATE);
DatastoreManager manager = new DatastoreManager(path.getAbsolutePath());
try {
DataStore = manager.openDatastore(TASKS_DATASTORE_NAME);
setUriPlusReplicators();
} catch (DatastoreNotCreatedException e) {
Toast.makeText(getContext(), "Unable to open Datastore!", Toast.LENGTH_SHORT).show();
} catch (URISyntaxException e) {
Toast.makeText(getContext(), "URI Exception!!", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
try {
setUriPlusReplicators();
} catch (URISyntaxException e) {
}
}
void setUriPlusReplicators() throws URISyntaxException {
Log.e("setUriPlusReplicators: ", "in setUriPlusReplicators");
URI uri = this.createServerUri();
Log.e("URI: ", "" + uri);
PushReplicator = ReplicatorBuilder.push().from(DataStore).to(uri).build();
PushReplicator.getEventBus().register(this);
PullReplicator = ReplicatorBuilder.pull().to(DataStore).from(uri).build();
PullReplicator.getEventBus().register(this);
}
private URI createServerUri() throws URISyntaxException {
Log.e("createServerUri: ", "in createServerUri");
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
String username = sharedPref.getString(CLOUDANT_USER, "");
String dbName = sharedPref.getString(CLOUDANT_DB, "");
String apiKey = sharedPref.getString(CLOUDANT_API_KEY, "");
String apiSecret = sharedPref.getString(CLOUDANT_API_SECRET, "");
String host = username + ".cloudant.com";
return new URI("https", apiKey + ":" + apiSecret, host, 443, "/" + dbName, null, null);
}
private URI createServerUri2(long twitterId) throws URISyntaxException {
Log.e("createServerUri2: ", "in createServerUri2");
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getContext());
String username = sharedPref.getString(CLOUDANT_USER, "");
String dbName = sharedPref.getString(CLOUDANT_DB, "");
String apiKey = sharedPref.getString(CLOUDANT_API_KEY, "");
String apiSecret = sharedPref.getString(CLOUDANT_API_SECRET, "");
String host = username + ".cloudant.com";
return new URI("https", apiKey + ":" + apiSecret, host, 443, "/" + dbName + "/_all_docs?", null, null);
}
void checkForRegisteredUser() throws DocumentNotFoundException, DocumentException, URISyntaxException {
BasicDocumentRevision retrieved = DataStore.getDocument(TWITTER_ID + "");
if (user.equals("new")) {
setQuizData(retrieved.getBody().toString());
} else {
newUser();
}
}
void setQuizData(String DataRetrieved) {
Log.e("setQuizData: ", "In setQuizData");
user = "old";
Log.e("DataRetrieved: ", "In " + DataRetrieved);
String[] ANSWERS = getResources().getStringArray(R.array.ans);
try {
JSONObject jsonObject = new JSONObject(DataRetrieved);
JSONObject jsonObject1 = jsonObject.getJSONObject("questions");
String qs1 = jsonObject1.getString("q1");
String qs2 = jsonObject1.getString("q2");
String qs3 = jsonObject1.getString("q3");
String qs4 = jsonObject1.getString("q4");
String qs5 = jsonObject1.getString("q5");
String qs6 = jsonObject1.getString("q6");
String qs7 = jsonObject1.getString("q7");
String qs8 = jsonObject1.getString("q8");
sp1.setSelection(Arrays.asList(ANSWERS).indexOf(qs1));
sp2.setSelection(Arrays.asList(ANSWERS).indexOf(qs2));
sp3.setSelection(Arrays.asList(ANSWERS).indexOf(qs3));
sp4.setSelection(Arrays.asList(ANSWERS).indexOf(qs4));
sp5.setSelection(Arrays.asList(ANSWERS).indexOf(qs5));
sp6.setSelection(Arrays.asList(ANSWERS).indexOf(qs6));
sp7.setSelection(Arrays.asList(ANSWERS).indexOf(qs7));
sp8.setSelection(Arrays.asList(ANSWERS).indexOf(qs8));
} catch (JSONException e) {
}
}
void newUser() {
Log.e("newUser: ", "In newUser");
user = "new";
}
void createDocument() throws DocumentException {
