google-cloud-print - 来自android的谷歌云打印没有对话框

Question

有人能告诉我是否可以从 Android 设备使用谷歌云打印进行静默打印吗？
目标是我的应用程序从 URL 或 SD 卡中获取文件，然后将其发送到特定的打印机 - 所有这些都不需要任何人看着屏幕或触摸任何东西。它实际上是由蓝牙连接设备上的条形码扫描触发的。

谢谢

Answer 1

嗯，这是可能的，但我不知道为什么文档中没有太多关于它的信息......

棘手的部分是仅使用 android 设备连接到谷歌云打印 API(没有第三方服务器，如文档所述:https://developers.google.com/cloud-print/docs/appDevGuide)，这就是我要解释的内容。

首先，您必须在您的应用中包含 Google 登录 API，我推荐 firebase API https://firebase.google.com/docs/auth/android/google-signin

然后你必须去你的谷歌 API 控制台:https://console.developers.google.com在菜单中，转到 证件滚动至 OAuth 2.0 客户端 ID 选择 Web 客户端(由 Google 服务自动创建)并将 保存到您的项目中客户 ID 和 客户端密码 键...在我的项目中，我将它们保存为“ gg_client_web_id ”和“ gg_client_web_secret ”，您将在下面的代码中看到。

接下来，我将粘贴所有代码，然后我将解释它:

public class MainActivity extends AppCompatActivity
    implements GoogleApiClient.OnConnectionFailedListener {
private GoogleApiClient mGoogleApiClient;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private static final int REQUEST_SINGIN = 1;
private TextView txt;
public static final String TAG = "mysupertag";
public static final String URLBASE = "https://www.google.com/cloudprint/";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    txt = (TextView) findViewById(R.id.txt);
    mAuth = FirebaseAuth.getInstance();
    // Configure Google Sign In
    GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.gg_client_web_id))
            .requestEmail()
            .requestServerAuthCode(getString(R.string.gg_client_web_id))
            .requestScopes(new Scope("https://www.googleapis.com/auth/cloudprint"))
            .build();
    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .enableAutoManage(this /* FragmentActivity */, this /* OnConnectionFailedListener */)
            .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
            .build();

    findViewById(R.id.sign_in_button).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            signIn();
        }
    });

    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {
                // User is signed in
                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
            } else {
                // User is signed out
                Log.d(TAG, "onAuthStateChanged:signed_out");
            }
            // ...
        }
    };
}

@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
    Log.d(TAG, "error connecting: " + connectionResult.getErrorMessage());
    Toast.makeText(this, "error CONN", Toast.LENGTH_LONG).show();
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
    if (requestCode == REQUEST_SINGIN) {
        GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
        if (result.isSuccess()) {
            // Google Sign In was successful, authenticate with Firebase
            GoogleSignInAccount account = result.getSignInAccount();
            firebaseAuthWithGoogle(account);
        } else {
            // Google Sign In failed, update UI appropriately
            // ...
            Toast.makeText(this, "error ", Toast.LENGTH_LONG).show();
        }
    }
}

private void signIn() {
    Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
    startActivityForResult(signInIntent, REQUEST_SINGIN);
}

@Override
public void onStart() {
    super.onStart();
    mAuth.addAuthStateListener(mAuthListener);
}

@Override
public void onStop() {
    super.onStop();
    if (mAuthListener != null) {
        mAuth.removeAuthStateListener(mAuthListener);
    }
}

private void firebaseAuthWithGoogle(final GoogleSignInAccount acct) {
    Log.d(TAG, "firebaseAuthWithGoogle:" + acct.getId());

    AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
    mAuth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

                    // If sign in fails, display a message to the user. If sign in succeeds
                    // the auth state listener will be notified and logic to handle the
                    // signed in user can be handled in the listener.
                    FirebaseUser user = task.getResult().getUser();
                    txt.setText(user.getDisplayName() + "\n" + user.getEmail());//todo
                    if (!task.isSuccessful()) {
                        Log.w(TAG, "signInWithCredential", task.getException());
                        Toast.makeText(MainActivity.this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show();
                    }
                    getAccess(acct.getServerAuthCode());
                }
            });
}

private void getPrinters(String token) {
    Log.d(TAG, "TOKEN: " + token);
    String url = URLBASE + "search";
    Ion.with(this)
            .load("GET", url)
            .addHeader("Authorization", "Bearer " + token)
            .asString()
            .withResponse()
            .setCallback(new FutureCallback<Response<String>>() {
                @Override
                public void onCompleted(Exception e, Response<String> result) {
                    Log.d(TAG, "finished " + result.getHeaders().code() + ": " +
                            result.getResult());
                    if (e == null) {
                        Log.d(TAG, "nice");
                    } else {
                        Log.d(TAG, "error");
                    }
                }
            });
}