Log.e("createDocument: ", "In createDocument");
MutableDocumentRevision rev = new MutableDocumentRevision();
rev.docId = TWITTER_ID + "";
gatherQAData();
/*HashMap<String, Object> map_main = new HashMap<String, Object>();*/
HashMap<String, Object> map = new HashMap<String, Object>();
ArrayList<HashMap<String, Object>> arrayTeachers = new ArrayList<>();
map.put("twitter_id", TWITTER_ID + "");
map.put("twitter_name", TWITTER_NAME);
map.put("questions", qa_hashmap);
/*arrayTeachers.add(map);*/
/*map_main.put("user", arrayTeachers);*/
rev.body = DocumentBodyFactory.create(map);
revision = DataStore.createDocumentFromRevision(rev);
PushReplicator.start();
}
void updateDocument() {
Log.e("updateDocument: ", "In updateDocument");
}
void gatherQAData() {
Log.e("gatherQAData: ", "In gatherQAData");
qa_hashmap = new HashMap<String, String>();
String a1, a2, a3, a4, a5, a6, a7, a8;
a1 = sp1.getSelectedItem().toString();
a2 = sp2.getSelectedItem().toString();
a3 = sp3.getSelectedItem().toString();
a4 = sp4.getSelectedItem().toString();
a5 = sp5.getSelectedItem().toString();
a6 = sp6.getSelectedItem().toString();
a7 = sp7.getSelectedItem().toString();
a8 = sp8.getSelectedItem().toString();
qa_hashmap.put("q1", a1);
qa_hashmap.put("q2", a2);
qa_hashmap.put("q3", a3);
qa_hashmap.put("q4", a4);
qa_hashmap.put("q5", a5);
qa_hashmap.put("q6", a6);
qa_hashmap.put("q7", a7);
qa_hashmap.put("q8", a8);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_submit:
if (user.equals("new")) {
try {
createDocument();
} catch (DocumentException e) {
}
} else {
updateDocument();
}
break;
default:
}
}
}
我可以获取存储在 DataStore 中的文档。但是我无法将文档存储在 Cloudant 数据库中。
仅供参考：我正在 checkForRegisteredUser 方法中查找文档。
是的，我做到了。下面是我的 checkForRegisteredUser 方法 TabTwo_Fragment.java
void checkForRegisteredUser() {
String url = "https://your_cloudant_user_name.cloudant.com/" + DB_NAME + "/" + DOC_ID;
RequestQueue requestQueue = Volley.newRequestQueue(getContext());
JsonObjectRequest jor = new JsonObjectRequest(Request.Method.GET, url, (String) null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
if (response.toString().length() > 0) {
setQuizData(response.toString());
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
newUser();
}
});
requestQueue.add(jor);
这是官方文档LINK。
这里DOC_ID是你要查看的文档id。希望这会对某人有所帮助。
Cloudant 中发生的事情是，默认情况下，cloudant 已经为每个文档提供了两个字段，即 _id 和 _rev，其中 _id 充当索引的主键。所以在 _id 字段上会有一个由 cloudant 创建的默认索引。如果您的文档中已有这些字段，那么 cloudant 将不会插入额外的 _id 和 _rev。 现在你可以在你的文档中有这个 _id 字段并根据你自己设置它或者让 cloudant 设置它。但是当您不设置它时，您将无法在主索引上查询 Cloudant，因为您不知道文档的 _id。 因此，要在存储的 twitter_id 等其他字段的基础上进行搜索或查找，您必须创建一个比 search/find 所能创建的索引更多的索引。 我们可以使用 cloudant api
提供的函数在 java 中创建索引public void createIndex(java.lang.String indexName,
java.lang.String designDocName,
java.lang.String indexType,
IndexField[] fields)
或者如果你在你的函数中分配 _id 而不是你可以简单地调用一个函数
db.contains(doc_id);
这要容易得多，因为您不需要创建任何索引并使用默认索引。
编辑-1 所以这里的db就是你获取的数据库实例。
Database db=client.database(db_name,create_flag);
其中 create_flag 是一个 布尔值 表示如果数据库不存在则应创建所以 true 表示是 create false意思是不存在就不要创建。 客户端是 CloudantClient 对象。 但是，如果您知道数据库不存在，您也可以调用 createDB。您可以按照以下方式进行
Database db=client.createDB("DBNAME");
如何获取 CloudantClient 取决于您使用的 cloudant api 版本。对于 ex 1.0.1 与最新版本不同。 在版本 1.0.1 中，您可以按照以下方式进行操作
CloudantClient client=new CloudantClient(URL_OF_YOUR_CLOUDANT,USERNAME,PASSWORD);
但在最新版本中他们使用
CloudantClient client=ClientBuilder.url(new URL("your url")).username("your username string").password("your password").build();
所以我不知道您为什么找不到 createIndex。我想您无法找到 Cloudant-api javadocs 。只需 google for Cloudant javadocs 或检查此 github GitHub link