private void getAccess(String code) {
    String url = "https://www.googleapis.com/oauth2/v4/token";
    Ion.with(this)
            .load("POST", url)
            .setBodyParameter("client_id", getString(R.string.gg_client_web_id))
            .setBodyParameter("client_secret", getString(R.string.gg_client_web_secret))
            .setBodyParameter("code", code)
            .setBodyParameter("grant_type", "authorization_code")
            .asString()
            .withResponse()
            .setCallback(new FutureCallback<Response<String>>() {
                @Override
                public void onCompleted(Exception e, Response<String> result) {
                    Log.d(TAG, "result: " + result.getResult());
                    if (e == null) {
                        try {
                            JSONObject json = new JSONObject(result.getResult());
                            getPrinters(json.getString("access_token"));
                        } catch (JSONException e1) {
                            e1.printStackTrace();
                        }
                    } else {
                        Log.d(TAG, "error");
                    }
                }
            });
}}

如您所见，在 onCreate 中，重要的部分是创建 GoogleSignInOptions 与 谷歌云打印范围 和 调用 requestIdToken/requestServerAuthCode 方法。

然后在 firebaseAuthWithGoogle 方法调用 getAccess 方法以获取 OAuth 访问 token ，用于发出我使用 Ion 库的所有请求: https://github.com/koush/ion

接下来使用 access_token，您现在可以向谷歌云打印 API 发出请求，在这种情况下，我调用 getPrinters 方法，在此方法中，我调用“搜索”方法(来自 google 云打印 API)以获取与已登录的 google 帐户关联的所有打印机..(将打印机与 google 帐户关联，请访问: https://support.google.com/cloudprint/answer/1686197?hl=en&p=mgmt_classic ) 注意 .addHeader("Authorization", "Bearer"+ token) ，这是请求的重要部分，“token”var是access_token，你 需要添加此授权 header 以使用 API 并且不要忘记在它到期时刷新，如下所述: https://developers.google.com/identity/protocols/OAuth2ForDevices在“ 使用刷新 token ”部分。

就是这样，你现在可以打印一些发送 POST 请求到谷歌云打印 API 的“提交”方法的东西，我建议去这里: https://developers.google.com/cloud-print/docs/appInterfaces并查看所有可用的方法以及如何使用它们(将参数发送给它们等)。当然，在该链接中也解释了“提交”方法。

编辑:

如何发送请求到“/提交”以使用 ION 库和 MJSON 库进行打印的示例 (https://bolerio.github.io/mjson/) MJSON 用于创建 JSON 对象，您可以按照您喜欢的方式创建它

private void printPdf(String pdfPath, String printerId) {
    String url = URLBASE + "submit";
    Ion.with(this)
            .load("POST", url)
            .addHeader("Authorization", "Bearer " + YOUR_ACCESS_TOKEN)
            .setMultipartParameter("printerid", printerId)
            .setMultipartParameter("title", "print test")
            .setMultipartParameter("ticket", getTicket())
            .setMultipartFile("content", "application/pdf", new File(pdfPath))
            .asString()
            .withResponse()
            .setCallback(new FutureCallback<Response<String>>() {
                @Override
                public void onCompleted(Exception e, Response<String> result) {
                    if (e == null) {
                        Log.d(TAG, "PRINTTT CODE: " + result.getHeaders().code() +
                                ", RESPONSE: " + result.getResult());
                        Json j = Json.read(result.getResult());
                        if (j.at("success").asBoolean()) {
                            Toast.makeText(MainActivity.this, "Success", Toast.LENGTH_LONG).show();
                        } else {
                            Toast.makeText(MainActivity.this, "ERROR", Toast.LENGTH_LONG).show();
                        }
                    } else {
                        Toast.makeText(MainActivity.this, "ERROR", Toast.LENGTH_LONG).show();
                        Log.d(TAG, e.toString());
                    }
                }
            });
}

private String getTicket() {
    Json ticket = Json.object();
    Json print = Json.object();
    ticket.set("version", "1.0");

    print.set("vendor_ticket_item", Json.array());
    print.set("color", Json.object("type", "STANDARD_MONOCHROME"));
    print.set("copies", Json.object("copies", 1));

    ticket.set("print", print);
    return ticket.toString();
}